4 AGM ?Distance? Leoch Batteries only 8 Miles Range? Main Wiring Harness Problem? 2016 GEM E4

Hey everyone; I’m new to the community, but I’d like to say thanks to all of you who have contributed to this great resource for GEM Cars. It’s the best one out here by far and without question.

I’m having some really weird battery problems in my 2016 Polaris GEM E4. I have FOUR 12V Leoch AGM ?Distance? Batteries rated at 120AH each.

For whatever reason, despite which battery I cycle into the 4th Battery Position (where the main Negative Connection Terminal for all the batteries in the array connect to the gem car) always measures a much higher voltage during charging, discharging and also while at rest and not charging than all the other batteries in the series.

Is this normal? I thought all these batteries were supposed to be perfectly balanced, but my scientific method findings were that whichever battery I cycled into the 4th battery position was also being reported by the Bluetooth BMS on each battery to be much higher than all the other batteries.

It’s so much higher much so that it causes the bATT VHigh Fault Codes and it was returned to the dealership in this condition after spending thousands on the replacement batteries and repairs that the local technician claimed was just one bad OEM Flooded Lead Acid battery. Someone needs to tell me I’m not crazy, this isn’t normal right?

I’m supposed to be able to obtain 30 miles per charge with this battery array/configuration. But I’m have big problems achieving more than 9 miles per charge and while admittedly doing most of some steep hill climbs, I expected more; especially where they indicate “Increased confidence, especially in hilly terrain” in the advertisements. I also got fault codes while doing the Hill Climbs 7 520508 1.

I’ve kept each bluetooth BMS with each Battery and at this point have cycled them all into this 4th position and they all point towards a problem with higher voltage with whichever battery is in that position.

This 2016 model was recalled and during the process, they modified the forward/reverse gear stick and added a rocker switch right next to the Tachometer and they also added a new 12v battery for some reason under the interior front dash that I worry may have caused or is currently causing these problems.

Is this just a wiring harness problem or something? Battery to Battery series connection problem, imbalanced draw?

Is this just the limitation on the weight of these heavy batteries? Looks like the advertisement for range to be based on flat road conditions driving and I live in Birmingham, AL.

Anyone that might be able to help me understand what’s going on here is highly regarded and much appreciated!


Is the red wire by battery #1 positive, (pos 4) disconnected? One or both ends?

I think this video might give a better perspective.

I see it’s still connected to the battery. If it’s connected at the front, the recall was not done correctly.
A relay is added to keep aux. battery charged, but the the 12v tap on the main pack must be disconnected.

I have an extra active battery balancer/ monitor that I picked up for my 2018, if you are interested.


Maybe this will help clarify my question.
This is the wire that is over charging battery #1.

It is used to power constant 12v systems when there is no auxiliary battery.
The added battery is kept charged with dc-dc converter by adding a relay. The red wire must be cut to isolate the new battery from battery #1.

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Does that work the same on the Ford think?

I haven’t found a 6 battery balancer yet.
It would take two of these 5s models.
They are relatively low cost. About $100 as I recall.

Two of them would balance 9 x 8v if they work on 8v batteries. Never tried on lower voltage.

I want new batteries on the Ford think because it literally only gets 4 to 7 miles and that doesn’t sound right. So I’m lost on the problem. Maybe you have some insight?

I just tested all batteries and all are getting close to 13v while one is getting 10.6. That may be my issue?

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Man I can’t tell you how thankful I am for you being able to help identify this problem for me.

Yes, as you point out, the thin red wire is definitely still connected to the positive battery terminal of battery 1 (position 4). You say that if this isn’t disconnected where you circled it in your photo, they didn’t perform the recall service properly??

So I just disconnect the Battery Ring Terminal of the thin red wire where you have it circled on Battery 1 (Position 4)?? I should wrap it in electrical tape and zip tie it off?? Additionally, you specified that it should be disonnected from the front of the GEM Car as well?? Both ends of this thin red wire need to be disconnected? You say it goes directly to the new AUX battery under the front dash?

It looks like the relay is first mentioned on page 9 of 14 of the recall bulletin, can you tell me which page and which step was missed?

Again man, I’m so thankful for you! I’m going into the office today to give it a try. Also, I’m PMing you my details for the Active Battery Balancer/Monitor. I’m so so so so thankful for you man, don’t know what I would do without you at this point. You sure know your GEM cars.

I don’t have access to update instructions. I only know that the 12v battery tap did not work out.
An auxiliary battery was added which is charged by the dc-dc converter when key is on.
As the added battery feeds the same “always on” circuits as the 12v tap did previous, the red wire from tap needs to be disconnected. If it remains connected, the dc-dc will also charge battery #1.
Somewhere I read to disconnect both ends and tape them up.
One end should be just as effective in isolating the first battery in string from and loads or circuits.

If auxiliary battery goes dead, something else was not updated properly.

Are you familiar with the Ford think battery wiring? I need to figure out this mileage issue as well.

Yes, that’s an problem.

Check the connectors to that battery. “Bright and tight” as Rodney says. If it’s a farked battery, replacing that one might help a bit, it kind of all depends on what condition the others are in. If they are all the same age, then you might be good for a few months before the next one takes a nose dive, or you could be good for a year. Voltage is only part of the equation, so many factors, it’s a crap shoot.

I’m trying to charge that single battery now to see if that will work. I have a 12v Noco Genius charger that might do the trick.

Definitely worth a shot.

If not, I don’t think I’ve heard of a lithium powered Think… that would be a blast to dirve… lithium, RWD, tall gears and a high rpm motor… Might eve be able to do some skids.

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