Charge error

Greetings all, my 2001 e4 will read 100% charge but the indicator will indicate a 40% drop within 1 mile and will decrease further down as you drive. I let it drop to 0% and I got the warning horn for low battery but the GEM ran fine. Right before this problem came up the speedometer quit working. I did replace the batteries when I bout the used GEM but I did not know I had to calibrate anything. I do not get any error codes or lights.Any help will be most grateful. Thanks, Don

How old are the batteries and what type are they; flooded lead acid (FLA), AGM, GEL? Are they “industrial” or “marine” grade deep cycle? Who made them? Are they 6 months old or 5 years old or something in between. How closely and well have the batteries been maintained? If they’re FLA have you checked fluid levels monthly and topped off as necessary? Is the charging profile of the charger matched to the type of battery? They all have different charging profiles and the wrong one will destroy your batteries or at least greatly shorten battery life. How often is your GEM driven? What level of charge do you typically achieve? Have you ever driven it to less than 50% before recharging?

Batteries [B]by far [/B]are the biggest problem you’ll have with any GEM and are the “weak link” in the GEM power system. There are a [B]lot [/B]of variables that need addressed.


Greeting Al, they are regular deep cycle.

DC 31, CCA725

And how old are they?

Hmm, my last post got out-of-order somehow. See above.

Hello again Al, the batteries are about 2 years old. We keep them serviced every 3 months. I don’t know any thing about the charging profile but I did replace the batteries with the same type that was in the GEM when I got it. My wife normally drives it everyday in the summer and about every 3 days in the winter. We also had the batteries tested at a local golf cart shop and they said they were good.The battery indicator shows 100% charge when we charge it but will drop 20% or more (indicated) within a quarter mile. I let the indicated charge run down to 0% and the car ran normal but the low battery warning horn sounded for the mile and a half back home. The speedometer stopped working a couple months prior to this. Thanks for your help. Don


Hmm, sounds like you’ve touched essentially all the bases on the batteries. Still given my experiences w/ my GEM, I’d lay pretty fair money on it being a battery problem and not something more exotic.

The controller measures the pack’s overall voltage drop and correlates that to a SOC (state of charge). Since it’s reading all 6 batteries (72V), it can’t tell if one battery is “bad” or “low” but indicates the status of the entire pack. If one battery isn’t pulling it’s load, the cumulative pack voltage will be low and the other batteries will discharge faster when called upon to power the cart.

BTW, sells a device that measures the SOC for each battery in the pack and that unit does a very good job of identifying exactly which battery is bad. I don’t own one but it’s on my list of “desirable upgrades”.

My inclination would be to charge the batteries to an indicated 100% and then test each cell of each battery with a) an inexpensive hydrometer to see where they are (showing either specific gravity or “% charge”) and b) a voltmeter across each battery to get a reading of the voltage on each battery. Unless something stands out immediately, I’d then run the GEM down and repeat these tests. I’d be looking for a cell/battery that is substantially “off” the readings for the other batteries. In my case, I had one battery that had one dead cell and two other cells that were “iffy”. I ended up replacing my entire string of batteries and that resolved my problem. That’s an expensive fix but it did solve my problem.

Not sure about your speedo problem. I’d suspect the RPM sending unit on the end of the motor to be the culprit there. It’s an electromechanical unit that senses motor RPM which the controller translates into MPH based on the various parameters it has programmed into it. If that goes, all sorts of problems arise. The controller will send more current to the motor to try to get it moving (since it’s not sensing anything happening) which can cause spurious errorcodes and of course draws down your batteries. Though from what I understand if it goes, the cart usually won’t run at all but shuts down almost immediately.

I suppose you could also have a wiring issue, a bad speedo indicator unit, maybe even a bum controller (maybe one that needs reprogramming?) as well although these start to get into the “exotic” category and I’m a firm believer in Occam’s Razor.

Do you have a competent GEM mechanic in your area? After testing your batteries, it might be time to get him/her involved.

Good luck!



One thing you never clarified was what type of “deep cycle” batteries you have.

For whatever it’s worth and in my experience: if they’re “industrial deep cycle” (e.g. made for industrial applications like forklifts, scissor jacks, etc and manufactured by Trojan or Dekka or a few others) that’s perfect. If they’re “marine deep cycle” (made by Interstate, etc), then I personally feel they’re pretty much worthless in the application you’re using them in and I’d expect to get only a couple of years out of them if that. Marine deep cycle batteries simply aren’t designed for the sort of heavy loads placed on them by the GEM application.

I had Interstate “marine deep cycle” batteries that were 2 1/2 years old when I bought my GEM used and was assured I’d get several more trouble free years from them. However I kept having problems w/ them dying on me a cell or battery at a time. I replaced one battery only to have another fail within a few weeks. Finally after much frustration and several tows home I bit the bullet and replaced them all with Trojan deep cycle 30XSH at nearly $200/each and my problems went away. It was a painful and expensive lesson but I learned it well.


Hello again Al, I checked the batteries and one of the original batteries is a “Delka Marine Master & RV” battery and the others are what Millennium Batteries said was the equivalent. That may be my problem but I have 2 questions, If I get new batteries how do I set the charger up and why would the GEM still run fine with the indication of 0%? Once again, thank you for your patience and help. Regards, Don

Couple of questions in my mind.

  1. Why does speedo not work?
  2. Why does it run OK w/ 0% indicated?

AFAIK, the % SOC is based on voltage drop. IF one of the batteries is kaput, the voltage could I suppose in theory drop sufficiently to show a 0% (I don’t know how the displayed percentage is calculated) but still provide sufficient power to run the motor. I doubt it’s a “precision” thing.

As far as the marine batteries are concerned, I’d lose the whole string and replace ALL with Trojans. [B]Resist[/B] the temptation to replace just one. Of course I’d test the batteries FIRST as I’d outlined in an earlier post. I’d be willing to bet that would solve at least some of your problems.

Yes I know, I know, I resisted that solution myself until finally I’d exhausted all other “reasonable” options.


Al as much as I would like for you be wrong I know that you are absolutely correct and I need to get new Trojan Batteries. I have a Zivan charger, do I need to set it to a certain selection? Sorry to be such a pain. Regards, Don


Well before I did anything else, first I’d test the batteries to verify that one is kaput. If one is THEN I’d replace the string. If not, then there’s something else going on.

As far as the Zivan charger goes, I can’t give you any advice since I don’t have that charger. I replaced the charger with a heavier duty unit from another manufacturer. I do know that you need to have the correct charging profile (FLA, Gel, AGM) matched to the type of batteries installed (FLA, Gel, AGM) or you’ll have problems galore! Someone else will need to advise you on setting your Zivan charger profile.


On the Zivan charger “F” isused for flooded. We have had this issue with the gauge quickly running down. It is one or two weak batteries. Here is how to find which batteries are weak: Drive the GEM untill the batteries are noticably depleted. Then, accurately measure the voltage across each battery. One or more will be lower than the rest. You may get something like the following: 12.5, 12.5, 12.5 12.5, 12.3, 12.5. Check them several times to be sure. Replace the lowest reading battery. Unless you need peak performance and range, it is not neccesary to change all six at ounce.