Question about recent battery replacement in 2008 GEM e4 -- Gel to AGM

I have a 2008 GEM e4 special addition that was running six 12-volt East Penn (Deka) Group 31 gel batteries that were over 7 years old. When fully charged, I would get around 6-7 miles before half of the green bars were gone on the charge indicator so I was having a bit of range anxiety (the owner’s manual says I should get 30 miles at 72 degrees).

Due to recent supply chain issues, finding Group 31 batteries has been extremely difficult, even here in Atlanta. I was not able to find gels, so I installed six NorthStar NSB-AGM31 batteries which are very good batteries (at least that’s what I was told). I took meticulous photos of all the wiring and checked and re-checked everything when I hooked the cables back up. All the batteries were fully charged (most were at around 13.3 volts sitting still).

I took the car out for its maiden voyage and got about 5 miles before half the green bars were gone (worse than the old batteries). Also, the last mile it was really struggling up the hills (around 13mph max) and the yellow turtle came on. I got her home but I am scratching my head.

This car has never given me any problems until now. Are AGM batteries not compatible with a 2008 GEM? I know gels were original equipment, but the guy at the battery shop said several GEM owners have purchased these NorthStars. Any insight would be greatly appreciated.


You need to change the charger algorithm. Gel batteries can’t be charged up as far as AGM, so your batteries are only starting out at 85-90 %. Once you’ve gone through a few cycles, you might need to reset the SOC (state of charge) indicator.

Search on DeltaQ GEM charger to see what profile you need to switch it to and how to execute the tappy-tap-tap method to change or kick down 2 bills for a programmer

Thanks @jrjava. You mentioned my AGM batteries are only starting out at 85-90% since my charger can’t completely charge the AGM batteries. However I individually charged each battery to full (13.2 volts each) just prior to install, and I only got 5 miles on my first ride. This doesn’t make sense. I could see this being the case if I ran the batteries down and tried to charge them up using the Gem’s charger.

I searched “DeltaQ GEM charger” and came across a PDF file from NEV accessories containing algorithm selection instructions on the DELTA-Q. However it’s for pre-2005 models and my car is a 2008.

The information I have been able to gather about DeltaQ GEM chargers mentions nothing about AGM batteries (everything is about gel batteries). So these are the questions I am hoping to get answered:

  1. Is there an existing (pre-loaded) algorithm already in my 2008 e4 that will work with these AGMs?
  2. If not, do I need to remove the charger and send it off to get re-programmed so it is compatible with AGMs?
  3. Is changing the charger algorithm something a Gem dealer could do?
  4. Is there a way to bypass the factory charger and install a 72-volt charger that’s compatible with AGM’s? I’m thinking I could mount it under the rear seat, run the leads to the main positive and negative, and run the charging cord out the back. However I don’t know if this would negatively impact the rest of the car’s electronics.
  5. What do you mean by “Kick down 2 bills for a programmer?” What type/brand of programmer are you referring to?

Thanks for your help. Sean


So looks like you may have a few issues going on.

First off, see the image below on how to check the charger profile and adjust it if necessary. If your GEM was stock with gel batteries, you should be on profile 14. You need to be on 32 for the AGM batteries (treat AGM batteries as flooded lead acid batteries if no AGM profile exists).

Programmer: QuiQ propgrammer from DeltaQ

It makes changing the profiles a breeze, but not something you typically need to buy unless you are working on the chargers often and upgrading them

Try the tappy-tap-tap method to change the profile. If that doesn’t work, LMK. I’ll entertain possibly lending you mine for for a pre-determined amount of time if you cover all shipping and leave a fully refundable deposit equal to the cost of replacement. Oh yeah, you’ll have to disconnect some wires to use it, probably take your dash partially apart as the PSDM interferes with the serial transmission.

As for the crap range…

Make sure all your battery terminal connections are clean and free of corrosion and that no battery connection cables have rotted partially through. .

Get a battery pack voltage measurement when they are charged and then after you drive X-miles. Get individual cell voltages too if possible.

Check if you have dragging brakes. Jack the GEM up and spin the wheels by hand. It will be evident if you do. Rear brakes (parking brake arms) are notorious for hanging up. That will absolutely kill your range.

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What jrjava says ^^^

In addition → What tires are you running? Check the air pressures?

Once you get the profile set for your new batteries take your car for a test run and do some Voltage checks on your batteries. Chances are your SOC meter on your dash will probably need to be reset. If the turtle came on then yeah, your V got real low. There may be one in the group that is bringing down the pack. Check them after a run. If not obvious then a load test may be necessary.

I don’t know those batteries but anything that says it is built as “dual purpose” sounds like a compromise IMO. 30 mile range out of these batteries is a bit ambitious.

What is the condition of your motor? it might need a service. If it has been worked hard in a hilly area then it may be smoked and consuming more amps. At least pull the motor off, give it a dust-off with compressed air and give it a good inspection. Make sure the comms are not scorched, brushes are sliding free in their holders and windings are not ugly black.

