Gem e6 battery pack

Have a gem e6 with new batteries 9 8 volts that slow down on a half battery charge what should I do this are some pictures of my issues

About all you can do is charge the batteries.
Either the batteries or cabling, can’t hold the voltage above the minimum required for high speed.
I guess you could reprogram for full speed, but it would only kill your batteries faster.
If batteries are new, maybe it will improve after a few cycles.
IMHO, I’m no expert on lead batteries, nor do I recommend them.

Some More info:
His controller is a New T4 that he got from Mike Mc from FSIP.
He also said that One of his 9” 8v battery’s has a compromised positive terminal. (I guess one of his battery connections was loose and it burnt the pos terminal and now he is using a secondary connection to that compromised battery. My thought was that the battery that got hot is possibly compromised


That is a distinct possibility, Dave. Melting a post is never a good thing for a lead battery.

Also, 9 batteries in series via flexible copper cables and counting on a bunch of 3/8" nuts to create good contacts by pressure alone is a lot of places to pick up extra resistance.

My first guess was to “load tes the battery that has a comprised post. Any good automotive shop will do a battery test for free

My first guess was to “load tes the battery that has a comprised post.

I was thinking he could just put a meter across it and take it for a drive. If the damaged cell is in the middle of the pack he can put the meter lead on the next post in line(so it measures the quality of the compromised connection).

If you had to guess what do you think Voltage drop would be on a FLA battery when he puts a load on it.
Example the battery is fully charged 8v and you take off a healthy battery would drop down to what? 7v 6v? Just wondering

Need a baseline on a good one first. What if the whole pack is clapped out.

I agree. I had a battey go out on what I thought was a perfectly good pack. 1 of the battery’s just cracked and gassed. The entire pack dropped below spec and the car went into turtle mode

Do a brake load test. If you have a dud it will show up in a hurry.

hook uo your volt meter to the full pack and take it for a ride. If you have a problem you will see a voltage drop. Then check each battery for a bad one.

Yeah, that is a given.
The ONE time I didn’t have time write a 73 line essay/explanation and you call me out on it!


Personally, I like Grant’s suggestion about using a load tester, you don’t really need historical data. It’s like the brake load test, when it tanks a bad battery, you know it. One of the reasons why I own a 400A load tester. Unlike the brake load test, you only beat up one battery at a time. Down side is, that for 9 batteries, I’d have to toss the load bank in the freezer of a bit every other test or so after the first few. Otherwise it will be so overheated that it won’t pull the desired amps.

@grantwest . I’ve seen the combined per-cell average voltage of a fully charged 36 cell FLA pack, which was otherwise healthy save 4 of 6 cells cooked in one of the batteries, fall to below terminal voltage per cell under heavy load, So between 6 and 7V for that one battery is a possibility.

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This is what I found so far one of my batteries that was the terminal was burned shows 8.3 volts and when driving goes down to 6 and even 3 volts other batteries show 8.6 and when driving 8 volts so am guessing just buy one new battery right ???

Yeaup. Just go replace that one for now

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wish you were close, have a few good used one for 100/ea