superduty dual battery questions?

[silvrzuki77]

First let me apologize if this is an ignorant question. I can build suspensions, roll cages, blah, blah, but I suck at electrical hands down!!! I have a 7.3 superduty that is going to end up sitting for a week or two while im away at work. How is it best to manage the factory dual battery setup so the both batteries get an equal charge? I have optimas in it right now which I regret and will switch to odysseys when I need to. Then the second question I have is that I plan on adding a engle or arb fridge. Should I add a 3rd battery for the fridge and if I do what system would beable to charge all 3? Once again SORRY if this sounds dumb I just dont want to end up with a dead batterys in the middle of death valley in the morning.
Thanks for any help!

 

[Martyn]

I wouldn't worry about having the truck sit for a week or two, that is unless you have a drain in your electrical system somewhere.

The batteries are connected in parallel each of them ground to the chassis and a long cable going from the alternator to the battery on the passenger side, over the top of the radiator to the battery on the drivers side.

Ideally you should have a double battery charger connected to both batteries, I have a smaller 6 amp charger attached to the battery on the drivers side. It's wired in with the block heater into a shore plug on the front bumper. Wired this way it will charge the battery it's connected to initially then start to charge both batteries. Not idea, but it was the charger that I had access to.

I run an Engel 45 off the battery system as it stands. Never been a problem. As I start to add other products like a propane heater, an inverter etc. I'm starting to look at putting a National Luna Power Pack with a Group 31 Deep Cycle battery in the bed of the truck and wiring it back to the main batteries for charge. What I like about the Power Pack is it's a self contained dual battery system that can be moved from vehicle to vehicle.

 

[silvrzuki77]

I have the common door hinge problem I believe so after several days it will drain off. I have a seperate battery charger attached to the passenger side battery but after reading stuff online I wasnt sure if i was doing more harm then good. I havent checked yet but probally one of the optimas is bad not sure it works and I dont want to buy batteries right at the moment. I like the block heater setup u have though. Thanks for the suggestions for the 3rd setup though. If you were to redo your primary chargering system any suggestions on what you would go with?

 

[Martyn]

I think the basic primary charging system is good. I'd get rid of the Optimas as soon as you can. When you replace double batteries you should replace them in pairs if you don't older weaker battery will fail in quick succession.

The only thing I will be doing with mine is replacing the long + cable with some new welders cable.

Not sure what the "door hinge" problem is, but if it is something to do with the interior lights staying on all you would have to do is pull the fuse for that circuit to eliminate the drain.

 

[Mike S]

I run an Engel 45 off the battery system as it stands. Never been a problem. As I start to add other products like a propane heater, an inverter etc. I'm starting to look at putting a National Luna Power Pack with a Group 31 Deep Cycle battery in the bed of the truck and wiring it back to the main batteries for charge. What I like about the Power Pack is it's a self contained dual battery system that can be moved from vehicle to vehicle.

Martyn

I have used the stock ('01 F350 7.3) dual Motorcraft batts with an Engel 45 for months at a time, and driving intervals of a couple of days. No problems. I think more batteries is probably overkill. I would opt for 2 charge controlled AGMs that I could combine from the cab with a switch for severe cold weather starts, etc. I feel no urgency since the truck ALWAYS cranks, and the fridge and other accessories never cause a problem.

 

[McZippie]

I use a Battery Brain Heavy Duty in my 7.3 diesel Excursion to protect the Batteries from going dead. The BB automatically disconnects the batteries at 12.01 volts. This is the ideal disconnect voltage to not damage the batteries from excessive low voltage and allows enough reserve power to start the engine. Another obvious reason for a BB, no need to have separate axillary and starting batteries, all batteries can be used for both functions.

My Excursion has two Odyssey AGM PC1750 under the hood, no need for a 3rd battery to power my Engel for a weekend of camping. I turn it off at night.

If staying in one place longer, drive or fire up the engine for 20 to 30 minutes and hold RPMs to around 1200 . AGMs charge quickly and your Alternator will charge the batteries to a 80% state of charge range in that time.

I've tested the above with amp and volt meters. It takes a very long time to get above a 80% SOC, so no need to drive or run the engine longer than 20 to 30 minutes.

http://www.batterybrain.com/batterybrain.pl

 

[Martyn]

Martyn

I have used the stock ('01 F350 7.3) dual Motorcraft batts with an Engel 45 for months at a time, and driving intervals of a couple of days. No problems. I think more batteries is probably overkill. I would opt for 2 charge controlled AGMs that I could combine from the cab with a switch for severe cold weather starts, etc. I feel no urgency since the truck ALWAYS cranks, and the fridge and other accessories never cause a problem.

Mike, I think you are right in regular conditions. Living up in Truckee with low winter temperatures my batteries are challenged getting the engine to crank fast enough to start the engine if I haven't plugged the block heater in.

I also have an on board air system with a 1.5 hp compressor. I've made the mistake of using the system without the engine running and it's lowered the dual battery charge down to the point where it won't start the engine.

If I'm cold weather camping using one of our Heatsource, lights, fridge etc. I think I'd like the power pack. As you said under regular conditions I don't think I'd need a third battery.