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Dual battery questions.

85 Jimmy

85 Jimmy

Sheepdog
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When I rewire my winch I'd like to set up some dual batteries. Before when I'd winch with a heavy load it would put a real strain on my battery.
I plan to use a drivers side tray from a diesel. The main purpose for the second battery will be for winching. Should I run an isolator? If so how would I wiring everything up?
 
You should run an isolator. This will enable you to charge the second battery, and keep it in reserve when needed. It will also allow you to self jump start because you have it isolated, or tie both batteries together for heavy duty use. The wiring is pretty straightforward. There are a number of dual battery kits available that provide the isolator and a remote control/monitor of the batteries as well.
 
I opted to just run both batteries in parallel thru a selector switch. The alternator charges whichever battery or batteries are selected. I just made sure the 2 batteries are identical.

I do see the value of being able to keep the batteries separate and there for keeping you from getting stranded. I just haven't wanted to spend the money on an isolator setup. If I do in the future I will use the selector switch to parallel the batteries for winching ops.
 
You're running a switch like this, correct?

Do you just run it in the 1+2 position, or do you switch between both?

With that switch do you just run the positive from each battery into it and one from the switch out to the starter?

image.jpg
 
The normal old school diode type isolators kinda suck. You end up with almost 1 volt of drop thru them. Not good for charging a battery fully. There are some high-tech no loss isolators but they are very expensive. Here is an option that I used. Use a marine battery switch that is made for two systems. Blue Sea 5511e. One half for the engine and one half for the house (winch). It is just a switch with 4 post on the back of it. It has three positions. Off where everything is off. On where the engine batt is hooked to the engine and the house batt is hooked to the winch. In the on position both systems are seperate from each other. Last position is combined. Both systems are hooked together. Under normal use I run in combined. Both batts get charged and both run the truck and the winch. It's nice to have both batts for the winch. If I run into a spot where the engine won't run and I need to winch myself out to fix the truck, I switch to "on" and then the winch has its own batt not hooked to the engine. I can run that batt completly dead winching and still have the engine batt to get the truck running.
 
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I like my setup except for a lot of welding cable running around:

dual_batteries.jpg


The relay lets everyone charge when ignition is on. Otherwise, one battery is totally isolated and can save your butt (set the big switch to one or the other, not both for normal stuff). The little toggle switch lets you override the relay in case one battery takes a complete dump.

I don't have a winch, but I'm sure you'd want to run that straight to one battery or the other. Then again, I can start through the big switch, so it might be okay.
 
Mastiff said:
I like my setup except for a lot of welding cable running around:

dual_batteries.jpg


The relay lets everyone charge when ignition is on. Otherwise, one battery is totally isolated and can save your butt (set the big switch to one or the other, not both for normal stuff). The little toggle switch lets you override the relay in case one battery takes a complete dump.

I don't have a winch, but I'm sure you'd want to run that straight to one battery or the other. Then again, I can start through the big switch, so it might be okay.
Click to expand...

I like this system too. So you leave the toggle closed most of the time so when the key is on both batts are hooked together and get charged right?
 
substitute an ACR for that relay, and that's how mine is.. :D

the bat switch combined with the ACR adds a TON of flexibility to a system like that.....
 
I had blue seas older one



9112_182x182.jpg





but I sold it to a customer in need, so I need to replace it... I might have to get the newer black plastic ones they carry if I can't find one of the L series, as they are discontinued these days....
 
AV8TER said:
I like this system too. So you leave the toggle closed most of the time so when the key is on both batts are hooked together and get charged right?
Click to expand...

Correct. I had to go look at ACRs just now since I'm not familiar with them. I think I personally prefer the relay since it's dead simple and allows the system to be totally symmetric in terms of which battery is "primary" or whatever. I think the ACR setup prefers to use one battery for starting too (correct me if I'm wrong), where the relay will run both batteries in parallel for start - as long as the voltage stays high enough to trigger the relay. The ACR's are pretty slick looking though.
 
I thought about that with mine but the little Blue Sea SI series ACRs Don't like alot of current. The ML series is good for 500 amp but they want a couple hundred bucks for them. Even at my price they are pricey. We had a SI that fried on a starting load from a C9 so I didn't want that with my winch. If you hooked the start interupt wire off the ACR to the winch controller so it would open when you winched it would work I guess.
 
it senses if one bat, or the other, is lower than the other. and closes the switch if one drops below 11, so they both charge, than opens the switch again when fully charged..

so it keeps your bats separated, unless you trigger the acr (parallel),




100_0829_zpsf10aa349.jpg






or have your bat switch on "all".. or one is below 11 volts..


both systems work fine... as do diodes..... they all have strengths and weakness's..

I just find the acr/marine combo to have the most redundancy, yet separation, creating flexibility in the system...
 
Here's the spaghetti pile I have on the passenger fender for all this stuff.

20140222_201018.jpg
 
:haha:


I ran that fuse block for yr's..... :waytogo:

wont be a single fuse in the K5 this time round... :pimp:
 
I prefer breakers also. At least you don't blow all your fuses on hand.
 
Cool. Since you laughed at my spaghetti, show me your clean setup so I can get some ideas on how to make it better. I think I have 7 separate sections of cable just for the positives. Not sure how to get around it without giving up some flexibility.
 
Be warned, with a dual battery switch, depending on how its wired, you can find yourself with the engine running and no battery hooked to the system.

This would be known as a Bad Thing.......

If you were lucky, all it would do would be fry the alternator diodes. Otherwise, the output voltage from the alt could reach levels that it would fry other electronic parts, like the computer.

As Ryoken knows, many of those switches have a set of smaller posts that are connected to the field terminal of a boat's alternator.
They kill the output of the alternator before the main terminals break, and to not restore it until after they are made to prevent that from happening.

FWIW, my '79 F150 ran for 10 years with dual batteries, a split electrical system, and a heavy duty diode isolator.
Since it was a Ford, it was easy to split the system.
I cut the output wire from the alternator, and ran it to the input of the isolator.
Hooked the other end to one side of the output.

Then I ran a heavy wire, 4 gage, from the normal battery input across to a second battery in the diesel battery spot on the other side of the engine.
I put a high capacity battery there, with 90 plates.
The regular battery was a thick plate high current cranking battery, and got its own charging wire from the second isolator output.
It went only to the starter solenoid.

Both batteries charged off the alternator, but the entire truck ran off the second high capacity battery. I could leave the headlights and radio on all night without running it down.
But, when I went to crank the engine, the other battery did the cranking.

Later, I ran a 2 gage wire from the two positive terminals with a Ford starter solenoid in the middle.
A momentary toggle switch under the dash fired it. If either battery got so dead that it would not work, flipping the switch jumped myself off without opening the hood.

I did lose .7 volts, but never had any battery problems. If you used an alternator with remote sensing, you could eliminate that problem.........

BTW, my winch was a shaft driven PTO, so there was no special electrical need.
 
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