Re: Battery Backup

[Mike Morrow-3]

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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[George, W5YR]

Mike, the output voltage of the VS-35M supply is adjusted to account for the
drop across the diode and to provide a float voltage of 13.8 as well as an
equipment operating voltage of 13.8 volts. My battery has been in service
now for over two years under this arrangement and remains charged and
available for service. I have external chargers available for equalizing
charging and the like.

Thanks for your note and comments. Big batteries are indeed convenient and
useful power sources.

73, George W5YR
Fairview, TX
[hidden email]
http://www.w5yr.com


----- Original Message -----
From: "Mike Morrow" <[hidden email]>
To: "George, W5YR" <[hidden email]>; "Elecraft" <[hidden email]>
Sent: Thursday, July 29, 2004 11:16 AM
Subject: Re: [Elecraft] Battery Backup


> 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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