SLA Batteries Starting to get hot.

[Dacflyer]

I have a 24v system 2P2S 4x 100AH SLA batteries, About 3 yrs old.
I was routine checking things, and I noticed 1st that solar kw for the day was getting higher than usual.
I then checked my batteries, and I noticed that 1 pair was hot ( over 100F ) I checked voltages and they were normal, about 13.5 per battery which is within normal range. I'm thinking that the batteries are starting to go bad. They never been discharged more than 15-20%
I went into settings and reduced cut off charge to 13V ( 26V ) this has helped some, but you can still smell the battery chemicals when I open the box.
I know that SLA are sealed, But is there anything i can do? or should i start searching for new batteries ?

The Batteries in my UPS's Usually would start heating up when they was getting close to EOL. I now have a temperature alarm attached to them to alert me.
I'm thinking to do the same for the 24v system, except, I'll have it cut off charging if the batteries get too warm.

 

[Rednecktek]

Was your controller trying to run an equalization charge? That'll cook a battery.

 

[MisterSandals]

I have a 24v system 2P2S 4x 100AH SLA batteries,

Happen to have a pic of the battery wiring?
What charger are you using and how many charge amps (array size)?

 

[Dacflyer]

Was your controller trying to run an equalization charge? That'll cook a battery.

It does from time to time,, but i have the voltage set to the same as float voltage.. so it can't do that...

 

[Dacflyer]

Happen to have a pic of the battery wiring?
What charger are you using and how many charge amps (array size)?

I'll get back to you on that...have to get you pictures.. But battery bank is 4x 100AH SLA 2s2p.

 

[Vigo]

If you can afford the downtime I would separate all batteries from each other and let them 'settle' and see what the resting voltages do. While the strings are in parallel, one string could be 'holding the other one up' in voltage and without current measurement between the two strings it would not be obvious that that was happening. The 13.5 readings on the batteries shows that the two batteries in series are not way out of balance with each other, but it wouldn't show if one string was trying to be 14.2 and the other one was trying to be 12.6 and they're only 13.5 because they're all hooked together.

Do you have a DC clamp meter?

 

[Dacflyer]

Happen to have a pic of the battery wiring?
What charger are you using and how many charge amps (array size)?

 

[Dacflyer]

Sorry bout late reply..

 

[Dacflyer]

Since I had adjusted voltage the other day, the batteries haven't been getting hot, but I'm sure there's still some damage to them.. The current is the same on both sets, about 1/2 volt difference in the sets.. As long as they are by cooking I'll just let them go.. I've never heard anyone adding water or electrolyte to SLA batteries..

 

[Rednecktek]

Since I had adjusted voltage the other day, the batteries haven't been getting hot, but I'm sure there's still some damage to them.. The current is the same on both sets, about 1/2 volt difference in the sets.. As long as they are by cooking I'll just let them go.. I've never heard anyone adding water or electrolyte to SLA batteries..

Well there's "Sealed" lead acids and Sealed lead acids. One has a removable cover that pops off to refill but the manufacturer doesn't want people messing with it so it says "Sealed", and then there are batteries that have the lids glued on and nothing short of a chainsaw is going to get you access.

Yours are truly sealed so you can't add any water without messing them up. No sense in worrying about that then.

 

[Dacflyer]

Well, If you could do anything with SLA,, What do they use ? I'm sure not just battery acid..