# F-450 Diesel - Batteries Dying



## TSG (May 18, 2001)

I bought a 2003 F-450 6.0 diesel last July. Starting around 5 months ago.. I went out after a long weekend off and the batteries were dead. I jumped it and went about my business. No problem for couple of months... and it happened again. Jumped it once again and no problems for another couple of months. Then a couple of weeks ago.. batteries were dying on daily basis. 

My neighbor who is a Toyota mechanic put a tester on it after we got it started.. and the alternator tested okay. So we thought maybe my trailer connection/brakes might be drawing so I tried disconnecting the trailer every evening. That didn't work. My neighbor had me put a trickle charger on it over night and he would take it into work and check it out. 

It started right up that morning and at 5:00 that evening when he brought it into the shop. He tested the batteries (750 cranking amps) and they tested @ 752 & 761 cranking amps. He checked for any draw on the batteries and nothing.... He brought it home and the next morning.. dead again. 

He brought me home 2 new batteries and it started without issue for 5 days and....... yep.. dead. :angry:

Anyone have any ideas as to what may be going on?


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## Flipper (Nov 1, 2001)

The trailer brakes would take over a week to draw if they are just connected, not actually braking. Make sure the alternator is good. A simple way is to make sure it is putting out more volts then the batteries. With fully charged batteries you should see 12.5 to 13 volts once you start the truck it should jump over 14 volts. If the trickle charger brings the battery up then they are probably ok. Bad batteries generally won't hold a charge at all or for a very short time.

How did he check for draw? A modern truck alsways will have some draw on the batteries when off, the clock, radio memory, alarm will show small draws. You need to put a digital meter meter on the positve side to look for amps, if it is drawing you will see something on the meter, if not then it is a battery issue. 

If it is drawing then you need to start pulling fuses one by one until it stops. First pull the obvious. Alarm or Keyless, Radio, make sure nothings plugged into 12volt jacks and make sure doors are closed so the dome light is off. 

As you pull fuses watch for the meter to go to zero. When it does you have found your draw.

If its dying overnight that does not mean it is a big draw


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## TSG (May 18, 2001)

Hey Flipper.. thanks for the reply! 

I don't believe it's a battery problem as they were replaced. Right?

I just think it is odd that for the first 6 months or so there were no problems. Then a couple of months at a time between dead spots. Now it has become daily. 

I have not added anything or made any changes to the truck since I bought it.

Weird........


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## SnoFarmer (Oct 15, 2004)

I know you cheeked for draw but how was it done.
Disconnect the pos lead remember you have 2 batteries.(not sure how you have yours wired)
You want to use a meter between your post post on the batt and the pos lead going to your fuse block.

now you will see some draw.
start pulling fuses, radio, hood light anything that may draw power normally when your truck is off.

Do you still see a power draw?
if yes keep pulling fuses untill it drops when it drops you found the culprit.
.


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## LawnProLandscapes (Nov 15, 2007)

TSG;593198 said:


> Hey Flipper.. thanks for the reply!
> 
> I don't believe it's a battery problem as they were replaced. Right?
> 
> ...


by chance is this happening when your heater/ac fan switch on your dash is left in any of the on positions? far shot since you said you didnt see any large draw on the battery, also did you check the wires from the alternator to batteries and such for good connections?


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## ColliganLands (Sep 4, 2008)

same thing happened to my dads ram 1500. it wound up being that corosion from the battery terminals had eaten through both positive cables and one ground(negative) cable this caused them to die slowly at first then it completely destroyed the batteries and they died everyday. We wound up replacing 2 batteries and all the cables now it runs great again.
good luck
Kyle


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## TSG (May 18, 2001)

Thanks for the replies so far.

I'm wondering if it could be the brake controller? I don't think the thing has ever worked properly.


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## SnoFarmer (Oct 15, 2004)

TSG;593310 said:


> Thanks for the replies so far.
> 
> I'm wondering if it could be the brake controller? I don't think the thing has ever worked properly.


If you do a voltage draw test you would know.


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## ServiceOnSite (Nov 23, 2006)

did you actually check the system the way EVERYONE has been sayin??? the brake controller would take forever to kill the batteries. look else where


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## TSG (May 18, 2001)

Well.. after 2 and half hours of testing we think we found the culprit. There was a draw of approximately 4 amps and when we pulled fuse number 45.. "Ignition switch Run/Start feed" the draw disappeared.

Anyone know what the problem is or what the fix is? Do I need a new ignition switch?

Thanks in advance..


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## Mark Oomkes (Dec 10, 2000)

How long have you had the new batteries? I've been lucky to get more than a couple years out of anything other than some real, real spendy ones.


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## ServiceOnSite (Nov 23, 2006)

i would leand towards the ing switch, or did you wire up and thing off of that circut? lights, cb, laptop??


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## ace landscape (Oct 2, 2008)

welcome to the curse of the HD fords...... my f550 has a mind of its own and sometimes wont start but will on the second or third try, they have lots of quirks and im sure theres many more to come..... good luck!


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## red07gsxr (Dec 22, 2007)

i would deff check to see if anything is spliced into the ign swtich harness. it could be drawing from it like said before. im not positive but isnt the trailer brake controller need a 12v source? if so they might have used your ign harness to get that 12v source.


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