# EVelotaxi?



## KrisWood (Apr 24, 2009)

Ok so I've decided my best bet (until someone responds with better info) is to build a frame inspired by that of the velotaxi (which would not be an exact duplicate by any means), using schematics and photos from existing ones to base mine off of. I'm making a 3D mockup at the moment to figure out where all the parts will go while I gather materials and hunt down a friend that can do the welding.


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## Jason Lattimer (Dec 27, 2008)

You might want to look into Crystalite hub motors. They can be purchased for any size bicycle rims and with 72 to 96 volt controllers they sell they will reach speeds in excess of 50 mph. They just aren't bicycles anymore at that speed.

Anyways, I like your design. I was planning something similar, but I have a tendency to upsize things when I finally get rolling. Look forward to your build. Looks like a cool design. If you want range estimates check out the wiki there are lots of useful tools that will help you calculate speed, range and such.


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## KrisWood (Apr 24, 2009)

After more research I've discovered a few things;

First, a few more photos of the Velotaxi drive train:

http://commons.wikimedia.org/wiki/File:Velotaxi2.jpg
http://commons.wikimedia.org/wiki/File:Velotaxi3.jpg

It also turns out it's an electric vehicle by default, powered by two 12v batteries. This makes the design even more encouraging. Here's an excerpt from the advertising materials from the manufacturer:



> *Everyday convenience and maintenance friendly*
> 
> The "City Cruiser" is tailor-made up to the finest detail: an ergonomic half reclining seat allows for effective power transmission. The 21-gear shift transfers the pressure onto the pedal of the back wheels´ differential gear unit. A contrived steering system enables an extremely small turning radius of the 305 centimeters long "City Cruiser". Hydraulically strengthened disc brakes offer optimal security on the road. A durable textile partition, the seat upholstery and the roof fastened entrance aid offer optimal traveling comfort.
> 
> ...


This gives me some good starting points in my design work. I'm definitely going to have to diverge in terms of body and frame from the Velotaxi, but the general concept of the drive train should work well. 

I'd like to keep costs as low as possible with the project so I'll be using as many recycled and salvaged materials as I can. I also don't know the first thing about welding, would bolting it together work? Hrmmm...

Btw now that I have a better idea of what lies ahead, could one of the mods change the title of the thread to "Velotaxi-inspired E-Ped"?


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## KrisWood (Apr 24, 2009)

How does one determine how powerful a motor and how many of what kind of batteries are needed to get what kind of speed and mileage?


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## Jason Lattimer (Dec 27, 2008)

I just went and searched on www.evalbum.com to compare components and type of vehicles they are used on. You can even search for certain types of components to compare one against another. That way you can get an idea of real world results.


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## KrisWood (Apr 24, 2009)

Thanks for this resource it's great to have a handy reference of what has already been used and works! 

Next question is, I'd like to spend as little as possible and recycle as much as possible. I've got a couple dead / dying cars that I suspect must have at least a few electric motors in them. What types of motors are typically found inside IC cars that could be used for this kind of project? The generator is essentially a DC motor isn't it? The power windows I know are probably worm drive and not terribly powerful. What about the electric fan(s)? What about the starter? I really don't know much about electric motors in general except the basic theory of how they work. How do I tell if a salvaged motor is going to be worth using?


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## Jason Lattimer (Dec 27, 2008)

I am afraid the only useful motor that you will find are the alternator and the starter. The rest are not terribly powerful enough for anything but a slow crawl on a wheelchair. Even at that I don't think the starter or alternator aren't that powerful either. Your best bet is probably the alternator. As far as checking it to see if it is still good, I am not sure. I would probably take it apart and clean the parts inside.


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## Amberwolf (May 29, 2009)

KrisWood said:


> Thanks for this resource it's great to have a handy reference of what has already been used and works!


Also check out the e-bike forums at 
http://endless-sphere.com/forums/
where you'll find all manner of bikes, prebuilt and custom, and drive systems, off the shelf and custom made, including those like my CrazyBike2 built of recycled parts. 



> The generator is essentially a DC motor isn't it? The power windows I know are probably worm drive and not terribly powerful. What about the electric fan(s)? What about the starter? I really don't know much about electric motors in general except the basic theory of how they work. How do I tell if a salvaged motor is going to be worth using?


There are ways to convert some alternators into motors, and there are at least two recent (one ongoing) threads about doing so and the results of this over at ES.

Starters are very momentary duty; they're not designed for sustained operation. Not worth using as a motor, though you could save the copper windings if carefully removed to rewind other motors with. 

I used two brushed pancake radiator fan motors to run DayGlo Avenger MkI's friction drive, and it worked well enough considering that it was all made from junk. Would've been much better as a chain drive but I had no reduction gearing or belts/sprockets available to do it in a small lightweight way, so i went friction drive that got me the best reduction I could. Ran very very hot (would boil water poured on the motors). Don't know it's Wh/mile performance for sure, but not very high, probably about 15-20. I'm sure I could make it better now if I had another pair of them.

Window motors...forget it. I did actually try this as my first experiment, and it does move the bike, if you are not actually *on* the bike. 

If you're anywhere in the Phoenix, AZ area, you can come see my crazy experiment in person (though it is not running just at the moment, undergoing some changes), or I might be able to help with yours. 

Since you know you want 30MPH for 50-100miles, you have an approximate energy need. But to figure out how much you'll actually need, you also want to know if it needs lots of starts and stops, or are you going that speed the whole way in one go, and if it's on the flats or on hills. 

At only 30MPH aero doesn't come into play nearly as much as at higher speeds, but it does make a definite difference. So knowing the shape of the vehicle will help, too. 

A tadpole (two wheels in front) is a more-easily-made-stable shape for aero and for making turns at speed than the delta (two in back) of the Velotaxi, especially for a tall skinny vehicle. The wider the track (pair of wheels) the more stable, up to a point. 


Now another thing you need to consider, if building this to go on the roads. If you are at 30MPH it's not a bicycle in most places, so you would have to most likely register it as a motorcycle or moped depending on local laws, and some laws (like Ohio, I think) don't much like custom vehicles at all, making it nigh impossible to register. 

I keep all my projects at 20MPH max road-operated speeds so that I may keep them as bicycle-class vehicles here in AZ. Some places actually restrict them to not even being *able* to operate them faster than that, at all, but here they just have to be kept at or under that speed (along with the usual "engine size" 49CC or less restriction, which doesn't really apply to electrics, but some places do have a limit of 750w or even less). 

I am working on a few designs for custom cargo trikes, most of which are tadpoles, one of which will be tilting, some of which have full suspension and some which have none. All are expected to be long on the drawing board before they get built, and most probably will never be built. 

Usually I use one of the bikes plus a big trailer to haul stuff, such as up to 5 or 6 40lb bags of dog food, or a couple of the dogs, etc. The cargo trike would just mean only one thing to deal with, less rolling resistance, etc. But possibly worse handling especially in turns at speed. That remains to be seen.
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## Amberwolf (May 29, 2009)

For power, well, the only cheap stuff brand new is lead, and that is pointless to use on a small vehicle if you want range. I've got about 60 pounds of it on CrazyBike2 now, and I only get 15-20 miles max out of it, and that's running them down to 80-90% DOD or more, which greatly reduces their lifespan. I've got old NiMH packs, which are better, but I don't have enough Wh to run CB2 on them. I am still building a big potentially 2KWh pack out of what amount to laptop battery cells, and that will be much better, but requires more monitoring electronics during charge and discharge to keep it (and me) safe, especially since they are "used" and/or aged cells. 

A new pack of LiFePO4 is one of the safest and lightest options, and if you size the pack for significantly more Wh than you will ever actually need, then it doesn't have to have a complex monitoring system (though I would still use one myself). There are also RC heli/car LiPo packs that can be safe to use, and get high Wh in a small light package. Neither of these is a cheap option, but they are better long term than the lead will be even if the lead is "free". 

Another option is finding service centers or other recycling centers that take in old power tool battery packs. Often there is at most one or two cells bad, and sometimes all that is wrong is a fuse or BMS board failed, or even a spot weld broken. Some of these places will *give* you the packs so that they don't have to pay to have them recycled; some will charge very little for them. Building a pack from them can be done in several ways, all of which have multiple examples over on the ES forums.


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## KrisWood (Apr 24, 2009)

Thanks for the replies!

Amberwolf: I've been reading your electricle blog for a few days  my car is a 87 Mercury Sable so the window motors will likely be identical to the ones you tried in the beginning. 

Rewinding a motor sounds very intimidating to me, I'm very right-brained and design comes naturally to me, but the engineering side is definitely NOT my strong point.  Also I'd have to figure out how to convert the alternator to DC current which I wouldn't know the first thing about in the first place either. 

Where are some good places to find junk motors that WOULDN'T need rewinding or conversion? I think for now I'm going to work on designing the frame and accumulate parts as I go along 

Edit: Ok I looked it up, there are less restrictions in Oregon for electric assisted bikes, but they are only allowed to go 20mph maximum, which I suppose I could live with. Mopeds on the contrary can go 35mph but must fit all the qualifications for vehicle safety under USDOT and ODOT laws. Part of the purpose of this is that I'd like to be able to use this as a bike, so I'll be limiting it to 20mph. On the bright side that gives me a number to work with, and I can focus on efficiency rather than speed.



> According to ORS 801.258, an electric assisted bicycle:
> Is designed to be operated on the ground on wheels;
> Has a seat or saddle for use of the rider;
> Is designed to travel with not more than three wheels in contact with the ground;
> ...


It also occurs to me that I could use a motor that can go faster than 20mph but with a controller that switches it off at 20mph. Is 1,000 watts a lot? Hmmm... Also I looked up the farthest place I ever travel to in my car, which is 89 miles. If we figure a max range of 90 miles I'll be happy, even if I have to pedal the last mile.  Around town I'd probably use no more than 10 miles per trip anywhere I go.

Ok on searching online for free stuff it looks like washers / dryers are available frequently, as are garage door openers, vacuum cleaners, and electric lawnmowers. Not sure if any of these would make good donors. Except for the garage door openers which lift considerably more than my weight, I don't think they'd have much torque... Still looking 

Hmmm found a few electric treadmills, those might do the trick.


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## Amberwolf (May 29, 2009)

KrisWood said:


> Amberwolf: I've been reading your electricle blog for a few days  my car is a 87 Mercury Sable so the window motors will likely be identical to the ones you tried in the beginning.


Probably close enough to be unhelpful. 




> Rewinding a motor sounds very intimidating to me, I'm very right-brained and design comes naturally to me, but the engineering side is definitely NOT my strong point.  Also I'd have to figure out how to convert the alternator to DC current which I wouldn't know the first thing about in the first place either.


You don't convert the alternator to DC, but rather just use a brushless DC ebike motor controller or similar to run it. Kelly makes a few that would be suitable for very large brushless motors, based on other projects I've read about. There are ebike-specific controllers that are quite powerful now; some on the order of 10KW or more, and Doctor Bass on ES has run one at 20KW for a short time recently.  At most you'd have to change one of the windings out for permanent magnets, but that is not necessary if you run a separate mini-controller for it, or just power it off a steady DC supply (depending on how you want it to work).




