Dual Batteries....in parallel and nothing else!

[gotoy]

Installed an additional battery in my LJ70 about a year back. Actaully the pair of them are directly wired in parrallel. Theres no switch or electronic circuits and I never upgraded the alternator either.

So after one years worth of offroading, winching like hell they have not let me down and still going strong.

Anybody else have this set up?

[GQ Bear]

Do you run a fridge or any other device which runs with the engine off. If so, how long have you left car unattended without starting? Did it kick over?


I can leave my fridge running for about 3 days before it shuts off. My main battery will still have enough charge to start the engine for weeks longer though.

[keencdk]

I had similar, with just a mechanical wind down on/off battery terminal. This worked OK for a while, however when one battery died, the good battery kept trying to charge it until the good battery went flat too.

Got both battteries tested and the dead battery was stuffed. Luckily the good battery was OK and after a charge it is still going, but it isn't good for the battery.

I now have a solenoid I bought from ebay new and delivered for less than $20. You can put a switch in the dash to "turn on" the solenoid and have both batteries in parallel when winching etc, but have the batteries seperated the rest of the time. Cheap and easy

[chimpboy]

There's nothing wrong with your setup, but it doesn't achieve what most people are aiming for with dual batteries - that is, allowing battery to go flat while the other one stays fully charged. This means more reliability and an ability to run accessories for long periods even with the engine off.

What you've got is like having one larger battery, which is fine but is not really "dual batteries" in the sense people usually mean it. It's sort of like having two left shoes and calling them a pair.

[drivesafe]

It's sort of like having two left shoes and calling them a pair.

That’s a good analogy chimpboy, mind if I borrow that quote.

[chimpboy]

It's sort of like having two left shoes and calling them a pair.

That’s a good analogy chimpboy, mind if I borrow that quote.

Only if, every time you say it, you follow up with, "Yessir, I got that from a fella named Chimpboy."

Just kidding

[David_S]

I have used an identical system for over 20 years. The only difference is that I have installed a manual cutoff switch on the second battery operable from the cockpit . I used welding cable for the connections to avoid voltage loss. I installed the switch as I was using the truck for a lot of desert trips in Saudi Arabia and I did not fancy trying to push start the vehicle in soft sand if I inadvertently ran the battery flat overnight. When I stopped for the night I just switched off the second battery. I never used fridges or other accessories other than a trouble shooting lamp.

I have done a lot of winching with this setup and have come to the conclusion that you should leave both batteries connected all the time. i.e. don't winch from one and then switch in the other later as there will be a large current drain from the charged to the discharged. I have never drained the batteries (both N70) during winching. I find the batteries last the usual 4-5 years. In recent years I have fitted a manual terminal switch to the main battery so that I can disconnect both batteries if I want to.

David

[Rainbow Warrior]

It's sort of like having two left shoes and calling them a pair.

That’s a good analogy chimpboy, mind if I borrow that quote.

Only if, every time you say it, you follow up with, "Yessir, I got that from a fella named Chimpboy."

Just kidding

LOL

I've got 3 batteries, with a solenoid link operated by the ignition circuit. I have moved nearly everything except the starter to be fed from the rear 2 batteries, under the ute tray, got room for a 3rd if I wanted, use them to run the 1700w inverter, which I use to power house stuff in blackouts

Left my headlights on for 12 hours one day, no problems starting