How to charge 2 battery system? - Diesel Forum

rrroadster · 06-13-2009, 12:24 PM

Hi,

I have unsuccessfully searched this matter.

2001 Excursion w/7.3L Powerstroke. The battery charge has dropped from work in progress.

I want to charge the batteries. I know there is a proper way to connect a charger to a dual battery system, but I can't find anything on it. So, how do you properly connect a charger to a 2 battery system?

Thanks in advance for your assistance.

KB

texas_psd · 06-13-2009, 02:43 PM

Never hook up a charger directly to the electrical system of any vehicle!! The safest way to charge the batteries is to remove them, top off with distilled water, test them if needed, then trickle charge overnight. Wal-mart sells some decent trickle chargers for around $20.

fddriver2 · 06-13-2009, 09:30 PM

What Texas said. I normally just disconnect the battery I'm charging from the truck, but leave it in the truck, trickle charge it overnight...

nitrogen · 06-14-2009, 08:54 AM

absolutely no reason to disconnect the batteries if you use a modern trickle charger. these trucks hook the batteries in parallel which means you still have 12 volts but 2x as many amps, just hook charger to 1 battery and the both charge. this is the same system every semi truck uses except they use 3 or 4 batteries and in 20 years plus diesel college no instructor ever suggested splitting to charge. now on some old heavy equipment where they hook batteries in series to get 24 it probably safer or easier to split them if you don't know, but that has NOTHING to do with how our trucks are wired

**SmokeyWren** · 06-14-2009, 09:58 AM

Look at the "jump start" procedures in your PowerStroke supplement, and that should give you a hint as to how to charge the batteries in the truck.

Hook up to the one battery on the driver's side - DO NOT hook up to the battery on the passenger's side.

Never "fast charge" a battery if you plan for it to live a normal life. "Slow charge" it at a max of around 15 to 20 amps, and use only an "automatic" charger so it won't overcharge.

Don't disconnect the battery cables. And never plug in the charger until after you have the charger cables connected to the battery. Connect the positive cable on the charger to the lead part of the positive battery cable on the driver's side battery. Connect the negative cable to a good ground somewhere near the front of the engine bay. Safety czars say to never connect to the negative post on the battery, but the reason is if you have a defective battery that is spewing gas, it could blow up because of any spark as you touch the cable to the battery post. (But I have charged dozens of car, tractor and equipment batteries - including my PSD - by connecting to both posts with no problem.)

The main caution is don't get in a hurry. It takes several hours to charge up the two huge batteries in our trucks, so use an automatic charger set on 15 amps and leave it on overnight. By next morning it should be down to about 2 to 5 amps "trickle" charging rate.

Then be certain to unplug the charger from shore power before you disconnect the negative charger cable from the truck.

444-4D · 06-14-2009, 10:11 AM

Smokey

Connecting a charger to the passenger side is ok. It will work just as if it was connected to the drivers side. Jump starting is different. The battery cable from the battery to the starter is larger than the cable connecting the batteries together. You connect to the passenger side battery when jump starting so all the starting current isn't sent thru the connecting cable. When using a small amp charger it doesn't matter.

fddriver2 · 06-14-2009, 12:18 PM

Well there you go.....