24 v lead acid battery not charging properly.

Thread Starter

novice64

Joined Jan 24, 2019
7
my golf push cart moves using 24 volt system . I could not get 24v replacement battery. I therefore connected 2 x12 v batteries in series to get 24 v output .
when I charge them the individual voltage of one of the two batteries goes to 15 volts while the other remains at 13 v while the collective voltage of the two is 28 v. voltage output on charger is set to 28.4V.
on the course push cart moves for some time, then suddenly voltage drops from 25 v to 23 v in a matter of few seconds.

Can someone please help me find the remedy
 

Alec_t

Joined Sep 17, 2013
11,901
Welcome to AAC!
You could charge the two batteries separately (obviously with a charger appropriate for 12V), or use a suitable charge balancer gizmo. Presumably the batteries are nominally the same type and capacity?
 

crutschow

Joined Mar 14, 2008
26,436
Are the two batteries identical from the same manufacturer?
Try charging them separately, as Alec stated, to balance them .
 

Thread Starter

novice64

Joined Jan 24, 2019
7
Are the two batteries identical from the same manufacturer?
Try charging them separately, as Alec stated, to balance them .
both batteries are identical in size and vintage and from the same manufacturer. I will try and charge them separately and get back soon
 

Canukjoker

Joined Jan 26, 2019
1
Hello, just wanted to throw my experience in here, I've killed my share of lead acid batteries, lol. NEVER use that series charger (24vdc) to charge multiple (2x12vdc or 4x6vdc) Pb batts, it's their nature to never be identical to each other, even if they came off the assembly line side by side. you have to charge them using individual 12v (13.8v ideally I guess) chargers to get the most from them, be that a network or controlled bridge charging system, or regular car battery chargers.

I used a 48vdc series charger to charge my ebike, it came with it, I didn't question it. Then one day, one of my 4 12v batteries refused to charge to peak voltage, which made the charger continuously push power into the other three batteries, which melted every single one by morning... I now use a quad output marine charger ment to charge 4x12v boat batteries at 15amp! Of course the batteries only take what they need so the amperage isnt necessary but it was a deal so I got it. I was using 4 smaller 12v chargers but that was a nightmare of wires. Moral of the story, I would not recommend series charging any amount of lead acid batteries ever, it will cause failures that are hazardous and costly.

Cheers!
 

Thread Starter

novice64

Joined Jan 24, 2019
7
hello. I charged both batteries separately and used them on the cart. There was no improvement. I put the batteries to test to find that the battery which was drawing high voltage has been damaged. The other battery is fine..

It looks I am going through the same experience which Canukjoker experienced. Now I recall having spoiled a number of batteries in last one year. Every time thinking that motor was not working properly or there was some leakage in circuit. Now I know what was causing this dilemma.

I probably have to replace that offending battery or is there any way to reclaim it?
 

MisterBill2

Joined Jan 23, 2018
8,032
my golf push cart moves using 24 volt system . I could not get 24v replacement battery. I therefore connected 2 x12 v batteries in series to get 24 v output .
when I charge them the individual voltage of one of the two batteries goes to 15 volts while the other remains at 13 v while the collective voltage of the two is 28 v. voltage output on charger is set to 28.4V.
on the course push cart moves for some time, then suddenly voltage drops from 25 v to 23 v in a matter of few seconds.

Can someone please help me find the remedy
It seems that the one battery does not have nearly the capacity of the other one. One way to see if it is a charging problem is to use a 12 volt charger to charge the one that only goes up to 13 volts. Fully charged they should each be about 14 volts. So charging them in series is not working. Use separate chargers, or get two identical 12 volt batteries. You do not have two identical batteries now.
 

Thread Starter

novice64

Joined Jan 24, 2019
7
both batteries are identical with same capacity and same manufacturer. I am charging them separately. the capacity of one of the batteries(the one drawing 15 volts) has reduced considerably. now they do not have same capacity. This battery seems to have been over charged and damaged.
Is there someway to rejuvenate damaged battery or is replacement the only option
 

MisterBill2

Joined Jan 23, 2018
8,032
both batteries are identical with same capacity and same manufacturer. I am charging them separately. the capacity of one of the batteries(the one drawing 15 volts) has reduced considerably. now they do not have same capacity. This battery seems to have been over charged and damaged.
Is there someway to rejuvenate damaged battery or is replacement the only option
There are schemes for rejuvenating wet batteries like them, but I have had no experience with trying any of those, soI can't offer any advice on that topic. A few folks have stated that an extended trickle charge helps, that is something possibly easy to do and not likely to cause damage, so it may be worth trying. I am amazed that there could be such a problem with batteries identical. Is it possible that one was used for some other application while you were not looking? Or even exchanged?
And now I am wondering if accidentally one was charged twice and the other not charged at all. Things like that can happen if others are involved.
 

Yaakov

Joined Jan 27, 2019
1,724
I probably have to replace that offending battery or is there any way to reclaim it?
The battery could be suffering from sulfation. This is caused by long term less-than-full charge state. The battery may be in use or not. If it is frequently charged partially then discharged, the normal sulfate crystals that form during discharge are not removed and led to reduced active material available.

The behavior you describe, of sudden drop off, is not a good sign. It probably means the battery is not recoverable. But there are charged that use pulses to eliminate sulfation. They can be successful in cases of "soft" sulfation, where the battery is lower than its rated capacity, but "hard" sulfation is generally death.

The sudden drop off symptom usually means hard sulfation, so the battery is probably toast.
 

Thread Starter

novice64

Joined Jan 24, 2019
7
hi
the batteries were bought in oct 18 and were only used on golf cart. This condition could be due to sulfation of -ve plate or may be corrosion of +ve plate due to over charge. This sudden drop in voltage is not understood
I will definitely try trickle charge method or may be equalization charge to recover this battery. I hope I succeed.
thank you
 

MisterBill2

Joined Jan 23, 2018
8,032
One thing that I had not considered previously is temperature of the batteries, either while charging or else while being used.If one battery is hotter than the other that may cause a problem. You do need to be sure that the electrolyte level in both batteries is where it should be, low electrolyte will be a source of problems.
 
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