> Does anyone know how you could test/troubleshoot an automatic float battery
> tender?
I guess it depends on how fancy it is. For a unit that only controls charge
voltage & current, a variable power supply and a load resistor ought to do it.
Monitor the voltage output from the tender (the simulated battery voltage), and
the current output. Start with the power supply at about 12.5 volts
(representing a cold but charged battery) and the tender should start out
putting out close to it's maximum current.
Hmmm, guess that sets the maximum resistance of the load resistor, 12.5 divided
by the max output current. It also will have to handle a fair amount of
dissipation, (14.5 ^ 2) or 210 divided by whatever the resistance is. If you
don't have something like that lying around, try paralleling some old headlight
bulbs.
Then bring the supply voltage up slowly to simulate a battery charging, and
watch what the DUT output current does. By about 14.5 volts, the charger should
go into float mode, and the current should drop to almost nothing (whether it
tapers or drops suddenly depends on the type of tender).
Then slowly lower the voltage (simulating self-discharge) and watch what the DUT
output current does. You should be able to go down to something like 13.5
without the current increasing, then the current should go back to maximum by
the time you get down to 12.8-13.0.
Check the description of your tender to get more precise values, as these are
just general guidelines from memory. Here's one :
http://www.bakerprecision.com/battend.htm
Of course, you _could_ just hook the tender to a battery and monitor what it
does as the battery itself first charges, then floats and self-discharges. But
that might take some time <g>
And if your tender also tries to "desulfate" the battery, then all bets are off.
Randall
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