In a message dated 10/2/2006 9:47:05 PM Central Standard Time,
beaker211@rogers.com writes:
> Does anyone trickle-charge their batteries over the winter? That is what I
> do with my RV batteries using a small solar panel. My understanding is that
> if you let batteries discharge, they will eventually lose their ability to
> maintain a charge down the road. For cheap batteries, this could be over the
> course of a single winter. Happened to me once.
>
Cranking batteries (as opposed to deep cycle batteries) have very thin plates
with a maximized surface area to maximize cranking amps. During discharge
the lead from one plate will dissolve into the electrolyte and with these thin
plates some of the plate surface will disappear altogether. When recharged,
the lead is deposited on the remaining plate structure and the result is less
surface area and less cranking current capability. I have heard estimates that
letting a battery totally discharge and then recharging it will result in a
50% reduction in battery capacity. I don't know if I believe that number but
in
my experience a few successive discharge-recharge cycles will render a
battery quite weak indeed.
But batteries are way oversized for most conditions anyway. The critical
conditions are very cold temperatures where battery capacity is reduced and
cranking current requirements are the most. And since we rarely drive our cars
in
those conditions a singe or even two complete discharges will not result in
noticeable degradation but will show up in a shortened battery life.
Trickle charging may not be any good for the battery either. You need to use
a voltage regulated charger or battery maintainer or you will overcharge a
battery even with a small charger. Overcharged batteries will break up water
into oxygen and hydrogen and these gases escape. Most batteries, especially
sealed batteries, have a mechanism to recombine the gases and tolerate some
overcharging but this is technique is not 100% effective and prolonged
overcharging
will eventually cause trouble. NiCad batteries, on the other hand, will
tolerate this kind of trickle charge but the chemistry is quite different and
the
technique doesn't translate to lead-acid batteries.
But small battery tenders are available and quite cheap. I bought a pair
from Horrible Freight a while back on sale for about $6 each. That's too cheap
to pass up.
Dave
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