Dual Batteries

Submitted: Saturday, May 08, 2004 at 19:16
ThreadID: 12704 Views:1702 Replies:2 FollowUps:0
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I know this has been done to death but I am trying something a little unusual. Pirahna advise me that the only dual battery system they can fit to a Terracan involves a 45A DC and costs around $900. I reckon that's next to useless. I'm trying a DC in a sealed vented box inside the car with charge coming from a $17 gizmo called a Projecta Charge and Start. It is designed as an alternative to jump starting. In the event of a flat battery you plug it into the cig socket of a running donor car and the other end into the cig socket of the car with the flat batt and leave it for 15-30 min and then start.

I figured this could be used from a cig socket and connected to a DC Batt to charge whilst driving. After trialling it today on an old (6 yrs) DC only holding about 40% charge, I estimate it to be charging at about 6 amps per hour. I'll check the voltage again in the morning to see if it holds and then I'm off for a 2.5 - 3 hour drive tommorrow and see what happens.

Of course the DC will need solid charging with a decent battery charger in between trips but this MAY be a cost effective alternative to keeping the charge up whilst travelling.

Wait for my next report.

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Reply By: Martyn (WA) - Saturday, May 08, 2004 at 20:57

Saturday, May 08, 2004 at 20:57
I can't see this working I'm sorry, maybe I've missed what you are trying to achieve. If you plug a fully charged battery into the giggy lighter and expect it to charge the flat battery under your bonnet I think you are pushing muck up hill. Jumper leads would work I suspect. The fully charged battery will equalise with the flat battery but it won't be enough to start the vehicle, as the fully battery discharges I expect you may after a longer period of time end up with two half charged batteries. If the flat battery is buggered the two of them will end up flat. This is the way I see it, there may be an auto spark that can advise you differently. Good luck if it works you've done well, I'll stick with what I have. Is the Terracan special in some way?
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AnswerID: 57766

Reply By: Eric Experience. - Saturday, May 08, 2004 at 21:55

Saturday, May 08, 2004 at 21:55
Forget the $17 gizmo, a piece of wire from the alternator to a fuse then to a switch then to your DC battery is all you need. dont make the wire to thick about normal flex wire is ideal as you can only charge at about 8 amps, if you use thick wire you will have problems when you start the vehicle, the thin wire limits the current to a safe level in the 5 seconds it takes to start the motor. Eric.
AnswerID: 57772

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