2004 GEM working on it for a friend

I’ve had this thing for a while putting it back together and installing the lithium batteries. Getting 86v. When I first installed everything and hooked it all up I was getting an error 16 over voltage I believe. Spoke to a guy who told me to install a Zion diode. When I clipped the wire he told me to install the diode on I lost my dash lights. So I spliced the wire back together without the diode assuming it would go back to normal but it didn’t. Messing around checking voltage in random places I turned the key and and bumped the peddle. The car started moving. I was shocked so I drove it around for a few minutes. No dash lights still. Pulled back in the drive way turned it off and cleaned my tools off of it now it’s back to doing nothing again. Nothing changed from driving it to parking it and trying to drive again. I’m kinda lost on what I need to do. Need someone who knows a little more about these things than I do. Lol I understand basic electronics and voltages but never worked on an electric cart before. Side note the one thing I do notice is all 4 blinkers are blinking like the hazard lights are on and it never did that before.

It sounds like a couple different things going on here.

Let’s start off by identifying exactly which wire you cut?

Since you were cutting the wire, What were you going to put inline on that wire?

What is the status of the cut wire now?

Ok so as far as the cut wire it was supposed to be ignition wire going to the control. It’s since been put back together. The zenar diode was removed and put back to normal. After posting this I decided to take the steering column apart to discover at the same time I did that some how the plug in the back of the display wiggled loose. What are the odds. Instead of using the diode I decided to remove one battery cell which dropped me below the voltage needed to allow the cart to drive and it’s now driving!!! With the display working.

Good job! Now- WHOA, whoa, whoa!!!

Before you screw things up too bad why don’t you put the other battery back in? This also involves throwing that diode back in (depending on where you got that info).

Chances are you already unbalanced the rest of the pack from the one you removed so you REALLY need to pay attention here.

If you continue to run with the pack (-1cell) - How are you charging them? Did you adjust the charger to a different profile?

1 Like

That’s actually the issue now this charger was supposedly I guess programmed to charge them the way they were with all the batteries but I was getting a fault on it anyway with all the batteries hooked up. Everything seems to be working fine the way it is now. Just need to get the charger in sync with the batteries now. Not sure how to go about that. It’s currently on number 135 profile. It’s a delta Q CHARGER.

For anyone here that might be able to offer advice you need to stop using the word supposedly and give us more accurate info. If you do not know, then backtrack a little bit and find out from the person that did that part of the work.

If you do not know who that person was you need to give us a bit more of the backstory on what you are working with.

  1. What batteries did you install?
  2. How many cells are in the pack?
  3. is there any sort of BMS(battery management system) on the cells?
  4. Charger- Delta Q ← good
  5. Profile - 135 - Did you count the lights yourself?
  6. Do you have a handheld Volt Meter?
  7. What is the status of the removed cell? (just unhooked/bypassed, or now fully removed from the car?)

Your (edited) quote:

his charger was programmed to charge them with all the batteries but I was getting a fault on it anyway with all the batteries hooked up.

You need to be more specific. Was the “fault” a charger fault code?
or a diagnostic display fault number on the dash?

Depending on the answers to the questions above ^^^^ a path can be offered to guide you.

If you are good on your own then stand down I will.

1 Like

The guy I who sold my buddy the batteries and the charger and the balancer things was answering phone calls and texts and was being very helpful at first. Now having a hard time getting ahold of him. He had the set up in his GEM and everything worked great when my buddy purchased it. It was delivered to me disassembled because my buddy painted it at the same time he purchased the batteries. He dropped it off to me to put it back together because he was selling his house and no longer had the space or time to put it all back together. It’s 27 lipo batteries. Not sure the specifics of the batteries as far as brands and stuff was told it should be 96 volts when I got it all hooked up I was only getting 89.6, the battery had been sitting for a while possibly drained I’m not sure. Once I got it all put back together I was getting error code 16 which is over voltage. The guy was walking me through installing the zenar diode when we lost the power to the display. Just had time today to tear it all apart and find the problem with the display and removed the one cell completely from the cart and was able to drive and do everything perfectly then I noticed the cart was loosing speed so I parked it and that’s where I’m at with the charger.

Yes I do have a multimeter

I counted the blinking lights on the charger (thanks to YouTube)

I know nothing about these carts or electric carts in general

I work with 230,000 volts for work so this is a completely different animal.

I say supposedly because I’m getting info second hand and all of this was purchased over a year ago.

It does have battery balancers that I had to hook up but one was making a weird buzzing noise so I disconnected it because they guy we were working with again recommended a newer style that could handle all 27 batteries on one balancer instead of needin two like we have currently.

I’m sorry most of my info is vague but I honestly don’t know much about them and if you want specifics I can take pictures or videos whatever you need and the help is greatly appreciated.

I know my buddy is anxious to get it back and I need the space in my garage back. Lol

Awesome! Now we have some meat to chew on. Not only did you fill in some important details but you also included pics of what you have. I also appreciate the little peek at what you must do for a living (you must have some awesome stories) but I’m not sure how much of that will apply here.

