OC & Modding Modify UPS with Li-ion/LiFePO4 battery and BMS

goDofWar_skr said:

Sounds interesting..
could you please let me know what it does and how one would learn more about it..

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There's a lot of videos on YT about doing this. Basically, you'll get much higher energy density and lifespan than a lead acid battery. With LiFePO4, it should be safer too.

The difficulty is matching up the charging/discharging voltages that the UPS uses, which are only designed for lead acid with what the LiFePO4 needs. But a 4S LiFePO4 pack will have a nominal voltage of 4*3.2=12.8V and a charging voltage of 4*3.6=14.4V. Afaik, that's pretty ideal and compatible with the UPS. The discharge cut-off voltage for a LiFePO4 is also lower than that of a lead acid battery, so you should technically be fine there too. Another problem is drawing too much current from it, because LiFePO4's are mostly limited to 0.5-1C where C is the capacity of the battery. A BMS will help manage some of these variables and protect the battery, just in case. But I've never done this, so I could be wrong about the specifics. If I do end up doing it, I'll let you know.