Using Club Car Charger on Lithium

Pat911

Active Member
One other point, the OBC does more than just control charge, it checks for charge/discharge cycles and will shut the cart down to protect the battery and controller if it doesn’t detect adequate charging. I’m unsure how the OBC will see the charge cycles with lithium batteries as the current draw will be very different than LA. When the BMS cuts off charge the OBC may see this as an incomplete charge cycle, and/or faulty batteries and prevent the cart from operating. Just something to be aware of if you encounter this problem.
 

Diode

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I posted the voltages that the obc and charger will charge at if that fits your battery profile then go for it
 

Cart Ken

New Member
Here is what I started with:
Cart: 2007 Club Car with OBC, unmodified, four 12 volt GC-12 batteries.
Charger: Club Car model 22110

Only change was to replace the lead acid batteries with four Nermak Model 1250 50 ah LiFePO4 batteries, each with its own built in BMS.

Total cost $840.

Most people would choose the 100 ah batteries, but because of my unique situation of never needing to go more than 1.5 miles between charges, I decided to save money and get the 50 ah model.

In my test drive, I was unable to notice any change in characteristics or performance between a fully charged set of lead acid batteries and the new LiFePO4 batteries.

Before I started my test drive the four batteries (which came charged) had individual voltages ranging from 13.33 to 13.64. After a 90 second charge (that was all it would take) and a short 1/4 mile test drive, the voltages ranges from 13.25 to 13.27.

Running the cart seemed to even out the voltage differences.

I then drove about 3 miles on my test drive. I check the wires and the batteries a few times, there was not the slightest bit of detectable heat.

After the test drive, total voltage was 53.0 volts, which according to a chart I found on-line indicates about a 80% charge level.

Sitting idle for a few minutes, the voltage rose up to 53.2 volts

I then hooked up the CC charger the same way I did with the lead acid batteries (still using the OBC).

The amp meter on the charger read 9.5 amps at the beginning, but I suspect it is not all that accurate. Toward the end, it was down to 8.9 amps.

After 57 minutes, the charger shut off with a voltage reading of 56.9 volts. After resting for 2 hours that voltage dropped to 54.3 with individual voltages between 13.40 and 13.77, which according to my chart indicates a 99% to 100% charge level.

I would have liked to see what would happen if I ran the batteries all the way down, but I didn't have the time and didn't want to get stranded when they died.

I am satisfied that my current setup will last many years.

Does anyone think I missed anything in my testing?

Ken
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Pat911

Active Member
Get yourself a shunt based state of charge meter as trying to judge SOC from voltage on LiFePO4 batteries is near impossible. LiFePO4 behave nothing like lead acid when it comes to voltage vs SOC as their discharge curve is so flat. The charts posted on the internet are a gross generalisation. The voltage is very flat from 20% to 90% SOC. Two batteries with similar voltages could vary widely in SOC. I recommend the Renogy 500A meter.

Secondly, I would recommend you start with a top balanced set of batteries, so I would charge each one individually to begin with.

It seems like the link you posted doesn’t have the 50Ah model but going on the specs of the other batteries Nermak sells it would be safe to assume they are rated at 50A continuous with no mention of peak amps/duration. I really think you’re going to struggle as 50A is very low for a cart battery. My stock 2014 Club Car precedent regularly sees 70A on acceleration and 30a-40a cruising.

I’m surprised you saw no gain in performance going to lithium. You should have seen a vastly improved acceleration and a snappier pedal response. That’s the first comment I hear from people going to lithium and it was my experience as well.

Cheers
Pat.
 

Tom47

Active Member
As Pat stated, voltage in relation to SOC is almost impossible with lithium batteries. The Renogy 500A meter recommended by Pat is what you need. Here is a graph that, although not specific to golf carts, gives a generic sample of the operating conditions.

I don't know what controller you have, but stock controllers are going to be starved for operating current with a max 50 amp continuous output. I would venture to say the lack of performance increase is due to this. You're not getting enough "fuel" to the "carburetor" so to speak.

For your short range operating parameters, you may well be fine with your setup!
 

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Cart Ken

New Member
The 50 ah model was on Amazon yesterday, today they are gone. Maybe I bought the last ones.

They are rated at 50 amp continuous, 120 amp for 3 seconds.

I was not looking for better performance, but would be happy if I got it. I am happy with the performance I am getting, and I expect the batteries to mostly maintain the same performance for many years of light use.

As far as balancing, after a quick charge and a short drive all four batteries were within 1/100th of a volt. Doesn't this mean they are balanced, or am I missing something?

I'll check out the Renogy meter.

I really think you’re going to struggle as 50A is very low for a cart battery.
I'm not sure what you mean by "struggle". I tested the cart and it performed well. Is there some reason it should suddenly stop working?

I thank everyone who provided information on this subject.

