Hello,

I think this post may be useful for you, althought my truck stock setup is a bit different because its a 3.0 Turbo Diesel 4Runner, with stock dual batteries.

The truck came with two 70Ah batteries joint in parallel.

My goal was to mantain the benefits of the stock setup:

- Cranking with double power
- Winching with two batteries

While solving the stock problems:

- Both batteries drainage
- If one batterie deads the other one goes behind

So I begin investigating and I found the solution in a solenoid named "Smart Start" made by Redarc Electronics from Australia.

I choose the SBI12, rated at 100A continous duty and 400A in-rush current.



This solenoid joints the two batteries in parallel when the main battery is over 13.6V and isolates them when the main is below 12.7V. And the cool think is that it only needs two wires, each one coming from each battery.

In the practice, this means that one or two minutes after starting the engine you've both batteries charging and 10-20 minutes before stopping it they're isolated (With normal power consumption).

And where is the solution to the cranking or winching with two batteries? It's the override function the SBI12 has.

When you apply 12V to the override wire on the solenoid, it joints the two batteries independently to the main battery state. So you only have to connect it to the crack engine solenoid or the wich solenoid and you'll have the power of two batteries to start the engine.

In my case, we had a bit more trouble because my 4Runner came from stock with dual batteries, joined in parallel and with the starter engine hooked in one (DS) and the rest of the truck (Including the alt) on the other (PS).

I wanted to use the PS battery as the secondary and the DS battery as the start one. Also, I replaced the PS (Accessories) battery with an Optima YellowTop 4,2, leaving the main battery because it was quite new.



My old PS battery was a bit leaky...



So we begin to unattach the fuse box to find the alt and car consumption wire



And we find that the wire going from the batt to the fusebox was the same that goes from the alt fuse to the batt, so we've two wires in one and the problem half solved.



Then we replace the batt-to-fuse/alt wire with a 20mm2 one and made it go between the body and the rad, as the stock parallel wire used to go. You can see it hiden inside a black pipe (Don't know the name in English) near the negative pole of the Optima. (Yeah, I've the winch solenoids inside the engine compartment.



This week this would be my battery mount, till I've time to build a new one!



The Redarc SBI12 solenoid





To connect both batteries I get rid of the stock wire and replaced it with some 33m2 OFC one. It's probably overkill but if you're replacing it it's easy to upgrade a little...



My friend Pedro (Peter) pressing the terminals



The solenoid in its place, I've to put the wire inside of black pipe, but I didn't have one big enought to hold that wire!



And the whole system finished:



Maybe someday when my standard (And main) battery deads I'll upgrade to a Optima Red Top, but it's not absolutely necessary because I start with the Optima + Standard so...

Now I'm safe to play with the carputer, the audio system, leave the fridge overnight, etc., I'll always be safe to start!

Hope you like it. Think that it's way more easier to do in a single battery truck!

David

 

looks good... be careful running one deep cycle and one starting. My dad had that setup and it does not work well, one of them (cant remember which) really gets overcharged.

We do something similar on our dual battery rigs (not my yota), run a oil pressure switch to a heavy duty continous duty solenoid. When the engine is on they are in parallel, when off they are isolated. My dad did this after his initial isolation setup, similar to yours, failed. It was a cheap fix and turns out it works better... It is nice to have two batteries for winching.

 

Yet another reason why Toyota SHOULD have made this engine available in the U.S. :pat:

 

does anyone have a good wiring diagram for setting up a two battery system in my 82 Toyota 4x4?

 

Simple.. dont even need a diagram...

Install battery number 2. Run large chassis grounds on both batterys, 2ga or 0 or bigger depending on load. Go to a marine store and get the biggest heavy duty continuous duty solenoid, up to you alternator output or larger if you have a winch. Also get a oil pressure switch. Install the oil pressure switch in a T with the oil pressure sending unit. Let the switch open/close the solenoid. Wire each battery together with the solenoid, using 2ga or 0, or bigger depending on load.

Now you have a dual battery setup that sperates the batteries with the engin e off, allowing a self jump, and combines them for charging and use easily and cheaply.

 

Cool. Not only that, but if your oil pressure fails, when you're significant other runs down the main battery until the engine seizes, you will have a second battery all ready to go when you replace the engine...

 

ouch.. .but sounds like a good story

 

Just a product of a silly digressive attempt at understanding the advantage of your setup.

However after having thought about it awhile longer, it is actually clever. What you've got is a way to avoid all spurious discharge, such as accessorises left on, and even the switch left in the ignition position while at the same time allowing for charging in normal running conditions.

Actually very clever. (but you knew that)

 

Thanks for all the good advice. I have an 82 4x4 truck that was given to me free. It does not have the best body because of rust but only has 124,000 miles on it. Plan on doinging a lot of herculiner spraying and not a lot of body work on it . Hope to have pics for all when I figure out how to resize pics to fit the limits here.