"UPS" dead after power cut

[JohnW2]

A UPS in the off state must not consume substantial current (holding an NC contact open..), ....

That's true, but I would have thought that the current needed to operate the coil of a (pretty tiny) PCB relay would be pretty insignificant in relation to the current being drawn by the inverter.

... nor must it connect its internal inverter and the incoming supply together....

That's obvioulsy very true!

... This pretty much requires all relays be NO.

I need to think about that. My first reaction is to suggest that it's more to do with the arrangement of the control circuitry ('interlocking'of relay functionality etc.) than to whether one uses NO or NC contacts, but maybe I'm wrong!

Schematics for common UPSes are educational and quite easily available (speaking Russian is usually to your advantage, however).

That sounds like an interesting and potentially educational exercise - I'll see what I can find!

Kind Regards, John

 

[JohnW2]

It does seem wrong that a UPS with a dead battery can't be plugged in and start the battery charging.

To be fair, I think that they (at least, mine) can do that - the problem in my case (as proven when I tried to charge the battery with a 'car' battery charger) was that the battery in question was 'unchargeable'.

Kind Regards, John

 

[ericmark]

Thank you for reminding me I must plug in my UPS to re-charge batteries. Not used much it's 110 volt and used to get 60 Hz for odd project.