> Where are some good places to find junk motors that WOULDN'T need rewinding or conversion? I think for now I'm going to work on designing the frame and accumulate parts as I go along


The catch is that most of the ones you can find as junk, for free, will need high voltage (100-130VDC), so you need a lot of cells or batteries in series, and typically are pretty high RPM, meaning they'll need a mechanical "gear" reduction using belts, gears, chains, etc. Most of these will be like that:
Treadmill motors
Lawnmower motors
vacuum cleaner motors
drills
saws
etc.
But they can all be run from DC. 

However, if you are willing to get batteries for it to provide that voltage, and use a controller that can handle that voltage, then you could have a motor/controller system that would do a lot of work for you.





> It also occurs to me that I could use a motor that can go faster than 20mph but with a controller that switches it off at 20mph.


This is a common way to do it with ebikes that are commercially made, or even controllers that may be used in such. Some have a little jumper wire in with all the other connectors that you plug together for "Euro speed limiting", which does just what it says. 

Since you will probably want a watt-hour meter to keep track of charge and discharge of your batteries (like a fuel gauge) anyway, then if you get one like the Cycle Analyst at http://ebikes.ca/drainbrain/ then you can use it to limit the speed, by having it monitor wheel RPM and have partial control over the throttle. It's already designed to do this.





> Is 1,000 watts a lot?


Not really. But it depends on how fast you want to go, how fast you want to get to that speed, and how much mass you're trying to move against how much rolling resistance (of the tires), how much wind, etc.

Also there are losses in your drivetrain, so unless they count that as 1000W at the wheel-to-road contact, you lose a few percent in the drivetrain too. Very little with chains, a bit more with typical belts and gears. 




> Hmmm... Also I looked up the farthest place I ever travel to in my car, which is 89 miles. If we figure a max range of 90 miles I'll be happy, even if I have to pedal the last mile.  Around town I'd probably use no more than 10 miles per trip anywhere I go.


Then I recommend having two battery packs. One short range, and one long range. Since the LR will be at least 10 times heavier than the SR pack, it's not worth carrying it unless you know you'll need it. 

On a bicycle-class vehicle, you're not going to want to carry lead for that range. I have 50-60 pounds of lead on CrazyBike2, and I can't get 20 miles out of it at any great speed unless I'm pedalling hard a lot of the time. So you'd need at least 250-300lbs of lead for yours, and probably significantly more, because every pound of lead you add beyond some percentage of your pre-battery vehicle weight is going to take more power to move than the previous pounds, and at some point you'll get *less* range out of it than with a smaller pack because of the pack weight plus all the structure you'd have to add to support it.

CB2 weighs with rider and typical cargo about 350lbs. CB2 has about 884Wh in the 60lbs of 4 x 17Ah 12V SLAs, but that's assuming 100% DOD which would destroy them. 50% DOD is 442Wh. It takes 30-35Wh/mile to move the thing, so...best case 14.73 miles, at average 15-17MPH speeds with lots of starts and stops, and average pedalling. Average/worse case is 12.62 miles. 

If I had instead the LiCo pack I'm building, in theory it should have around 2200Wh, at only about 30lbs. Even if I limit it to the same 50% DOD, that's still 1100Wh, which means it has nearly three times the usable power at only half the weight. Typically it should be possible to limit the LiCo to 60 or 75% DOD, giving even more range. 

SInce the bike would be about 30lbs lighter, it will probably knock about 3Wh off the 30-35Wh/mile, bringing it down to 27-32Wh/mile. That means best case range could be 40.74 miles, and average/worse 34.38 miles. That's still assuming only 50% DOD. Using 75% DOD, that becomes 61.11 miles and 51.56 miles. 

So there is a comparison for you on the difference between one possible lead-sled problem, vs a lithium battery solution. Numbers could end up different for the LiCo, because they're not typically made for EV use, but they can handle it if sufficiently parallled. 

I have some 10 Thundersky 60Ah cells I'm working on getting, and those will not be quite as good: 1980Wh total, 990Wh at 50% DOD, 1485Wh at 75% DOD. It'll weigh the same as my lead, 60lbs or so. 49.5 miles best, down to 42.43 miles worst. 




> Ok on searching online for free stuff it looks like washers / dryers are available frequently, as are garage door openers, vacuum cleaners, and electric lawnmowers. Not sure if any of these would make good donors. Except for the garage door openers which lift considerably more than my weight, I don't think they'd have much torque... Still looking


GDO motors are usually geared worm drives like your power windows.  So ar winch motors.

Fisher and Paykel make a washing machine that uses a large brushless DC motor, which has already been successfully used in a larger-than-ebike class trike, by F&P over on the ES forums. But most of the dryer and washer motors are AC induction motors. You could use them but you'd have to provide high-current high-voltage AC. Not easily practical on an ebike. 

Before you go looking for motors, you should decide if you're going to use lead or not. Then design the vehicle, at least the basic idea, and figure out how much that is going to weigh. That will narrow down your motor choices, probably. 

You can always use multiple motors, but it is a lot less efficient to do that. At that point, you are now carrying around the weight of another whole motor for only a portion of extra power; a motor that can do twice the work of another motor will probably not weigh anything like twice what the other motor does.  Plus you now have the extra weight of another controller, and another transmission, or part of one.
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## KrisWood (Apr 24, 2009)

Thanks for all the info, this gives me much more solid numbers to plunk around with during this design phase! 

Ok so 89 miles is not going to work at least in this first version, that greatly simplifies the design requirements!

My average running around town is 10 miles round trip, but if I want to go downtown and back I'd better double that, so let's say 20 to 25 miles would be ideal. I cannot go over 20mph and cannot exceed 1000w power output, and that seems to be at the motor as far as I can tell? I don't want to buy anything at all if I can help it, though I know some things will be unavoidable.  I'd like to keep weight as low as possible for during pedaling. Your comment in the blog about regeneration not being worth it on CB2 decided me on going brushless. I intend to add two 12v solar panels to this eventually and that should generate more than regeneration ever would. I have until my car dies which could be days or years at the current rate, so no particular hurry and I don't mind working on it as I find new parts.

So, that gives us the following design goals:

* Keep cost, weight, and complexity to a minimum, recycling as much as possible
* Max Motorized Speed: 20mph (the law says nothing about pedaling being added to that hrmmm)
* Max Distance: 20 miles (This gives a maximum constant run time of 1hr)
* Power Source: 24v DC
* Max Power Output at Motor: 1000w (This gives me a limit of 1kw/hr output?)
* Weight: ~30lbs
* Max Weight Burden: 300lbs (I'll very rarely if ever exceed this, I weigh about 165lbs myself)

Now to figure out what I need to work with to get this  I don't mind starting out with 2 12v SLA batteries and upgrading to lighter weight / more efficient batteries as time goes on, and don't expect to hit all targets with SLA.


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## KrisWood (Apr 24, 2009)

Here's the drive train as I'm envisioning it so far. The orange represents the pedal chain, the blue represents the combined pedal and motor chain. The green chain connects the motor to the drive combined drive axle. In the velotaxis they've got a direct drive on the rear axle, with the pedals attaching to I think a freewheel to keep the motor from turning the pedals. This probably won't work for my project for two reasons:

First, I'm unlikely to find a motor that will be suitable for that setup.

Second, I would like to be able to pedal without turning the motor at all.

For this I will need to combine the pedal and motor drives through a third chain to the rear wheels. I'm thinking this should go immediately under or behind the seat and would like to keep it as close to and slightly below the center of gravity as possible.

The batteries will likely go below the rear seats / cargo area, also below the center of gravity toward the rear.

I'd like to add also that with my current 21 speed mountain bike I don't use more than about 3 gears anyway, the lowest, middle, and highest of the rear gears. The front shifter is extremely inaccurate and difficult to shift without knocking the chain off altogether, otherwise I'd probably just use the front gears and leave the back alone. Because of this I suspect I'll go with very few gears in this trike to keep things as simple as possible, either only one in front and three in back, or more likely three in front and one (with no rear derailer) in back.


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## Amberwolf (May 29, 2009)

KrisWood said:


> Your comment in the blog about regeneration not being worth it on CB2 decided me on going brushless.


You can do regen with brushless (BLDC) as well, as long as the controller supports it. 

The only real reason regen is not being done on CB2 is because I would need to build a clutch system that allows me to engage the motor when I am either accelerating/maintaining speed with the motor or when I am braking, and have it switch automatically to both of those. Then when I am just coasting, have it disconnect the motor from the drivetrain. 

It's possible, with a dog-clutch type system that has a neutral and an engaged position. I just don't have the ability to build such a thing right now, and cost to buy the parts is too high. 

If coasting weren't such a high priority on our flat streets to save energy, I would not worry about it, and I'd just do the regen for braking ability alone, even if I did not care about recovering the power (which I also do want to do).

So...regen can be worth it depending on:
--Where you ride/drive: if it is all flat and you don't have to stop/start very often (not riding in traffic, you'll probably not use it enough to be worth the drivetrain complications. But if it is really hilly, or you stop/start a lot, like I do, it could be worth it.
--Your ability/desire to make some sort of clutch for the motor that engages only during motor use or braking. 
--Or, your desire for coasting ability. 




> I intend to add two 12v solar panels to this eventually and that should generate more than regeneration ever would. I have until my car dies which could be days or years at the current rate, so no particular hurry and I don't mind working on it as I find new parts.


Solar panels are probably not really a good idea to carry onboard, unless you get really efficient large-surface-area ones, or also carry mirror arrays to focus on them and potentially a suntracker. You're almost certainly better off just carrying more battery of the same weight. Probably would cost less, too.  Use the solar at a fixed-point recharging station, at home or at work, etc. 

The thing is that the extra Wh/mile you use up carrying their weight and fighting their aero drag probably won't be made up for by the sunlight they collect, even down here in AZ. 

If they are not big heavy panels, but rather just cells you've placed wherever was convenient, it could be efficient enough to be worth it, but they'll also be more fragile than in well-made panels. 

To see if it is worth it, you'd need to run the numbers on the actual panels you want to use in a test in your location/environment to see what power they actually generate. Then you'd need to know what Wh/mile the vehicle gets, preferably per-pound, so you can guesstimate how much more power per mile it'll take to carry those panels, and then see if the equation comes up higher on the correct side. 

Also, you'll need a lot more than 24V worth of panels to recharge higher voltage battery packs, unless you are using that to run an automotive "inverter" to then run your regular wall-powered charger off of. If you do that, then because of inefficiencies in the inverter and charger you are almost certainly not going to get enough power from solar panels you can carry on a bicycle-class vehicle to make it worth carrying them, for the purposes you sound like you're going to use it for.





> * Max Motorized Speed: 20mph (the law says nothing about pedaling being added to that hrmmm)


If it is like AZ law, it will say something like "is a bicycle when *operated at or less than* 20MPH, and thus if you use it faster than that while the motor is running, you're no longer just a bicycle and are now an unlicensed/unregistered moped or motorcycle, with all the potential legal issues that brings, depending on how the police that see you feel about it. 

Realistically, as long as you are obeying traffic laws and being safe, I'd bet that no one will care. YMMV.  

California laws are even more specific. Don't know about yours. There may be local ebike or bike clubs that even have websites pointing out the specific limits and how they have been interpreted there. Here there is a site http://azbikelaw.org that is quite helpful.



