Dual Batteries

has anyone put dual batteries into an originally single battery mid eighties bronco before? just curious on any serious complications.

i have but i didn't put my second battery in the engine compartment. mine is in the back and it's main purpose is to supply my entertainment system in the truck but up front i have an off roaders battery that pumps the living dead to life.

you shouldnt have a problem with putting in a second battery. I personally have never scene a second battery in the engine compartment, just on the rear like grande said for stereo equipment. Depending on the what you intend to use the extra battery for you might want to get an isolator (saves you from draining both batteries)

You can add a standard Ford Aux BatteryRelay. It can be mounted any where you like, and is feed from a 14 GA fuse link attached to the charge terminal of the starter relay. the output is routed to the battery, where ever you want to mount it. I've seen the battery mounted on a trailor to run equipment there. The control is from C1961 on the fuseblock fuse #6 which is only hot in run and accessory positions. That way when the ignition is off you can run whatever from the aux battery without draining the main battery. When running your engine it charges along with your main battery.

This is part of the trailor kit that is mounted on the driver side of the firewall.

Good luck, >-

PS you may have to increase the alternator size.

Here is a full thread from FSB on Dual batteries. I hope this will help you.

http://fullsizebronco.com/forum/showthread...=dual+batteries

That is a good link. However, the isolating relay serves the pourpose of preventing draining the main battery which is the RIGHT WAY when running things that will put a large drain on the battery. That way you do not have to worry about having battery power to start the truck after a night of running an inverter to power your AC equipment while camped out, (I know, what kind of camping is that, but people do that nd that is the reason for an isolator relay). As far as paralleling batteries, you can add as many paralleled aux batteries as your alternator can charge. After all, why would you need a aux battery for normal truck operation. A well charged small battery is good enough for that. No RV shop would add a aux battery setup without isolation. >-

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I have just recently added a second battery to my engine compartment. I looked around for a kit and found the one offered by Painless to be the most reasonably priced. It took me an afternoon to install due to the fact I had to make all new cables but it works great. Like the guys said above, the isolator is the way to go. You have better battery management. You have 3 settings which are controlled from a switch in the cab, one allows you to jump start your main from the aux battery. Pretty cool.

Unless you have a high output alternator, dual batteries is ******* your electrical system. Now it's having to charge both batteries, that's why farad caps are bad, so a better alternator is good to get, unless you can figure out how to install dual-alternators, too, which would be cool. I think I have something in one of my Lowrider maagazines about that. I've seen a Honda Civic with 4 alternators and 16 10" or 12" subs in it on TV, so I'm sure 2 batteries and alternators should be no problem. Probably easy enough to get an alternator bracket, longer belt and a one-wire alternator. Sounds about like the easiest and best way to go.

This is how I did my dual batts (a must for the diesel). I have a 100 amp 1-wire alternator, and made a custom battery tray. I have a whole bunch of pics in my albulm.

Has anyone ever used a second battery to power a block heater?

Joodan said:

Has anyone ever used a second battery to power a block heater?

Click to expand...

I wouldn't suggest it unless there is no way to power the heater from a normal electrical outlet, but with an inverter and a deep cycle marine battery, you may get away with it.  It mainly depends on how much the heater draws.  You will definitely need to have an battery isolater to prevent draining the main battery.  That way you will be able to charge both batteries when the engine is running but only put a drain on the aux battery when the engine is off.  You will probably need to boost your alternator size.  Recharging the aux battery will be a problem if you are not running the engine for long enough to top it off.  Also, I would suggest a way to turn off the heater when the engine is running.  Relay control of both functions is a better option than switches, they don't depend on you remembering to operate them.

As to my suggestion of a marine deep cycle battery, a battery shop should be consulted to get their suggestions.  Paralleling batteries like in a Diesel engine setup will not work properly.  That is only done to give enough power to start a diesel engine and does not provide isolation of the aux battery.

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