Dual Battries

[bodacious]

Yea, I meant to spell it that way. I had a pretty hard winch pull today. I got my John Deere 4x4 tractor stuck, up to the chassis. I had my K5 hooked to it, double lined the Warn XD 9000i, my Dodge 2500 Mega Cab Cummins hooked to the back of the K5, the front of the Dodge tied to a pine tree. I didn't take pics, cause I was kinda pissed and didn't have any real "high quality" help, so I had other things on my mind. Anyway, I was pulling on it, and it was coming. I let off the winch a few times to let it cool, but when I almost had the tractor out, my K5 died. Well, I got it jumped off, and finished winching the tractor out, while another truck's battery was hooked to mine. This got me to thinking I've seen trucks with dual batteries in them, but have never really studied it. What all is involved with rigging up a system like this? Or, will just 1 yeallow top Optima do? I really don't winch often, and this was, by far, the hardest pull I've done in years, so a dual set up might be over kill for me. Anyway, what do ya'll think, and does anybody have a detailed explaination and/or instructions on setting up a dual battery system. I'll be looking for a left side battery tray now, I guess. I will probaly go ahead and get the Optima tomorrow, though.

 

[badmix]

First off , I did straighten up those wires, lol.

Im using a HELLROARING Dual Battery Isolator.

I picked up a driverside batt. tray from LMC, fit perfected.

I ran a heavy gauge wire from the starter to the isolator and from isolator thru a Buss fuse and then to the aux battery. Im using my battery as a backup only, no accessories are drawn off this battery. I only use it to combine with my other batt for winching, etc.

Now the way my system works, ive got a switch in the glove box connected to the isolator (all the lil wires). I have 3 positions

UP = both batteries are combined for extra power like winching

Middle = both batteries are being charged by alternator but all power is drawn from main batt.

Down = the aux battery is taken out of the system to including not being charged, I use this when im working on the electrical system and disco my main battery, if I didnt flip the switch, id still have juice so to speak.

I borrowed a crimp tool from Napa and made my own power cables. The whole process went pretty well and has been on my truck for about 3 years with no issues.

 

[Mr. Pickle]

Great write up. As an easier option you could ditch the isolator and have a 2 battery system. I had this on my Jeep (trail only) and it did fine. I think a lot of it is preference.

IMHO, based on your description, 1 yellow/red top would be just fine for you.

 

[badmix]

Great write up. As an easier option you could ditch the isolator and have a 2 battery system. I had this on my Jeep (trail only) and it did fine. I think a lot of it is preference.

IMHO, based on your description, 1 yellow/red top would be just fine for you.

The problem is without the isolator, if you have an electrical draw or short or battery issue, itll take them both out. That is why I set mine up as a Backup. Ive had a draw on my primary battery b4 (ended up being the tach was wired hot),while it drew down my main battery, my aux batt. was left fully charged. and all I had to do with flip the switch, combine the batts an start my truck.

 

[Fordum]

Been there done that.
I ran duals on my ’79 for 10 years.
Didn’t use them for winching, since I had the PTO setup for that. But it would have worked for that too.

Very easy to wire up.
Buy as heavy a diode isolator as you can find. Cut the output wire from the alternator.
Hook the end from the alternator to the center post (input) of the diode isolator.
Hook the cut-off (truck) end to one of the outputs.

Disconnect any hot wires from the main battery and hook them to the aux battery along with the winch lead.
Run a fairly heavy wire from the other diode output to the main battery positive.
Your aux battery is now your main use battery. Everything will run off it like it did with your original battery and it will charge the same way.
Your original battery now runs only your starter, but charges from the alt.
At this point, you can leave the lights on, radio, whatever, and you will always have a hot battery to crank with.

But, this does not get you any extra power for winching.
It does, however make sure you can crank if you run your battery down winching.
However, if you run the aux battery completely down, you will not have enough power to fire the starter solenoid or run the ignition electronics.

I always had a set of jumper cables with me, and since both batteries were already hooked up with a common ground, I only had to jump positive to positive.

Most of the time though, if I switched off everything I left on and waited, the dead battery would build up enough charge to fire everything.
That plan bit the dust during a hurricane.
I had driven up when it was getting close, with my lights on.
Several hours later, I needed to go somewhere with the rain and wind howling.
Found out I had left my headlights on.
Had to jump myself off in the middle of a hurricane.

The next week, I added two pieces of 2 ga battery cable and a Ford starter solenoid.
I hooked a piece to each battery positive terminal and put the starter solenoid in-between. With a momentary contact pushbutton switch from starter battery to the firing terminal.
From then on, all I had to do was push and hold the button and the two batteries were tied together until I released it.

J.

 

[6.2Blazer]

I won't deny the above setups would be nice to have, but I also don't think they are always necessary. My '90 diesel K5 came stock with dual batteries and there is simply a cable hooking the two positive terminals together, and ground to the chassis on both. Most factory setups are like that, and several guys in our club do it that way. Cheap, simple, and nobody has ever had any of the issues that are arguments above for having all of the other stuff (but again, not saying it would not be nice).

Did you keep the engine revved up any while winching, or did you just let it sit at idle the whole time? Alternators only put out a fraction of the juice at idle versus higher rpms. Revving the engine to 2-3k while letting the winch cool would definitely make a difference.

 

[bodacious]

Yup, I was revving the engine while winching. I always do. I guess I was at about 2K. I have a tach, but I wasn't watching it.

 

[bodacious]

Thanks for the info, guys. Rihgt now, I'm just going to go with 1 yellow top Optima. Looks like it will be tomorrow before I get to pic it up, though. Had to work on the "Honey Do List" today.