# first electric car



## onegreenev (May 18, 2012)

DON'T USE DONUT TEMP WHEELS. EVER. As for the marine batteries, you may be lucky to have them last 2 years. What charger are you using? Is the car set up for 72 volts? 72 volts will be pretty crappy performance but it will do just fine in town. Don't expect to go hotting around town. Top speed may be around 50 or less. 

What are you expecting in the way of performance and distance and life of the batteries? 

Many people have bloated expectations because of the information available and not having done homework. I know because I started in the same place. I even purchased things before I really knew what I should have purchased or stayed away from. 

Now that you have the vehicle you can build a great little car. What motor does the little car have? What controller, What charger, What voltage is the system. Do you have photos of the vehicle? We like photos. 

We will help and we will help you with the reality of things. 

Pete


----------



## Ziggythewiz (May 16, 2010)

Congrats on your EV! My first pack was a set of marine floodies. You'll be lucky if they last a year, but they should pay for themselves anyway.


----------



## emosun (Jul 21, 2012)

onegreenev said:


> What charger are you using? Is the car set up for 72 volts?


It's an "Eagle performance series 72volt / 12amp model 7212"

The car is actually 36v , but the charger is 72 so I figure I'll need 6 batteries to use the charger correctly.



onegreenev said:


> What are you expecting in the way of performance and distance and life of the batteries?


I'm hopeing for 30-35mph and 15-20 miles range. As for the batteries I'd really like them to last as long as possible but still be cheap.

My work is only 10 miles round trip on slow roads so if it could do that then I'd be happy.



onegreenev said:


> What motor does the little car have? What controller, What charger, What voltage is the system. Do you have photos of the vehicle?


It has a 24v forklift motor , not really sure specifically what motor. The controller is the same one from the forklift (ev100) with the controls just connected to the vehicles controls.

It's currently configured to be happy at 36v. He said he tried 72v on it but the batteries and wires got hot. When I test drove it on 36v it seemed fine to me so I think I'll leave it there.

I'll get some snaps of it when the sun comes up.


----------



## emosun (Jul 21, 2012)

Oh , I'm also aware that I'll have to make some sort of heavy duty switch system so that I can have the batteries as a 72v string to charge , then switch them to two 36v strings for when I'm driving.

I was only wondering about doughnuts because the cars top speed is roughly 30 to 35 currently , as far as I know that's all doughnuts are rated for anyway so thought it couldn't hurt.


----------



## Ziggythewiz (May 16, 2010)

It doesn't make sense for things to get hot running at 72V, it should be the opposite if the controller and motor can take the higher voltage.

I'd recommend using 8V GC batteries for a good balance between initial cost and longevity.


----------



## onegreenev (May 18, 2012)

If the controller can be configured to run 72 volts I'd run 72 volts vs 36. Your charger is a 72 volt charger. It would make things less complex. If your wires are getting hot then I suspect that the wires used are under sized. I use and most use 2/0 size welding type cables to connect the batteries and to the controller and motor. You will have better performance but you don't and most likely won't use it all at those speeds but it won't be as much of a slug. What you have is a large Golf Cart. Being such a large vehicle compared to a Golf Cart it would be wiser to try to get it to be happy at 72 volts instead of the 36. You really don't want it to struggle all the time. 

As for using those spare tires? Even at those speeds I would not. They are rated for 55 mph or less but still only for temporary use. You can if you need, find small real tires for your car. Coker makes some good skinny tires. I'd use real road rated tires rather than those Old out of date unsafe temporary donut tires. 

If you do decide to use them, do so at your own risk and never exceed the speed ratings of those. Most also have crappy tread as well. The are really only made to get you back home or to a service station so you can have your real tire fixed or replaced.

Yes, I am aware that some folks do use them. 


Pete


----------



## PStechPaul (May 1, 2012)

I found a manual for the EV-100 controller (note 10MB):
http://www.fsip.biz/Documents/EV100.pdf

Other manuals are available at:
http://www.fsip.biz/GEManualsDownload.html

It appears to be capable of 24-84V, so I agree that it would be best to use that, which would be much better than switching the batteries around for charging, as well as the problems that can occur with a parallel connection.

From what I have read of the manual, this controller is designed for a shunt wound motor (although it may also operate in series mode or separately excited mode) and incorporates forward and reverse as well as speed control by field weakening and PWM.

It may have other options such as seat switch, brake switch, plugging, top speed limit, auxiliary 24 VDC contactors, and regenerative braking. The controller is usually pre-configured for the particular truck and motor(s) but there may be enough information to make the adjustments.

This controller actually uses SCRs for the PWM control. This is unusual for modern controllers, but it can be done by briefly reversing the current through the SCR by means of a pulse transformer, or by briefly bypassing the current by means of a capacitor, which appears to be the method used here. This is the first time I have seen such a controller so I am making some assumptions based on a brief overview of the schematic. The manual is very comprehensive and it is a rather impressive controller.


