Dual Battery Question

Joined: 21 Aug 2003 Location: Birkdale

Evening All,

Thinking of putting a multi battery set up in my new car and was wondering if I could fit 3 batteries off the parrana dual battery unit (1 starter and 2 deep cycles wired in parallel)?
Will it overload the unit or can it take it?
My theory is that with the batteries wired in parrallel the unit will think that the 2 deep cycles are one big battery and charge it accordingly?
Anyone done this?
Dose it work?

CHEERS

SASS #Onfire

Joined: 03 Nov 2003 Location: Melbourne

thats alot of batteries.

what you running off them?

Joined: 24 Nov 2002 Location: Melbourne

Hottie monster, thats a no brainer answer!!

What your doing should be ok.
Remember if one of the batts in parallel is crook it will bring both down.

Bazzle

Joined: 19 Jan 2004 Location: cocklebiddy

Why bother with the extra weight .Go out and get a couple of optima batteries,they are rated up to 1500cca and only the size of a normal car battery. Smile

Joined: 06 Feb 2004 Location: Southern Lowlands - Sydney

You'll want to have a good alternator. 3 batteries - 130amps at least.

Joined: 31 Mar 2003 Location: Brisbane or 169.254.243.241

chrismal wrote:

You'll want to have a good alternator. 3 batteries - 130amps at least.

Gotta watch some of those and look at the engine speed required
to produce 130A. Most of the time it is like 3500rpm, something your car wouldn't do for a great deal of time and thus for the rest of the time
it is producing 90A or something.

Look at their speed Vs Amp rating, their cooling, and try to research
wheter they enjoy charging endlessly on a permenant basis (cause that is what they will be doing)

Tom

Joined: 16 Sep 2003 Location: Canberra

i dont see why you would have any troubles.. i agree that if the deep cycles are wired in paralell the system will think its 1 big battery.. just make sure they are the same...
no reason u should need alternator upgrades..u got 3 batteries so they take 3 times as long to go flat, so its ganna take 3 times as long to charge, so theorecticly your no worse off than one person with 1 battery and an alternator putting out a third as much..

make sure all wires real fat, and all conections are of high quality... Smile

happy powering

Joined: 31 Mar 2003 Location: Brisbane or 169.254.243.241

Slayer wrote:

i dont see why you would have any troubles.. i agree that if the deep cycles are wired in paralell the system will think its 1 big battery.. just make sure they are the same...
no reason u should need alternator upgrades..u got 3 batteries so they take 3 times as long to go flat, so its ganna take 3 times as long to charge, so theorecticly your no worse off than one person with 1 battery and an alternator putting out a third as much..

make sure all wires real fat, and all conections are of high quality... Smile

happy powering

True but it all depends on what he has now, some alternators tend to burn out diodes when they are contiunally charging flat out, (which this setup will be) I would a least make sure I had a bosch 80A/85A unit, good, reliable, will charge for years, and replacable and usually in stock at 90% of auto electricians (good when you are in the sticks)

Also there are two schools of thought on the big ass cables, one is that it provides the best charging method with the least voltage drop, the other is that they can shock the batteries with charging load which can destroy batteries when they are not brand new. I don't quite know which of these I subscribe to as they seem to both makes sense. I go with medium sized cables which are a fair amount over-rated for the job and keep it at that.

Tom

Joined: 28 Sep 2003 Location: in the shower..

I tend to agree with Slayer. Running the 3 batteries under normal operations will not cause excessive load on your alternator. Once the batteries are fully charged, they will pull little to no load from your alternator. The current that is required to charge a battery is inversely proportional to the charge left in the battery. e.g. If the battery is flat, it will draw a lot more current from the alternator when it starts charging. This is due to the potential difference between the battery cells and the voltage output of the alternator and the internal resistance of the battery. The only time I can possibly forsee it being a problem is if you have been camping all weekend and you run the batteries flat. If they all try and charge simultaneously, that may overload the alternator. If you are concerned about it, install a manual isolator between the two deep cycle batteries and allow the pirana dual battery isolator to do its job.