[aprssig] Battery testing

Robert Bruninga bruninga at usna.edu
Tue Jul 22 13:24:53 EDT 2014

Save those old Headlamps.  The HIGH beam filament is usually still good and
makes an excellent load (near constant current) for battery testing at 5

I  put it on a fully charged (5 year old) 20 Ah battery and it dropped from
13.8 down to 10.75V (the full capacity drop-out point) in 3 hours.  Thus
the capacity of the battery is about 15 Ah.

Here’s why I did the test:  I had to pre-test some 20 Ah batteries to find
one to carry up a half-mile 300’ hill and then 100’ tower and run my
station for 4  hours guaranteed.  Years past, I had lugged along several
batteries (heavy!) to make SURE my station would operate (since I never
have any idea of the capacity of all the junk batteries I have lying

This year, I  PRE-tested my batteries with the headlamps. One was 15 Ah,
another was 14, the third was 10 and the worst was 1 Ah?  Wow, my luck
would have been to take the 1Ah one.  But this way, I only had to carry the
15 Ah one and had full confidence it would last the entire event.

So don’t carry unknowns into the field.  Test them first with a headlamp.

Just a tip,

Bob, Wb4APR
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