----------



## emosun (Jul 21, 2012)

onegreenev said:


> If the controller can be configured to run 72 volts I'd run 72 volts vs 36. Your charger is a 72 volt charger. It would make things less complex.


Course it would be even less complex if I left the system it was made for in place rather then trying to mess with it. I get the feeling I already mentioned I like the performance as is .

I'll just skip using spare wheels if they are going to be a problem.

What I'm more concerned about is the batteries. Just want to make sure they won't melt or anything if I use them. I figure the voltage is real low so it won't be real hard on them?

@PStechPaul , your entire post went straight over my head. lol . Hopefully it means something good and not bad.


----------



## emosun (Jul 21, 2012)

I contacted a golf cart repair company and I can get 6 12v golfcart batteries from them for 300$ , but they are 4 to 5 years old.

Would it be better to get 5 year old golf carts batteries for 300$ , or brand new boat batteries for 300$?


----------



## Ziggythewiz (May 16, 2010)

Get new ...


----------



## ruckus (Apr 15, 2009)

Dude, put on the doughnuts, keep them pumped to 150psi, and tear it up! 

(then tell us what happens) I'll put money that they do great.

Many people do not understand tires and especially those spares.

1. The reason for the 55mph speed limit has nothing to do with the tires. It is because they are a different diameter from the stock tires and running 2 different sizes causes the differential to spin. Higher speeds can stress the differential, especially if it is limited slip or you have AWD. If you have the same size on each side, this is not a factor. Sounds like your EV won't be doing 80mph any time soon anyway. 

2. Since these tires have a very small footprint, they require very high pressure (like 80-120 psi). Many of these sit in the trunk for 10 years and get down to 40-60 psi. Of course they have a high failure rate at 50% pressure. That would be like driving regular tires on the freeway at 15psi. 

3. I have personally taken old crappy worn out 36psi tires and pumped them up to 70psi and ran them at high speed and on dirt roads for another 20k with no problems. It was the only way to get over 30mpg in a Subaru Legacy. Cops pump their tires to the absolute max on the sidewall and use much higher pressures when they do training exercises. So don't be afraid to use 10-20 psi over the sidewall rating for radically increased range AND tire life.

ps. If it's only 72v and short range, spend the cash and get some lifepo4. JMHO


----------



## Woodsmith (Jun 5, 2008)

Check out how your insurer, and local regulations, would see running on those space saver spares full time before you spend money on them.


----------



## ruckus (Apr 15, 2009)

Woodsmith said:


> Check out how your insurer, and local regulations, would see running on those space saver spares full time before you spend money on them.


Criminy, here come the lawyers with their fine print.. You can use 1930's tech to drive, steer, and stop your car, but nooooooo, can't use efficient tires.

Nope.

How does your insurance company feel about your conversion of a perfectly SAFE (deadly) vehicle to electric drive?

I dare you to tell them about your conversion...

(ok, his advice is really good, but all of this stuff is out in space as far as the insurance company is concerned)


----------



## onegreenev (May 18, 2012)

ruckus said:


> Criminy, here come the lawyers with their fine print.. You can use 1930's tech to drive, steer, and stop your car, but nooooooo, can't use efficient tires.
> 
> Nope.
> 
> ...


Space Saver Tires are TEMP tires only and not rated for full time use. PERIOD. I would not use them at all.


----------



## emosun (Jul 21, 2012)

Honestly I suppose I can decide for myself if I choose to use doughnuts or not so I'll call that one closed for now.

Really I'm just wondering between the choice of newer boat batteries for 300 , or 4/5 year old golf cart batteries for 300 , which would be best?

I already got 1 vote for newer boat batteries so just interested in what others votes are for.


----------



## onegreenev (May 18, 2012)

5 year old GC Batteries or New Marine for the same price? 5 Years is beyond their real life so it is pretty much a no brainer which way to go. Since your not going fast and you really only have a large golf cart I guess the marine ones will be fine for a year or so if you don't hit them too hard but you do need to use them. Just try not to abuse them. 

As for the tires, just buy real tires that are narrow for your light weight skinny tires. They are designed for street use and safe. Using the spare style tire is only inviting disaster. You will get away with using them for awhile. They have sidewalls and fewer belts on the tread. The tread is no designed for full time street driving. Rated at only 50 mph or less and won't last. Easy to puncture. Really, think about the use of those temp spare tires. 

Yes it is your choice but if I happen to be behind you when all hell breaks loose because of your tires failed you will want to run fast. Don't put my life or anyone else's in danger because you wanted to save a buck. Its fine you don't really give a poop about your self but you share the road with others. Your not the only one. BE SAFE. 

That is the ISSUE. Not that you can or can't. JUST BE SAFE. Using those spares is NOT SAFE.


