Feeding UPS off battery and converter?

[Mac the Knife]

As you may all know, the electricty supply is a bit wonky in SA at the moment..

I used to get by with a trio of APC UPS'es for brownouts and brief dropouts, but now the dropouts can last an hour or more.

I have 3 big deep discharge marine 12V batteries constantly on charge from smartchargers.and 3 decent converters (12vDC to 240V AC)

My question is whether I can plug the UPSes into the converters and thus sail through blackouts without fiddling with things.

Possible? Dangerous? Silly?

Advice please

Mac

[PDR1]

You would be better off simply adding the big batteries in parallel to the batteries in the UPSs. There would seem to be little benefit in taking 12vDC, converting it to 240vAC, converting it back to DC and using that to charge 12v batteries in a UPS that would then convert it back to 240vAC for use. You're describing running a UPS from a UPS...

PDR

[Mac the Knife]

Point taken, but would the little chargers in the UPSes handle a large battery?

Thanks

Mac

[golfbananajam]

Originally Posted by Mac the Knife

Point taken, but would the little chargers in the UPSes handle a large battery?

Thanks

Mac

You might also end up with a control circuit issue with the addition, potential, extra current available from adding the batteries in parallel, best to consult whatever documentation you can find from the UPS manufacturer.

[FakePilot]

Some UPS have an external connector for larger 12volt batteries. Also there are heavy duty inverters for sale. Hah! Soon you will discover all about why powering everything with batteries is tough.

I think mixing battery types in parallel is a bad idea.

[Mac the Knife]

The usual little UPS sold for home use has a a 12V motorcycle battery desisned to give your machine a message to shut down gracefully (5-15min). The circuitry is designed to give you enought amp/hrs to do that only - it cannot handle prolonged loads without overheating.

There are real UPSes that really wil give you several hours, but they are big, heavy, noisy and ferkin' expensive - PDR1's answer is theoretically correct but impracticable unless yer wants to spend mucho dinero. Better to buy a little genny and hope it starts.

My solution is relatively cheap, seems safe enough and lasts me a couple of hours. Just add batteries in series for more time, but be prepared for a l-o-o-o-n-g recharge.

Mac

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