I was given some brand new sealed lead acid batteries. I have no real need for them right now, but I don't want them to go to waste. I'm trying to figure out the best way to store them, unloaded, for many years until I'm ready to use them for something.
Would storing them in a cool basement, attached to an intelligent float-charger work? When I say intelligent, I mean it monitors the voltage and cuts on and off to keep the charge topped off.
Approximately how long could I keep the battery stored like this and not have significant degradation?
Best Answer
You're unlikely to get more than 5-7 years from the batteries even stored as your propose.
This link describes many factors that contribute to shortened or lengthened life and notes "Recent industry experience indicates that a 4 to 7 year VRLA battery life is more likely"
http://www.power-thru.com/documents/The%20Truth%20About%20Batteries%20-%20POWERTHRU%20White%20Paper.pdf ...
"A European study of over 1,000 installations, of various system voltages and cell capacities, containing about 35,000 cells concluded that VRLA batteries require replacement after 5 to 8 years of operation. The shorter lifetime (5 years) was associated with batteries operating at 110 V or higher system voltages. The longer lifetime (up to 8 years) was applicable to better quality batteries and those of lower system voltages. Absorbed Glass Matt-type cells demonstrated a higher failure rate than did gel-type cells."
These are for commercial quality batteries, it's unclear what you have, though if you know and can refer to the datasheet you'll get a more specific answer. The batteries in the study are generally used in UPSs so are kept on float charge, as you propose, except for a drain 1-2 times a year on test.
This is a link to a VRLA battery with a 20 year design life on float charge, so it is possible but again extremely unlikely this is the battery you have.
http://gemenergy.com.au/wp-content/uploads/2017/01/Section-26_05-2015-02-Absolyte-GP-Industrial-Batteries-Overview.pdf