----------



## ruckus (Apr 15, 2009)

Ok, original poster wants votes on batts. I vote for new. At least you are starting from a known point.

As for the tire thing. Were talking about an experimental vehicle which could suffer many types of failure including sudden unexpected acceleration or bursting into flames. A flat at 25 mph is not 'dangerous'.

As for whether they are effective, this guy tested them and found them to be worse than regular tires. 
http://ecomodder.com/forum/showthre...ance-space-saver-spare-tire-donuts-19094.html

So being ineffective AND 'dangerous' probably takes them out of consideration.

Cheers


----------



## emosun (Jul 21, 2012)

ruckus said:


> As for the tire thing. Were talking about an experimental vehicle which could suffer many types of failure including sudden unexpected acceleration or bursting into flames. A flat at 25 mph is not 'dangerous'.


I thought the same thing. Not to mention , it's a geo metro. Even if it was brand new the thing is a little rolling deathtrap , lol.

I had a blowout on a e350 cargo van once going 65 miles perhour and ended up fish tailing all over the place and THAT was dangerous. I think a flat on a geo that can't actually go the speed limit will be less dramatic.

I suppose I'll go with the newer boat batteries.

Think I'd also like to clarify that I LIKE the fact that it'll be like a slow little golf cart. If I wanted speed and power , I'd drive my 17mpg , AC , big v8 2006 crown victoria. And if i wanted economy , I got a 20 year old 4cyl honda accord for my long trips.

I WANT this to be a slow little toy.


----------



## PStechPaul (May 1, 2012)

Sounds like some good options for a little utility car and "test toy". If you can't set up the controller for the full 72V of batteries, I'd just use three of them and keep another set as a spare, or just go with the $150. You can start there, monitor current, and if it seems to sag too much then go with another set in parallel. But the full 72V would be sweet, and if the motor can handle it you'll have a fairly peppy car.

If you can get the donuts for next to nothing they're probably OK for test drives and short trips, but I wouldn't compromise safety if you take it over about 30MPH or in serious traffic.

Be safe, have fun, and learn much!


----------



## emosun (Jul 21, 2012)

The guy that built the car said all the (contactors/contractors?) weren't made for 72v and that the wires would all have to be replaced too , so I suppose I'll leave it at 36.

Also the motor appears to only be 24v so I'm already pushing it as is.

Here is my home made wiring diagram for charging two 36v strings with a 72v charger. The only way I can ensure the system won't short circuit is to use a knife switch so the wires cannot possibly get crossed when going from driving to charging mode.

The reason I have to use a 72v charger is because it's a 400$ charger that he simply GAVE me.


----------



## emosun (Jul 21, 2012)

Course this could be avoided if only 3 boat batteries could get me 15 miles. then it would only be 150$ and I'd have plenty left over to buy a 36v charger.

Do you think only 3 batteries could get me 15 miles?


----------



## Woodsmith (Jun 5, 2008)

I have a 24v motor on my tractor that is happily running on 48v with a view to going 72v in the future.

It could be an idea, if you want to stay with 36v, is to sell the 72v charger to raise the funds for the 36v charger and batteries.


----------



## PStechPaul (May 1, 2012)

Well, I have heard that an EV typically uses 330 W-Hr/mile, but really good ones (or those driven very carefully under ideal conditions such as smooth flat roads and little wind), might do as well as 160. So let's say you can get 200. The deep cycle batteries I was looking at, at Tractor Supply, are 105 A-Hr each, for $85 each. So that is 12*3*105=3780 W-Hr. If you took them down to 60% of charge, you could go 3780*0.6/200=11.34 miles. If you are really lucky and don't mind banging the batteries really hard, you might just barely get 15 miles. But the batteries would soon weaken and then you'd be back to 10 and finally 5 or so.

It might be worthwhile to get a second opinion on converting the controller to 72 volts. I think it has a maximum speed setting which would probably limit the motor to 36 volts. I really doubt that the contactors would care about 72 or 36 volts. The controller has a chopper that drives the coils with 24 volts, and the contacts should be able to handle it. The wires will handle the same current, just a higher voltage.

Is there a fork lift shop near you? If you take really good photos of the controller using the manual as a guide, looking for such things as controls, part numbers, voltage ratings, and such for everything, maybe one of us can help you adjust it, or the forklift pros might be willing to do it for a nice lunch and a case of beer.


----------



## PStechPaul (May 1, 2012)

emosun said:


> The guy that built the car said all the (contactors/contractors?) weren't made for 72v and that the wires would all have to be replaced too , so I suppose I'll leave it at 36.
> 
> Also the motor appears to only be 24v so I'm already pushing it as is.
> 
> ...


Your diagram confused me because of the reversal of the red/black for +/-.

