# 125 or smaller conversion



## datahar (Sep 6, 2010)

*125 or smaller conversion - Build started, pg3*

I am about to start a conversion of a small motorcycle for my daily commute.

My base bike will be a 125 or smaller (currently got my eye on a honda h100)
I weigh 55kgs and my target range is 30miles. My commute has one hill that I see could be a problem, for 1/4 of a mile. Speed wise 60 would be nice, but will likely aim for 40mph. Lead acid batteries will be the batteries of choice, atleast to begin with.

I guess my question, (which is likely a very common and annoying one, so I apologise), is what sort of motor can I get away with for such a set up?

This is to be a budget bike, so I can save my fuel money to tackle a more financed build. 
Ideally my motor budget would have been £100 (you can laugh don't worry) 
I have been trawling ebay, but the only thing I have really found was only 620w Emoteq, which does not sound anywhere near the mark?

Aslong as I can (just) burn off a moped still I will be happy 

Any suggestions / criticism would be appreciated

Many Thanks 

Jimmy


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## frodus (Apr 12, 2008)

you'll need more of a budget for a motor. I'd suggest finding a forklift motor used somewhere (check forklift repair places, they might have one for cheap).

That's a small motorcycle so you won't need a huge motor to get 60mph, but with lead, the acceleration will be slow.


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## datahar (Sep 6, 2010)

Thanks, I will keep a look out

spotted a newman 5hp single phase, AC would mean a design change a little but no biggie, just waiting back on it's V before I decide if it would be suitable.

I am right in thinking 5hp would suit my needs aren't I?


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## frodus (Apr 12, 2008)

single phase AC motors won't work well. They have very low starting torque and I don't know of any single phase AC inverters widely available that can run off DC.

Get something made for an EV.


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## datahar (Sep 6, 2010)

Right got it, stop being cheap 
I will try and concentrate on prepping a bike and the batteries this month, keep motor money to one side and come back next month with double
That said there is a motor refurb spot in my town, will have to go have a word with them.

Thank you!


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## frodus (Apr 12, 2008)

Absolutely go do that. Take your time and find a decent motor (DC is usually cheaper to start with). Look around for a series wound forklift or golf cart motor. With a golf cart motor, make sure it's not a female splined couple, it's a PITA to adapt to a motorcycle. Make sure it's got a shaft output.


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## MalcolmB (Jun 10, 2008)

Hi Jimmy
It's good to see someone local here. I definitely don't want to discourage you but getting 30 mile range won't be cheap unless you're good at scrounging for parts. I converted a Cagiva 125 a few years back using an Etek motor and lead acid batteries. I wanted to keep things as light as possible, i.e. no heavier than the original bike, and ended up with 15 miles range. The batteries died within a year because I was often discharging them close to their maximum capacity. To get 30 miles from lead acid you need to add a lot of weight in batteries, which makes the bike heavy and increases your torque requirements. It's a vicious cycle.
If you really need 30 miles range I'd suggest going as lightweight as possible to minimise motor and battery requirements and start looking at lithium batteries, which are about a quarter the weight of lead, but likely to be a good deal more expensive. The alternative, if you can find cheap lead acid batteries and a second-hand series wound motor, as Frodus suggested, is to look for a heavier bike capable of carrying a minimum of six 60Ah batteries, which obviously means a much heavier finished bike.

Malcolm


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## datahar (Sep 6, 2010)

Hi Malcolm

wow that IS a staggering figure, here was me hoping 30miles was going to be easily achievable 
My actual commute is 20miles almost exactly 

A shame to hear the suggestion of a larger bike, I think I have just secured a 125 for pocket money
I will wing it I suppose, get the bike, find a motor then figure out what's going to be the best way to power the thing.
Controller I will be doing DIY along with a full replace of the bikes loom

Is there an obligation to keep the mechanical speed and odometer? 
I was considering hacking up a sat nav to be my instrument panel and also keep sat nav mode functionality (another drain on the power  ), though this luxury would come later on, I don't plan on getting lost on way to work.

Seeing as cheap and cheerful as a starting project doesn't seem possible, I guess I will have to keep dependant on the ICE for a little while longer and get this done properly.

Also one local man to another, would you recommend any sources that are UK friendly to find a suitable motor?

