GEM powered with (7) 12v gel batteries

As the title reads, I have (7) Deka 8G31 batteries in my gem. Long story short, guy said I needed (6) 12v batteries when I really needed (9) 8v batteries. Nonetheless, it is what I have in there now. I have a Delta Q charger that I would like to reprogram to full charge all 7 batteries. Does anyone have any suggestions?

There are no profile for that in a 72v charger. You need an 84v deltaQ, which is somewhat rare.
Worth your trouble though as it will boost performance and range.

Or what most do is use a 12v charger on the added battery.


Dude, don’t fret, your gem will love the extra voltage. The salesbag actually did you a favor with their frack up. More range and potentially more speed. All you need to do is mount he extra battery, install some extra battery cables to hook it up and depending how you connect it, possibly an 84 → 72v shunt on pin 1 of the controller. If that’s all you do, you will get more range and better acceleration. If you want more speed, you need a programmer or get a magic magnet from @Inwo, who usually also has the shunts if you need them.

You can charge the extra battery with any basic 12V portable charger that is compatible with gel batteries. .

Oh, and check your DQ to see that is is set for the proper profile for the six (6) 12V gels. Wrong profile = premature battery death.

The links to how to do it:

Rodney’s original thread:

The thread where Dave and I went a bit over the top, but found a way to do it without the shunt and without having to disconnect the 7th battery to charge as we isolated it on the other side of the contactor from the main pack.

I used lifepo4 pack for #7 in that experiment, but others have been successful with the same wiring arrangement and traditional batteries

I think there is an easier way. I have thought about moving the positive charger wire from psdm to the #6 positive battery. The charger would then only charge 1-6. Then put the other batteries after #6 with dedicated chargers. Gauge on dash wouldn’t work but I think batteries would charge fine.

@mdixon - Hey! I was wondering what happened to you. Last I remember you were off and getting your motor rebuilt.

Alright, lots of information to digest. My 72v is on the correct profile, I made sure of that when installing the initial 6. So it’s either upgrade my charger to an 84v or connect the one battery to a separate charger. Dumb question, so I would need to disconnect that battery from the cycle and bypass it each charge? I found an 84v charger for $500, what’s the going rate for a used 72v charger?

I also need Hood and trunk/bumper/bed for it (2014 e6) if anyone knows where one is.

Depends how and where you connect it. Each of the three methods have the battery wired up in a different location on the circuit.

I recall that Rodney’s original method required you to disconnect the 7th battery for charging.

If you follow the wiring diagram from Dave that is posted in my thread, you can leave everything connected.

LithiumGods suggested method should also work without disconnecting anything, You will need a voltage shunt on the controller harness connector for this wiring arrangement.

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