> * Power Source: 24v DC


This I highly recommend you at least double. Almost nothing you're going to find to recycle will operate all that well at 24V, but some will at 48V. Also, generally the higher voltage you go with, the less average current draw you need to make to have the same power output. This is easier on your batteries, makes for smaller wires, connectors, switches, relays, etc, and makes parts generally easier to find. 




> * Weight: ~30lbs


For what part? The bike? I'll have to say that is very optimistic.  I have some very cheaply made bikes that are just plain bikes that weigh nearly that much with nothing on them except what came with them, not including any motors or even just adding lights! 

I'd say you can expect any trike to weigh from 80 to 150lbs, *before* batteries are added, especially if you use lead (SLA, etc). Possibly before adding the motor and stuff, too, depending on what kind you end up with.

CB2 by itself without the 4 SLA on there weighs almost 110lbs, and I started out with two of the lightest bikes I had, of the strongest metal (cromoly). 



> Now to figure out what I need to work with to get this  I don't mind starting out with 2 12v SLA batteries and upgrading to lighter weight / more efficient batteries as time goes on, and don't expect to hit all targets with SLA.


You can do a lot with SLA, but you will probably need to go to more than two of them in series, at least 48V, to be able to get the kind of power you'll need without quickly draining or killing them, or else using humongously heavy high-Ah batteries. 

SLA have a high loss to what is called Peukert effect. Basically means the faster you pull out the power, the less of it you get in total. Remember where I show above only basically getting half the power of the batteries out? Well, if I was only using 24V, I'd probably only be able to take out 1/3, maybe less, possibly only 1/4! 

I originally used two 12V 31Ah batteries for 24V on the first long run for CB2. I also had a smaller motor of only maybe 350W instead of the 650W that's on there now. Including about a 2 hour rest in the middle, and pedalling HARD for the last few miles, and bringing those batteries down to dangerously low levels (probably 80 or 90% DOD), I got 22 miles or so. Theoretically I had 744Wh to work with. At what might've been only an average (due to mostly me doing the work the last few miles) of 20-25Wh/mile, I ought to have gotten at least 30 miles, but due to having to supply a lot more current to get the same power output, I only got about 2/3 of what I could have for that DOD.

Even just using 36V would not just add 1/3 to my range, it could potentially double it, depending on how much Peukert losses there still are, how much extra power it takes to haul the extra battery weight, etc. 

So using 36V of only 17Ah batteries, weighing not a lot more than the 24V 31Ah, I could get more range, with less stress on the batteries. If I killed the batteries dead like I did with the 31Ah, I could probably get the same out of it. 48V I know I could get even more. Since I use a motor that takes more power (but accelerates lots better) then I don't actually get more range out of it, but I would if I used the smaller motor. 

So...nothing wrong with trying SLA, since it is available for free or almost free if you look around for old UPS or wheelchair/powerchair batteries (ask places that fix these...they might give them to you just so they don't have to pay to recycle them). Just keep it's limitations in mind, and be efficient with it. 
________


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## KrisWood (Apr 24, 2009)

30lbs was for the trike frame itself, I didn't think to include the rest >.< thank you for the reality check  I think my current mountain bike is about 25lbs without me on it, but it's not really suitable for this kind of project and I don't really want to cut up my only functional bike anyway. 

As quoted from the Oregon DOT website earlier in the thread:



> Is equipped with an electric motor that has a power output of not more than 1,000 watts and is incapable of propelling the vehicle at a speed of greater than 20 miles per hour on level ground.


I would interpret this to be on motor power alone. Nothing there about cutting the motor at 20mph and being on pedal power alone past that point.  Still, police may take a dim view of such "grey area" interpretations of the law.

Do Peukert losses effect other battery types? I shudder to think what four 12v SLA would weigh if I run out of power and have to pedal home.

For solar panels I am planning on building the solar cells into a fuselage around the trike. They would have a protective plexiglass (or similar clear durable material) shell over them so they are not damaged during use, and individual cells do not weigh terribly much. The hard part would be fabricating the fuselage itself. This step is so far in the future though that it's not really worth worrying about for now. I'll be happy if I can even pedal this thing in the next few months without a motor or power assist of any sort. 

As may already be guessed, I live in Oregon. It's very wet here and very hilly. Climbing hills with any kind of motor resistance is not going to be fun, I'd need a clutch of some sort and cannot afford that right now. The freewheel approach should be buildable from recycled bicycles and should be free or very near it, just a matter of waiting for the right parts to come along. At least Portland is a fairly large city so it shouldn't be too terribly difficult to get recycled parts. 

By the way, does my drive train image above look workable?


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## Amberwolf (May 29, 2009)

KrisWood said:


> 30lbs was for the trike frame itself, I didn't think to include the rest >.< thank you for the reality check  I think my current mountain bike is about 25lbs without me on it, but it's not really suitable for this kind of project and I don't really want to cut up my only functional bike anyway.


Yeah, all the stuff I used for CB2 came from a bike shop's trash pile; I asked if he had any junk for cheap and he said Hmmm, we went out back, and he said I could take whatever I wanted since it was trash to him, stuff people had donated or abandoned. I called a friend with a truck and.... 

Freecycle.org has bikes on it in various condition all the time for free. sign up for your area's lists and keep an eye out.  Respond quickly when you see them!




> I would interpret this to be on motor power alone. Nothing there about cutting the motor at 20mph and being on pedal power alone past that point. Still, police may take a dim view of such "grey area" interpretations of the law.


That's pretty much what I *think* the CA law says. So you should be fine as long as the motor is not running at all if you are over 20MPH, and if you can demonstrate to the officer that it is not possible to get the motor to operate faster than that, if they even bother to stop you. If you're within the actual road speed limits and are not going faster than what most people consider safe on a bike I doubt they'll care. Go 40 on it and they'd probably stop you for being reckless and endangering yourself anyway. :lol:





> Do Peukert losses effect other battery types? I shudder to think what four 12v SLA would weigh if I run out of power and have to pedal home.


I have done that. It sucks. 

Peukert affects all forms of chemical energy storage, but of all the common ones only lead is that bad. NiCd, NiMH, and lithium are all much better. If you're willing to read thru the many threads on ES about it, and build your own pack from cells, you can recycle used powertool batteries for next to nothing, just discarding the bad cells. If you have more time than money this is a cost-effective way to get a lithium pack.  It's been done by many on ES. I'm working on a similar type of pack build, except I bought mine already harvested, just for really really cheap. 



> protective plexiglass (or similar clear durable material)


That's gonna be heavy. Even if it's thin. If it's thin enough to flex, you either have to build standoffs under it around the cells so it can't impact them when being pressed by people leaning on it/etc, or leave a big air gap so it can flex inward without impacting. 

If the cells are not pointed at the sun, they don't get as much energy. Even just a little bit off-center generates a fair bit less power. That's an experiment you can check with a bright LED flashlight and a solar calculator. 




> I'll be happy if I can even pedal this thing in the next few months without a motor or power assist of any sort.


That's what I said when I started building CB2, and I built it a lot faster than I expected, but ended up with a lot of major flaws in the design tha thave come back to haunt me. 




> As may already be guessed, I live in Oregon. It's very wet here and very hilly.


It is also probably not sunny all the time, so solar doesn't work as well as here in the desert. I've looked into solar as range extender from time to time, but so far unless I had a bundle of money for "amorphous" cells that contour fit whatever I'm doing and aren't fragile, there's no good way to use them on a small vehicle like a bike. Just takes too much power to move them relative to what the vehicle can carry vs what they give back during a typical ride. 

If I was going on a crosscountry trip or something, then they would be invaluable even if heavy, because I could recharge even in the middle of the desert.  Just takes a long time. 




> Climbing hills with any kind of motor resistance is not going to be fun, I'd need a clutch of some sort and cannot afford that right now. The freewheel approach should be buildable from recycled bicycles and should be free or very near it, just a matter of waiting for the right parts to come along. At least Portland is a fairly large city so it shouldn't be too terribly difficult to get recycled parts.


If you put a freewheel on the motor and on the pedals, you don't have resistance from either one to either one, and both freely drive the wheels.

I don't have that on CB2 only because I had no way to implement it with the skills and stuff I had avaialble. but someone on ES is fixing that for me.  I did try a few ways but I kept destroying them with the power thru them, so I had given up on freewheels until now. 


> By the way, does my drive train image above look workable?


Basically yes. The one thing that makes an integrated pedal & motor drivetrain good in a bike is that you can go thru a regular fully shiftable bike drivetrain, like I do in CB2. There are commercial setups like StokeMonkey and Cyclone that do this; I did it differently because of what I had but it does the same thing.


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## KrisWood (Apr 24, 2009)

I found a free working treadmill on craigslist. According to the manual it's a continuous 2.9hp motor (doesn't say what the electrical specs are) that comes in two variations, one with a flywheel and one without. Is it worth going and picking it up? hmmm...

Found some photos of the motor, it's 130V DC, permanent magnet, 6000rpm

Oh screw it I'm gonna go pick it up if it'll fit in my station wagon lol.

Edit: Doh, someone got to it faster than I did! And here I thought 9:30am might be too early for my fellow scavengers!


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## Amberwolf (May 29, 2009)

It's never too early; there are people like me that work late and thus are up till dawn instead of waking up then, and so they see some of these things and nab them.  

Treadmills if in working condition can go for enough money to be worth picking up and reselling on CL again. So even if you can't use the motor that's in it, someone else can use the treadmill itself as a whole thing, or sometimes they buy them for parts for others or their own projects like yours, for the non-working treadmills. THat can make them worth picking up when they show up. 

I got one from Freecycle oh, a couple years ago, and have used a number of parts from it for things. The motor itself was the first motor to power CrazyBike2 on successful bench tests, but because of certain mounting issues I wanted to solve without welding, I ended up using a powerchair motor instead. So it was never road tested. Probably will try it out on a different bike idea at some point, since I built a reduction system for it. It's somewhere in the blog.

Another thing I might use it for is finer control of speed on my lathe (which also came from Freecycle). Take the electronics from the treadmill and use them to control the motor off of AC power just like it was designed to be, with a v-pulley grubscrewed onto the shaft instead of the flywheel/pulley.


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## KrisWood (Apr 24, 2009)

Yup, I read that part of your blog yesterday  The drive train in CB2 is actually very close to what I had originally envisioned. I'll just have to be more quick to react to these ads 

It also occurred to me that really the motor should be one of the last parts I do, because what motor I can use is really determined by the batteries and the controller. When I know my electrical specs any motor within the range of those specs will do as long as it's able to deliver enough torque. It'd also help me decide which kinds of motors to keep an eye out for instead of just scooping up scrap parts I don't need. Then again mounting issues can be avoided if I get the motor and batteries first, and develop the body to fit their dimensions instead of the other way around hmmm...


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## Amberwolf (May 29, 2009)

KrisWood said:


> It also occurred to me that really the motor should be one of the last parts I do, because what motor I can use is really determined by the batteries and the controller.


Well, sort of. Ideally you do it sort of the other way around. Design the vehicle with a range/speed/environment goal in mind, with a place for enough actual usable Wh to do that, of whatever battery you are going to use. (preferably use twice the Wh you think you need, so you have it if you need it later and never risk running the pack too dead).

Then pick a motor that can do the work of moving that at your desired speed 
in that environment. 

Then pick a controller that can run that motor at the power level it needs plus a little overhead for wiggle room. 

