[emosun]

Hi all. I just purchased my first electric car which is a 1997 geo metro with fork lift parts.

The car currently has 3 12v golf cart batteries which are very very old and don't hold a charge anymore. At least only enough for me to test drive it before I bought it.

I don't want to spend a fortune on batteries , but after talking to the guy that built it , I'm thinking about getting 6 12v deep cycle boat batteries. Only because they are only 50$ each. He indicated that they may only last 3 or 4 years , but that sounds fine to me. I just want to make sure that these won't blow up or something. I can pay 300$ ever few years or so , but not thousands upfront.

Also , I hear that doughnuts work better then the stock wheels because of their small footprint to cut down on resistance. It currently has 1 doughnut on it and am wondering if I should just change all the wheels to doughnuts.

[onegreenev]

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]

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]

Originally Posted by onegreenev

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.

Originally Posted by onegreenev

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.

Originally Posted by onegreenev

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]

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]

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]

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]

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]

Originally Posted by onegreenev

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]

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$?