I am looking for an UPS that would be off when the ac mains power is on. Off as in inverter as that just wastes power. And turn on in the event of a mains power failure.
Also possible self build as I already have a 1.5KW inverter 4 X 100Ah at 12 volts sealed AGM batteries and 80 amp charger.
So I would need something that can turn on DC to inverter in case of mains power loss, at the same time disconnect mains and switch on AC from inverter. Time delay is allowed.
I can't give you any advice on a "self-build" solution and this probably isn't the right forum to get answers for that but I can tell you that our Back-UPS range is what your looking for.
When the mains is on it goes straight to the sockets (only the battery charger uses any power) and when the mains is off it uses the batteries.
There is other things you can do with new Smart-UPS such as putting them into green mode but the Back-UPS is probably what you want.
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