[mikep]

hi my name is mike i have a 1983 posche 944 and ive installed a GE 9 inch 36-48 volt motor out of a fork lift, clutchless, been driving it around with toggle switches and solinoids, ok i bought a logisystem 700 amp controller and it worked great for 10 minutes then poof nothing i just got it back from texas under warranty and now am afraid to conect it again i have 5 batteries 1 for the car 12 volt acc 4 deep cycles for the motor my question is should the motor batteries be grounded to the body as is the acc battery and is there any thing else that im not thinking of when driving with the solinoids the car would scratch the tires and go about 25 mph witch is ok for the speed limit in my town is 25 all over i can get it to go faster with more batteries to hold 48 volts but the wife said no more money yet any help would be greatful thanks thanks for the replies the motor housing is grounded through the mount but the battries are set only to the motor terminals and the controller i will try to get a picture on soon im only into this a little over 1000$ 500 for car 200 motor 330 controller plus a couple hundred for misc i built my own coupler from the clutch disc and ametal disc and 2 iron pipe flanges that i filled spline grooves in, alot of work but it cost 8$ and works shifting can only be done with foot off gas and my motor mount is an old exercise bike frame battery trays are metal shelves and bed frame angle iron. the controller never got hot before it died and logisystem sent it back with wiring diagram only no note

 

[Anaerin]

No! Your traction pack should NOT be grounded to the car body. Especially not if you're connecting the batteries in series (Which would cause a dead short between at least 3 of the batteries). Instead, the traction batteries should be connected +/- to each other, and isolated from the chassis. Something like this:

/===================[Motor]=====[Controller]====================\
|                                                               |
|                                                               |
\=== - [12v] + ==== - [12v] + ==== - [12v] + ==== - [12v] + ====/

The accessory battery can connect to the bodywork as usual, but the traction pack should most definitely not.

 

[Woodsmith]

Yes, as above.
Keep all the pack, controller and motor electrics isolated from the frame. There are lots of safety reasons as well as functional ones for doing this.

Have you any photos of your installation?
Any news as to why the controller blew up?

 

[rwaudio]

Hi mikep, do you have any pictures of the build? I'm working on an '86 944 that is going to be my EV, and I have an '83 944 that I'm bringing back to life with the engine out of the '86.

Good luck with the controller.

 

[DavidDymaxion]

Greetings fellow Porsche EVer! I'm also 48V at the moment but hoping to be higher soon. I loved hearing you could get some wheel spin.

What's the voltage rating on the controller? Some controllers have a lower voltage spec (in other words, you must have at least xx Volts to run the controller correctly). Is 48 V enough for this controller's spec input voltage?

Also you could turn down the controller limits to the minimums, minimum amps, minimum ramp rate, etc. to start off as conservatively as possible.

Was the controller getting hot? Did it have adequate cooling?

hi my name is mike i have a 1983 posche 944 and ive installed a GE 9 inch 36-48 volt motor out of a fork lift, clutchless, been driving it around with toggle switches and solinoids, ok i bought a logisystem 700 amp controller and it worked great for 10 minutes then poof nothing i just got it back from texas under warranty and now am afraid to conect it again i have 5 batteries 1 for the car 12 volt acc 4 deep cycles for the motor my question is should the motor batteries be grounded to the body as is the acc battery and is there any thing else that im not thinking of when driving with the solinoids the car would scratch the tires and go about 25 mph witch is ok for the speed limit in my town is 25 all over i can get it to go faster with more batteries to hold 48 volts but the wife said no more money yet any help would be greatful thanks