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Thanks for your willingness to help out @jrjava and @AssyRequired. Here’s what I found:

  • Jacked up rear end and spun the wheels. No brake drag at all (not even the slightest). Same with the fronts.

  • Tires are Cooper 185/60R14 (stock from the factory on the special editions). Air pressure good.

  • Motor is the factory 7.0hp GE unit that was standard on the special editions. It’s never given me problems and pulls strong to 26mph (governor limited), assuming of course the charge is good. I don’t believe it is worn out as this vehicle spent its entire life in the Villages of Florida (flat as a pancake) until I bought it. We have extremely minor hills in this part of Atlanta.

  • I ran the volt meter across all the batteries. Every battery was fully charged (13.2 - 13.3 volts prior to install) and I ran the car about 5 miles on its maiden voyage before my issue started. I have not charged the car since the problem occurred. Here’s what I found:
    – Main positive to Main negative = 72.9 volts
    – Battery #1: 10.3 volts
    – Battery #2: 12.3 volts
    – Battery #3: 12.4 volts
    – Battery #4: 12.5 volts
    – Battery #5: 12.5 volts
    – Battery #6: 12.4 volts

All batteries seem consistent except for #1 (the one underneath the back seat, far right side that hooks up to the frame-mounted fuse). Even though the entire system has 72.9 volts, could this one low battery cause my problems? The place I bought these batteries from load tested them all before I took possession . . . all passed. I will see if I can get a replacement, but that still leaves me with a not-friendly-to-AGMs charger problem.


How long has it been for this battery swap?

#1 is very much a problem. This is after 5mi and essentially at rest. Measure this with a 100A load and it probably drops to 7 or 8v. (Gem cars can pull 300A when really pulling hard).

Something happened to this battery. You could try to boost this battery back up with your external car charger but confidence will not be high.

The other notable point is that after your 5mi run it looks like most of your batteries are resting at 90%. Depending how low they go when loaded they might be ok.

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Yes, it most certainly can be the cause of the problems. 12V batteries are fully charged at 12.6 or more and are considered dead at 12V (40%). A reading of 10.3V is far below the minimum and is possibly damaged. If you can get it replaced that would be ideal.

Why it is dead is yet to be determined. It could be a dud or do you have extra electronics hooked up to it? Like additional lights or stereo? Other equipment?

As for the charger, start by following the directions on how to count the blinks at power up and determine what profile it’s set to. Then, if it’s not correct for the new batteries, here is a video on how to change the charge profile. If it’s the original charger, use the GEM profile numbers. If not, post a picture of the model # / serial number sticker - different variations have different software loaded.

Living in high humidity increases the chances of issues with the brushes & holders. If the motor has an inspection grill / band that you can unbuckle to take a look at the condition of the brushes, holders and commutator, it wouldn’t hurt to do so.

@jrjava, @AssyRequired ,

The new batteries have only been in for a couple of days. I took it out for its first ride last night.

Everything is stock on the car. No additional lights, stereo equipment, etc. This thing has lived a pampered life.

I will try to get a replacement battery for the one reading 10.3 volts.

Is there an easy way to get to the charger or does the dash need to come out? I can’t find any info on dash removal. Any suggestions . . . I don’t want to be breaking any of this plastic.

@jrjava – you mentioned a video in your message but I don’t see a link. Could you tell me how to view it?

A while back I inquired about getting the motor freshened up but couldn’t seem to find anyone local interested in doing it. But I only called 2 to 3 electrical motor shops before I gave up.

Thanks so much fellas. I really appreciate your help.

The other notable point is that after your 5mi run it looks like most of your batteries are resting at 90%. Some of them are down to 70%. Depending how low they drop under load they might be ok. Try to get all the batteries up to the same V before starting off on the next run. All the batteries are supposed to travel up and down at the same rates. Due to company quality control this is sometimes not possible. This is one reason why it is good to get the batteries all from the same run. Mixing batteries usually does not produce good results.

Technically, when the first battery reaches 50% you should stop driving. Anything below that and it damages that battery. The weak battery designates the range of the pack.

The tricky part is that with the present (stock) monitoring system you have no idea when that happens.

12v battery SOC%

Your charger will be up front, under side of the shelf the Motor Controller is mounted to. It is yellow with black fins. It has it’s own display panel that is visible from the driver side if you look over the tire and past the shock (wayyy under there).

Did you check what profile you are using now?

To check current charge profile

  • Flip the Battery Disconnect switch OFF (bottom of the fuse panel).
  • Plug in the car as if to charge. Look at that panel on the Charger (not the dash).
    The display will light up, do a boot-check and then blink a pattern.
  • Count those blinks. If a multi digit code there will be a short pause between the blinks then a longer pause before it repeats the code.
    It will repeat the code maybe 3 times and error out with a Red(2) - Battery out of range.
    This is normal. (Duh - You switched it off for this test).