Then pick the actual batteries to deliver that Wh, which can be more smaller cells for a higher voltage at a lower current, or fewer bigger cells for a lower voltage at a higher current. 


Note that this is not how I usually do it, because I'm happy when I get the thing to pull me around on the road and not fall apart.  And I really just try to use whatever junk I already have, rather than hunting down specific things to do the job the right way. 



> When I know my electrical specs any motor within the range of those specs will do as long as it's able to deliver enough torque.


Power is actually the word you're looking for there, rather than torque. Only because you can change the amount of torque any motor provides by changing the "gear ratio" from it to the wheel, which will decrease the speed to increase the torque and vice-versa, but both deliver the same power. 



> It'd also help me decide which kinds of motors to keep an eye out for instead of just scooping up scrap parts I don't need. Then again mounting issues can be avoided if I get the motor and batteries first, and develop the body to fit their dimensions instead of the other way around hmmm...


Mounting issues can be worked around even with a specific body design in mind, as you can always modify the design a bit to accomodate them. It's not maybe as neat a process, but this way you can build at least a basic body to test it's pedalability and handling, to make sure the design is functionally sound and safe at the speeds you want.


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## KrisWood (Apr 24, 2009)

It seems fate has forced my hand. My 87 Sable Wagon died today, I think the engine seized up from lack of oil (it's had a bad leak since I bought it back in November). While trying to get it started up again I noticed that the radiator fan (which is the large chunky metal kind) I had assumed to be driven by the crankshaft was actually powered by a rather sturdy looking though compact 12v motor with a fairly heavy shaft. It didn't say if it was DC or not but I've got a good feeling that it might be. I'll have a better idea once I've got it off the car.

It turns out that my car was carrying her ID in her wallet, and she's an anatomical donor!  I think I'll name my prototype Sable in honor of her noble sacrifice.

I'm going to rework my plans a bit, take an inventory of parts that look like they can be easily liberated from the car, and post a new project thread once I have a better idea of what I'm doing. I think it'll still be similar to what I'd planned on originally but the purpose of the current thread was to gather information, rather than to be an actual project thread, so I'd rather start fresh and include every step of the way as I go along (and there will be a LOT of steps). Wish me luck, and stay tuned!

Edit: I looked up solar cells again. They weigh about 8 grams each and produce 0.5v in optimal sunlight conditions. This means ~56.7 solar panels per pound. They are not a serious weight consideration. The real weight would be in body work to support and protect them. If the entire body is constructed of solar panels let's figure about 8 sq ft of useable space, at 3"x6" that's the equivalent of four rows of sixteen cells, for a total of 64 cells producing a maximum potential power output (which would never happen since the body is three dimensional and the cells would never be all on one side) of 32 volts weighing in at 1lb 2oz total.I think this sounds doable if a suitable protective shell could be produced (something I'd like anyway because it'd help keep me dry hehehe). I'd be happy if it even puts ~12v steadily into my batteries during a slightly overcast day. 

Checklist at the moment:

* Learn some basic electrical theory so I know what all the technical terms mean
* Take inventory of easily recoverable parts from the donor (Igor, fetch me some brains!)
* Redesign the trike to take the available materials into account
* Make or obtain tools to build this thing with. (a shopping list would be handy here though I don't intend to spend any money on tools if I can help it, my birthday comes up in a week and my parents are asking what I want this year hehehe)
* Make a new parts list based on the new design
* Start gathering dead bikes and putting this thing together!

I think my wishlist for the birthday will be a car battery charger, whatever that thing that measures electrical current is, and/or maybe a soldering iron.


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## KrisWood (Apr 24, 2009)

Good news! I found a source for batteries. On the way home today I stopped at a local service center that repairs appliances and power tools. At first they were a bit wary, and said they have no extra stuff, but when I said what it was for they softened up and became more helpful. They do indeed have used batteries that they discard, though they give them to a recycler on a regular basis. Still they said they often have them laying around waiting to be recycled, and if I check back occasionally they can see what they've got and I can have it if I want it. They would have checked while I was there but I had no way to transport them today so told them I'd just call them later.

I also passed a house that had a bunch of garbage bags and boxes out front, and a large pile of electric motors of all shapes and sizes. Unfortunately the resident said it wasn't garbage and he needed to keep them. Ah well, can't always be lucky!


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## KrisWood (Apr 24, 2009)

Silly question here while I'm trying to wrap my head around volts, amps, and watts to understand how many batteries I'll need of which types and how long they'll last. To simplify the equation I'm using things I'm familiar with in every day life.

1 AA NiMH rechargeable battery that I use for my camera holds a 1.2V charge for 2500mAh of continuous use. That's 2.5Ah.

Using a 12V motor, how do I tell how long it will last using 40 of these batteries with a potential voltage of 48V? Do I need to know the amps or watts of the motor first?

Maybe I'm understanding the whole concept wrong hmmm...


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## KrisWood (Apr 24, 2009)

I finally got ahold of one of my bike fixing friends and we figured out a way to do this with an extremely simple frame design:

The front half of the frame is a 20" bmx, with possibly a 24" front fork. The rear frame is the bottom of a shopping cart, bolted to the rear chainstays of the bmx frame. The rear dropout holds the axle for the pedal freewheel, motor freewheel, and the drive sprocket for the chain to the rear axle.

Between the two of us we've got all the parts needed for a prototype, minus the shopping cart which we'll have to salvage from somewhere. I'm hoping to get started on actual construction next week


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## Amberwolf (May 29, 2009)

KrisWood said:


> 1 AA NiMH rechargeable battery that I use for my camera holds a 1.2V charge for 2500mAh of continuous use. That's 2.5Ah.


True. This means that it can put out (in theory) 1.2V at 2.5A for 1 hour. 

But...

Remember also that it is 2.5Ah at a specific rate, called the C-rate. Meaning, Capacity rate, or how fast you can drain it without damaging it or a few other things. 

Capacity=2.5Ah, so C rate of 1C=2.5A (since it doesn't measure time). 2C would be 5A, 0.5C would be 1.25A, and so on. 

Most little batteries like that can't supply that much current that fast and still give you the full amount of power, though, so in reality that 1.2V at 2.5A wouldn't last an hour, it would probably last about 15-30 minutes.  

Also, most of those NiMH cells in D, C, AA and AAA sizes are rated in Ah for something like 0.01C or less, meaning you might be able to draw enough current from them to light up an LED and still get their rated capacity. Some of them even in a high power flashlight might only get 1/10 of their capacity! Since they don't tell you at what C-rate that Ah capacity is for, it's not exactly a scam, since it is actually possible to get the rated capacity at some small drain level, but it isn't helpfully representative of what the battery is useful for. 

Typically, physically larger cells or batteries (groups of cells) can supply more current for more time. Exceptions to this everywhere, but a rule of thumb nonetheless.





> Using a 12V motor, how do I tell how long it will last using 40 of these batteries with a potential voltage of 48V? Do I need to know the amps or watts of the motor first?


Sort of. First you need to do a little more math (I hate math). You have 40 1.2V cells (in series, I assume). That means you have 40 x 1.2V = 48V nominal (voltage under rated load). Since there is only one stack of cells, it's what is called 1p, or 1 parallel string, so you have still only the same 2.5Ah that each cell is capable of. (if you used 2p, or two parallel strings of 40, you'd have 5Ah, and also capable of twice the C-rating). 

To find out how much power capacity that pack actually has, you multiply V x Ah, or 48 x 2.5 = 120Wh. That's 120 watt-hours, because it could supply 120 watts for one hour, or 60 watts for two hours, etc. If the cells are rated 2C then you could even get 240W for half an hour. 

But the faster you draw power out of the cells, the less total power you get. In reality, if you tried to draw 60W for two hours, you might actually get 100Wh total. If you try to draw 240W for half an hour, you might get only 180W total, depending on the cell specs and capabilities. (numbers are speculation)

If you put several parallel strings of the cells together, you could get much more total power capacity *and* much higher available current draw. But it is larger and weighs more and is more complex. (plus certain types of cells like NiCD and NiMH don't parallel well for various reasons). 


So, now you have 120Wh of capacity. How much power does the motor draw? Knowing that it was designed for 12V only tells you that you are going to run it at 4x it's rated voltage, which doesn't say too much about how much power it will need. It *is* likely that it will take significantly more power than it shows on it's label, because it'll still take the same amount of current (at least) but it will now also be at a higher voltage.

Total power is still V x A = W. 

Let's just say it's like my radiator fan motors. They draw maybe 10A under load, each, as a friction drive on my old DayGlo Avenger drive at 36V. At 48V that'd be 48 x 10 = 480W. (which might melt them if they're not ventilated and at least air cooled) 

Your "pack" of 40 cells only has 120Wh, so even if you discharged it till it was totally dead (which might damage it) you could only run the motor for an optimistic 15 minutes. 120Wh / 480W = 0.25h

Probably the current draw being 4C would make that more like 5-10 minutes at best, and I'd go for the really short side of that with AA cells. 

Now, all of this so far assumes 100% depth of discharge, or DOD. If you do that, you'll probably damage the cells, with any chemistry or type of battery. So mostly people say to go no further than 50% to 80% DOD. That means in reality you'd only have 120Wh x 80% = 96Wh that you can actually use. Many controllers or other systems on EVs and bikes have a Low Voltage Cutoff or LVC to prevent total discharge of a battery, so it doesn't get damaged by running it down too far. It can be annoying to know you have more power in that battery than you can ever realistically take out, unless it's the last time you need to use it.  Realistically you could keep using it at 100% DOD for a while, but it will become less and less capable, rapidly in some cases, and certain types of battery are not all that safe to recharge after you do this (like LiCo, the kind in laptops and stuff, and what I have here to build my pack from eventually)




One more factor, called Wh/mile. This means how much power your vehicle as a whole draws to move it down the road. If your trike ends up very heavy, like in the 100-150lb range, plus another 150-175lbs for passenger/cargo, it'll probably take you 25-40Wh/mile to move it down a level road with normal frequent traffic stops at 15-20MPH, based on my CrazyBike2 results so far. Wh/mile is a variable figure, because it depends on a lot of factors that can change from ride to ride. Wind, average vehicle speed, weight, rolling resistance of tires, slope of roads travelled, etc. 


Let say you use something more reasonable (than a pack of AA cells) for a bicycle battery but still NiMH to keep the comparison the same, like my DayGlo Avenger currently uses. It's got a pack made of 9Ah NiMH D cells, probably by Sanforce (i think) that makes decent to good ones for high-C-rate use. There are 36V worth of them, which has a total nominal power capacity of 324Wh. Realistically I can only expect to get 260Wh out of that at best. 

DGA tends to take around 10Wh/mile, toodling around with just me and no cargo on level roads with typical traffic stops, doing some pedalling (maybe half my unassisted effort, if that), at about 13-15MPH. Usually the current draw is around 8-17A, or 1-2C. 

So in theory, I could get about 26 miles on that pack. In reality it usually works out more like 15, because this pack is old, and because it's actual capacity has declined as it aged, as well as that at the 1 or 2C rate I'm pulling power from it, it couldn't deliver it's full total capacity anyway. 


