[Functional Artist]

Howdy,

I have a question about batteries getting hot when charging.

I build Go Karts I for my kids using parts from electric scooters & a riding lawn mowers.

My kids rode one around for awhile yesterday(~30 min.), They didn't run it completely dead but, it wasn't as zippy as when they started.

So, last night I hooked up the charger

the label says:

POWER CHARGER
model: CH36-1.8S
INPUT AC90~130V/50~60Hz
OUTPUT: 0.1~1.8A
For Lead -acid battery

label on side says:
ETS LVD
IN: AC110V
OUT: DC36V/1.8A
short circuit protect

(it came with the donor scooter)

to the 36V battery pack (3) 12V 12AH SLA).

This morning when I unhooked it, the batteries were very hot & the charger was hot too.

I have had batteries get warm before when charging but, not really hot.

Battery issue, charger issue?

Any advice would be greatly appreciated.

 

[major]

Howdy,

I have a question about batteries getting hot when charging.

I build Go Karts I for my kids using parts from electric scooters & a riding lawn mowers.

My kids rode one around for awhile yesterday(~30 min.), They didn't run it completely dead but, it wasn't as zippy as when they started.

So, last night I hooked up the charger

the label says:

POWER CHARGER
model: CH36-1.8S
INPUT AC90~130V/50~60Hz
OUTPUT: 0.1~1.8A
For Lead -acid battery

label on side says:
ETS LVD
IN: AC110V
OUT: DC36V/1.8A
short circuit protect

(it came with the donor scooter)

to the 36V battery pack (3) 12V 12AH SLA).

This morning when I unhooked it, the batteries were very hot & the charger was hot too.

I have had batteries get warm before when charging but, not really hot.

Battery issue, charger issue?

Any advice would be greatly appreciated.

Hi,

Welcome to the board. Kinda hard to tell what the problem is. Typically those scooter components are pretty cheap (low quality). I suggest you get a good low current (like 2A) 12V battery charger and charge each of the 3 individually. If all 3 then behave suitably, blame your 36V charger. It may be that one or more of the batteries are bad. At minimum have on hand a voltmeter. Read the 3 voltages when it starts the slow. Also before and after charging. Data can help diagnose things and get you familiar with DIY EV.

major

 

[EVfun]

Just a quick test would be to charge the pack then disconnect the charger and leave the gocart unused for 12 hours. Then go back and check the voltage on each battery. My guess is that you have 2, 12 volt batteries and one has become a 10 volt battery (charged and rested voltage about 11 volts.) This can cause a charger to go into thermal runaway quite easily.

It could be a bad charger, or all the batteries may be worn out, but I got a hunch you are seeing a thermal runaway issue. I abuse 24 volt Optima packs in my work. What I outlined above is very often how a pack dies.

 

[Functional Artist]

Thanks, for the replies.

The charger came with the scooter, I've used it several times without issue but, it could be the problem.

FYI:

I do not charge thru scooter's electronics. I agree cheap.

I took the batteries out of the kart, connected the charger straight to the battery pack & charged them on the workbench.

I checked them individually (today) with my meter.

1- reads 13.6V
2- reads 13.1V
3- reads 13.5V

The batteries on this little kart (for now) are 3- 12V 12AH.

Is it best, as a rule, to charge them individually? (Like 12V @ 2A)

or charge as a pack like 36V @ 2A?

Recommended charger?

Thanks again,

 

[Sunking]

It is called Thermal Runaway a very common problem with SLA batteries. You have one or more shorted bad cells in 1, 2, or all 3 of your batteries.

Edit Note:

Battery 2 is your problem child. The bad news is you do not mix old and new batteries, especially any type of lead acid. You need new batteries.

 

[Functional Artist]

Yes, good call! It is a mixed pack.

I know not to mix different types, voltages & AH's but, didn't think about not mixing old & new. Noted, I will not mix again, thanks.

Kinda confusing though, batteries # 1 & #3 are used, battery # 2 is new.

How badly do you think the "new" battery got damaged?

Should I try (2) new batteries with that one or just go with (3) new?

 

[major]

Yes, good call! It is a mixed pack.

I know not to mix different types, voltages & AH's but, didn't think about not mixing old & new. Noted, I will not mix again, thanks.

Kinda confusing though, batteries # 1 & #3 are used, battery # 2 is new.

How badly do you think the "new" battery got damaged?

Should I try (2) new batteries with that one or just go with (3) new?

You see opinions posted, from me and others. Be careful not to take things as fact until you verify. The voltages which you listed appear to be high for open curcuit battery rested. So, just reaching here, if the three batteries were on a charger, or measured just off the charger, the ones showing higher voltage may in fact be the bad ones with high internal resistance.

Batteries are a bitch. I found the only way to know for sure is to load test. That's difficult to do without proper instruments. However a fair approximation can be done using the same load for all 3 like a car headlamp. Observe voltage and time and compare results on a simple graph of volts vs time at every minute or 5 depending on how fast readings change.

major