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Subject: Re: Charging a battery from a car battery
X-Newsreader: Forte Agent 1.92/32.572
Date: Tue, 03 Dec 2002 12:37:57 -0500
NNTP-Posting-Date: Tue, 03 Dec 2002 12:38:02 EST
Organization: Bell Sympatico
I am not discussing the full system that I am not familiar with , but
if one connects a dc source to two batteries through a diode in
series with each battery , one battery will never get power from the
On Tue, 3 Dec 2002 09:41:15 -0000, "Kijoma"
>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, email@example.com (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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