I think I accidentally deleted the link while writing the post. Here it is:

They are not. Classic Gem chargers do not support AGM.
It would have been best to ask here first buy later,
However, you can have your charger sw changed to support agm charging.

I found my Delta-Q charger and accomplished the steps @AssyRequired posted. It displays a single flash–pause–4-flashes, so that is program 14 which is GEM DEKA 8G31 gel.

According to @jrjava, all I have to do is set the charger profile to 32 in order for it to be compatible with AGMs (using the tap method shown in the video). Do I have that right?

@inwo, you mentioned AGMs are not compatible with GEMs. Fair enough. Unfortunately I couldn’t find six Group 31 gels in the entire Atlanta metro area, so I went with what was available and trusted the salesman. Am I opening up a can of worms by keeping these AGM batteries, even if I set the charger to program 32? I am wondering what the second- and third-order effects of this action would be long term (sorry for the military lingo there).

I have no problem returning the batteries if it comes to that. I’ll have to wait until who knows when to find gels. Unfortunately my old (but still usable) gels have already been turned in for recycling.

Right now I feel like Clark Griswald from the movie Vacation . . . turned in old wagon – expect to receive new wagon – old wagon gets put in car crusher – forced to buy the family truckster. Ha ha.


It totally depends on what your goals are for the car.
Some people get these things on a fluke and don’t really know what to do with it.
Others get it for a campground runner, mail/ice cream retriever.
Sometimes these cars fit into a neighborhood scenario so well that it becomes a primary vehicle. Being actually street legal is a real bonus if you have a network of slow speed roads to use.

Depending on your needs, skill set, and what you have in your toolbox, there are other options available far beyond the old Lead acid tech. Downside is - NO DEALER WILL KNOW WHAT TO DO WITH IT. You will be the guy from here on out.

Do a quick search in the archives and use variations of keywords and phrases like lithium, conversion, SDI22, Lithiumgods, Inwo,

Prices range from

  • cheaper than what you have invested in your current lead pack,
  • I don’t care, I want to drive for 100 miles.

These are exciting times.

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@AssyRequired just hit the nail on the head…

You paid, I’m guessing around $2500 for the 6 AGM batteries?
For about that same price, you can get a lithium pack if you are willing to return all of the AGMs and do a little bit of modifications to the GEM yourself.

With lithium packs the voltage will be a bit higher and the GEM will be 300 lbs lighter, so it will perform much better and have more range. And, you’ll probably never wear out the battery pack. Getting 30-35mph sustained cruising speeds with the lithium pack is easy.

You can also spend more than $2500 and get crazy range and performance.

@AssyRequired - I live in a golf cart community outside Atlanta and we use our GEM all the time to get groceries, run errands, etc.

If I could go lithium I would (within reasonable cost, and the $2500 @jrjava mentioned is certainly reasonable). Trust me, I’d rather put the money I spent on these AGMs towards lithium and drop the 300+ pounds. I already researched the LithiumGods option but every time I asked Mike when he had stock available it kept getting pushed back. Plus I got the impression I’d be on my own as far as installation is concerned given there was no formal customer service network or installation manual provided.

This past spring I spoke with Ride-4-fun and they said they were a month away from offering a drop-in lithium pack for pre-2016 models. However as of today they still display “coming soon” on their website and I wasn’t comfortable being a test–bed for an entirely new system. So that’s how I wound up here.

I can pretty much hold my own with just about anything mechanical on this car (brakes, suspension, etc.) However when it comes to the electrical system, I am a bit out of my comfort zone. The unfortunate reality is that despite having no less than 8 dedicated golf cart shops in town, NO ONE will touch this GEM. They just laugh and hang up. So it’s all on me and those of you on this forum who are generous enough with your time to help me out.

You could also try contacting @Inwo about a battery pack. Sometimes he has them available or can possibly build one. Sometimes they come with the BMS already installed too, so 90% of the work is done.

The packs from Dave and Mike, the SDI for example, are almost drop-in. You just might have to do some minor modifications to the battery bay to fit and secure them. You can also get lose cells from Dave, but building their own battery pack from scratch isn’t for everyone.

Mike and Dave don’t leave people hanging on installs, while there might not be a formal manual, they will guide you through it and there are also those of us here that have done these conversions a number of times.

I think the rumored R$F lithium battery might actually be LFP (lifepo4 - lithium Iron Phosphate) based. That technology is a bit on the bulky side and somewhat dated at this point for vehicles. Two new Samsung 94Ah SDI cells can fit into the space and weight of a single 60Ah FLP cell, and further increasing the suckage factor of LFPs is that they only charge to 3.7V whereas those two Samsung cells can charge to 4.1 volts, so you need less of them.

I have inventory. Like 80 modules available for immediate shipping.
I don’t advertise, preferring to work on my own projects. LG has a lot to deal with after getting flooded. Scotty and I have batteries to be picked up, dropped off by @GHTransport , or shipped.
sam 22s on shelf
Wet profile may be better than Gel profile, but reprogramming charger for agm is better.