First is the battery. You have a common cell that many have played with here in this forum and had fairly decent results with. If you want to learn more about them and other installs use the magnifying glass tool (upper right of screen) and do a search for “Green cells”. It will return all sorts of tidbits like this:

LiFepo4(also known as LFP) . These are the square cells you see. If you buy a drop in replacement for your car or boat they will be Lifepo4 chemistry . These are one of the safest chemistries available , They are thermally stable to 518 degrees . There are hundreds of Youtube videos of manufacturers putting nails thru them, shooting them , charging them to twice their max voltage . In almost all cases they smoke but don’t catch on fire .But heat them to 518 degrees and they will .
Many people consider them safer than a flooded lead battery . Try to charge a lead 12v battery to 24v and it will go boom . These are a consumer lithium battery and widely sold . No car maker uses these in an EV . The reason is low power density and voltage . They do not hold as much power for their size or weight as other lithium . And They have a lower voltage per cell so you need more of them for an application . These work great in a gem but you need 25 to 28 for a Gem . They require a lot of connections to make a pack so more possibilities of connection problems .

They have a specific voltage range they like to live in. If you go outside this range (upper or lower) and it permanently damages them.

Since you do not know how they have been treated, I’d start by probing the individual cells and seeing where they are currently sitting. There are alot of them, so get some tape and write the voltage on each one as you go. Look for one or more that may be bad.

Those little bars going across the posts are balance boards. They are most likely set to the upper limit of the battery and then they start shunting power around the cell. Depending on the maker, they may have little status lights that tell you status as they charge up(but they look covered in the pics). These balance boards can only do a few amps but by then the rest of the cells should be caught up and the charger should shut off. By removing one cell, the charger will keep pumping power and the cascade begins. I’m not sure of the availability for extras but some guys might be able to find a few sitting around in their shop.

By the looks of your charger, the installer has conveniently left a list of what is programmed in there. Zooming in I see #135 highlighted and listed as 93.385V so I wouldn’t expect 96 as your buddy expects. We can teach you how to switch between the profiles but it is quite a user hostile experience that some people can do without issues, while others run off screaming horrible new words.

Hi, I have done two installations using these green LiFePO4 cells I purchased from Dave (@inwo) on this forum. His advice, which has worked well, was a total of 25 cells and using algorithm #164. Only get the over voltage alert if I unplug just when charging is complete. If it sits a few minutes, or I turn the headlights on, it clears pretty promptly.

One things the cells need are containment or they expand, that’s why they are bundled in stacks of five by straps. I also learned that 15 over the front plus 40# of steel plate was necessary to give adequate traction and limit wheel slip. Put the other 10 under seat. Am currently running in a 2 seater and have both great range as well as power.

Are yours secured to the cart in any way?

1 Like

Good reply, one note the straps are not the balance boards, just the flexible connectors. Here’s what the balance board @Inwo sent to me look like installed, as well as how I secured (along with a band-it clamp) to the cart.

1 Like

I am currently looking around for best voltage info for these packs. I haven’t played with them. Others may jump in with best/expected numbers. Your charger setting sounds quite low.

Gahh! Good call RD! I didn’t catch that! those are not balance boards!
Give me a D’oh!

Balance boards go across the terminals of the same battery. Connector straps go between the batteries. MY BAD!!

I left the house to go to dinner but I will jump in to this thing again tomorrow. When I check pack voltage now I’m getting like 68.9. Far lower than when originally installed which is to be expected if they have been depleted. They are banded together with steel bands and blocks of steel on the ends. They are not secured to the cart itself mainly because I haven’t fully finished it so I haven’t even given that thought. I appreciate all the info you guys have and will do my best to follow your directions to the fullest. The cart is sitting in the garage now the charger is not hooked up. When you hook the charger up it goes through it’s initial light sequence then shows the profile it’s currently in. When you plug in to the cart the red light at the bottom begins flashing. A few times that I’ve tried plugging it in the 80% battery light begins flashing and I assumed that was the charging indicator. But nothing ever happened the batteries didn’t charge. That’s where I’m currently at.

These are 3.2v cells. Charge to 3.65v, but drop back quickly after charging.
25s is best for stock voltage.
If you get the pack unbalanced it’s a huge time consuming job to get them back.
If you don’t have them balanced, even one charge or discharge cycle will ruin a cell or two.

1 Like

I have extra. It looks like you skipped a couple.

So check voltages individually like previously mentioned? To confirm they are all at the same voltage or to determine if a cell is bad or not? Then we can go from there. I feel so stupid right now when it comes to this thing.

These batteries are near the same voltage through their full range.
The only time you can balance them is full, 3.6v, or empty, 1.8v.
Things go south quickly at either end. When full there as no place for more energy to go, cells will heat and gas, damaging them.
It’s easy to see with the balance boards. Red light when full. When a cell goes red, you must stop charging or monitor to make sure it doesn’t go much over 3.7v. 3.8v or more for a 30sec or so isn’t a killer.

If charger shuts down before a cell goes too high you’re good to go on the top.
You then need to check on the bottom. Make sure a cell doesn’t go below 1.8v when car shuts down on low voltage. If one does it has low capacity, or was not full to start. Make sure that cell is full next charge cycle.

In theory, this is a one time check. But who knows the cell history?