Dual Battery - Crank Assist

[bluem00n Lurker Find all posts View Profile Close bluem00n]

Hi All,

Has anyone installed or read a dual battery install where the primary purpose of the aux battery is as an emergency cranking battery, secondary to powering fridges etc (which the AllRounder is capable of).

Installs I've searched/found either have fuses/breakers either side of the isolator, or no fuses/breakers at all.

I agree having fuses/breakers inline is the correct (preferred) way to install but they will prevent the aux from crank assisting due to the aux battery CCA being higher than the rating of the fuses/breakers. Of course, raising the rating of the fuses/breakers defeats the purpose of having them.

However, having no fuses/breakers is generally a big no no, due to the damage that can be caused.

So the question is, how can the system be wired to enable aux CCA to flow back to main without melting the isolator that enables the charging of aux to occur?!

Any ideas? Gratefully received.

Note: My understanding is RedArc Start Assist appears to equalize the main-aux voltages which will be of no use if the main battery is degraded and unable to produce the CCA required.

Regards,
bm

[winniliss Avid PP Poster! Find all posts View Profile Close winniliss]

Use jumper leads similar to this rating:

http://www.supercheapauto.com.au/onl...om=40702#Cross

Winston.

[LeighW Avid PP Poster! Find all posts View Profile Close LeighW]

The Redarc does say "assists", to start off of the aux your probably looking
at around 400A or so, some batteries can supply 900A-1000A CCA.

Your not going to get a VSR that will handle that current, generally starter
cable is not fused but you can get terminal fuse boxes that will handle starting
currents, I have one on my Diesel Prado and have not problems with it.
Of course if you use these then the cabling must be up to the task.

If you really need a second start battery, I would suggest you use a normal
VSR to charge it and install a 400A of above isolator switch that you can turn
on to "link" the batteries if required.

Leigh

[bluem00n Lurker Find all posts View Profile Close bluem00n]

Thanks for your replies chaps, much appreciated.
I reckon it'll be jump leads until I get round to devising a system to do the job inline..!
Will let you guys know if I manage it.

Cheers
Tim

[winniliss Avid PP Poster! Find all posts View Profile Close winniliss]

Thanks for your replies chaps, much appreciated.
I reckon it'll be jump leads until I get round to devising a system to do the job inline..!
Will let you guys know if I manage it.

Cheers
Tim

I always carry a set to help others out as well. A win win situation. Just spray INOX on the clamps every now and then.

Winston.

[Craigo72 Junior Member Find all posts View Profile Close Craigo72]

I originally had my dual batteries set up with a Redarc smart solenoid but after deciding that I wanted to keep a fridge running in the car 24/7 that system wasn't up to the task. I also still wanted to be able to have the back up jump start ability if needed. I fitted a redarc bcdc1220 which meant I had to remove the start solenoid. All I have done is fitted a dumb solenoid in place of the smart solenoid which still gives me the ability to jump start without having to carry jumper leads. If needed just press the button on the dash to kick the solenoid in and hit the start button. Happy days and a constantly cold fridge.

[Warnsie Junior Member Find all posts View Profile Close Warnsie]

Check out traxide.com.au

They have a couple of different isolators that can be used to revert to another battery to crank over the motor.

[starbuck76 Member Find all posts View Profile Close starbuck76]

Easiest and cheapest way is to stay with the in-line fuses (safer) and just use jumper leads as previously suggested.

[ko7624 Junior Member Find all posts View Profile Close ko7624]

You could use a 4 position isolator switch. OFF/MAIN/AUX/BOTH. The Narva one is rated quite high(1500 amps for 10 sec & 300 amps continuous) and is what I use to select which battery to run my winch on. I also use this exact same switch for selecting which battery I want to use to start my boat as that where I REALLY want a back up option. Narva part #61084BL. Other companies make them too but I havent seen any as compact as theirs for the same current rating and price.

PS I have no affiliation with narva other than owning a few of these switches.

Cheers,

Ken