ups battery
 

My pc in my locale has to have a UPS just to attempt realistic chores for any amount of time without having a mental snap over sudden shutdowns.. most in the north would agree, brown outs galore, and when storms come down it is no height to them, pc death imminent. Anyway, the excuse for paying alot for a home pc backup ups is a good one.

and I found something interesting after seeking a new battery, it has been 6 years.
going by dimensions, the battery can be upgraded in my apc 500-es, by about 2000 mah. 1 dollar more than the original. this saves another dead battery needing a place to get recycled or dumped, as it adds time. A thought to ponder in the ecomod realm, batteries are getting better for everything.

The mAh rating doesn't necessarily add life to the battery, it just adds time to the discharge rate.

If you're interested in using a larger battery, and don't care what the setup actually looks like, you can use a the internals from any UPS and hook them up to just about any battery you want, put it in a project enclosure, etc...

I had a UPS that I built from a couple car batteries and an invertor that allowed my computer to run for several hours before it went too dead.

Back when I cared about computers... Not so much into them anymore.

Make note that a discharged car battery can overload the UPS charging circuit when the power is restored.

How, exactly? The UPS charger (in mine, anyway) only charged like 3 amps at 12V... I'm not sure how a battery can overload a charger, when the charger is outputting it's max power any time it's charging.

"Overload" wasn't the best word to use. What I meant was: The charing circuit may provide insufficient current to charge a dead battery in a practical amount of time. Also the circuit wasn't intended to operate at full capacity for extended periods of time, as this isn't a condition that occurs when using the OEM battery.

Ah - the charging circuit is usually equipped with thermal protection, so that if it gets into a dangerous condition, it stops charging.

I never drained the batteries while using mine, but it never took more than a day to recharge completely to the point that the UPS' charger would stop outputting voltage.

Of course, the idea of a UPS isn't to allow you to keep working, it's to provide you with a surge buffer and keep your machines running (hopefully) until the power comes back online, or until you can get a real backup system running, or to provide you enough time to finish what you were doing, and shut down/turn off safely.

My older APC unit has a small fan that comes on when charging/discharging. I would feel more comfortable about using that to recharge large batteries.

The sealed lead acid batteries that are in UPS systems are in there because they ship well and you can forget about them until the fail and you have to buy new, a regular flooded deep cycle battery should last longer, be cheaper to buy and as it gets older you can top off the water instead of buying a new battery, add a desulphater to it and it should last 20 years.

I'd prefer an AGM battery. They are less likely to spray a fine acid mist over everything if they're somehow overcharged, and they'd last just as long in a UPS application.

If I still had mine, I'd probably replace the (long since dead) batteries with lithium variants. I used to have a source for "dead" laptop batteries, which I could get for free, and repair for very little money. (It's often only one or two dead cells, not the whole battery.)