Laird67

Adding a second battery charging system to my 2007 F150 supercrew 5.4. I have a dog box in the bed which has its own 12V battery system. Thus, I want to charge dog box battery with the alternator (95amps I believe).

I have purchased a Northern Tool 120amp battery isolator (http://www.northerntool.com/downloads/manuals/171214.pdf) and installed this in my engine compartment. I have run all of the wire (4G) and installed two inline fuses, one right after the isolator to the second battery (Labeled 2), and one right before the second battery. I have run wire from the starting battery to the isolator (Labeled 1), and have organized the alternator positive (one that runs to the starter battery) wire so that I can hook it to the isolator(Labeled A), without splicing.

My only question- I need to add a wire from the isolator(labeled E) to an ignition “run” wire(I assume this means a positive wire only when the truck is running). What I am assuming is this wire keeps the isolator from turning the charge onto the second battery until the truck is running. But I am not sure where I should run this wire too.

So being a good boy I went to my locale Ford dealer with the Northern Tool isolator directions, explained my issue. After an hour, the technician came out and told me yep we can do this for $400.00.

So I am here trying to figure out what wire I should slice into for the engine “run”, any help would be greatly appreciated.

Thanks Chris

TungstonTiller

Laird67,

I am not much help for you. However, you may try a "Car Audio" store, for assistance with your installation. If you choice not to do it yourself.

I'm interested in an isolater down the road. Keep us posted on how it turns out.

Also, post some pictures of your dog box!
Best of luck & welcome to the site.
-Tung

wde3477

Eh, not sure here - may be a matter of grabbing a voltmeter or wiggie, and walking through the fuse panel until you find the source that meets the criteria.

Figure the function of the 'E' wire may be more toward the isolation function - not to allow current flow when the engine is off???

Not sure what value the Ford dealer would be adding, other than knowing where to plug the 'E' wire into - sounds like you've already done most of the installation work.

KAH

I am not sure that I fully understand the problem here. That being said, I will venture my guess.

Find a wire that meets the criteria of being hot when ever the ignition is on.

Use that wire ( with fuse ) to power a relay that is connected somehow to the positive terminal of the battery. That should do it.

Or, I would contact the isolator people for more information.

Please let us know how this comes out.

Ken H.

Just call me Sean

iTrader: (1)

Don't over think this. The ignition positions are OFF, ACCESSORY, RUN, and START. The lead you need will be hot in RUN. This doesn't mean it will only get power while the engine is running, it means it will get power in the RUN position. If you don't want it to get power until the engine is running then you need to hook up a toggle switch, but if you forget to switch it off then it defeats the purpose of the isolator. Unless you hook it to a RUN wire and a toggle, then if you forget it will still turn off with the key and work as the wiring directions call for. If you want it to automatically come on only when the engine is running then you can instead hook a relay to the oil pressure sensor. When the engine starts and there is oil pressure then the relay will energize and allow the isolator to connect. When you turn off the engine and there is no oil pressure then the isolator will disconnect. The oil pressure sensor should give a ground signal when there is pressure so the relay would have to be wired to energize with ground.

Laird67

I agree, all I need to find is a wire that is hot in the RUN position only, not when the truck is actually running.


But that is my problem, not sure where to look for a wire that is HOT only in the run position. The isolator directions call for a 6.5 amp fuse in this line so it is not drawing much, I think it is only to trigger the isolator to open.

At the dealership the tech mentioned that he was going to tap into a line in the steering column, which would be fine but not sure how to find that wire, i.e color etc.

Any help on that would be great.

Thanks Chris

Mr B

Sounds like the dealer was going to wire directly into the ignition switch? You can get the wire color identifier using a haynes or chiltons manual. I checked mine for a 97 model and the ignition switch wires are clearly labeled. Not sure if these two trucks are similar, but you should be able to pick up a manual at an auto parts store or on-line.

Just call me Sean

iTrader: (1)

You can tap into a RUN wire anywhere. Under the hood, at the fuse box. Just check the wires with a tester. Don't tap into the column, it would be a pain.