Thank you


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## frodus (Apr 12, 2008)

Yeah, lead is not very power dense. I'll be getting a max of 40-50miles with my 5kwh pack of lithium, but I doubt you can fit over 2kwh of lead on that bike without it being super heavy. For 30 miles on a somewhat light motorcycle you'd need somewhere around 3kwh (100Wh/mile, 30 miles, 3kwh, from the batteries). Lead can put out maybe 75% of it's energy under load due to peukert effect + not being able to discharge completely without ruining them. That would mean you'd need close to 4kwh+ of lead acid batteries. Not small, and by the time you buy them, and replace them in 2-3 years, you could just save and get a ~3kwh lithium pack.

DIY controller? Do you have a background in power electronics? I don't suggest trying to do it on your own unless there's a kit you have in mind, it's far cheaper and easier to get an alltrax or curtis or something similar used. You'll spend more time, more money and more frustration building and designing one yourself.

To make it legal, there may be a requirement to keep the odometer with your department of motor vehicles (or uk equivalent). Check the regulations in your area.


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## MalcolmB (Jun 10, 2008)

If you're keen to keep the weight down and good at hacking stuff, I'd suggest looking at the brushless DC motors originally developed for RC applications. They're tiny and relatively cheap. The control side can be difficult, as the existing controllers have trouble running these motors at low rpm/high torque, but a number of people are working on it. Here's one project on Elmoto: http://www.elmoto.net/showthread.php?159-Suzuki-RG250-Conversion.

I've not found any good, cheap supplier of motors in the UK. Mine have all been ebay finds. The classified sections of the forums can also be a good source. If you have a fork lift breakers yard or motor rewinders nearby they can be worth checking out for series-wound motors, but these are heavy motors, 25-30 kg upwards.

There's no need to retain the mechanical speedo and odometer for the MOT. I just used a Cycle Analyst, which combines speedo and battery charge meter.


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## frodus (Apr 12, 2008)

Isn't there a requirement for odometer disclosure if he ever sells the chassis?


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## datahar (Sep 6, 2010)

That's one helluvan RC!
I think, firstly I will go to my local motor winder, if he even trades anymore.
But I really like the look of those RC motors, think I might HAVE to experiment with them, even if just to be able to say its powered from a remote control toy if anyone asks 

Ah that's good, didn't really want to keep the old clocks, wasn't sure if mileage needed to be kept recorded for MOT purposes

For the odometer, if I recorded the mileage prior then used a digital one I will be keeping the record legit, be nice to have a clean meter to see how much I'm electric


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## Salty9 (Jul 13, 2009)

Odometer disclosure is not required in Oregon if the vehicle is over ten years old.


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## datahar (Sep 6, 2010)

well looks like I get to keep my original budget for the motor
http://www.hobbyking.com/hobbyking/store/__5139__Turnigy_80_100_A_180Kv_Brushless_Outrunner_eq_70_55_.html
just need to find it somewhere available to buy now 

speedometer and odometer I think I will manage with a cycle computer, with a fabricated array of (lights, full beam, indicators) underneath. An ammeter will be mounted onto the tank

Hopefully I will be receiving my donor bike over the weekend, a true mystery all I know is it's a 125 and was £20, then I can get some proper planning going.


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## MalcolmB (Jun 10, 2008)

That Turnigy motor has a maximum power output of 7 kW, so its continuous rating is likely to be half of that or less. 7 kW could get you to 60 mph, but the motor will overheat quickly at that power level. Remember these motors are designed to be mounted in the airstream behind a prop, where they have very effective cooling. Just to warn you that you pay a price for the low weight of these motors, they are much more susceptible to overheating than a big series-wound motor, which has a lot of thermal mass.

The motor used in the project I linked to earlier is rated at 12 kW continuous. I would try to find something closer to that.


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## MalcolmB (Jun 10, 2008)

I found the link I was looking for: http://endless-sphere.com/forums/viewtopic.php?f=30&t=16728&start=1530

This is a motor still under development, and they're still working on a controller capable of running it for high-torque applications. The thread is over a hundred pages long...


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## datahar (Sep 6, 2010)

Ah thanks Malcolm!

