Here is all of the information I know about the GEM so far. I am doing this to help a coworker finish a project so there may be some disconnect from what he knows and what he has relayed to me but below is a list of everything I know.
2007 GEM EL XD
Stock tires and wheels
Custom 72V pack using 2013 Nissan Leaf Modules
10 modules in series
LiMn2O4/LiNiO2
Nominally rated at 7.6V / 65Ah per module
3.5V / 32.5Ah per cell
Nominal pack = 76V
Max voltage per module = 8.4V
Max pack voltage = 84V
Dilithium BMS System
Thunderstruck TSM250072-30 canbus charger
The old batteries and charger have already been removed and trashed/recycled. The main thing I need help wrapping my head around is just generally how to wire everything. This is the first time I have ever done a project like this so I have very little knowledge on how it works. Any advice or guidance would be great!
The proposed voltage(76 nominal) is inline with normal Pb batteries and so is the peek so that’s all good.
My concern is the total storage capacity of only 65Ah. Stock Pb battery storage capacity are usually over 200Ah and the Gen 4 Leaf batteries I used are 116Ah and have less range then when I had Pb even with deeper discharge capabilities.
So that battery pack will give you, or your friend, too little range. If you can put another pack of the same size in parallel with the pack you listed, giving you 113Ah of storage capacity would make it a more usable configuration.
As for installing it, it’s pretty much a drop-in solution when you know basic electronic theory. Remove existing Pb batteries, disconnect the pigtail in the front battery compartment from the speed controller and replace the controller connection with the battery cable coming from the under-seat battery compartment. Now you have 2 battery connections(Pos/Neg) in the rear battery compartment waiting for a battery pack to be connected.
For the charger, disconnect and remove the existing charger and install that using the same battery and power connections. Your BMS should provide instructions for installing and how it connects to the battery charger and it’s CAN bus.
FYI, the Gen 4 Leaf battery modules are NOT the same as the 2013 batteries modules and I’m a bit concerned that this was overlooked.
@Todd I have little doubt it will work, as I stated the range is what might not be satisfying. What is the range you are getting with that 65Ah setup and typical terrain(100% flat, slight uphill/downhill, etc)?
The leaf cells will work fine in a Gem , I have done multiple . You wire them in series , 20s . Max charge on those cells should be 4.05v each 81v pack voltage . 4.2v is absolute max but will severely shorten their life span , nissan does not charge them that high . Assuming you bought them on Ebay , They will probably have about 42ah left in them .NONE are anywhere near their original 64ah . So expect range in the 15-20 mile range . Leafs are one of the easiest installs .