Actually you can get by with a DPDT switch if the car controller is disconnected while charging, or if the charger is only connected when charging and removed before running the car. You could also use a DPDT power relay. Here's a 30A one for $25:
http://www.surplussales.com/Relays/REcontacts-1.html

Wired properly, the paralleling contacts would only see 30 amps when you're pulling 60 amps on the motor. And such contacts will typically handle 3x their rating for short bursts. You're probably not going to pull over 100-150 amps for very long.

You can also add a power diode crosswise on the string for charging, if both sides of the pack are disconnected from the car while charging. Then you can use a DPST switch or contactor for parallel. But if you already have the knife switch, that's probably safest.


----------



## Ziggythewiz (May 16, 2010)

emosun said:


> Course it would be even less complex if I left the system it was made for in place rather then trying to mess with it. I get the feeling I already mentioned I like the performance as is.


Except that it wasn't made for it. It wasn't made for anything, apparently. As I understand, you have a motor, controller, and charger that are made for 72V. You have contactors and 3 dead batteries that are made for 36V. Sounds like you're closer to 72 than 36. If you like it at 36, you'll love it at 72.

You will not get 15 miles on 3 marine batteries. You will be lucky if you can get that on 6. My car could not not get 15 miles after 8 months using 10 marine batteries.

PStechPaul left peukert out of the equation calculating the range you can get. Take what he said and multiply by .6 

Expect around a 5 mile range for 3 batteries and a 10 mile range for 6.

About your contactors, how many are there? You don't need more than 2 and can get by with just one. $50 and you're running at 72V instead of 36. If I could double my car's performance for $50 I would have spent that in a second.

Whatever wires you're running will probably work better at 72 than 36.

As for switches, you will be pulling lots of amps continuous because of running at a lower voltage.


----------



## emosun (Jul 21, 2012)

PStechPaul said:


> Your diagram confused me because of the reversal of the red/black for +/-.
> 
> Actually you can get by with a DPDT switch if the car controller is disconnected while charging, or if the charger is only connected when charging and removed before running the car. You could also use a DPDT power relay. Here's a 30A one for $25:
> http://www.surplussales.com/Relays/REcontacts-1.html
> ...


I suppose I like the knife switch because it's really simplified and doesn't require any electricity to function. It also disconnects from the car while charging , and disconnect from the charger when driving with only a single lever. Thing is , the best switch I could find is rated at 100 amps , I have no idea what kind of amperage 3 boat batteries have tho.


----------



## emosun (Jul 21, 2012)

Ziggythewiz said:


> Except that it wasn't made for it. It wasn't made for anything, apparently. As I understand, you have a motor, controller, and charger that are made for 72V. You have contactors and 3 dead batteries that are made for 36V. Sounds like you're closer to 72 than 36. If you like it at 36, you'll love it at 72.
> 
> You will not get 15 miles on 3 marine batteries. You will be lucky if you can get that on 6. My car could not not get 15 miles after 8 months using 10 marine batteries.
> 
> ...


I think he also mentioned that at 72 the batteries simply depleted twice as fast and the performance gain wasn't really worth it. I think 36 should do me fine.


----------



## PStechPaul (May 1, 2012)

Yes, Peukert's number. OK, I found one calculator that actually works:
http://www.ajdesigner.com/phpbatterylife/battery_life_peukert_number_time.php

I don't know how much current you will draw, on average, but I think I assumed it would be 50A, or 1/2C. This is only about 2.5 HP, and that's really low for a road vehicle, but if you can get by using 5HP only half the time because you can coast down hills, maybe this will work. So the calculator gives a discharge life of 1.42 hours with Peukert=1.1, and just under an hour at 1.2. So, it depends if you can average 15 MPH at a 50 amp average draw. 

Another way to look at it is using 330 W-Hr/mile, if your actual battery capacity is 50 A-H as the 1.2 Peukert says, you would have 3*12*50=1800 W-Hr and 5.4 miles. And that's running the batteries flat. The other thing to consider is the efficiency of the controller and motor, although that may be figured into the 330 figure. And as the batteries sag and become more depleted the motor will draw more current to maintain the same power, or at constant current/torque your speed will decrease.

Maybe if you replace the donuts with bicycle wheels?...


----------



## emosun (Jul 21, 2012)

What would you say spec wise would be an ideal battery for this car. not battery setup , I like 36v. Just the battery to be used. If 50$ batteries wont last me even a year. Then how long does a 150-200$ battery last? I would hope it's 3 to 4 time more.

Today I compared the sheer size of the old golf cart batteries to the size of the boat batteries I was going to buy and THAT is what convinced me not to do it. I was going to buy them today , but they just look so small.

I've decide I'll attempt to save up for better batteries. Till then I'm just going to work on the car itself which is rusty and dirty. I replaced the hood and passenger door as a start.


----------



## emosun (Jul 21, 2012)

So given that you guys have won , and I'm not using boat batteries or doughnuts, whats the kind of battery I should be shooting for?

