I have owned the subject truck since new. It know has 73,500 miles on it. The past year it has been relegated to mostly sitting in the driveway, backed up to our fifth wheel RV, ready to pull it. I have to keep a battery charger on it to keep the batteries charged. I tried a trickle charger to use after the batteries were charged, but that didn't seem to keep the batteries charged. I do try to drive this truck once a week, but sometimes that period slips to two weeks.

I have two questions.

1. I assume the two batteries are wired in parallel so, theoretically, if I hook up the charger to one battery it should charge both batteries. But, I am finding the battery I did not have the charger connected to still takes some extra charging.

2. How many amps does this truck draw to run all the electric gizmos when it is just sitting in the driveway with the engine off? This truck as sitting is pure stock. I do have an Edge Fusion that I use when towing, but I unhook it when I park the truck for an extended period.

 

The batteries are wired in parallel. If connecting to one battery is not charging the other, then you might have a battery cable problem. Check for corrosion at all the battery terminals, and all the ground lugs.

The parasitic power drain should be less the 50 milliamps. If a standard 1.5 amp trickle charger won't maintain the batteries, then you have an excessive draw and need to start looking for it.

Or your batteries are just shot. You could take them out, charge them well individually and have them load tested.

 

Good advice, David. I'm betting that on an '05, the batteries are just weak. They should be tested, and replaced in pairs.

The 6.0 takes a lot of current for the glow plugs, and they stay on for up to 2 minutes. During that time even strong batteries will be pulled down to the mid 11's voltage, and during cranking may be in the 10's. Older batteries that are losing amp hours just won't handle that.

 

Are these the original batteries? If so make sure the batteries are clean and cells are at proper fill level with distilled water. Clean battery post and battery cables with post cleaning tool...then spray cables with a battery cleaner/acid indicator of some type...this might give you a clue as to whether you have a problem going on with a cable. CRC (and others) make the stuff and it is available at auto parts stores. What trim level is your truck (XL, XLT, Lariat, etc.)? How many amps does your charger provide? If my memory serves me correct I think at rest the current draw is somewhere around 30 to 50 ma (engine off, lights off, been sitting with no doors opened or anything activated for at least a 30 minute period...this assures the electronics all go to sleep). Keep in mind that battery posts can look clean and still not provide good contact. I make it a point to clean every couple of months on my truck. You can also put a couple sets of those battery post/cable clamp protectors on your batteries after you clean them...they look like red and green discs and go around the post before you put the clamp on...these will slow down the corrosion process. Hope this helps.

 

Thanks for all your thoughts, but...

These batteries are about one year old. The posts are cleand, and, they do have the battery post protectors. I do not think I have a battery problem. I do pride myself in keeping my truck serviced properly. My battery charger is a big commercial duty charger that is too heavy to carry. It is on wheels.

Have any of you with this engine let your truck set for ten days and checked if your truck would start? My guess is that it would not, but perhaps I am wrong. When I drive my truck regular I have no problem with the battery charge, but let it set ten days without a charger and I just get the starter relay kicking. I have to hook my charger up in the start mode to get the truck going.

 

Take the batteries out and charge them overnight at about a 2 amp setting...then load test them individually. It is possible that you have a bad battery and since they are wired in parallel it would pull the other battery down. I can let my truck sit for about a week (that is the longest I have had the opportunity to do so) and it will still start fine.

 

I have not let mine sit like that. But I do not think it is normal for the batteries to go that low in a week or 10 days, whether it is gas or diesel.

So I think you either have 1 bad battery, or you have a residual power drain.

I would suggest that you disconnect both batteries grounds the next time you shut it down for a week, and then reconnect before you start it. The condition of the batteries at that time will tell you which problem you have.

 

Will you do any damage to any of the electronics by unhooking the batteries. I hink I have heard the FICM can be damaged if not powered.

 

It can be damaged if under powered, which I fear you are doing by starting it with barely enough boost from the charger. I am not aware of any damage caused by the truck sitting with no battery. In fact, reseting the PCM is a very common practice, and that is done by disconnecting the battery for 20 minutes.