48v 100Ah Evoltion low battery voltage
 

I have a customer with a Club Car precedent, a company installed a 48v 110Ah Evolution battery in March. The cart is lifted, Stock Controller, Eric Cart, they said the company replaced the motor now the cart is slower than it used to be. I went out to see what was going on, No fault codes, Throttle goes to 100%, Speed sensor is working, Battery voltage holds, cart did 21mph. They had put a new factory 3.3 hp motor in. I am guessing the motor they had before when the cart did 27 was a high speed motor. I put a flight systems high speed motor in the cart, it now does 30mph. Cart ran without a hitch, customer got battery to 65% and it started bucking due to low voltage. Took it home to charge and the charger/AC cord got really hot. I went out, checked it on the handheld, only error code was Low battery voltage. We haven't done a ton of lithium carts, so I am kind of new to the non lead acid game. Anyone have any suggestions on possibilities, or what to look for. All connections are tight, wires are good. I would think the system should run that motor fine, I have used plenty of them with stock controllers in lead acid cars without an issue. Any help would be greatly appreciated.

Thanks in advance.

Re: 48v 100Ah Evoltion low battery voltage
 

So what is the battery voltage? ‘Low Battery Voltage’ doesn’t tell us much. Also, how did the customer know they were down to 65%? Do they have a coulomb counting meter on there or simply from battery voltage?

Cheers
Pat.

Re: 48v 100Ah Evoltion low battery voltage
 

Pat,

Thanks for the quick response. 65% was seen on the battery meter that came with the lithium battery. It has the colored bars as well as a percent indicator. I read the low battery voltage from the handheld through the curtis programmer Fault menu. How she explained what had happened, it sounded how it would act if battery voltage was low on a lead acid cart. Battery sitting at rest 50.08v now. Any other information you need, please let me know and I will get it.

Thanks again,
Mike

Re: 48v 100Ah Evoltion low battery voltage
 

Pat,

Thanks for the quick response. 65% was seen on the battery meter that came with the lithium battery. It has the colored bars as well as a percent indicator. I read the low battery voltage from the handheld through the curtis programmer Fault menu. How she explained what had happened, it sounded how it would act if battery voltage was low on a lead acid cart. Battery sitting at rest 50.08v now. Any other information you need, please let me know and I will get it.

Thanks again,
Mike

Re: 48v 100Ah Evoltion low battery voltage
 

When it's fully charged what is the voltage? 57V?

I know when my Leaf pack gets to 50.0V it's time to charge or my LV cutout is going to kick in real soon......like 200 yards soon.

When the controller demands power the battery voltage drops. Likely below whatever the BMS for that battery is and likely cuts power off so the lithium battery is not destroyed.

Re: 48v 100Ah Evoltion low battery voltage
 

I haven't charged it yet, was trying to get a bit more information on lithium setups before I really jumped into it. She brought it home after it bucking, plugged in the charger. AC cord got extremely hot and the charger was extremely hot as well. I know in a lead acid scenario the charger will get hotter when the voltage is lower but I didn't know if this was correct with a lithium set up as well.

Thanks,
Mike

Re: 48v 100Ah Evoltion low battery voltage
 

Lithium should be charged with a charger set for Lithium. If you're using a LA charger, that may be the reason for the heated cord.

Re: 48v 100Ah Evoltion low battery voltage
 

At 50.8v that battery is dead. I know with LiFePo4 batteries these voltages are estimates. But I think it should be close. Look at the chart not the graph.

Re: 48v 100Ah Evoltion low battery voltage
 

Hi Mike,

As others have said, 50.8v is a flat 48v lithium battery. That voltage would have recovered a little so it probably got down to 48v before the BMS started protecting the cells.

Also, I’m not suggesting that you are as you haven’t confirmed it, but reinforcing that you CANNOT use a lead acid charger for lithium. Lithium batteries require a constant voltage, constant current (CV/CC) charger or power supply. Depending on the design and the CC setting, they can get quite hot but the incoming power cable shouldn’t, it should be rated to carry the required current. Due to the CC topology, The charger will get hot regardless of battery charge except when the battery is almost full, when it changes over to CV.

The discharge curve of LiFePO4 is very flat, so a voltage based state of charge meter is only good for telling you when your battery is full or flat. It is useless for anything in between. Best install one of these.

https://www.renogy.com/500a-battery-...xoC0UYQAvD_BwE

Cheers
Pat.

Re: 48v 100Ah Evoltion low battery voltage
 

I think with your resting voltage at 50.8, you are just at the "knee" for that lithium battery. Continued use (with voltage at 50.8V0 without charging results in a rapid voltage loss.

Charge now and always recharge when the voltage gets to 51.0