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Subject: Re: Charging a battery from a car battery
Date: Tue, 3 Dec 2002 09:41:15 -0000
NNTP-Posting-Date: 3 Dec 2002 09:41:15 GMT
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diodes = baad ..
most of these units wire to the alternator warning light circuit.
if there is no power on the alternator light (engine stopped or off) the
second battery is switched off.
when the engine is running, the relay energises and parallels the batteries.
dont do this with a sealed battery tho as if its flat the inrush current
from the other battery/alternator will probably do it damage.
you basically need a small boost switching regulator that can give a current
limited output which is essentially constant regardless of source battery
oh and hook it to a relay/transistor to the ignition circuit so its off when
the engine is off.
"Vlad" wrote in message
> Just 1 diode in series with each battery
> On Tue, 03 Dec 2002 03:26:56 GMT, firstname.lastname@example.org (klmok) wrote:
> >On Tue, 03 Dec 2002 00:22:15 -0200, Bruce Douglas
> > wrote:
> >>I am trying to make a battery charger for charging my sealed lead
> >>batteries from a car on occasions when I am away from mains power.
> >In RV camper shops they have a battery charger isolator for charging
> >the second battery. It allows the alternator to charge both the main
> >battery and the second battery but won't let the second battery draw
> >juice from the main battery when to alternator is not running.
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