Gentlemen, my job requires me to use my truck as an office for the jobs that I go on. I will be running a laptop, printer, and other electrical devices that require 110V. I would like to add an additional battery to help provide the power needed for these devices. I’ll also be using a power converter to provide the 110V needed for the printer and other devices. I’ll connect the power converter to the second battery.
My question is, how do I hook up the second battery to get charged by the alternator?
Will the second battery help with power for the rest of my electrical system when it is connected?

 

The answer to your question is, simply connect a heavy-duty battery cable from the new battery's positive terminal to your truck battery's positive terminal. And, use a heavy-duty cable to connect the new battery's negative terminal to the truck battery negative terminal, or, to a good ground (your choice here).

That will charge both batteries through your alternator and, you will be using BOTH to supply power to your truck for starting or for running your laptop and printer.

The second battery now gives you more "reserve" power for everything. Essentially, twice the capacity of your single battery.

But, do you really need it? I used to recharge the battery in my laptop off of my vehicle battery through an inverter, and the current draw was pretty small. I can't believe a printer would add that much.

If it does, just start and run your engine for a bit.

- Jack

 

if you start running alot of additional electronics off of your battery/batteries, you may want to condsider a higher output alternator as well. the more amps you suck the harder the alternator has to work.

 

I should have added the part about the heavy duty alternator as well, but I was in a hurry and it sort of slipped my mind.

With two batteries in parallel (the way you want them wired), you are going to double the charging current demand on your alternator. Normally that won't be too much of a problem unless you also are using your air conditioner and lights and have maybe run both batteries down to say, half charge (where they'd really be sucking power to recharge). I can't think of any other HUGE current draw items on our trucks, but maybe someone else can.

In any case, I'd want the 130 amp alternator if you have two batteries. If you have the factory towing package, you already have this. (The standard alternator is a 90 amp device).

- Jack

 

I have a 1000 watt inverter, I got it for a steal... I've ran all sorts of stuff off of it without a problem... I've never had a dead battery.

Remember; this is a truck battery, not a car battery.

 

RVs and conversion vans also use a battery isolator that keeps you from running your primary battery down when using your invertor with your secondary battery. Basically, it is a big diode that allows the vehicles charging system to charge both of your batteries, but will not allow current to flow in the other direction. This isolator would be a good investment if you will be sitting for long periods using your office equipment (with your engine turned off). You can actually use a deep cycle marine battery for your secondary battery, as it isn't used to start your truck. Isolators are available at most auto parts stores as well as at RV supply stores.

 

Thanks for all the great information. It’ll really help when I set up my truck/office.

 

Humvees We daisy chain two batteries.... to H/O alty... 24 volts...

 

Right, but those batteries are connected in series. You do this to an f150, you're going to melt fusable links and blow fuses. The batteries have to be wired in parallel on our trucks.

Any idea why you're using a 24 volt system on military Hummers? Is it to support a radio pallet?

- Jack

 

hi every one I have a 07 ford f150 lariat 4x4. I have been adding stuff to it like more light and a winch. so I was going to put a second battery but I have no idea where to put it or how to do it. I have been looking all over the internet but not having much luck