Lithium ion Battery Questions | Cartaholics Golf Cart Forum

First time caller, long time listener.

Okay, so I have a TXT PDS with 23" tires on the stock 350a shunt controller,.

The lead acid batteries crapped out, so I went with a 36v Kepworth litnium LifePo4 battery. It seemed to work great at the beginning. The first thing that went wrong, was when I was climbing a steep hill. It shut down due to overcurrent. Okay, no problem, I can deal with that. A 30 second rest is all it needs.

Then, we took it to a campground for Memorial Day weekend. It seemed okay, we were slow cruising, then I noticed it slowing down, then, it just stopped. The monitor showed it had 89% battery life. Waited 2 minutes, it took off again. But, all weekend long, it continued to 'thermal shutdown' on us.

I contacted Kepworth, they said my golf cart is too powerful. Huh??? It’s a stock 36v motor with a 350w shunt controller. The tires are oversized, but that's the only mod.

They wanted me to add a 2nd 36v pack, but there's no way, these Kepworths are huge.

I ended up sending them screenshots of the 3rd page on the monitor. This page shows the health of each individual cell. After it has rested, the cells are all very close, but when the cart dies, one cell is much lower.

So now, they want to send me an equalizer plate to put on, but they don't think it will solve the issue. It should, if the plate does its job, but this is not my area of expertise.

I took the cart to a local repair place, they think it’s the battery.

At this point, I'm ready to send the battery back and buy two 36v enjoybot batteries and parallel them. It looks like they will fit.

So I have questions:

1) is this the right upgrade?

2) How do I hook up the charger? Do I need to use a + buss bar and a - buss for both batteries and charger to marry, or can I just hook the charger to 1 battery (I'm guessing the answer is no)?

3) Will this be too much for the controller and/or motor?

4) Will this upgrade benefit me when climbing hills?

5) I'm assuming I'll need to charge both batteries seperately to equalize them prior to hooking them together?

I think that's about it… for now.

Do you have one 36v battery or 3 x 12v batteries? It sounds like you have one 36v battery but the manufacturer wants to send you a balance board to you to install on the battery. Thats not a simple task, not difficult, but definitely not plug and play.

It sounds like you have one bad cell, a balance board will just hide it, not fix it. Send it back and get a better battery with real customer support that’s designed for cart use. Look at Eco Battery or Epoch.

A quality battery should never shut down on you unless you’ve let it get too low.

Yeah, it's a single 36v battery.
Lucky me, I get a bad one. They seem to think my cart damaged the battery. I'm not sure how that's possible.

Yeah, it's a single 36v battery.
Lucky me, I get a bad one. They seem to think my cart damaged the battery. I'm not sure how that's possible.

No way your cart damaged their battery. It's impossible. Their battery has a BMS board in it that is there to prevent damage from external devices. If your cart presented a load that the battery couldn't run then it should have shut down. More likely, they're using cheap or second hand cells that aren't up to the task, with the BMS setting set too high and allowing too much current to flow through those inadequate cells. That's how these cheaper batteries are claiming high currents. They are trying to get out of a warranty claim.

No way your cart damaged their battery. It's impossible. Their battery has a BMS board in it that is there to prevent damage from external devices. If your cart presented a load that the battery couldn't run then it should have shut down. More likely, they're using cheap or second hand cells that aren't up to the task, with the BMS setting set too high and allowing too much current to flow through those inadequate cells. That's how these cheaper batteries are claiming high currents. They are trying to get out of a warranty claim.

I agree with this. If the battery is properly designed the BMS will shut down before damage can occur. Sounds like you got a battery with a bad cell no way around it. You get what you pay for, there’s a reason these amazon batteries are a third of the price of reputable brands. They can claim whatever they want about how long their warranty is, most of those sellers will try to blame you, give you the runaround, or just ghost you. They could care less if that account gets banned, they probably already have 10 other accounts selling the exact same thing under a different name. Not that Amazon actually cares that people sell garbage products on their platform as long as they’re making their sellers fees. Buyer beware is the name of the game with these budget lithium batteries.

No way your cart damaged their battery. It's impossible. Their battery has a BMS board in it that is there to prevent damage from external devices. If your cart presented a load that the battery couldn't run then it should have shut down. More likely, they're using cheap or second hand cells that aren't up to the task, with the BMS setting set too high and allowing too much current to flow through those inadequate cells. That's how these cheaper batteries are claiming high currents. They are trying to get out of a warranty claim.

They have been very helpful and have told me they will refund my money on a return. But they want to test it first and now they're telling me their engineer is on vacation for the next two weeks. Ugh.

I agree with this. If the battery is properly designed the BMS will shut down before damage can occur. Sounds like you got a battery with a bad cell no way around it. You get what you pay for, there’s a reason these amazon batteries are a third of the price of reputable brands. They can claim whatever they want about how long their warranty is, most of those sellers will try to blame you, give you the runaround, or just ghost you. They could care less if that account gets banned, they probably already have 10 other accounts selling the exact same thing under a different name. Not that Amazon actually cares that people sell garbage products on their platform as long as they’re making their sellers fees. Buyer beware is the name of the game with these budget lithium batteries.

