Re: Battery Backup
Posted by
Mike Morrow-3 on
Jul 29, 2004; 5:16pm
URL: http://elecraft.85.s1.nabble.com/Re-Battery-Backup-tp369255.html
George / W5YR" wrote:
> The + output terminal of the VS-35M Astron supply goes to the anode of a
> high-current diode
Hi George,
I assume that the Astron output voltage is about 13.8 vdc. Assuming a 0.7 vdc voltage drop across the diode, your deep discharge battery sees about 13.1 vdc.
Is that enough to maintain long term battery charge, or enough to fully re-charge the battery following a long period of operation on the battery?
I also use a deep discharge battery for backup power. I charge it with a regular battery charger that can raise the voltage high enough during charge to reach TVG (total voltage for gassing). End-of-charge voltage with the charger still on tends to run above 16 vdc. On USN submarines, we would charge our main batteries until we got individual cell voltages in the range of 2.7 to 2.8 volts per cell. Deep discharge batteries also like periodic full discharges followed by a vigourous equalizing charge. Most commonly available automobile parts store chargers are not really designed to deliver a proper equalizing charge.
On camping trips at a fixed site, a deep discharge battery is my primary power source (radios, lights) for days at a time, even when I'm QRO with my TS-50S. Every ham should consider keeping a 85 Amp-Hr (or greater) deep discharge battery around for power outages. It beats powering up a gasoline-fueled generator.
73,
Mike / KK5F
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