Battery degradation after sitting unused for a long time?

[Anonymous user]

I bought a BE750G on Craigslist  a couple years ago. It was new, unopened. It turned out I didn't need it for the application I bought it for so it has just sat in the box, unopened, since then. 

I was going to pass it along to a friend so just now opened it and connected it to power. The datasheet taped to the side of the unit has a tested date in 2010. After being plugged in for 24 hours I still get the red light telling me the battery is bad. After removing the battery I put a voltage meter on it and it shows just 8V.

My question is would it be expected for the battery to go bad from just sitting unused for 5 years?

[Anonymous user]

In short: yes.

Lead acid batteries have a fairly high self discharge rate when stored. It's recommended to keep them in a cool area and charge them every six months when in storage. If allowed to sit around in a discharged state, they'll start to degrade, usually through sulfation. The damage that takes place is almost always irreversible.

Stronger cells within the battery may also "reverse" charge other, weaker cells within the battery. Damage done in this way is pretty much fatal to the cell in question.

A new battery should certainly get this unit working again, if someone wishes to use it. A generic replacement battery with suitable characteristics, while not endorsed or approved by APC/Schneider Electric, may be used.

[Anonymous user]

Thanks for the quick reply. That's the answer I expected, although I was holding out hope that there was a way to reset it. So, off to the battery store.

[Anonymous user · Accepted solution]

Here few words about my own experience, however a UPS of other brand.

800VA one, purchased year 2004 for one Windows XP pc with 19inch TFT.

Since purchase in continues use. I guess it has dry battery.

Up to now the original battery inside.

Since about 2 years ago it is backing up an 27 inch all-in-one computer instead.

I do not remember real power outage, either those had too seldom to memorize, or not a one indeed.

However once a year a deep discharge is made

by disconnecting mains supplying the UPS and continuing normal work during power outage.

Last such test was made this week, results: it took one hour and few minutes to drive it 

to state where the acoustic tone becomes more frequently.