It got really good reviews, I thought this was going to be a good option. Hopefully it's just a situation where I was unlucky and got one of the few with a bad cell.
Man, it doesn’t take much to make a battery fail.

It got really good reviews, I thought this was going to be a good option. Hopefully it's just a situation where I was unlucky and got one of the few with a bad cell.
Man, it doesn’t take much to make a battery fail.

A couple of points, a lot of those reviews may be fake, and it does take a lot to make a well designed battery fail.

A well designed battery will have cells that are up to the task, in this case, being able to supply at least 100A to 150A continuously with peaks up to 300A for 10 to 30 seconds. They may have 3 or 5 second peaks of over 500A. Then a BMS will be installed to protect those cells if the load tries to draw more than the current the cells can safely supply. Note, that if the cells are operating within their design limits, they shouldn't fail and it's the BMS's task to ensure that occurs.

Note, that I'm talking Amps above, not Ah. They are totally different things. Ah's is how much energy the battery stores (range), Amps are how fast it can deliver that energy (required for acceleration, going up hills etc.).

Okay, so if I move on from this battery and go with 2 100ah batteries, will that help with the stress caused by the 23" tires? I didn’t put those tires on, they were onit when I got it last year. The lead acid batteries did okay, the cart was just slow on inclines.

Look at @Pat911’s post above. You need to look at the discharge amp limit, not amp hours. The discharge current is how many amps can flow at once, the amp hour rating is how many amps are stored inside the battery total. The fire department can have a full tanker of water, but it won’t help if they’re trying to spray it through a drinking straw.

Okay, so if I move on from this battery and go with 2 100ah batteries, will that help with the stress caused by the 23" tires? I didn’t put those tires on, they were onit when I got it last year. The lead acid batteries did okay, the cart was just slow on inclines.

No; not really. Think of your battery as your fuel tank. More AH is like more gallons so with more AH you get more range not more torque. One good battery should handle your needs unless you need more range. If you need more torque you will need to upgrade your motor. Before you go buying a motor designed for more torque you will need to make sure your controller will provide the current (amps) to feed it. Think of your stock motor as a stock motor and your controller as a carb. You will get more torque from an after market motor with your stock controller and a good battery that won't shut down on you. Your stock controller may be able to have settings changed and that would be like putting bigger jets in your carb. If your stock controller can't be programmed to feed a high torque motor you would have to replace it as well. If you think that is going to happen you may as well go with an AC conversion set up for a few dollars more. If that won't satisfy your need for speed and torque nothing will but it is not cheap. I plan on going with an AC conversion kit at some point and I will have a good DC motor and controller to put in another cart or just sell them to recoup some cash.

Once you get a battery that functions as it should if you are not happy with the performance start looking at motor/controller packages.

Gone Wild  
Join Date: Oct Posts: 159 lithium battery questions I have a 48 volt club cart with an ac motor, It currently has six 8 volt batteries that I'm planning to replace with four 12 volt lithium batteries. I'm wondering if anyone can give me advice on cable size. Also, I'm told to balance the batteries first by wiring them in parrallel and charging them for 24 hours. Can I use smaller cables for this? Thanks Gone Wild  
Join Date: Apr Location: Western NY Posts: 2,415 Re: lithium battery questions Quote: Originally Posted by surfdog Yes, thanks for the replies, unfortunately, I already have the four 12 volt batteries, purchased before I knew you could buy a single 48 volt battery.
If your commited to using them you will need to purchase a 12v lithium charger and from time to time you will need to charge each battery up individually to rebalance them or as you use them they will slowly go out of balance and you will loose more and more capacity.

Also do not power 12v accessories off of one battery. use a 48v to 12v reducer instead. otherwise you will just make your battery pack even more out of balance shortening the lifespan further.

Your other option is one of the special chargers made by companies like Noco for charging series packs like this found in rvs and boats. Gone Wild  
Join Date: Oct Posts: 159 Re: lithium battery questions Thanks, I have a 12 volt charger I use for my cars etc. and a 48 volt charger to use for charging the cart. Maybe I need a 12 volt charger for lithium though. Didn't think of that. No one has ventured to answer my questions though. Gone Wild  
Join Date: Sep Location: Minnesota Posts: 1,951 Re: lithium battery questions Quote: Originally Posted by surfdog I have a 48 volt club cart with an ac motor, It currently has six 8 volt batteries that I'm planning to replace with four 12 volt lithium batteries. I'm wondering if anyone can give me advice on cable size. Also, I'm told to balance the batteries first by wiring them in parrallel and charging them for 24 hours. Can I use smaller cables for this? Thanks
Most say 2ga or 4ga for the wire. I just used what my cart came with (unsure on size) it has been working fine but will be changing to 2ga when the new set arrives. Changing because I upgraded my controller as well and want to make sure I am not leaving performance on the table.

Yes balance them first before you put them in the cart. You can do that by charging them all with a 12v lithium charger one at a time or in Parallel.

When you say smaller cables what is your definition of smaller cables? How many amps will your lithium charger be pushing? I would not go smaller then a 8ga.