Ken
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Pat911

Active Member
Hi Ken,

By struggle I mean carrying a bit of extra weight, passengers etc. and/or going up hills. That's when the current draw will increase. The Renogy will display on the fly current as well, it's very handy to have. You have dropped a lot of weight going to lithium, you should definitely see improved performance.

I know I said that the voltage charts were meaningless, but having a look at what Tom posted above, the difference between 40% and 80% charge looks to be about 0.5v, and that's a 48v pack. at 12v its about 0.125v. You say your batteries are within 0.01v and that is close, but it still may be 10 or 20% difference. Without a top balance you're really starting from an unknown state. Also, if your batteries were truly balanced, your charger should have shut off at 58.4v (16 x 3.65v), not 56.9v.

At best, you have one battery at 14.6v (4 x 3.65v) and the other three at 3/(56.9-14.6) = 14.1v. At worst you have three at 14.6v and one at 56.9-(3x14.6) = 13.1v. Most likely, you have a mixture of voltages in between 13.1 and 14.6v at charger shutoff. They will settle and come closer after charger shutoff but it doesn't mean they are balanced.

Lastly, as I already noted above, the OBC did not stop the charging, one of the BMS's did. In your case, the OBC will never sense a full charge and it has the ability of disabling the controller should it think that the batteries are inadequately charged. That's the reason the OBC must be bypassed for a standard lithium install. I don't know how the OBC treats partial recharges, it may get to the point in a few charges time (don't ask me how many, I do not know) where it thinks there's a problem and shuts the cart down. If this occurs you should bypass the controller shutdown line.

Cheers
Pat.
 

Cart Ken

New Member
By struggle I mean carrying a bit of extra weight, passengers etc. and/or going up hills.
I will have to recrute some extra people for a load test.
You say your batteries are within 0.01v and that is close, but it still bay be 10 or 20% difference. Without a top balance you're really starting from an unknown state. Also, if your batteries were truly balanced, your charger should have shut off at 58.4v (16 x 3.65v), not 56.9v.
I'll try it today and see if it makes any difference.
 

Cart Ken

New Member
it may get to the point in a few charges time (don't ask me how many, I do not know) where it thinks there's a problem and shuts the cart down. If this occurs you should bypass the controller shutdown line.
I'll keep an eye out for this happening.
 

Pat911

Active Member
Excellent video Tom, explains things perfectly.

Top balancing by parallel connection is the best way to balance but requires removal from the cart.
 

Cart Ken

New Member
Final Report on LiFePO4 change over.

Here is what I started with:
Cart: 2007 Club Car with OBC, unmodified, four 12 volt GC-12 batteries.
Charger: Club Car model 22110

Only change was to replace the lead acid batteries with four Nermak Model 1250 50 ah LiFePO4 batteries, each with its own built in BMS.
https://www.amazon.com/dp/B09Y3DNKB2?ref=ppx_yo2ov_dt_b_product_details&th=1
Total cost $840.

Most people would choose the 100 ah batteries, but because of my unique situation of never needing to go more than 1.5 miles between charges, I decided to save money and get the 50 ah model.

Batteries were parallel balanced with a battery charger that had a LiFePO4 setting, and then left to sit in parallel for 24 hours after the charge completed.

Because the new batteries are much smaller in size, I had to fill in the holes in the frame with thick outdoor plywood to build a mounting platform. I then strapped all the batteries down with a long ratchet strap.

The cart has plenty of pep, but top speed hasn't changed. I believe because of the cart's speed governor.

I saved over $700 by getting the 50ah batteries rather than the 100ah batteries, but there is a price to pay. The 50's have a continuous output rating of 50 amps as compared to the 100's with a continuous rating of 100 amps. As long as I don't stress things, all is well, but if stopped at the bottom of an incline and I stomp on the accelerator, one of the BMSs will kick off. I had anticipated this, but I thought it would just stay off for a few seconds, but it stays off forever until I remove one of the battery wires and put it back on. I'm guessing that the OBC has something to do with this. I have found that it is easy for me to resist the urge to stomp on the accelerator, so as far as I'm concerned, the cart is fully functional.

I am still using the original Club Car 22110 charger (and OBC), plugged in exactly as I did with the LA batteries. It starts out reading 9.5 amps. In the last few minutes, it drops to 4 amps. Everything shuts down at 57.4 volts. (14.35 per battery). The recommended charge voltage is 14.4 to 14.8.

After charging and resting, the voltages on all four batteries were all within 1/100th of a volt, with a combined voltage of 53.4.

I plan to periodically monitor the individual voltages and address the problem if I get more than 1/10th volt difference between the lowest and highest, I will re-balance, or charge all four, one at a time. I also plan to leave them in parallel for the 7 months of the year that the cart is not in use.

Conclusion: What I'm doing may not be the best for the batteries, and if they only last 90% as long as properly cared for batteries, I don't care. My solution seems good enough for my needs.

If anyone thinks I missed something, let me know.

Ken
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