Hi, I am having trouble and am stumped on this one.
We have the lithium battery pack in a 2018 GEM E6.
The temps got low which is when we started having this problem.
The battery pack voltage is around 53, which is typically plenty of charge to drive around.
When you turn on the key, it shows no charge, but you can drive it around with full functionality and power for about 60 seconds even though the display shows 0% charge.
After about 60 seconds, the display reads “bat loTEMP” and there is not enough power to move the cart you can feel the cart trying to move, but the power seems to be cut.
When you turn it off and wait a few minutes, you can continue this cycle over and over.
If you plug it in (Zivan Charger) it will indicate charging for about 60 seconds and then switch to the “bat loTEMP” error and not accept a charge.
Originally, I though it was a low temp battery because it was cold out and maybe the internal battery heaters were not working. I waited for a warm day (55 F and sunny) so I knew the battery would be warm. The same exact thing happened with no change. I unhooked both batteries (lithium and small 12v computer battery) hoping the system would reset. There was no change. I then moved it into a heated garage (65 F) for 24 hours and the same thing is still happening. I changed the converter dc-dc sevcon converter in the battery compartment for a spare we have, but that didn’t help either. I unplugged all the connectors, blew them out and reconnected and am still getting the same error. No blown fuses.
We have digital wrench, but are not experts in using all its functions. I erased the error codes, but they just return immediately.
Please help!!!
Is this a factory battery from Gem? or did you install something else?
Are you sure it has battery heaters? (I think this was only a recent addition to new batteries).
Do you know how cold the temps actually got to? The car has been up to 65 for 24 hours, but see if you can feel the battery to see if it may still be cold.
Thanks for the reply, This is the factory lithium battery from GEM. This particular battery pack does have heaters in it and has worked fine in past winters. (One time I took the cover off to see what was inside and there were heaters).
When I brought it in the garage, I used a thermal imaging camera to check the outside temperature of the battery and it was reading around 58 on the shell after the 24 hours. I know this is not the internal temp, but it should have been pretty close after the 24 hours.
Page through digital wrench and see if it tells you the actual reading the temp sensors are reporting.
Since you had the top of the pack removed, can you locate the temp sensors? If not too buried, see if Is there a way you can pull them out and warm them up?
Power up sequence
I am having trouble with your sequence of events/errors. If you clear the errors (through digital wrench), then KeyON, I could see how the errors would return.
I unhooked both batteries (lithium and small 12v computer battery) hoping the system would reset. There was no change.
How long did you unhook both batteries for this reset?
====
Now that the battery is warm-
What happens when you clear the errors, then plug in charger?
The DigiWrench page you show (above) seems it looks like LoTemp might be cleared and now LowVolt is mostly what it is upset about.
A few updates. We are in Chattanooga so temps are now around 40 during the day and 20’s at night.
I hooked up our digital wrench software to see if I could get some readings. We have an identical cart to the one I am working on. This morning on the working cart, the digital wrench was reading a battery temperature of 69.8 f. This cart is working properly and the battery heaters are working because it was only about 25 degrees out.
We have another similar cart, but a year 2022 that was giving a “bat loTEMP” so I hooked it up and the battery on that one was reading a temp of 28.4 f, so the heaters were not working for some reason (but that is another thing. I haven’t messed with that cart at all.)
I then hooked up the digital wrench to the broken cart and the the temp was pegged at -40 f. It was definatly not -40 degrees out. It stayed at -40 f for the several hours I was working on it in. This leads me to believe it could be one of these problems. 1.The thermistor or temperature sensor is either grounded out or faulty. 2. The sensor is stuck in open circuit caused by a broken wire or faulty sensor. 3. Whichever wire feeds the temperature signal to the computer is broken or grounded.
I could not find anything that looks like a temperature sensor. to follow the wires or test the resistance as I warmed it up.
I’m still stuck. Tomorrow, I will just start wiggling wires and searching for a temperature sensor.
I have included pictures of the digital wrench readings for the different carts. There are also pictures of the internals of the lithium battery. I could not find anything that looks like a temperature sensor.
Battery should be under warranty so I would let them handle it.
That was going to be my next question, and might be a consideration before you go any further.
It appears you are missing other info too. Batt volts on the top is 0v but the BMS may have shut down the output.
It is possible the heaters tried to kick in due to the bad temp sensor and the battery consumed itself trying to stay warm.
It might not be good practice to go in and randomly wiggle things, but the boards are marked nicely. Look around for a plug marked temp sensor and follow the wires back. Also- There may be more than one sensor.
I don’t think the warranty is an option. This cart has been passed around quite a bit and the local (2 hours away) Polaris is not that helpful.
The cart thinks the battery is dead, but it is reading ~53 volts at the terminals.
I know it is not the best to just start moving wires around, but we don’t have many options left.
I am not able to find a temp sensor in the battery pack. I wonder if it is located inside the heaters? Close up pictures of the board below. Anyone see a temp sensor?
The actual sensor probably won’t be on the board. I was more/less looking for the plug to come in and attach to a labeled plug on the board. (not seeing it first glance).
The sensor will be attached to a battery. Most likely on one of the connector bars. It will be about the size of a popcorn kernel and have two wires going to it.
I found the sensors.
In the battery pack, there are 3 boards. Each board has 4 heater connector headers. Each header has 4 pins. 2 pins for powering the heater, and 2 pins for the temp sensor. I found this because one of the wires going to the header was marked with a smeared “temp”. Each of the header connector wires splits and is then branched off in parallel to feed/read 2 sets of heaters and sensors. so there are a total of 24 heaters and 24 temp sensors in the battery pack. I started testing each sensor individually. The garage temperature was around 55 degrees and the resistance was reading at 1295 ohms. All of the sensors were reading similar resistance. I placed a small electric heater under the car and started to warm it up. The resistance slowly decreased letting me know that the temp sensors were working correctly. From there, the sensors connection path lead into the board and get converted to a digital signal eventually leaving the battery pack.
I am now confident that the problem is not within the battery pack.
The temperature on Digital wrench is still reading -40 f which is the minimum value possible.
What are some other things to look at?
If this were taken to a dealer, what would their repair flowchart look like?
There were also reset pins on each board, I wonder how I can reset the boards or if this would help. Does the reset need a specific voltage or just to be bridged like on an arduino board.
I find it odd that when you measure the sensors, all appear to be within reasonable value of each other.
I also find it interesting that you can measure the battery V on the output. It might be that the BMS does not actually control the output but rather only monitor and report issues to the BMC, which does the power management. So this might be a communication issue or there is a glitch in the BMC.
I have not had a chance to play with DWrench. Can you find a settings tab/page that allows you to do an offset/calibration on the Temps value?
The next step might be to swap out components. You mentioned that you have some other carts that you were doing testing on. Are those your personal carts, - or - are you a shop that has access to other customer carts (in which case- part swapping may not be a good idea).
I am leaning towards this not being an actual battery issue, but might be a BMC issue.
Wait, that can’t be. Oem battery is 12s. If battery has been overcharged by a clueless mechanic, it’s not safe. Get it outside until draining it to less than 4.2v/cell.
I had one brought in in that condition. Scared the hell out of me until I rolled it out of garage.
this can be caused by manually charging or a mis-flashed bmc.
Max volts is 12x4.2v=50.4v, and that is only safe when battery is perfectly balanced.
