Just for my own edumacation... swollen SLAs

[SparkyJJO]

I have an old APC Smart UPS Sua1000NET that runs my modem, router box, NAS, etc. Every few years I have to replace the pair of SLA batteries in it as they get weak (they sit charged 99.9% of the time, rarely does the thing cycle).

Recently it started to complain again that the batteries were shot. Ok. Then today the whole thing suddenly shut down while emitting a pathetic, quieter than normal but steady "screeeeeee-------" push buttons, nothing, unpluggedz still pitifully sounding its single tone. So I yanked the batteries and... oh.




I'm curious, what would cause such bloating of a SLA battery?
Interesting too that the bloated side of each battery was the sides touching each other.

 

[Any name you wish]

We have similar batteries at work. I am interested if they still have a voltage to them. Our SLA did even as the case was cracked and we could see the plates. Gasses do still build up in these I would imagine. Maybe you also have an issue with your UPS charge circuit. Should check that as well.

 

[Lt.Dan]

I would imagine overcharging would do this?

 

[OzSolar]

Maybe you also have an issue with your UPS charge circuit.

Overcharging is the most common cause.

It may be charging as designed but I don't know how to fix it. I've always suspected that keeping sealed 12v battery much above 13.0v for 24/7/365 does eventually end up damaging them.

If they weigh less now than when new it is from the loss of water while being overcharged. AGM's are recombinant batteries which mean they should never change weight under normal circumstances.

 

[SparkyJJO]

I do not know if the SUA1000NET allows for adjustment of the charge voltage or not. I assume these things always overcharge at least a little bit, but in all the years I've had this unit and the 3 sets of batteries this is the first that severely bloated. I have had previous sets get a slight puff to them at end of life but never something this crazy.

No leaking from either battery.

 

[chriscappuccio]

I get this after 3-4 years with APC UPSes, where cyberpower UPS seems to keep its SLAs working for more like 6+ years. I thought it was the APCs chronically undercharging and sulfating the poor batteries but never did any actual research into the problem.

 

[OzSolar]

No leaking from either battery.

I'm not sure you would but that's just guess. If you still have the batteries would mind humoring me and comparing their current weight to the weight when when new?

 

[Browneye]

Yep. Our data tower UPS's batteries all do this. They get replaced every three years or so.
Sometimes it's really hard to get the battery trays pulled out due to battery swelling.

 

[SparkyJJO]

I'm not sure you would but that's just guess. If you still have the batteries would mind humoring me and comparing their current weight to the weight when when new?

They're still sitting in the basement. I can weigh them but I have no idea what they weighed when new. The little rubber caps are still intact.

I'll check voltage for kicks. They have some, enough for the UPS to scream anyway.

Yep. Our data tour UPS's batteries all do this. They get replaced every three years or so.
Sometimes it's really hard to get the battery trays pulled out due to battery swelling.

Yeah same here but this is the worst I've seen this unit ever do.

 

[Delmar]

Curious what happens when you over-battery the SUA1000. The charging current is absorbed by more lead. Internal 18AH's and external 35AH's

 

[SparkyJJO]

I've thought about it. I would have to put a cooling fan on it I think to keep it from overheating during an extended runtime. It doesn't have the external battery connection since it isn't an XL.

 

[chriscappuccio]

Yep. Our data tower UPS's batteries all do this. They get replaced every three years or so.
Sometimes it's really hard to get the battery trays pulled out due to battery swelling.

Curious what happens when you over-battery the SUA1000. The charging current is absorbed by more lead. Internal 18AH's and external 35AH's

So, maybe 10 years ago I started taking APC 1000 UPSes and putting SB50 connectors on the battery cables and using them with TWO 100Ah 12V AGMs for more storage. They seem to handle it quite well. Still have plenty in service. The AGMs last forever in this configuration, unlike the SLAs that they came with.

At the same sites (tower sites) I migrated to the Sigineer-style U-shaped charger/inverters, but the ones I was buying had a 20ms transfer time which was too much for some equipment. Finally went with Xantrex 818-2010 which can be configured to 10ms time and has a strong enough charger for 4x 100Ah 12V AGMs.

 

[Delmar]

I've thought about it. I would have to put a cooling fan on it I think to keep it from overheating during an extended runtime. It doesn't have the external battery connection since it isn't an XL.

The XL cooling fan even runs when the depleted batteries are recharging. Loud but effective.

 

[Substrate]

The float voltage is usually too high, or has drifted. Check that.

Typically, 13.8v after absorb has finished is too high if left on forever. 8 hours max after absorb.

13.6v is a more reasonable value for 12-48 hours. 13.4v is a long-term maintenance float but you can't *start* with that or you'll never achieve a full charge and will sulfate. 13.4 is something you fall *back* to when the previous 13.6 or 13.8 has been applied and timed out.

Most of the supply chargers are dumb - and rarely temperature compensated. So early demise.

Another common issue is swapping AGM for GEL, when the ups calls for AGM. Consumers don't know the difference, they all "look sealed to me".

If your replacements are TRUE gel, then the CV voltage needs to be lowered to 14.1v or less. Despite what it may say on the case. Decades of shade-tree UNknowledge has left the cheapies to try and push the "gel and agm are the same". They are not. But sells more batteries when they swell like this.