I don't know about "toast", but I've got a theory...and am fleshing it out in a
3-part Kitplanes series right now...

With a fresh battery, a "trickle charger" that puts a small amount of current
into the battery and then "tricles down" as the battery voltage gets up to a
point does just fine.

However, as the battery ages and the internal resistance goes up, it requires a
higher and higher voltage from the trickle charger to bring itself up to what it
senses as "full charge". (I could snide comment about human males working the
same way, but I will refrain {;-) ) This higher voltage actually
overcharges the battery and forces the electrolyte out the spigots. (The mental
image fairly blushes...)

I'm working right now on a "cyclic" type of charger where the charger puts out a
full slug of current up to a precisely limited voltage (13.6 to be exact) and
then completely shuts itself off and lets the battery self-discharge itself down
to some much lower voltage (12.6 to be exact) and then repeats the cycle. The
folks at Concorde turned me on to this trick and they claim it is the ONLY way
to keep a recombinant gas battery happy. Seems to me it is the way to go with
flooded plate as well.

April, May, June 2004 Kitplanes columns.


Jim




"Roger Long" om
shared these priceless pearls of wisdom:


-
-Is the battery toast? Are these maintenance trickle chargers inappropriate
-for long term connection?

Jim Weir (A&P/IA, CFI, & other good alphabet soup)
VP Eng RST Pres. Cyberchapter EAA Tech. Counselor
http://www.rst-engr.com