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[aprssig] UPS

Dave Baxter dave at emv.co.uk
Tue Jan 2 09:23:33 UTC 2007

Sorry to go back to this, but only just seen the thread.

As others have said, the best way to use a UPS, is use it as it was
designed, to back up 115 (or 230) Volts AC, for equipment that needs it,
and use more regular or custom devices to "float charge" dedicated 12V
battery or batteries for radio's TNC's and whatever.

Note also, that in many UPS's the internal batteries (again as already
said) are not always 12V (never seen one with less than 24V myself over
hear in the UK) and also not always if ever "Ground Referenced", so
hanging other equipment off the UPS's battery could (as also mentioned)
not only screw up the UPS's internal battery sensing for charging, but
could also risk all sorts of DC ground offset and loop problems, ranging
from at best odd noises to smoke!

Best use them as the makers intended....

Take care..

Dave G0WBX.

> -----Original Message-----
> From: John Gleichweit
> Sent: Wednesday, December 27, 2006 11:55 PM
> To: TAPR APRS Mailing List
> Subject: Re: [aprssig] UPS
> I have a couple of small UPSs in use around the house. The 
> 400va unit that I have powering the headend for the network 
> (dsl modem and wireless router) uses a single 12V x 7AH 
> battery, similar to the one that is the battery back-up for 
> the burglar alarm in the house. 
> The other one is a 1400VA unit and uses a pair of 12V x 14AH 
> batteries in series for 24V into the inverter. That's used to 
> power a server that's online 24/7. 

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