Can I incorporate a 12v/100Ah lead-acid battery to replace the 12V/7Ah battery in my PC’s UPS?
My concerns are: Will the charging circuits and the AC-DC inverter be destroyed when the higher capacity battery is installed? Will the current normally used by the charging system in the UPS be enough to charge the higher capacity battery?
It’s possible that the charging circuits won’t work right because the higher current requirement of the larger battery might cause the circuits to think that a short circuit has occurred. They may also have a charging system that dumps a lot of power in when the voltage is low, expecting it to rise in a certain amount of time. When that doesn’t happen, you could have trouble like cooking the UPS circuits or auto shut down.
The UPS current might be large enough to charge the battery (eventually), but the UPS might be engineered to endure only the amount of power that the fully charged 7Ah battery could put out. The 14x longer run time could cook the UPS circuits.
Your present system will give you about 800W for 6 min, so you’d only go to about 1.5 hours with the larger battery. If you really need more time than 6 min to shut things down, just plug the minimum into the UPS. Computer, monitor (get an LCD to reduce power), maybe Internet modem. Leave the printer, scanner, and audio amp on a surge protector instead of UPS…
Sounds like a lot of risks that could result in having to buy a replacement anyway. I’d just go for a UPS of the right size; you might try a local government auction. I bought a 1500Wh UPS for under $20 once (used to be for the sheriff) — and it worked great. It would’ve cost me $1000’s new…
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