Hopefully all that makes some sense, and doesn't ramble too much. 
________


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## KrisWood (Apr 24, 2009)

Wow, lots of information, thanks! I would never actually use 40 AA NiMH batteries, if for no other reason that they'd be very cost prohibitive, but it was a battery I had close at hand to grab numbers from.  For my prototype I'll be using my car's battery to start with (it's almost new so hopefully still in good condition).

The first prototype has a target goal of 5mph (unassisted by pedaling) with a pedal assisted maximum range of 5 miles. I think we should be able to do this with the radiator fan and the car battery.  After that we'll have a much better idea of what to expect from a motor and batteries, and will have a frame and drive train to switch them out on to try different combinations while working on Prototype 2.

The best part is we've found free recycled sources for just about everything now, and will only need to pay for LEDs and the controller.

On that note, what exactly IS the controller and how does it work? Are there controllers in my car that we could use?


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## Amberwolf (May 29, 2009)

KrisWood said:


> For my prototype I'll be using my car's battery to start with (it's almost new so hopefully still in good condition).


Given it's weight vs the power you'll get out of it, you'd be much better off looking for used powerchair batteries. They are meant to be deep cycled. Car batteries are not, and will last a very few cycles that way.  Plus theyr'e really heavy, and if they break you get acid all over, which can corrode things in places you didn't even realize it got into. 

If you can't get used powerchair batteries free, look for datacenters or computer repair places that service or have larger 24V or 48V UPS units. It's not uncommon to replace the whole battery pack in those even though only one of them is actually failed--the others are aged at least a few months to a couple of years, and might fail too. SInce the UPS must be reliable...you can get free batteries. Or at least really cheap. If they have to pay a recycling fee to get rid of them then they will rpobably give them to you so they don't have to do that. 


IF it's all you've got, go for it. I collected used car batteries just for this purpose for a while, but ended up not having to use them, fortunately, as I was donated some used powerchair batteries and then a dead UPS full of them, etc. 

If you can find lots of actually dead or unusable (to you) lead-acid batteries, there is probably at least one place where you live that recycles them and pays money for them. Might not be much for one, but enough of them would net you money for smaller more powerful batteries. 



> The best part is we've found free recycled sources for just about everything now, and will only need to pay for LEDs and the controller.


LEDs for what? If it's for indicators and such, just pull them out of broken or discarded electronics.  



> On that note, what exactly IS the controller and how does it work? Are there controllers in my car that we could use?


Probably not. there probably is a cotnroller or two somewhere, but it is likely integrated into a system that requires the car computer to tell it what to do. Hacking that might be interesting and fun, but not quickly productive, unless you have significant reverse-engineering skills and electronics knowledge already. 

All the motor controllers do is chop up the power into little slices based on the throttle input. If you set it to full throttle it supplies full power instead of chopping it. At half throttle it turns power off half the time, and the other half at full. At 1/4 throttle it turns it off 3/4 time, on 1/4, and so on. Imagine someone flipping the power switch on and off really fast, and holding it on for different percentages of time for different speeds. That's essentially what it does.

You can build one yourself but by the time you get done blowing up parts learning what not to do, then unless like me you got them all out of other "dead" electronics you will pay much more for all the blown parts than just buying one off the shelf, even brand new.


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## KrisWood (Apr 24, 2009)

For now the car battery is all I have, and I don't even have a way to charge it >.< I'm not TOO terribly worried about it though, as this first prototype is more a proof of concept than something that will get ridden every day. It'll be put together, then taken apart and put together a bit better as new parts come in. 

As I mentioned a few posts earlier, I found a service center that fixes appliances and power tools that says I can have their old batteries that are headed for recycling, just a matter of waiting and collecting the right kinds. Of course I'll still have to figure out how to charge them. >.<

The LEDs are for the turn signals and headlights, I'll need bright ones for those, but Harbour Freight often gives away free LED flashlights with any purchase so will just have to keep my eyes on their ads in the paper.

What can I get a controller out of that will work? Couldn't I just use an analog switch / potentiometer (for example a dimmer)?


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## Amberwolf (May 29, 2009)

KrisWood said:


> As I mentioned a few posts earlier, I found a service center that fixes appliances and power tools that says I can have their old batteries that are headed for recycling, just a matter of waiting and collecting the right kinds. Of course I'll still have to figure out how to charge them. >.<


For that, go look at the various toolpack threads on Endless Sphere.  Several good solutions.



> The LEDs are for the turn signals and headlights, I'll need bright ones for those, but Harbour Freight often gives away free LED flashlights with any purchase so will just have to keep my eyes on their ads in the paper.


For everything except the headlight, go find motorcycle/scooter shops or junkyards and see if they'll give or sell cheap the cracked ones they pull off vehicles they're repairing. I just got some like that for my DayGlo Avenger and kennel trailer:
http://endless-sphere.com/forums/viewtopic.php?f=2&t=18671
http://endless-sphere.com/forums/viewtopic.php?f=2&t=15570 (toward current end of thread)
WAY WAY cheaper than building out of individual LEDs or cannibalizing flashlights, both of which I have also done. 

Then you can use the flashlights in a big cluster as a headlight. FWIW, there are some good deals on http://ledshoppe.com but there's no way to know how bright they really are until you get them. Stuff that uses Cree LEDs you can lookup the LED itself on CandlePowerForums and find out info and beamshots, etc. Anything else, well, it's a guessing game. 

If the headlight is for you to see by, try to stick to flashlights that have a single very bright LED and good focusing optics. If it's just to be seen by others, then multi-LED lights work better as they usually have a larger surface area (but are poorly focused and don't throw a beam far enough to be useful).



> What can I get a controller out of that will work? Couldn't I just use an analog switch / potentiometer (for example a dimmer)?


A pot(entiometer) can be used to set a controller's output, but unless you use a VERY large wirewound pot, like for stage light dimming, you'll destroy the pot with the currents necessary to drive a motor.  Those stage light pots are VERY heavy and large; they will almost certainly be bigger and heavier than your motor, up to twice as much! I have one here if you want pictures.  

It also wastes huge amounts of power. With a pot, the power not being used up in the motor is still being used up wasted as heat in the pot, when not at full throttle. With a typical switching (PWM) controller, such losses are maybe 1-25%, depending on it's design, usually on the low end of that range.

If you don't mind having only two speeds ("stop" and "go real fast") you can just use a switch, but it has to be a beefy switch rated for *at least* the full stall current you will draw thru that motor, and it must be rated at DC (not AC) volts. Even then, it's still going to age it's contacts pretty quickly to use it to switch the full motor power. 

There is another way called a contactor controller, that basically uses sealed relays designed for switching high currents to connect the batteries to the motor. If you have one battery, it's just on/off. If you have two in series, then it can be full on, half on, off. Three in series gets you four speeds, and so on. But it is hard on the batteries below the top because they see more use, and you can't easily charge the whole set as a set because of that. You wind up having to individually charge each battery to avoid getting them out of balance and either damaging them or running out of power a lot sooner than you thought you should. 

A dimmer won't work because it requires AC. Theoretically you could use a 12V battery, an AC inverter for a car to run wall-power stuff from, a dimmer, and an AC capable motor, but realistically the dimmer will not handle a motor type load and probably will blow up. They make dimmers that will handle small motors like fans, which you might find used, but mostly you're going to have to dig hard or pay a lot for ones that could do big enough motors to matter to your project, assuming you can even find one. 

There is a user by the name REdiculous on Endless Sphere that recently built a pusher trailer that uses a 12V battery, an AC inverter, an SCR controller for motors, and a treadmill motor, and it does work but it is not very efficient (at a guess, less than 50%), and has some issues he's worked around.


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## KrisWood (Apr 24, 2009)

Ok that answers the dimmer / pot question, but what about sources I could pull a controller from? I'm not going to be able to buy or make one, so I've got to know what to keep an eye out for on freecycle / craigslist.


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## Amberwolf (May 29, 2009)

Sorry; ran out of time to finish yesterday. 

Rmember that the motor controller has to be more or less matched to the motor and how you're going to use it, plus the battery voltage, so when you go looking for one you'll have to keep those in mind. 

The radiator fan motor would probably work at 12V-36V, maybe more, as long as it is a brushed motor and not brushless. If it's brushless, or BLDC, then it probably has a "controller" inside it already, but not meant to handle the power levels you're going to ask of it, and not at higher than the 12V it was made for. To use a BLDC fan motor, you'd have to probably pull out the original controller board and just run wires out of it for the three phase wires to something like an Ebike brushless controller (probably a sensorless one). 

Basically you don't have a lot of choices if you can't do electronics work to at least modify one. It has to already be able to easily handle the power you will draw thru it, and has to operate at the voltage you want to use. There are controllers in a lot of things already, but they aren't made to run anything other than what they're already in.

Almost all motor controllers that will take the power levels you need are made for at least 24VDC. Frequently but not always they have a low-voltage cutoff (LVC) that to protect things turns off the controller at around 20VDC or higher, so a single car battery won't run them.

Some of them don't have the LVC but still won't work at only 12V, others that don't have LVC will work when the battery is fully charged but due to design may blow up when it drops down to 10-11V or less. 

As long as the motor you are going to use is just a brushed DC motor, many kid's scooters and adult scooters like ScootNGo have controllers in them that will work, at 24VDC and up. These are the easiest things to get going, for a very basic project. That's what I used to start out--a blown controller from a ScootNGo, which I first fixed with parts off a dead motherboard from a PC, and later modified with high-power capable parts after I blew it up a few times. Generally they are not meant to handle a lot of power and they are not well-protected from abuse or accident, so you would have to be easy on them. 

Good news is lots of kids get these Razor electric scooters, let them sit over the winter (summer here), and the SLA batteries in them die from not being charged. So they sit around unused and the parents want to get rid of them, so you can ask around or watch craigslist and freecycle for them. Then you also get a motor, throttle, and maybe even an "ebrake" handle with a cutoff switch in it, assuming none of that has been broken by the kids. 


I've seen some fancier vacuum cleaners that use an electronic controller for the motor, rather than just running mains power to it. But those controllers are still meant for 110VAC, and will take modification to run on DC, if they can even do so (some could, some couldn't). And they'd still probably need 100-150VDC to do their work. Then you could use them to drive the original vacuum motor, and use a really high-ratio "gear reduction" (done with belts to keep it quiet) to get it down to speeds your wheel can use, and up to torque levels your vehicle will need to get it moving.

Some newer (last 20 years) cars do have separate motor controllers for things, and they are probably nearby or built into the things they operate. But again, they also probably require communication from the car computer to really control their speeds. That could be hacked, by tapping into the point after which that communication is translated into a speed control voltage, but you'd have to know enough electronics to at least get near that point before poking around, unless you just happen to have a pile of them to play with.  

Anything that has a speed dial on it to smoothly control the motor speed will have a controller in it. You could probably adapt it to run at least it's own motor for your project, with minimal electronics fuss. Running a different motor requires learning which kinds of motors work on what kinds of controllers, and matching them up. It's generally easy but takes some research each time. 

Anything that just has a switch for different speeds probaly does not use a controller, just different windings inside the motor, and is probably powered by AC. 

Any bigger vehicle (golf cart, powerchair, etc) powered by electric motors has a controller for that, but will almost certainly require at least 24-48VDC to run it. They will also be quite powerful and capable of more than you will ask of them, in general, so it's unlikely to blow up just from running it normally. You'd want to very carefully trace out all the wiring from it to the rest of the vehicle and draw it out before removing it, though, since many are "OEM only" so you cannot get wiring diagrams for them and usually are not well-marked. I have a Curtis golf controller on CrazyBike2 right now. 

