I have a 2006 e4 GEM (all stock), and I’m looking to do a lithium conversion. By chance I just inherited a packaged 16 cell, and 12 cell lithium block that I will not be able to remove cells from so I’m kind of stuck in the 84-117V range, when I put them in series. I’m actually a lithium battery engineer so I’m familiar with the batteries I just need some help integrating them.
Looking through the forums it looks like the first thing I need to do is the voltage spoof to get rid of the overvoltage error that I’m seeing when I turn on the vehicle. So from this situation I have a couple questions.
1.) How do I do the spoof? Is this something I can do myself or do I need to purchase something for this? I think @Inwo may have some info on this?
2.) Is 117V to high for some of the components, or has this been done before with the stock components? If this is too high I can just run a certain voltage range until I get batteries more appropriate for the components.
24s is a pretty hard limit without a different controller.
Have you looked at leaving the extra cells and tapping at 24?
Is it by chance a Chevy Volt? They come in 16s and 12s modules.
I run a 28s in my 48v Tomberlin by cutting at 14s, connecting 2p14s.
Unfortunately that really isn’t an option. The “modules” are totally enclosed and I’m familiar with the manufacturing process, and taking any of the series cells out really isn’t an option. They are actually batteries from an old Brammo Motorcycle.
Do you have any recommendations on another controller?
So it sounds like 100V (24 x 4.2V/cell) is pretty much the limit then even with the spoof?
Yes, 24s is max with what we know now. Mosfets are 120v. We are pushing the limits.
Lots of options for controllers. All lose dash functions like speed. Maybe you could talk FSIP into building a 96v T4.
Look at the AC motor threads. You can buy a 120v 300a Sevcon on Ebay for about $400.
An 8kw motor for $400.
If interested, I can invite you to some of the private threads discussing our progress. @Troyin909 has one running with an 80v controller in his Gem. I have the same in a golf cart. @MikeKC is almost ready to roll with his ac conversion. He plans to run 25s Tesla battery.
We can use another engineer during our early testing.
2006 is a T-3 correct? = Bad controller. Not much you can do with that controller and high voltage from what I understand.
AC/Sevcon would be a much better solution but as @Inwo stated it is still in mid testing. But we are close.
Thanks for the responses. I would love to help out with your engineering efforts. If you invite me to those private threads I would love to take a look. I’m actually a BMS engineer so I’m vary familiar with how these battery system controllers operate.
Thanks for the advice on the AC/controller set up. Maybe I can just look in my car to see if it’s a T3 or T4. How do I tell? And sorry for all the silly questions but what does the “T” stand for?
Ge controllers changed over the years . Cant really tell you what all the differences are . T3 is ok but you cant lower the field current on it to make the shunt motor spin at a higher rpm .
But If you raise the battery voltage you can get similar results .
You probably have a T4 and therefore can
Also heaters can NOT take the extra voltage . Disconnect if you have one . Besides controller you also have a Dc/Dc converter . Don’t know what voltage limit that is .
@Inwo do you mind if I look at some of the private threads you are discussing for the AC motor conversions? I would love to take a look and see if I can help out?
Also pm Troy, Mike, and Grant for current status and performance. They have so much time and money invested that they aren’t yet ready to make it all public.
Small donations to offset some of their paid consulting cost, may yield more details.
Even paralleled, your range would only be 3-4 miles if you are lucky.
At $250/ea, 12 of them would be $3k, for that you could possibly get a Bolt battery from Dave. A Bolt battery will give you crazy good range and speed.
12v / 160Ah in a lithium package for $250/ea would have been an incredible steal.
Probably best to start your own thread to ask about battery advice, get more responses that way. Put in there what are you trying to get out of the cart and how comfortable are you at wiring stuff up, mounting it and modifying it.
