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Re: [Shop-talk] solar battery maintainer

Subject: Re: [Shop-talk] solar battery maintainer
From: Randall via Shop-talk <>
Date: Mon, 6 Apr 2020 00:00:32 -0700
Cc: "'Shop-talk'" <>
References: <> <> <>
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A 5 watt panel should have no trouble keeping a normal car battery up as
long as it gets full sun at least a few days per week.

If not, I suspect you've got either a leak, or a vampire load.  Lots of
stereos, alarms and even the computers on some modern cars draw a little bit
of power all the time.  Clocks are another suspect.

Leaks can be pretty subtle, too. Toughest one I've hunted down was a relay
that had a tiny bit of salt spray on the phenolic plate that carried the
terminals.  Evening dew would sometimes get the salt damp enough to conduct
and turn the relay on.  Found that one just by dumb luck, happened to walk
by the car one night and saw the indicator light on the dash.

Also had trouble with an old motorhome; turned out to be mud that had gotten
thrown up onto the solenoid that charged the camping batteries.

-- Randall 
56 TR3 TS13571L once and future daily driver
71 Stag LE1473 - awaiting engine rebuild
71-2-3 Stag - awaiting gearbox rebuild 

> Perhaps they have bought me a few extra days from time to 
> time, but each of them has repeatedly left me with flat 
> batteries. They will not keep a battery charged over a 
> season, or even a particularly long stint in the driveway or 
> at an airport.


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