Looking at the Turnigy there have been several successful conversions of small bikes and mopeds, so I might not get my goal of burning off the mopeds, but I do get my dream of an electric commute.
Whereas the nice looking motor in your link may be something I upgrade to in the future

Cooling yes I agree, I will have to have a think, maybe look at farbicating a larger scale version of how the smaller outrunners self cool with the rotor on back, coupled with blasting air at it through scoops at the front

So now I know my motor, I get to plan my batteries
and in a couple of days hopefully I will have my bike

excited


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## otp57 (Feb 7, 2012)

datahar said:


> I am about to start a conversion of a small motorcycle for my daily commute.
> 
> My base bike will be a 125 or smaller (currently got my eye on a honda h100)
> I weigh 55kgs and my target range is 30miles. My commute has one hill that I see could be a problem, for 1/4 of a mile. Speed wise 60 would be nice, but will likely aim for 40mph. Lead acid batteries will be the batteries of choice, atleast to begin with.
> ...


Check out the Mars 709 it will work for that bike you are building.


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## MalcolmB (Jun 10, 2008)

Glad to help. I think if I was starting again I'd go for this 'Bantam' approach as well, keeping everything light and simple. It just seems to be the best fit with electric technology at the moment, for leisure/commuter use anyway. Keep us up to date with your progress!


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## datahar (Sep 6, 2010)

ooo A bantham now that'd be a nice conversion 
Attached is a graph of my commute one way, looking at it like that makes my task seem even more daunting, but that's my target 









otp57, Thanks I had a brief look at work, but couldn't seem to find a seller of that motor unfortunately


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## frodus (Apr 12, 2008)

Motenergy, it's no longer Mars.


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## datahar (Sep 6, 2010)

Well hopefully I will be able to get some progress soon / actually get started 

I decided for the price I was going to take a gamble with the RC outrunner
I have ordered the outrunner, ESC, 6s worth of li-ion cells and a 6s charger

6S is probably optimistic and will probably go upto 12s with dual chager (the charger will be built into the battery pack which will be removable) 

Then depending on success of the experiment I will buy the rest of the batteries

unfortunately to save on cost all the components will be coming from China, so it will likely be a tantalising drip feed over the month 

All this will be going into a moped of all things, it was a £50 buy, 03 plate 125 miles since new, been sat in a backgarden since, so is going to be interesting to see it's condition, I am hoping I can restore the 'redundant' parts enough to make a bit of profit on ebay 

I will be utilising the CVT transmission, this hopefully solves the low speed issue with outrunners


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## datahar (Sep 6, 2010)

Finally got my hands on the "bike"
Got it home and stripped down, the frame needs a clean down and paint, but luckily isn't rotten, my idea of salvaging the motor for resale is out the window and the engine block is also part of the frame, so I will be cutting out the redundant bits.








before:








After:


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## marcexec (Feb 11, 2009)

Are you going to keep the original belt drive?
Then your outrunner might work well, has been done on ES.
http://endless-sphere.com/forums/viewtopic.php?f=10&t=38598

I'll be using one on a geared bike 

forget the 12kW Colossus for now, that's one for future projects (I have been through the whole 100+ pages...)


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## datahar (Sep 6, 2010)

Hi,

Thanks for the link! Missed that one when I was doing my research 

Yes I will be keeping the CVT system, I currently have the ped in a position ready to accept the motor, just need to get the arduino and throttle controlling the motor properly.

Then I get to put it all back together and test


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## marcexec (Feb 11, 2009)

You are building your own brushless controller with an Arduino?
That's cool.
But you know there are plenty controllers out there for a couple of bucks, right?
i.e. RC controllers (Hobbyking, Castle Creations etc.), specialized EV controllers (Kelly, Golden Motor), and my choice: already hacked e-bike controllers (XieChang, AKA "Infineon", modded by Methods, Lyen and others)
Did you add hall sensors?
You might want to check my build over at ES:
http://endless-sphere.com/forums/viewtopic.php?f=12&t=35865


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## datahar (Sep 6, 2010)

marcexec said:


> You are building your own brushless controller with an Arduino?
> That's cool.
> But you know there are plenty controllers out there for a couple of bucks, right?
> i.e. RC controllers (Hobbyking, Castle Creations etc.), specialized EV controllers (Kelly, Golden Motor), and my choice: already hacked e-bike controllers (XieChang, AKA "Infineon", modded by Methods, Lyen and others)
> ...


No, I am using as much RC kit as possible, the arduino I will be using to translate the throttle to the ESC

Just having problems using all the RC components together at the moment, hoping its just a case of wrong settings on the ESC


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