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plans36 avatar image
plans36 asked

Can someone help suggest the proper product i need?

Hello all,


New to the forum. I have a work van with an onboard air compressor that has an elec. Start motor. I recently installed an automotive 12 volt battery to independently power the electrical starter of the air compressor from the vehicles 12v battery/alternator.


The battery is installed at the rear most of the vehicle with the air compressor. The air compressor does have an onboard charger but after about 15 min of run time, I measured a mere 12.56 volts I don't beleive this us enough to keep the battery in a healthy state of charge, as most alternators on 12v vehicles put out about 13.6 to 14 volts.


There is a 12V cigarette lighter style outlet right next to the battery that I would like to tap into to help maintain the charge of the battery, but think if I run wires straight from the outlet to the battery I risk the potential of back feeding and blowing a fuse or worse damaging the vehicle wiring. Almost need a diode of sorts to keep that feom happening so I came across these products via Google search.

I'm basically looking for a DC to DC battery maintainer/tender. what product would best suite this application? Can I use the wires from the cigarette lighter outlet to power said product I imagine they are 14 or 12 gauge and supply maybe a max of 15 amps (fused) sorry for not researching the exact amps of the fuse. It is a Ford Transit 250 van.

Please advise, and thanks in advance.

-Plans36

victron products
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1 Answer
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kevgermany answered ·

Car type AGM batteries normally charge around 14.4 V. But this is the cut off voltage. Off charge with no load The voltage will drop and should stabilise around 12.5-12.7V with very slow decline. The voltage you're seeing may be the way the compressor is set up, or may be a tired battery on the compressor. If you can disconnect the old compressor battery and see what happens with the new battery alone.

The Orion DC:DC chargers are the product range you need. A 12/12–xx where xx is the max charge current.

Run cables from the battery, those cigarette sockets aren't too good for continuous use a high current. Select cable size using an on line calculator and depending on the max output current of the Orion. If not sure, go up a size or two. Don't forget a decent fuse on the battery end of the positive cables.

A few things to watch.

The setup you want can flatten the starter battery and leave you stranded. So make sure the Orion is set up to only charge when the van engine is running. Details in the manual. Your transit probably has a smart alternator. This can make it harder to set up the Orion.

You will need to do reasonable amount of driving. Batteries need time to charge fully.



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