best dual battery set up

Ohhh Noooo Derek
here we go again on Alternators...?? LOL

Hi Derek.
I've recently bought a 2003 Prado GX (V6 petrol), and want to put another battery under the hood. It looks like the power steering resevoir will need to be moved - do you know if this is the case? I am concerned among other things about voiding the warranty (but will talk to Toyota bout that).

Craig.

Yes it needs to be moved. It fits between the brake master and the air filter.

It is very easy to move and you use the exsisting pipework and bracket.

Thanks Derek, I appreciate that.
Craig

Hi Oldplodder

The main alt was 50 or 55 amp and the other was 60 amp - given to be by a friend. It was very easy mount on the 3.5l V8 in the series 3 (1981 model).
Don't actually have the tojo yet but very keen on the 120 - not sure of its alt size, just need to find one I can afford (and sell our tribute)

We carried a solar panel for a while but sometimes found it a bit of a hassle to find somewhere to stow it, get it in the sun - but vehicle in shade (we should have had a longer lead), was worried that someone might pinch it if we left it in the sun in a campground while we went for a wonder. We don't have that old one any more but maybe there is a smaller modern one we should seriously consider.

The second battery is mainly for an Engel - no winching at this stage. It is just that dual alternators, I think, is the only system where the instant the vehicle is running, two batteries are getting the proper charge they need.

With a solenoid, if one bat is lower than the other it won't be charging nearly as quick as it could (I think). Also if second bat is flat and engine is run for too short a time, could flatten the starting bat!

While a smart system switches between the two batts, charging one at a time.
Also, I remember hearing that the smart systems don't quite get either battery all the way to 100% charge.

So if we were camped somewhere for a week or so, with 2 alts we could run the engine for a shorter time each day to keep the batts topped up.

I think maybe we'll have to look at a smart system (rotronics maybe) and an easy to pack solar panel.

Regards

Steve

hi wheelleybin

i'm an amateur in this regard so i'm sure there is better info to be had than i can supply, but.....

as i understand it there are basically two approaches to charging separate starting & accessory batteries with one alternator.

One is most commonly done with a simple solenoid (and timer i think), or sometimes done with electronics (the cheaper rotronics kit might be an example). So that some minutes after the car has been started, the second battery is automatically connected in parallel. The alternator then sees the two batteries as one for less than ideal charging.

The other "smarter" system only has one battery connected at a time. This might work with first the starting battery being charged, then being disconnected while the accessory battery only gets charged. While the system constantly monitors the starting battery so it is switched back in - on its own - if it falls to say, 70 or 80 % charge------- and 'round we go again.

I suppose this second example is referred to as 'smart' as it is more complex, expensive, and much better than a parallel system.

...my thoughts anyway

Cheers

Steve