I still wanna keep it 36v. So whether it's 3 or 6 batteries , which will give good lifespan and a half decent range (15 miles) for under 1000.


----------



## EVfun (Mar 14, 2010)

Golf cart batteries. These are real deep cycle batteries that won't die a horrible early death in deep cycle service. 

If you are going to keep it at 36 volts I'd say feel free to run doughnuts. You should be slow enough that it isn't a concern. I'm not sure they are more efficient, they are designed to function for a short time at a low cost with the ability to hold a lot of weight for their size. They aren't part of the cars EPA rating (except by making it lighter) so I doubt they are optimized for low rolling resistance. 

36 volts is not a good choice if you want freeway speeds. You would be talking about 400 (or so) amp loads at freeway speeds. Golf cart batteries don't mind peak loads that high, but they will complain about continuous loads that high. Not only that, they don't have the capacity to do this for 20 minutes.


----------



## onegreenev (May 18, 2012)

emosun said:


> So given that you guys have won , and I'm not using boat batteries or doughnuts, whats the kind of battery I should be shooting for?
> 
> I still wanna keep it 36v. So whether it's 3 or 6 batteries , which will give good lifespan and a half decent range (15 miles) for under 1000.



Dude, there is no win here. We are trying to help you with good information. You do not have the experience we have and you really should listen. It is fine to check our our information but we do have lots of good stuff to give you. Lead Acid Batteries will not last long. Not even the expensive ones in an on the road electric car. 36 volts is great for a Golf Cart on the golf course. Not on the street. Your car, even though it is small is not a super light weight. 1,986 lbs.

72 volts is out of my minimum recommended voltage for ANY street driven CAR. NEV's or smaller need not apply. 

But if your dead set on low voltage you can do an around town car with 72 volts but it will take a bit to get to 45 mph. Up to 30 and your fine. Beyond that your going to piss off a whole lot of people. An NEV can do better. 

Your car is set up for 72 volts so use it. It will not use your power twice as fast. It will allow higher speeds in a reasonable time. 36 volts will not. Heck I have an old Three Wheeled Cushman Truckster that I will be putting in 36 volts and I figure it will be just about right. For your car? 72 volts absolute minimum. I had trouble getting my VW up to 45 mph with 72 volts. What makes you think you will do as good with 36? Your gearing may be a bit better than the Bug but don't expect decent with 36 or 72 volts. 

I do however understand the desire to build now and use what ever you have at your disposal. You might just consider doing a Trike or Bicycle or Motorcycle instead. It will be much better suited for lower voltages. 


Good luck on your build. I hope you the best. Sorry to hear you got a rust bucket. I do hope you did not spend much on your ride. 

Pete


----------



## emosun (Jul 21, 2012)

EVfun said:


> Golf cart batteries. These are real deep cycle batteries that won't die a horrible early death in deep cycle service.


What's the rough price on a new 12v golf cart battery as jumbo as the ones I'm using now? I tried google but it's like super secretive on battery prices , like as if they are embarassed how much they want. lol



EVfun said:


> 36 volts is not a good choice if you want freeway speeds.


The car only goes like 30mph max I'm not expecting freeway speeds , I have gas cars for the freeway.


----------



## emosun (Jul 21, 2012)

onegreenev said:


> What makes you think you will do as good with 36?


Because I already drove it with super old batteries and it seemed pretty nippy to me. If I use the same batteries but newer , it'll either be the same or better.

I don't wanna touch/alter the engine because I'll break it or mess something up. Then I'll have zero way to fix it.

Body work and paint and rust repair is easy. Figuring out engines is almost impossible which is why I wanna leave all that alone and leave it at 36. It works at 36. I like 36. It goes just fine at 36 and if I leave it alone it'll stay that way. I'm terrible with engines and I can't afford to alter it. I gotta leave it as is or I have a totally dead car.



onegreenev said:


> Sorry to hear you got a rust bucket. I do hope you did not spend much on your ride.


I actually traded it straight up for a 77 ford maverick I had. Granted he may have got the better end of the deal , but I got an electric car with all the hard stuff done which was the engine bits.

It was worth trading the better car for a junky one just so I didnt have to do the engine.

It needs lots of rust repair , rockers are totally gone. Doors are all rusted out too and the interior is really gross.


----------



## onegreenev (May 18, 2012)

Well then your set on your decision. So with that how far will you be needing to drive and what speeds are you expecting this to run at 36 volts? Distance will be your key to the batteries you pick. You need mostly AH's so you can run the car for a long period. You won't have to worry about air drag at such low speeds. 

I know your wanting to do this but I will still try to get you to at least think about bumping the voltage. Drive till you no long accelerate then shift gears. You should have no issues about over speeding your motor at that voltage level unless you give full throttle with NO load. If you have a SepEx motor you will not need to worry about over speeding your motor. 

Still waiting for the photos of the motor and controller setup you have. I am interested in the motor and what kind you have and how its setup. 