You could also use the motor from such a vehicle, and it will be very heavy duty for something like your bike/trike, but it will also take more power to run, and will need more batteries carried as a consequence.
________


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## KrisWood (Apr 24, 2009)

Hmmm that gives me a lot to research and a lot to think about. For the prototype I want to use one 12v car battery because I already have one that's just sitting in a dead car, would a 12v motor be capable of making any speed difference in the trike at all as opposed to pedaling alone? Can I run the battery straight to the motor with an on off switch (for all or nothing) just for testing, or would that blow it up?

After the prototype is working I'm planning on taking it apart to make a second prototype which is more fully functional, target is about 24v to 36v in batteries, though car batteries are probably not going to be worth using there because they'd be so heavy. The second prototype will need a motor capable of driving the bike 20mph, and a controller capable of smoothly adjusting the motor's speed at that voltage. I have zero funds to put into this though and am relying entirely on scavenged parts so we'll see if anything ever comes along...

Am I correct in understanding that the battery always outputs its full power regardless what is being drawn off of it? By this I mean that the controller would always be receiving 12v off each battery regardless of what it's actually outputting to the motor, and thus any excess would be lost as heat, using the same amount of power no matter what? Is it possible to only draw half the full voltage from the battery to make it last longer? For example use two 12v batteries and draw 6v from each of them?


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## KrisWood (Apr 24, 2009)

Ok I'm reading up on controllers now; it seems even a simple switch is still a controller. I think I'll take some old PC fans and make some controllers from scratch to get a better idea of how this works

Aaahhh I see now. A PWM controller only draws full current, but in short bursts, as opposed to drawing full current and passing on only a portion of it. There is no energy wasted as heat in the controller because all of it is being passed on to the motor.

Ok I understand how it works now, no need to build one from scratch. In fact I doubt I could build one from scratch from the available components and tools I have handy. It does however tell me what I need to look for. What I need is a controller that can handle the desired voltage, and a motor that can receive it and not blow up. I'm gonna have to do a lot of scavenging to find one that will work, I guess.


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## Amberwolf (May 29, 2009)

KrisWood said:


> Hmmm that gives me a lot to research and a lot to think about.


Unfortunately it does get complex fairly quickly when you are limited to DIY and salvage options. With a budget everything gets easy, as there are even kits to do this kind of thing. Sometimes as cheaply as $200 or less, on sales, that have everything but the battery, and just use a motorized wheel to replace one of the bike's original wheels. This is what DayGlo Avenger has on it right now. I don't like it as much as my DIY stuff, but it does work and it is more reliable right now.  

DIY is more fun, and often cheaper (but not always), but it is definitely more of a challenge. That is part of the fun, to me, but to many they are only DIYing because they have no money for any other method, and they don't have the patience or willingness to learn the skills needed to do DIY, and give up. I'm one of the ones that didn't give up yet. 




> For the prototype I want to use one 12v car battery because I already have one that's just sitting in a dead car, would a 12v motor be capable of making any speed difference in the trike at all as opposed to pedaling alone? Can I run the battery straight to the motor with an on off switch (for all or nothing) just for testing, or would that blow it up?


It won't blow it up as that motor was designed to run off that battery.  You just wont' have any control over it's speed. It will be all on or all off. The issue is that at zero RPM of startup, you'll have a LOT of current suddenly flowing thru that motor, and depending on how long it takes to reach a speed where the motor is running closer to it's originally designed RPM, it could be enough to damage it over time. 

A controller would allow you to ramp that current up from a little to full and be gentler on it. 

I used the switch-only controller methods in early DGA fanmotor tests, and it does work, but it is not the happiest thing to do to them.  


Find out what RPM the motor runs at normally, at 12V, with just the fan still on it. Then when you start setting up the gearing or chains or belts to drive the wheels, calculate out what gearing you will need to let the motor reach something close to that RPM when the vehicle is moving at the desired max speed. Since you're asking a lot more of the motor than it was made for, it will probably never reach the same RPM, but I'd gear it to at least try. If it can't do it then you will probably need higher voltage to achieve the same RPM, which will essentially double the power output thru it if you double the voltage. 

If you double the voltage, you should try to regear it again so that the RPM is close to what it would have been at the 24V fan-only speed. You don't have to re-measure, just double the original RPM number. It's a linear relationship. 

The reason is that as you spin a motor faster, the voltage it develops across itself (from acting like a generator) will tend to equal the voltage coming in, and reduce current a lot, keeping the motor cooler and less likely to melt down. 




> Am I correct in understanding that the battery always outputs its full power regardless what is being drawn off of it? By this I mean that the controller would always be receiving 12v off each battery regardless of what it's actually outputting to the motor, and thus any excess would be lost as heat, using the same amount of power no matter what? Is it possible to only draw half the full voltage from the battery to make it last longer? For example use two 12v batteries and draw 6v from each of them?


You will always have the same voltage out of any battery, but the current draw from them varies based on load. Look up Ohm's Law, which is the basis of a lot of electrical stuff (probably most of it), and it will help you a lot in figuring this kind of thing out. 

Inside the controller is where the voltage gets "cut down", to vary the motor speed. Most of them work by turning on at full voltage, but only for part of the time, then turning off for part of the time, switching this very fast via PWM. Changing the percentage off on time vs off time (duty cycle) is how it varies the motor speed. The coils in the motor smooth that out and make it work as if it was a smoothly changing voltage matching the throttle input.

Dimmers for your house lights do the same thing, as do those little dark-triggered nightlights, which is why they appear to flicker rapidly when there is just enough light in the room to almost turn them off. Power is only getting to them in tiny little spikes just enough to start turning the light on, then it turns off for a relatively long time, and the bulb is off so long it cools and doesn't produce light for most of it's time, so it looks like it's flickering rather than just dim. If the electronics in them didn't require AC to work, you could use these for motor controllers, with a few modifications. 


Remember that contactor controller I described above? That sort of does what you are wanting to do more directly, if you have multiple batteries. It draws only from the first in the stack when set to low, then the next setting draws from the first two, next setting first three, and so on. The smaller the batteries' voltage, the finer control you have, but the more contactors you must have. Also, it wears out the bottom batteries sooner than the others, so you have to do more maintenance on them to mitigate that. 

You could use large-capacity Lithium based cells (or parallel arrays of smaller ones) with contactors at every series cell connection, and get ~3.3-3.7V increments. Using individual lead-acid cells, you could get ~2V increments. If you could find them in large enough sizes (not likely) you could use NiMH or NiCD for ~1.2V increments. But this is all a lot of wiring, a lot of connections, and the more of those you have, the more losses you have, and the less power actually makes it to your motor.

Does save on knowing much about electronics; just needs basic electrical knowledge to draw up the wiring diagram and hook it up.


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## KrisWood (Apr 24, 2009)

Ok that makes a lot of sense. Now, where would I find a 12V DC controller?


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## Amberwolf (May 29, 2009)

That's the catch--I don't know of any you can commonly just find and use as they are, at least for salvage stuff, as I said about the car stuff, or scooter stuff, etc. You'd probably have to modify it to work for you, either because of the voltage or because of the control interface. Or because they won't handle the power levels you need.


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## KrisWood (Apr 24, 2009)

I found one! My PC has a 12C DC fan controller in it with an analog pot to control the speed. I removed it and sure enough it's just a little box with a knob and 12v leads for input and output.  Now to figure out what to do with it 

Here it is, will this work?

http://www.zalman.com/eng/product/Product_Read.asp?idx=206

Edit: Replaced the link with one to the manufacturer's specs.

Hmmm, according to the specs, anything over 6W will fry it, that can't be good...

Ok it's not a PWM after all, I wonder what it is *sigh* The manufacturer also has a PWM version but I'm not spending money on it hehe. I think I'll try this anyway and see what happens, I've never used it once so it'll be no loss and just *might* work for testing at least hehe.

Further reading reveals that it's not a PWM or a rheostat but a Variable Voltage Regulator. 

Calculated it out, at 12V and 6W, a CPU fan draws a maximum of 0.5 amps. And here all this time I figured voltage is voltage is voltage and it would always be the same. What do amps and watts have to do with the controller?


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## Amberwolf (May 29, 2009)

That's the thing I meant when I said that you will have to modify most of the 12V controllers you find in things, for one of those reasons. 

Basically if it's smaller than a pack of cigarettes, it's unlikely you could run evne a small vehicle motor from it, anyway. 

You'll need to estimate the final vehicle weight plus rider/cargo/passenger weight, plus motor and batteries, and then use one of the many online calculators to figure out how many watts it's going to take to move you down the road.

Then, knowing that, you can figure out how much power it's going to take, and how much power the controller must be able to handle. 

Those little Razor scooters, that weigh like 15-25 pounds, for just one person? They are 200-300W, typically. Controllers are often rated not by wattage but by amps, though. So since you're going for 12V, then to get 200W out of it it'd have to be able to handle 200W / 12V = ~17A. 

That's assuming your motor draws only that much under the load you'll have. And remember that it will take much more than the "rated" wattage to get your vehicle moving; if you help start it up by pedalling heavily until it's going a little then that will reduce it's startup current needs significantly.


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## Amberwolf (May 29, 2009)

KrisWood said:


> And here all this time I figured voltage is voltage is voltage and it would always be the same. What do amps and watts have to do with the controller?


That's where you'll need to read up on Ohm's law and basic electrical theory. Basic motor theory will help too.

This site:
http://www.4qdtec.com/pwm-01.html
might help some with the motor and controller part. It's a good explanation with diagrams, since mine didn't help.

You might still need the basic electrical stuff first. I'd start with Wikipedia's Ohm's Law entry and work from the references the article draws upon (listed at the bottom) for further information.


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## KrisWood (Apr 24, 2009)

Oooooh that makes a lot of sense! So to get it right I'm going to have to calculate backward from the target speed and range under load?

Maximum speed under power in Oregon is 20mph
Maximum wattage is 1000W

I know I want to use a 12V motor for now.

1000W / 12V = 83.333 amps. Considering that most batteries I've seen mentioned are under 14Ah that means it'd drain the battery in a matter of minutes..?

Oh, and at 1000W and 83.333 amps I'd probably far exceed the 20mph limit...

A more sane 500W gives us 41.667 amps which would give us about 20min at max power with 14Ah batteries? I'm starting to see why distance is such a big issue! More batteries = more weight which = more watts to push it down the road which runs down the batteries faster!


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## Amberwolf (May 29, 2009)

Remember that just because they have some particular limit, isn't what your vehicle actually needs to move. It might require more power to move your vehicle than is actually legal if it's heavy enough, or if there are hills/slopes/etc., depending on the speed you're trying to go.

For instance, there is a hill here (listed as a mountain but that's only because it's a flat desert here. :lol that would take my Crazybike2 about 2-3KW to go up at 20MPH. I can provide at best 30-50W of that by pedalling to help, if I have to do it all the way up (it's pretty long). It's a lot less power to go slower, but it's still more than most limits permit. If my motor was truly limited to under 750W I would have to walk the bike the two or three miles up that hill, because I could only go about 5-6MPH at that power level, and the bike would just fall over on it's side, as I couldn't keep it upright and balanced at that low a speed. Getting off and walking, holding the throttle to keep the bike at the same speed I limp up the hill, is the only way to do it when limited that way.

