One of the old motorcraft's finally kicked the bucket.. Was down to 10v.. Was the passenger side one.. Drivers side is still showing 12.5v..I replaced both, but kept the driver side as a backup, and gave it a good charge.. 63000 miles, 3 years.. Not bad for OEM batteries here in Phoenix, AZ..

 

I think you did well.... I learnt a long time ago that when one battery in a diesel truck takes a crap, the other is not far behind. If you don't replace them together, the remaining old battery will just be a burden on the new one by causing the starter to draw even more amperage since the voltage is down..

 

I replaced my OEM batteries at 125,426 miles and at 37 months. My son's KR 6.4 crapped out at 36 months. I swear there is a timer embedded in Motocraft batteries.

 

I was able to get 4 years out of the ones in my 6.4.

 

I shouldn't open my fat mouth, but I'm at 3 years 8 months and 62,000 miles and so far my batteries seem fine. My 6.0 only made it to about 3 years 4 months and maybe 50,000 miles before they died. My brother had a 2001 F550 7.3 and the original batteries went about 8 years of which 5 of them it ran a snow plow. It really is a crap shoot at best.

 

batteries here in Phoenix, AZ don't last long because of the summer heat..it kills everything.. batteries, tires, belts, hoses, alternators, starters, speakers, interior pieces, paint, tires, tires, and did I mention, TIRES..
3 years is pretty good for a battery here..best I ever got was 5 years out of an old "DieHard" that I had in my Bronco..it probably would've lasted longer, but I left the lights on one day, and it died..would not take a charge after that...
I have to make sure I keep all seldomly used batteries inside for the summer(eg. boat, camping trailer)..or they will be no good after a year..I've had RV batteries crap out in a few months because I left them in the heat...

The dealer where I get my truck serviced did warn me that the batteries were getting weak.. I'm just glad it died in front of my house, and not out in the middle of nowhere..funny thing is the driver's side battery was all dirty and nasty looking, and it was the good one.. the passenger side was clean and looked good, and it was the 10v dead one. Is the driver's side battery the main battery used for the starter? I noticed it has much thicker cables than the passenger side..

 

Mine in my 2011 have just bit the dust at 15,000 miles. Pretty sorry batteries if you ask me. My Dodge still has OEM factory batteries in it and don't show any signs of croaking yet.

 

Best battery story my family has had is my step father's 99 SD V10. Still had the factory battery when he passed and we sold it to a friend of mine in 09. Friend drove it until 2012 and it was still going strong. I'm expecting a bit less from my 6.7....

 

You may as well go out and buy them now.

 

Bought my 2011 F-250 diesel in December 2010. 173,600 kms and batteries are still good but I know time is creeping up. I figure I will need front brakes real soon too! replaced the rear for $800 or so. Ah, the jobs of maintenance on heavy duty trucks. Replaced the tires with Toyo All Terrain 2's about 10,000 kms ago and they are great.

 

After extensive research, once my bass boat batteries began to die, I bought three new Sears Platinum PM-1 (same as Odyssey) and they are fantastic, but heavy. When my truck batteries fail, I will replace them with the Odyssey's for sure.

 

Ever wonder why flashlight manufacturers advise against mixing old and new batteries? It will work, but the light output fluctuates, and the batteries start to leak. They "fight" each other. Every cell has to be on the same sheet of music, an auto start battery is no different. Mismatched cells/batteries don't do any favors for the charging system either.

Auto batteries in parallel are just a single larger capacity battery and must be charged in parallel for rated performance and longetivity. Even (especially) new batteries should be thoroughly charged prior to installation, regardless of what the kid behind the counter tells you. Given that a pair of good quality batteries is approaching three bones, a 20 dollar charger will pay for itself quick.

New batteries are also "hard" when new, they require 10 or 20 start cycle discharges and charges to break in and reach full rated capacity. An outboard charger "sized" to about 10 or 20 per cent of the ampere rating of the battery and applied to periodic equalization will get the maximum lifespan and performance out of them. With parallel setups this would typically be around 20 amperes for a slow "trickle" charge - most retail chargers are not capable of this.

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Mine lasted 150k, I just replaced them with a pair of DieHard Platnium AGMs since they're the same as Odysseys

 

Had my truck to the dealer for a minor warranty repair. As part of their "service" they checked my batteries. #1 checked 1100 and he said that was good because it is only rated 750. I told him it has two batteries, so he checked the other one, and wouldn't you know it, it checked the same! These folks have no clue.