Glad you only traded. Trading a Maverick? Interesting. I drove one a couple times in High School. My Step Dad owned it. It sucked. Same with the Pinto. My VW Bug was way better.


----------



## PStechPaul (May 1, 2012)

There was a recent discussion about possible inexpensive Lithium batteries:
http://www.diyelectriccar.com/forums/showthread.php/possiblei-18650-5ah-celli-76581p2.html

I found some fairly small packs at www.hobbyking.com where LiPo were about $0.30/W-Hr and the LiFePO4 were about $0.65/W-Hr. These seem to be good quality and are capable of up to 20C or more. Also, I don't think Peukert's number applies. So, if you want to get 15 mile range, use the 330 W-Hr/mile figure and you will need about 5000 W-Hr. This will cost at least $1500 to $3000. And you will need another charger and a BMS. But the system should be reliable and will probably last 5-10 years. 

What I might suggest, and I think it's a necessity for any EV, is a good set of instrumentation. At minimum, a voltmeter and an ammeter. But you may also want a "battery fuel gauge", and a temperature probe on the motor, and a tachometer. Ultimately, a datalogger will be very valuable, and there is a thread at http://www.mytractorforum.com/showthread.php?t=239700 where I show what I've done. There was a link there to a cycle analyst used for bikes and other small vehicles but also usable in a car: http://www.ebikes.ca/drainbrain.shtml It's about $120-$150 but that seems reasonable and these guys seem to be good to work with.

Once you really know the parameters of your vehicle, you can more accurately determine what you need and the actual performance of various batteries. You might even consider getting some used car batteries from a junkyard, probably $20/each, and use them just for testing purposes. They might also come in handy as emergency power if you keep them charged up and use inverters for AC equipment. But you can just hook them up and drive your car around the neighborhood and take lots of measurements. As a "poor man's datalogger" you can just run a videocam of the meters as you drive, and that is also ideal because you can add voice cues such as "now I'm going up a hill" or "now I'm trying to accelerate as fast as possible in first gear". A ten or fifteen minute video will give you a wealth of information. 

As a final thought, your controller and motor may or may not be very efficient, and the motor will eventually need to be serviced. In fact, you should at least check the brushes and make sure the bearings are properly lubricated, and all the connections should be cleaned and tightened. If you can take pictures of these things it will help a lot.


----------



## GerhardRP (Nov 17, 2009)

EVfun said:


> Golf cart batteries. These are real deep cycle batteries that won't die a horrible early death in deep cycle service.


I did some Peukert effect calculations a while back and found that U.S. Battery golf cart batteries were consistently better than other brands. That is if you calculate the 1/2 hour capacity, it is a higher percentage of the 20 hour capacity.
http://www.usbattery.com/usb_golf_p1.html
Gerhard


----------



## PStechPaul (May 1, 2012)

The 232 A-Hr battery had 122 minutes at 75A. That's 152 A-Hr at 0.32C. The Peukert number is 1.1, which is pretty good. But they are probably expensive. Best to check local dealers.

A similar battery on eBay is $120 each:
http://www.ebay.com/itm/6-Volt-Golf...736?pt=LH_DefaultDomain_0&hash=item2563329ab0


----------



## GerhardRP (Nov 17, 2009)

PStechPaul said:


> The 232 A-Hr battery had 122 minutes at 75A. That's 152 A-Hr at 0.32C. The Peukert number is 1.1, which is pretty good. But they are probably expensive. Best to check local dealers.
> 
> A similar battery on eBay is $120 each:
> http://www.ebay.com/itm/6-Volt-Golf...736?pt=LH_DefaultDomain_0&hash=item2563329ab0


The numbers you give work out to a Peukert number of 1.22
Gerhard


----------



## emosun (Jul 21, 2012)

Today I went out and bought 3 brand new golf cart batteries (500$) and will go back for 3 more soon. Also bought a replacement rim and tire so the car will be on the stock wheels it came with , think I'll start a project thread.

Till then you guys wanted a picture of the motor i think


----------



## onegreenev (May 18, 2012)

ADC makes good motors. It's small but usable. That controller will do as well. If you upgrade later do so when the controller or motor crap out. Until then you have good bomb around the back street electric car. I'd almost bet you will want to up grade faster than you might think but it is a start. Use it when ever you can. 

What batteries did you buy? You going to use the three old ones for now as well? Good contactors in that sucker. There should be plenty of documentation about the controller you have. Find it and download it and study it and how it all works together. You will learn over time how things work. Clean it up real good. 

Pete 

Thanks for the pics.