Since the lead batteries you're going to use are even heavier than mine, you may have an even worse problem since you also want to carry the kids as passengers.


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## Amberwolf (May 29, 2009)

KrisWood said:


> A more sane 500W gives us 41.667 amps which would give us about 20min at max power with 14Ah batteries?


Actually, a lot less. Remember I talked about C rate? Most lead-acids are rated for 20 hours. Meaning, you can get 14Ah out of them if you take 20 hours to draw it out. 

If you draw it out in one hour, you probably get 1/2 to 3/4 of that, depending on battery construction, age, etc.

Do it in 20 minutes, and 1/4 to 1/2 of that, at a guess. 

It's called the Peukert effect. There's a wikipedia article on it that explains it pretty well. 

So if you drew a constant 40A out of a 14Ah lead-acid (PbA) battery, you'd probably only get at most 7Ah out of it. 

And that 7Ah would be 100% DOD, meaning that it's drained to the point where damage could occur to the battery from sulfation, since it's a PbA type. 

This is the part where you want to size the capacity of the batteries to be somehow proportional to their C rate and how many A you are really going to draw from them.


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## KrisWood (Apr 24, 2009)

Before I can figure out the batteries and motor I must first figure out how much work is needed to move this thing down the road. For that I must approximate the mass and the desired velocity.

The Velotaxi is 145Kg without a load, so I'm using that for now to approximate my frame without a load. I weigh about 175lbs but I'm rounding up to 180 in case I'm wearing heavy clothes or gain a little weight. That gives us ~82Kg. Searching online gave me a mass of 34Kg for a large 12V car battery.

This gives us a minimum approximated mass of 261Kg, this will go up if we add more batteries.

1 Watt = 1 Joule per second

J = (kg*m^2)/s^2

We know the kg, now we need a target velocity (m/s). To keep it simple let's say 10Km/h, we can always adjust this later when we've got a formula in place. 3600 seconds in an hour so we now have:

J = (261*10,000^2)/3600^2 = 2013.888889

Here's where I get confused. J = W*s so do I divide J/s to get the number of watts?

W = 2013.888889/3600 = 0.55941358

Or since the J already had the s eliminated does W = J?

Also if the number of necessary W are always the same for a given km/h and W = V*A, does that mean that the more volts I have available the less amps I draw from the batteries?

Edit: Meanwhile I've found that there are two models of Velotaxi; The CityCruiser and CityCruiserII. The older model used a 500W motor and had an average run time of 4hrs between charges. The newer one I haven't found anything about the motor, though photos show a hub motor with a freewheel on either side, one with a chain going to the pedals and one going to the rear differential. This gives it a 2 chain setup instead of the 3 chain one I'd envisioned. Also I found out how the battery setup on the CityCruiserII works. It's got at least 24hrs range running off a battery charged by a methanol fuel cell:

http://www.efoy.com/en/pedelec-benefits.html

Unfortunately the fuel cell is over $2000 for the cheapest versions, and the methanol is a proprietary blend one must buy from the manufacturer. In the United States they are not available for consumers, and only the military and commercial customers are allowed to buy them.


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## KrisWood (Apr 24, 2009)

Found a free electric treadmill, gonna go pick it up now!  Will post more info once I've got it taken apart and know what I've got 

Here's a diagram of it: http://www.fitnessrepairparts.com/diagram/4127

Hooray my friend dropped off the treadmill! It was pretty easy to take apart and I'm holding the motor at this very minute. 

It's a 120VDC Permanent Magnet motor. 2.25HP 6200RPM and 18 amps.

It looks identical to this one on eBay and was made by GS Electric.

http://cgi.ebay.com/Weslo-Cadence-X...1QQcmdZViewItemQQssPageNameZRSS:B:SRCH:US:101


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## KrisWood (Apr 24, 2009)

Amberwolf: How did you get the flywheel off yours?

Like in your blog I've discovered that the flywheel does indeed seem to be about as heavy as the rest of the motor combined. I'd rather not pedal around with an extra 6lbs I don't need


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## Amberwolf (May 29, 2009)

Looks like your motor is similar to mine, same company:
http://4.bp.blogspot.com/_zHr5qzOZQ...Uw/s1600-h/TreadmillMotorWithPulleyAndFan.JPG

I took my flywheel off with first the lathe to cut into it deeply from the face, with the pulley clamped in the chuck. I could not cut into it from the rear because the tool holder would not stay in place whenever the tooltip touched a blade on the back of the flywheel, even just a little, and they went almost all the way to where I needed to cut. 

So I used my angle grinder to grind away the back in a rough circle till it was flat enough to lathe away till it met the front cut. It's just soft cast iron on mine, so it was very easy to cut into.

If you don't have access to a lathe, you can probably use the treadmill motor to do the cutting. Leave it mounted in the treadmill but with the belt off, and use a lathe cutting tool (held in vice grips if you have to) to slowly cut into the flywheel just outside of the pulley's diameter, on the face. Eventually you'll reach the point where you've cut as deeply as possible from the face, and you'll have to start cutting from the back. But at least you now have a perfectly round circle as a guide. 

You'll need to now remove the pulley/flywheel from the motor. It is probably threaded on, in reverse direction from the motor's spin. Getting it off is really easy: Put the belt back on and tension it up. Swap the + and - wires on the motor so it runs backwards. Start the treadmill at a very low speed. Keep an eye on the motor and it will quickly spin off the pulley/flywheel, if it's threaded on. Possibly in less than a second. Be prepared to cut treadmill power immediately (via the pullcord safety on the console is an easy way).

Use a Dremel or angle grinder to cut thru the blades/fins on the back of the flywheel, and finish the cut thru it.

Put the pulley back on the motor, leave the belt off, swap the motor wires back, and run it. Use the cutting tool to finish the outer circle evenly.


Note that you might have to build a pivoting clamp to hold the lathe cutting tool, so that your circles end up cut perfectly. Doing it by hand you may not be strong enough and steady enough to hold it in place perfectly, and you may end up out of round.



Note also that on mine I left quite a large flange on the back; this was so I could use it with the alternator fan, which is simply friction fit against the back of it using rubber water hose gaskets on the pulley side, and flat washers smaller than the bearing hole on the motor side, to keep the fan pressed against the pulley so that the pulley pulls the fan around but in case of accidental impact with something (wire, fingers, etc) the fan can be stopped by the impact rather than shearing thru whatever it hits (especially with fingers!), without damaging the motor at all. 

The alternator fan is very noisy, but it is very effective at pulling air thru the motor. A squirrel-cage fanblade rotor out of a vacuum cleaner would work to, but I never got around to trying it to be sure. The alternator fan fit *perfectly* and was the first thing I tried, so I had no good reason to try anything further.


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## Amberwolf (May 29, 2009)

Now, the bad news. A treadmill motor is going to need a lot of current to run, especially at lower voltages, to do any useful work. Mine takes (I think) 21A. 

Also, treadmill duty is not continuous duty. It usually means you could put a hefty load on it for a while, 15-120 minutes, then needs cooling off time. If you force-air cool it like I did, or better, it can take more. Mine is up to 2.1HP, at 120VDC I think it is. Might be 100VDC. Probably says on yours' nameplate. 

I posted back in my blog about it for what various possible RPMs and power levels I estimated I could get out of it, with different voltages and whatnot. 

It's all about gearing it down and letting it run as fast as it can. That means running it at as high a voltage as you can get. If you could put 10 12V 20Ah batteries on there in series, you'd have a heckuva power source, but it would mean around 150-180lbs of batteries if they were SLA. If they were car batteries, that'd be more like 400lbs or more. If you could use toolpack batteries, like A123 from DeWalt, you could get away with 35-38 batteries (about 3.5 "36V" packs' worth) in series, with 3 or 4 strings of them in parallel, and have the same (better actually) pack for probably 50 pounds. What that pack would give you for range/etc depends on the rest of the vehicle weight.

But anyway, for reduction, if yours like mine was made for 7000RPM at it's max labelled voltage, you could use it with a 70:1 reduction (multiple stages) to drive the regular bike drivetrain at the cranks (as mine does) to further use the bike gearing to help with efficiency on hills vs flats.


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## Amberwolf (May 29, 2009)

Regarding a controller for it, there is one in the treadmill. I don't know on yours, but on mine it is a separate board that takes wall AC input, turns it to DC, and chops it up to send to the motor to vary it's speed. The PWM chopping control input comes from a separate board that is inside the standup console with all the controls on it, but you don't need that part--that you can build with a 555 timer circuit or two, once you know enough basic electronics to build from a schematic (there are at least dozens of sites with 555 schematics, and most include a PWM for motor control or light dimmer in there somewhere).


That controller *could* probably be modified to take 12VDC input and chop it up, rather than 120VAC, but it can't output enough power at that low a voltage to help you. 

Better is to find a 1KW or 2KW (constant, not peak) inverter for a car (like you'd plug into a cigarette lighter to get AC power in the car), to get 120VAC from your 12V battery. Then run the original treadmill controller with your own PWM circuit and throttle, to drive the motor.

It will probably be 50% efficient at best. But it will work, as long as you are not making the motor do all the work of getting you started, as the inverter and possibly the controller probably can't handle the peak load like that. They might, but....


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## KrisWood (Apr 24, 2009)

That's a lot of information to parse 

I'm fairly committed to staying as low on voltage as I can realistically accomplish. I don't need the full power of the motor. My motor is almost identical to yours except it's 18 amps instead of 21, and 6200rpm instead of 7000 but the voltage is the same. Am I correct in thinking that the amps stay the same at all times for the motor? Will it always draw 18 amps no matter how many volts I put through it? If so, the watts should be fairly easy to calculate.

I had really hoped that the controller from the treadmill would work for this but I think you're right: The controller board is right next to the power input from the wall and I don't think it gets converted to DC before going through. I guess I'm going to have to figure something else out. 

As I said before I have zero funds to put into this. I'm relying entirely on salvage. I also have very few tools, none of them powered. I've got several wrenches of various types, a few kinds of pliers, tin snips, screw drivers, hammers, and jewelry working tools including a heavy clamp of the sort that bolts down to a table (I forget the name of this type, I use it for sawing rings for chains). Lathing the flywheel off the motor is going to be near impossible. The only way I could do it would be to bolt the motor and the clamp to a table, add some sort of cutting tool to the clamp, and hope it doesn't go flying when the motor starts.

I intend to have this entirely chain driven since I'm not going to be able to get the original pulley off the treadmill roller anyway. I'll be happy removing the flywheel and pulley entirely. I guess I'll bolt it back into the treadmill and switch the wiring as you suggested.  Then I'll just have to hope one end of the shaft will be the same diameter as a bike axle for fitting the sprockets to it... If the bit of shaft that sticks out of the housing on the other end is already the right size, I might just leave the flywheel on for now and use that end.

Since I have no money the controller's going to be the hard part. In weeks of watching craigslist and freecycle I've not seen a single electric scooter or mini-motorcycle come up. At least it's almost yard sale season.  Maybe I can get the chip manufacturers to send me free samples (I've done that before with opamps for a sound card for my computer). I'd still have to come up with money for the shipping though. *sigh*


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## Amberwolf (May 29, 2009)

KrisWood said:


> That's a lot of information to parse


I'm just good that way. 



