Dual Battery Systems

Andy,

Search the archives there is a plethora of information.

I'd recommend staying away from ARB or Pirahna, not because they do a bad job, it's just they are too expensive. You'll do a lot better with an auto elec.

Or you can go where I had mine done. Talk to Chris at Battery World, Wantirna. He's a terrific bloke and doesn't charge too much.

Cheers,

Jim

G'Day Andy Q

Mate, you don't have to be a rocket scientist to do it yourself.......

1... Mount Battery,
2....Connect to main battery in Parrallel. (50 amp wiring at least)
3....Install continious Solenoid in Positive line operated by the ignition.

Thats it.
That way the Aux Batt will only be connected to the main battery when Ign on and will recieve charging from alternator when running, and thereby isolating the Aux Batt when Ign off , maintaining a fresh main battery at all times for starting.

Better than the fancy ones that stop when voltage gets to a certain level and cuts everything off. Just monitor the battery voltage,,,,Easy.

Hi Andy,

In all but one of my vehicles I have used the Piranha system and i have never had a problem with it.

In my first 4WD however, I used a system not unlike what Jenco has suggested, the only diference I had was to install an inline to be able to disconnect the second battery completely. I learnt the hard way, that just using the ignition as a switch was not enough. When the ignition is turned on, it parallels the two batteries, therefore, if the second battery is dead flat, you end up with two half flat batteries, this is not always enough to start the vehicle.

Finally, By using a smart solenoid system like the ARB or Piranha system, you are able to use to different batteries, ie: Starting and Deep Cycle etc.

Hope this helped.

Hey, thanks to all of you that replied, all good sound advice. I suppose it's just a matter of confidence when it comes to fitting ...I have just finished installing a top shelf and map reading lights, next is the Helton heating unit for the shower so a dual battery system can't be all that hard.

Andy

There's a view for every 4WD ever made I reckon! I only know I've had a Piranha on my 80s since 1998, and its worked all the time - no fuss, no problems.

Max

Hi. I suggest that you read post ID 25021 dated on 25/7/05. The comments total over 13pages and I'm more confused than ever.
I personally use an 80 amp continuous rated solinoid and 18mm2 cable and do not have any problems. The solinoid cost me $40.00 from our local auto lecky

Stay with something basic to hightec is no good can play up in the outback . Solinoid are good but can stuff up so carry a spare

You could count the amount of failed arb or tjm modules which have failed on the toes of Darryl Beatties right foot.....

Both units do virtually the same job but both have different benifits...

Pirahna isolates both batteries once car turned off and will let the aux batt flatten leaving the starter batt untouched ready for starting....

Smart solenoid does the same thing "BUT" once the aux batt is getting useless it will scab power out of the starting battery and will then stop scabbing once the starting battery is down to 12.7volts... So you may get another day of fridge using the Arb version using identical batts in both cases...And its no problem starting a car from 12.7volts...

Doing the cheap way and paralling the two batts can cause probs as much as if you flatten the aux batt then turn the ignition on you can get two pretty sad batts if not careful...

Pirahna comes with a 5yr warranty... Arb is one year....

We are trialing two cars with each system and happy with both....

Jenko

The basic switched solenoid is, as you say, the simplest way of paralleling batteries. But there really are some very strong arguments for the Redarc approach (that delays switching until the starter battery is well up to charge - which takes about 1-2 minutes).

The first is where you turn the ignition key, note a king brown heading your way - or get distracted by the missus - and rethink your priorities. If you fail to turn off the ignition, the starter battery may discharge into the starter battery -leaving neither or b oth able to start the vehicle.

The second and increasing need is where an AGM battery is used as the auxiliary. These batteries have very low internal impedance. This causes them to grab most of the available charge current - and in the event that AGM is deeply discharged - will do so at the expense of the starter battery.

I really do recommend some form of voltage sensing relay. They are not a waste of money. I prefer the Redarc because it is ultra-simple to install. There are several good products in this area, but beware of cheapies.
Collyn Rivers

Andy
I started with a solenoid and experienced some of the problems mentioned above so I changed to the piranha DBE150S had it for about 7 years with out any hassles, however recently changed to a Rotronics system ~$240

Read the various manufacturers web sites and make a decision based on what they tell you there.
Some manufacturers actually do recommend different batteries are suitable to be used with their systems and some don't recommend different batteries, is horses for courses.

As mentioned above you should not use an AGM battery and a wet cell starter battery with a solenoid, for the reasons stated above, similar can be said for Deep Cycle batteries as well.

Hey Andy

Everyone puts up a good point but I still go with the K.I.S.S. method. " Keep it simple stupid"

If you are confused go back to my recomendation and follow PandJ's advice and use an oil pressure switch to activate the continious soleniod. That way the solenoid will not engage the aux battery until the motor has built up oil pressure , saving your main battery for starting.

A good system is one you can understand, and thereby, fix if needed.

But in the end they all work, just some better than others. Listen to all the advice and then you can at least make an informed decision.

Collyn has replied.

He has forgotten more than most of us have ever known.

Andy,

Take what Collyn has to say as gospel. The rest of us have varying degrees of knowledge, some good, some not so good.

I'm not bagging anyone here, a lot of good experience and a lot of people are happy with what they've got.

I followed Collyn's advice over a year ago and installed a Redarc and an AGM. I don't think there is a better dual battery setup available. Super fast charge, no chance of a flat start battery etc. If the start batt dies, flick a switch on the Redarc (if fitted) or link it with a screwdriver and you've got a big 100 a/h, 700 cca AGM to get you going.

Mine cost $700 as opposed to a Pirahna set up with a piddling 55 a/h wet cell deep cycle for $900. Admittedly my AGM is in car (and removeable) which makes it double as a portable power supply.

My two bobs worth. I have a redarc with a calcium starting battery and a wet cell deep cylce as the aux. The redarc is the best dual battery isolator I have had experience with. The satrting battery is charged before the aux is brought into line.
SIMPLE AS THAT.

My only regret is not listening to my auto sparkie who tried to talk me out of getting the wet cell deep cycle. It does run the fridge for as long as I usually need but the compressor runs slow unless I start the car and wait for the redard to cut in.

I use this system Traxide more than happy and Tim who runs it is very helpfull.

Simple to install and heaps cheaper than all the rest.

Baz.

Thankyou to everybody, all your comments and suggestions have been noted. I will be soon making a decision on what, why, how I'm going to do with them all.
I'll let you all know and how it's gone when I'm finished.
Thanks again for all your help
andy