24 Volt Mini UPS Schematic need help

Dodgydave

Joined Jun 22, 2012
9,069
A simple mains 220V ac coil relay across the supply will detect power fail, with a set of dpdt contacts to switch off the battery from charge to output will do.
 

Dodgydave

Joined Jun 22, 2012
9,069
Best to have the battery under charge constantly and take the load from the battery terminals so it keeps topped up, like in a car, then when the mains fails the battery supplies the load,

you just need to monitor the low voltage on the battery to disconnect it from being discharged too low, an op amp comparator will do that.
 
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