Error code 15 when LCD shows fully charged

I have a 2005 GEM E2. It had new batteries installed 3 moths ago, I use it to drive around the campground on weekends, the LCD on the dash will only drop down 2 or 3 bars, and I always charge it when I get home. Today as I driving it went into turtle mode and stopped after about 1 mile. When I turned the key off and back on the -15 error code was displayed but the LCD still showed full charge. came back 15 minutes later, turned it on, no code, full bars, and drove back fine. I was having similar issues before the battery change (hoping replacing the 3 year old batteries would help). Have maybe 30 miles on the new batteries. Maybe a charger issue? How do I measure charger output? The charger profile was set for battery type. I’m charging it now, will see if the charger shows an error code. Any ideas? I hate that stranded feeling.

Do you know what charger you have?
I’m guessing a 05 will have a Delta Q. It is yellow with black fins. It is mounted up front under the speed controller.
There is a panel visible on the driver side down low if you look above the tire.

When plugged in and charging it will show a status on it’s LED panel.
What lights do you see?

I just plugged it in, so right now it haws the second from the top (AC) light and the bottom light. (6 bars)

Ok- that is a good sign.
Second Q- What type batteries did you remove? and what did you put in?

If you changed battery types, did you adjust your charger?

I have Interstate deep-cycle SRM-31 batteries 675 CCA 845 MCA. It had NAPA 8231 when I got it. the charger profile is set on 13. Can I check the charger output with a multi-meter?

Ignore soc imo. -15 is low voltage and always (almost) dead battery or bad connections. As per Rodney “tight and bright”.

Y- Ignore the LCD meter for now. There are things that can mess with the calibration/accuracy. Sounds like it is out of whack.

Let the car go through a full charge and verify voltage with your multi-meter.
It might be time to do a full battery check-up.
When was the last time you watered?
Check each pack to see they are all still happy.
Check all connections.
If all is healthy then reset the SOC meter.

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basically new batteries. been on the charger maybe a half dozen times and always turned off the main breaker after charging while it sits in the garage. cables all tight. water levels good. Where else can i look for a loose connection? SOC meter? How do i reset that.

Don’t know how accurate my meter is, but getting 80 volts while charging. kinda waiting to see if it goes through a complete charge cycle.

Now that it has been a couple of hours what is your display telling you now? (specifically the 1-6 charge rate bars).
Note that your charger is probably mounted upside down in your car.

SOC meter should only be reset when charge cycle complete. Probably a good idea to let your batteries cool off a bit too.

SOC Reset 2009
Turn the key on.
Push and release the TRIP/ODOMETER switch until it’s showing the
While holding the switch down, turn the RIGHT signal on, then the LEFT
signal, then return the blinker to the center.
Release the TRIP/ODOMETER switch. You should be seeing data (P0105) on
the display now.
Turn the RIGHT signal on, then off repeatedly until the display reads:
SOC (State Of Charge).
Push and release the TRIP/ODOMETER switch. Now it’s remaining capacity in
You can now raise (or lower, for that matter) the SOC with the blinker
When you’re happy, Push and release the TRIP/ODOMETER switch. The display
reads: DONE.
Turn the key off.

so an update on the charger, It’s been on about 5 hours and the AC light is still on, the bottom light is still on (the one with 6 bars) and the 80% light is on. checked the voltage at the batteries, getting about 85 vdc now with the charger on. Does this sound right?

Yes. your batteries were dead. Charger is going thru a full charge cycle. You gauge will probably be pretty accurate now.

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Gads! I would have thought it would have gone down to 4 by now.

Are your batteries hot?

Another update on the charge cycle, after the first 5 hrs. or so on 6 bars it took another 3 to gradually get down to 2 bars with the completion indicator flashing, where it stayed for another 3 or so hours then went solid green. At that point I checked the SOC meter and it read 99%. While that all sounds normal, it doesn’t explain my original problem of the dash LCD showing full bars when the batteries where obviously dead. This is what really frustrates me. Is the dash notorious for being inaccurate? Do I need to monitor the charge cycles close every time? I plugged the charger in when we got home 2 weeks ago and I always check under the fender to make sure it comes on. Can something be draining the batteries that much just sitting in the garage with the main breaker on? I used a heavier gauge cord this time, could that be the key? Any insight or opinions on this would be greatly appreciated. Thanks in advance.

A Gem can be fully charged but if left to sit unplugged, it will slowly drain the batteries to Zero. Since the Gem is off the gauge will not go down. The Gem will have low/dead batteries but full bars. Every Gem will do this. The answer is to leave it plugged in with the master switch on. The charger will auto restart and keep your batteries topped off and your gauge accurate. Gems with DeltaQ chargers only.

In concept the SOC meter is a simple register. It keeps track of the electrons going in and out and compares the count to what it thinks should be contained in the box. In reality they can be quite complex. Sometimes it just gets a little mixed up.

The smarter ones I have dealt with will keep track of the last discharge cycle, does a calc compared to voltage remaining and constantly adjusts as it is being used. I haven’t played much with the one built in to the Gem to decide how accurate or how smart it is.

One thing that the SOC meter cannot adjust for is if one of the batteries is taking a dive.

Part of your battery “check up” needs to be checking the voltage on each battery. Write these numbers down. Maybe even keep a log book. Ideally they should all be fairly close to each other and work as a balanced pack. In practice they can get out of balance and not work as a team and may need help getting back into step with their mates. If gone unchecked, that lowest battery can dip below it’s bottom threshold and starts to do damage. If the other batts are still high you may just notice your car is running slower and continue on your errands.

Now that you have completed a full charge try plugging it in again and give them another charge to top them off and chance to equalize. Do a Brake stand/load test and look for a weak one. Keep an eye on that battery.

After running the car a while check the V again and look for one dropping off faster than the others.

This may expose a clue as to what is going on beyond observing the SOC meter.

I agree with you, they are not dead battery they are super dead; needs new battery.