Some days ago a friend of mine gave me his old APC – Smart UPS 1400 because the batteries after 5 years on-line were gone and he preferred to buy a new (but cheaper) UPS instead of replacing them.
I immediatly opened it and found that it uses two sealed batteries with 7,5 amp-hour capacity and 12v nominal voltage connected in serie to obtain a final nominal voltage of 24v.
I checked the price for the right APC replacement batteries but it was far too expensive so I decided to do a mod using two solar energy system batteries I had from my house in Italy.
The two solar energy system batteries were brand new and are rated 55 amp-hour capacity and 12v nominal voltage each one so they give 24v / 55ah when connected in serie.
These are some pictures of my “dirty work”:
I did some tests and now my system (NAS, firewall and gigabit switch) can work uninterrupted for more than 3 hours in case of black out!
Not bad for an old but revived UPS!
Cheers!