> The Schottky diode approach works best with a
> switching supply that is inherently current-limiting.
> Some linear supplies cannot start under load,
> following a power outage. Although it may take a
> day or two to recharge an AGM battery when it only
> sees the float voltage.
What voltage/condition exists on the DC Supply line when
the battery is depleted and the charger is not able restore
the battery for x-amount of time. Is the radio/repeater
out of service during a/the low voltage condition?
> Ideally, the AGM battery should be bulk-charged at a
> higher than normal voltage, and then put back on
> float voltage once it is fully charged.
> But, that process involves a more complex and
> expensive setup than most folks want.
A&A Engineering and Xantrex make a few really neat charge
controllers that are worth looking at.
> My Schottky diode setup works just fine and is simple
> to implement. Some folks may argue that a low-voltage
> disconnect feature is needed, but many radios simply
> stop working once the supply voltage drops much below
> 9 or 10 volts- sort of a built-in LVD feature.
But most all of them probably still draw current... unless
they are of a fairly recent generation.
> Of course, some radios and controllers will continue
> to draw current all the way down to zero volts, and
> I avoid such power hogs for that reason.
It only takes one wasted bank of dead site batteries to
be replaced to put value into a low voltage disconnect,
which is fairly easily constructed with less than $30 in
parts typical. How much current (energy) a device draws
in regular operation is a different animal of how events
unfold during a loss of power revert to battery situation.
If you're at a solar only site sometimes you have to
live with limited energy sources where the Low Voltage
Disconnect will save your bacon.
cheers,
s.