----------



## PStechPaul (May 1, 2012)

The Peukert calculator I found did not work properly to calculate the Peukert number. It was rather difficult to find a good formula for it, but here it is:

Where B8=Rated Capacity, B9=Rated Hours, B10=Current, B11=Actual Life:

 *k=LOG(B11/B9)/LOG(B8/(B10*B9))*

I made it into an open office spreadsheet:
http://www.enginuitysystems.com/files/Peukert.ods


----------



## emosun (Jul 21, 2012)

onegreenev said:


> What batteries did you buy? You going to use the three old ones for now as well?


I bought the same batteries that were in it , I think the size is T1275? all new.

The old ones I'm only going to use so I can use the charger , after the new ones are charged I won't use the old ones to drive the car anymore.

My next paycheck I'll take the last 3 old batteries in and get 3 new ones to replace them totaling 6 new batteries.


----------



## onegreenev (May 18, 2012)

Pricy little boogers aren't they. Take good care of your batteries. 

Here is some excellent information for you. 
http://www.evdl.org/lib/index.html


----------



## PStechPaul (May 1, 2012)

It would be very interesting and helpful to document the results you get with these batteries. I might be willing to build a simple datalogger for you if you can connect the inputs to the shunt and the battery terminals. You would need to take a portable PC with you with a serial port or USB-serial adapter (which I can also supply). Do you have a voltmeter and ammeter? You can get serial LED displays for about $20 each. A 100A 100mV shunt is about $10. 

I know you are not comfortable with experimenting but basic instrumentation is vital for an EV. What does your dashboard look like? 

I think people would like to know just how well (or not) these batteries perform. The manufacturer might even be willing to sponsor you if you supply good data. Maybe we can take bets on how long they will last!


----------



## emosun (Jul 21, 2012)

PStechPaul said:


> I know you are not comfortable with experimenting but basic instrumentation is vital for an EV. What does your dashboard look like?


I was thinking about just getting a basic led golf cart battery meter.

I'm not sure how well any super data calculating would do , considering the car isn't made very well and the voltagfe is real low and the range isn't expected to be very good. All my data would have so many flaws. Not really an ideal data collecting machine i think.

The dashboard is just the same one the car came with , the gas gauge and speedometer and temp gauge do nothing now tho , lol.


----------



## PStechPaul (May 1, 2012)

I purchased an inexpensive VA monitor for $5, and a multifunction power analyzer for $24:

http://www.hobbyking.com/hobbyking/store/__471__157__Tools-Watt_Meter.html

Otherwise, you should get a voltmeter and ammeter for the dash:

http://www.mpja.com/0-50VDC-Class-25-Analog-Panel-Meter/productinfo/8720+ME/
http://www.mpja.com/0-100A-DC-Class-25-Analog-Meter-and-Shunt/productinfo/19260+ME/
http://www.mpja.com/Digital-Panel-Meters/products/52/


----------



## emosun (Jul 21, 2012)

I was thinking maybe something like this

http://www.ebay.com/itm/NEW-36-VOLT...336?pt=LH_DefaultDomain_0&hash=item4d0256deb8


----------



## onegreenev (May 18, 2012)

emosun said:


> I was thinking maybe something like this
> 
> http://www.ebay.com/itm/NEW-36-VOLT...336?pt=LH_DefaultDomain_0&hash=item4d0256deb8


That would work just fine. Just be sure to get one within the range of your battery pack voltage. 

As for data collecting any vehicle is fine for data collecting. Low or high voltage. Do manual data collecting. You might get a kill-a-watt meter to connect to your charger so you know the watts in. That way you can measure your miles vs wattts in to get watts out. You can data collect all sorts of things. Data collecting will be a great benefit to you and others. You will find out what it takes to move your vehicle and how far it will go on x amount of power available. You need an AMP meter too. Any good analog one will do just fine. Take readings from your amp meter at peak acceleration and while cruising. Those other meters shown above are weak in the ability to handle amperage that a car would pump out. For an RC they are great. Id bet anything you pump out more than 100 amps during acceleration. Bet you get into the 400 plus battery amps. Being such a low voltage system you will use lots of amps to get to speed and you may even use a bunch to maintain that speed. The higher the voltage the less amperage is needed to maintain cruise and the faster you can accelerate if you choose to do so. 

Pete


----------



## PStechPaul (May 1, 2012)

The cheapest, easiest, and arguably the best datalogger would be a camcorder secured to the seat of the car and focused on the instrument panel. Then you can follow it frame by frame to see how the gauges react to various driving conditions over time. And you can provide spoken commentary as well. The $24 power analyzer I found will do the job well.

As for the current capacity, yes, the 100-130A limits of these units will be inadequate. But you can get a 1000A 100mV (or 50mV) shunt for about $30-$50 and you can remove the on-board shunt and run the signal leads to the analyzer. You want a remote shunt anyway, located close to the battery terminals. An analog ammeter can also be connected to the same shunt signal wires. You will need to calibrate the meter for the exact shunt characteristics but that usually just involves changing a small resistor or adding a pot. You can change the meter scale by covering it with an adhesive printer label cut to fit. With a simple CAD program you can make a nice looking scale:


----------



## emosun (Jul 21, 2012)

Actually if I could just get a simple meter that showed when the battery is full and when it is empty I think that's really all I need. Do you think that one I linked earlier will be good enough for that?