> Am I correct in thinking that the amps stay the same at all times for the motor? Will it always draw 18 amps no matter how many volts I put through it? If so, the watts should be fairly easy to calculate.


Amps will be determined by the load on the motor vs it's RPM, and the volts applied to it. It's not always the same (although there might be places on my blog that say so as I once misunderstood). Some motors are rated at their no-load current on the nameplate, like my Invacare powerchair motors. Some are rated at their full-load current, meaning that is the max current that they can handle. Some are rated at their stall current, meaning the max current they could possibly draw at their rated voltage, but that doesn't mean they can handle that much current all the time. Unless it says which current the rating is for, you can't know. You can guess, based on what the motor was for and how that equpiment would operate, and any duty cycle it lists on the label, if any.

As a motor spins, it creates it's own electromagnetic field, called Back EMF or BEMF. This induces a voltage in the coils that as it spins faster, increases. Eventually it nearly matches the input voltage.

When BEMF voltage is equal to input voltage, no current (amps) flows. Since nothing is 100% efficient, then they're never quite equal, so it does always draw some current. The greater the difference between BEMF and input voltage, the greater the current draw.

When you first power up a motor before it spins, current is nearly infinite, called Stall current; if you kept the shaft from moving and left it this way, the motor would melt, your controller would blow up (if it was not protected) or your batteries would run out or be damaged.  This is the max current that your system has to withstand. You can measure stall current by locking the shaft with a high-current ammeter in series with power supplied to the motor at a low voltage (so that there is not enough power in watts to just melt things right off). You also need to be measuring volts across the motor at the same time.

Knowing the volts you're putting in, and the current flowing thru, you can calculate the motor's resistance (which is too low for you to directly measure with typical hobbyist meters). Knowing that resistance, you can then calculate the current that will flow at higher voltages under stall conditions. You can also calculate power (watts) that will be used. 





> I had really hoped that the controller from the treadmill would work for this but I think you're right: The controller board is right next to the power input from the wall and I don't think it gets converted to DC before going through. I guess I'm going to have to figure something else out.


It does get converted to DC, but at a high voltage, and stays that way as pulses to the motor. If you look at the controller it probably has one or more large plastic-wrapped cans (capacitors), various other components, and a heatsink with thumbnail-sized black-encased bits (IGBTs or MOSFETs) bolted to it with leads to the board. Possibly other black encased bits (diodes or bridge rectifiers) elswhere on the board. Those are what turn it to DC and control the pulses to teh motor.




> Lathing the flywheel off the motor is going to be near impossible. The only way I could do it would be to bolt the motor and the clamp to a table, add some sort of cutting tool to the clamp, and hope it doesn't go flying when the motor starts.


Or bolt or clamp the tools to the treadmill frame near where the treadmill mounts, if there is clearance around it. 

If necessary, you can simply sit there with any tool sharp enough to cut into the flywheel face, and run the treadmill motor while holding the tool in the slowly deepening groove. Takes a lot longer, but it will still work.

Alternately, with the flywheel off the motor, hacksaw tangentially across it so that you are only left with a polygonal shape just outside of the pulley. Put the pulley back on the motor, power it up and hold a flat file as the motor spins so that it slowly takes off the pointy edges and leaves it all round.




> I intend to have this entirely chain driven since I'm not going to be able to get the original pulley off the treadmill roller anyway.


If it is plastic like mine, it will slide off the end. Place a block of wood against the opposite side of it, and tap the wood with a hammer or a rock or whatever, lightly. Turn the pulley a bit and repeat. Do this until it comes off the end. 




> Then I'll just have to hope one end of the shaft will be the same diameter as a bike axle for fitting the sprockets to it...


It's not. 5/8" diameter, probably. If you have no way to use the pulley, then take it off the motor, line up the chainrings you're going to use with the center of the pulley, drill holes thru the flywheel to match the ones on the chainrings, and bolt the chainrings to the flywheel. Then put the whole thing back on the motor. 




> If the bit of shaft that sticks out of the housing on the other end is already the right size, I might just leave the flywheel on for now and use that end.


That end can't take a load, it's only made for the little optical sensor wheel or magnet wheel they put on it used to monitor motor speed. To put a side load on it like a drive, you have to use the pulley end. 



> Since I have no money the controller's going to be the hard part. In weeks of watching craigslist and freecycle I've not seen a single electric scooter or mini-motorcycle come up. At least it's almost yard sale season.  Maybe I can get the chip manufacturers to send me free samples (I've done that before with opamps for a sound card for my computer). I'd still have to come up with money for the shipping though. *sigh*


Depends. OnSemi and some others will ship samples for free to a business, and you can get motor controller chips, MOSFETs, etc, but then you have to design a controller around that and build it and actually make it work reliably. Their application notes will help, but they never really flesh out the power stages, because that tends to be application-specific. PCB layout can be important. If you don't use a PCB but instead just hand wire everything, sometimes there are problems with unpredictable behavior, or parts just dying or smoking/etc. It might work fine; it might not. Making your own PCB is possible too, but will require some more learning and an old laser printer for one popular method. 

For now, you may be best just trying what you can with only a switch for the controller, at only 12V it may work ok depending on loads/etc. Just make sure you have a backup disconnect of some sort in case the switch welds shut inside so you can easily turn it off still.


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## KrisWood (Apr 24, 2009)

Thanks for all the info! I think I'm getting to a point where I'll just have to build it and see what happens, then make adjustments as I go along. For the prototype I was thinking I'd use a switch anyway as the main goal is the drivetrain. I'll try to get get a real controller for V2.


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## KrisWood (Apr 24, 2009)

Well, my friend who repairs bikes for a hobby has dropped off the face of the earth *sigh* not unusual for this particular friend but things were just starting to look promising.

Anyone have ideas for where to find free bikes / bike parts?


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## Amberwolf (May 29, 2009)

KrisWood said:


> Anyone have ideas for where to find free bikes / bike parts?


Freecycle.org, craigslist free section, bike shops sometimes have a junkpile in back you can ask about (or if it's not illegal there, dumpster dive for their trash). 

Really cheap ones can often be had at yard sales and thrift stores. Just watch out on the yard sale things if you see a place that "always" has cheap bikes, because some of those places seem to be selling some fairly expensive stuff for awfully cheap, if you get my drift.


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## KrisWood (Apr 24, 2009)

Well, I've been doing a lot more research and here's what I've come up with:

First off I found a tutorial on doing solar power and it does indeed seem doable:

http://www.instructables.com/id/Solar-Powered-Trike/

Another useful thing explained there is that he used 36v with a 20amp motor, which gives a maximum power at the motor of 720w. If I were to use a similar setup, assuming that my motor's max amps is 18a as shown on the label, that would give me 648w at full power. If I go with 48v that'd give me 864w. Either way it should be more than enough power to push my prototype around. Then it's just a matter of finding batteries that'll provide that much power for more than a few minutes. 

Also I've been researching how to actually build a trike in the first place. Bad news is I certainly don't have the tools to do all of it, especially welding. Good news is one site even showed a wooden recumbant made from two 1x4 planks sandwiched together around parts of old bikes. If that can be done, I should be able to build my prototype similarly. 

Further research on designs lead me to the discovery that what I want to build is actually called a "velomobile". That is, a bike or trike enclosed by a preferably aerodynamic fuselage. The last few days I've been wondering what this could be made out of since I certainly can't fabricate it out of plastic or fiberglass (and wouldn't want to either since they're not terribly biodegradable). Then it occurred to me that early bi-planes were made out of canvas stretched over a wood and metal frame. If canvas can fly, it can enclose a trike.  A frame should be relatively easy to construct compared to the mechanical stuff. The doors could be done like a cloth top jeep, closed with a zipper and maybe even locked for when I take it to the grocery store.  We shall see when I get to that point. Let's get it working first.

I found a neat site promoting velomobiles here:
http://www.triketrek11.com/index.html

Next up, I've been looking into trike designs, and have found a wide variety that are quite nice. I am definitely leaning toward a tadpole eventually. It just makes too much sense to pass it up in favor of the more difficult to steer delta, especially when it's cruising at full speed. I'm also finally sold on going with a recumbant design, as it will be more aerodynamic.

I found a ton of info including plans on these sites:
http://jetrike.com/plans.html
http://www.ihpva.org/Projects/PracticalInnovations/index.html

I do think that this first trike will definitely need to be delta for simplicity's sake. It doesn't need to be perfect, it just needs to be a good test of concepts so that I can build a more efficient second prototype.

With the current ideas I'm going with, the first prototype will be a bit on the heavy side, won't steer terribly well, and will have very limited range, but I hope to at least get 5mph out of the motor. Stay tuned!

Oh one last thing. I found a cool non-profit in my town that builds bikes for people that need them but can't afford them. I'm going to see about volunteering there to gain some knowledge about how bikes actually work and how to build / fix them. It should be fun! 

http://bikefarm.org/


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## KrisWood (Apr 24, 2009)

I cut my first two pieces today! 

I've decided on a modified Thunderbolt tadpole design after all. It'll be more complicated on the steering end, but simpler on the drivetrain end. It will also allow me a lower center of gravity and better steering. I'll do the two back seats on either side of the drive wheel, and make them removable for when the kids aren't with me.

Most of the velomobiles I've found online seem to be a tadpole configuration, so they should be easier to modify to this design as well.

I will probably have to end up buying some parts because I've no idea how to attach them otherwise, mainly the crank.

It feels so good to finally be building!  Once I have something to show for it I'll start up a project thread for it. 

Wait a tick, hold everything, I found plans for a wooden one! http://www.borisbeaulant.com/ OMG <3 I think I'm in love hehehe


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## KrisWood (Apr 24, 2009)

Research complete! I now have all the info I need to build the tadpole trike prototype 1. Prototype 2 will be electric assisted and a bit more aesthetically pleasing, and then a "production" build.

While drawing up plans for the parts I'll need on paper I realized that since I'm building in wood, constructing the frame the same way a metal one would be made is not going to be terribly practical. On the other hand I've been making model boats for a few years now and boats are of course made from wood.  Immediately a visual design popped into my head, to construct the frame in the way I would a boat of that size. Since there would really only be two ribs (one to support the front wheels and one to support the seat) it'd still be pretty lightweight, and with the joints and curves used in boat building, it'd be a lot stronger and prettier than if I just use blocks of wood angled together like the metal in the Thunderbolt blueprints.

That got me thinking about names for my project. Since I'm not using the car as a donor for anything anymore, I won't name it after that. It had occurred to me to use a variation on the name "Thunderbolt" since that's what I'm modeling her after, but the best I could come up with was "ThunderVolt" which while catchy and punny, didn't quite fit. With the conception of the boat based aesthetics a name suddenly dawned on me.

The "Tempest", after the Shakespeare play.  It retains the storm themed element of the design it's based on, and very thoroughly fits the weather we're having right now. I'll probably name each prototype after a character in the play.  This ought to be fun! I'll scan my drawings in a moment and start a thread for the project.

Thanks for all the advice everyone!


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## Darxus (May 10, 2010)

Project thread: http://www.diyelectriccar.com/forums/showthread.php/project-tempest-wooden-tadpole-46000.html


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