second battery

Hi Ron, are you sure your alternator is only 30 amps.

The smallest alternator are USUALLY 45 of 55 amps.

As for the cable, if that’s 6mm auto cable then it actually only about 4.5mm2 which is way to small for any long runs.

To charge a battery in the rear of any vehicle you should use 10mm2 or thicker.

Cheers.

If you are running NOTHING else off it then the alternator would keep the batteries afloat, however if it is the normal vehicle alternator, then I would be looking for at least 55a or 80a is better.

I wouldnt use anything less than 8mm wire and run a feed thru a Redarc battery isolator from the starting battery to the oe in the back, I would also run an earth wire from the starter battery to the one on the back, i.e. two wires down to the second battery, I would also then run a earth cable from the second battery to the body somewhere in the back of the vehicle.

Ron, I`m no sparky but I have two N70ZZ`s under the bonnet of my 2.8d D/cab hilux. And have just bought a agm deep cycle 100amp for the rear under the tray.
I was advised to use 4 gauge wire as it can carry more amps for charging.
I have decided to buy one of those amplifier wiring kits that the young fulla`s use for their stereo`s which has about 6m of red 4 gauge wire for positive, 1m black for negative, and a heavy duty fuse link . I think they are about $60 at auto parts shops. 4 gauge is about the same diameter as your battery cable 10-12mm.
Also should`nt the 4runner alternator be 65-80 amps ?
cheers

Are you sure your alternator is only 30 amps.

The best way to do your battery set up is as follows....

1) Use an 80 amp Redarc Smart Solinoid.
2) Connect a battery cable from your starter motor battery input terminal to the input terminal of the Smart solinoid.
3) Connect a battery cable from the output terminal of the Smart solinoid to the + terminal of your aux 100amp battery.
4) Connect a battery cable from the - terminal of your aux 100amp battery to a large bolt or the original earth point of your vehicle.
5) Connect a wire from the + terminal on your 100amp aux battery to a multi fuse holder.
6) Take all you aux equipment (fridge, camp lights etc.) off of the multi fuse holder.

For keypoint 2,3,and 4 use a minium of 3B&S cable.
For keypoint 5 use a minium 6B&S cable.
For Keypoint 6 use minium 4mm auto cable, 5 or 6mm is better still. (Depending on current draw and cable lenght.)

Never use a isloator switch for batterys always use some form of smart solinoid to controll the charging....it's set and forget.

We see so many people using 4 to 6mm auto cable to charge there batterys, most time 3B&S cable is over rated but it does not cost much more and it does not take any longer to install plus you know it will work OK.

The main concern for wire size is current draw and lenght, with a flat aux battery it is not uncommon to see 200 to 400amps of rush in current when connected to another battery.

The fuse holders we use are from http://www.carroll.com.au/zone_files/product_pdf/carroll_catalogue_p49.pdf
and are the BFK one at the bottom of the page.

Always solder the wire to the fuse holder and spray all connections with a high grade electrical protectant greese.

Hope this helps

Regards Richard

Hi Ron o

Your wire size will be more of a limitation than the alternator, looks like everyone is saying to up it.

From your brief 2nd batt description it looks like a different type that requires a slighter higher voltage than normal one, and its further away.
Again , not the best idea although it will work but at less capacity than what it could be.

Robin Miller

Doubt you have a 30 amp alternator.
There used to be 30 amp generators, but that was the 60s and earlier.
The early alternators in the 70s were 45/55 amp.
Most cars now have at least 60 amp up to 100 amp or more.

If it is 30 amp, yes it will charge those batteries, just takes a lot longer. :o)

When I run down my N70ZZ 2nd battery after running the fridge for 2 days while stationary, it takes 4 to 6 hours of steady highway driving to recharge. Thats with a 80 amp alternator, while running the engine, fridge and the other accessories when driving.

Ron, I had an 84 Nissan 4x4 720 petrol with a 2.2ltr motor and it come standard with a 35Amp alternator. If your Hilux is this age it may be true that you have only a 30amp particulary if its a 2WD. Mine would start sending the battery flat when running a few driving lights (also the standard 4 head lights ) after 20 minutes. I had a fridge freezer drawing 20 amps so if I went on a camping trip at night I had a problem. I changed the Alternator to 85amp and never had a problem after that.
Any auto electrician would confirm what you have and quote a replacement. With the wiring, you could should run straight from Alt. so as not to blow the fusable link on your std battery if something went wrong down the back, but would ensure you have a fusable link off and at the alternator to your aux battery wire.

6mm sq cable will give you ~O.1v drop in 4 mtrs.
Go up to 10mm sq cable and the drop in about nil.

You should use a "fuse" device and also "isolate" the two batteries, so the Cranking battery does not go flat when running accessories connected to the HGL.
There is various ways to do this, and whatever method is mentioned some one will say the other way is better lol...

Make life easy for yourself and use a system that has a written warranty by the manufacturer, stating it's capable of successfully charging two different types of batteries, if you don't get it in writing maybe there is a logical reason it's not supplied, there are various companies that make excellent isolation devices and give a written warranty it will work as you require it.