The car in reality only has to go 11 miles in a day. Not each and every day, but some.

From what I saw as far as electric golf carts are concerned is they usually have a 25 ish mile range. So I figure with two extra batteries then a golf cart and the added weight I should be able to get 11.

I was told the electric motor in the car is tiny anyway , so don't want really strain it any more then it needs to be.


----------



## Ziggythewiz (May 16, 2010)

I don't think you want just a full or empty, but if you have lead batteries a simple DVM is enough to tell you, with experience, how full you are.



PStechPaul said:


> The cheapest, easiest, and arguably the best datalogger would be a camcorder secured to the seat of the car and focused on the instrument panel.


Cheap, yes. Easy and best, no. If you use a camera you have to watch it frame by frame, or whatever sample rate you choose, and record the numbers somewhere useful. 

The best logger would be something that automatically logs the data for you.


----------



## Mike Leach (Feb 3, 2012)

I would like to weigh in on this. Personally I am just about finished my first electric conversion. I am using the same controller but a bigger motor. I was going to go with 48 volts but decided to go with 72 volts. The higher the voltage, the lower the amperage. You want to keep your amperage as low as possible. If your going to have 6 batteries, I would hook them up in series and run 72 volts. I think that once you start driving your EV, you will be using it for more that commuting to work and the extra power running 72 volts would make it much more enjoyable.

I am not one of the experts, like I said, just finishing my first, however I have done a lot of research and if the pro's on here recommend something, I would take there advise seriously. They have the experience and have already made the mistakes they are trying to keep us from making.

Good luck with your EV.


----------



## Woodsmith (Jun 5, 2008)

Having got one now I would recommend the High Current Cycle Analyst (DrainBrain) for monitoring the voltage, current, power, and battery.
One version of it also has a datalogger as well, and that will be my next purchase to make a semi stand alone portable EV monitoring instrument.

Installed on my tractor I can see the instantaneous power, max power, battery capacity, state of charge and an approximation of remaining range, as well as volts, amps, road speed, etc.


----------



## PStechPaul (May 1, 2012)

I have already made a simple version of a similar design using a PIC. It has four differential inputs which can be used for current or voltage, and other inputs which can be used for temperature, RPM, or other purposes. It has a two line 20 character LCD. It also sends the data through an RS232 connection to a computer at 4 readings per second for datalogging.

If you'd like to help make such a unit for general use I'd be happy to provide information. You can see what I have on:
http://www.mytractorforum.com/showthread.php?t=239700

Here it is with a joystick motor control:


----------



## emosun (Jul 21, 2012)

Mike Leach said:


> I was going to go with 48 volts but decided to go with 72 volts. The higher the voltage, the lower the amperage. You want to keep your amperage as low as possible. If your going to have 6 batteries, I would hook them up in series and run 72 volts. I think that once you start driving your EV, you will be using it for more that commuting to work and the extra power running 72 volts would make it much more enjoyable.


See I get the feeling people don't realize that I have SEVERAL gas powered cars for speed and enjoyment.

The only reason I would up the voltage is if it would make the wires less hot. Right now thats my problem , the wires all get very hot while the car drive and I'm GUESSING this has to do with the high amperage and low voltage?


----------



## Ziggythewiz (May 16, 2010)

That, or bad connections. What size wire and what's your average current draw?


----------



## emosun (Jul 21, 2012)

The wires are like 4 or 2 gauge. I've doubled up alot of them which helped , but some of the wires cannot be replaced.

Some of the wires go INSIDE the motor and the terminals can't be accessed. So I'm basically stuck using those tiny wires. I figured the easiest way would be to up the voltage and maybe then it wouldn't get so hot?

As far as current draw I have no idea , I'm guessing it's a lot. I'm not going to buy a science lab to figure it out.


----------



## Ziggythewiz (May 16, 2010)

Yeah, that's pretty small. Most people use 1/0 or better, and you'll be pulling more amps than most. Upping the voltage will help. Do you know how many amps your controller can put out?

You don't need a science lab to figure out your current. You can get a digital ammeter and shunt online for around $30. I wouldn't consider a voltmeter or ammeter as optional. You need at least one of each. 

The meter you linked earlier would only sort of work at 36V. I would never recommend a dumb meter that tries to think for you. Those are for OEM drivers that aren't capable of thinking for themselves. You can get a DVM for 1/5 the cost that tells you much more (an actual voltage!). 

An EV is much more fun to drive when you know exactly how much power you're using. You need an AH counter for that, such as the cycle analyst someone mentioned earlier, or the JLD404 that I love. I'm getting 225 wH/m and was ~280 just a few weeks ago


----------

