Replace just 1 battery?

[y2kram]

Curious about changing a battery. Truck is now 2yrs old (but over 36K mi). Went out yesterday morning and the batteries were dead.

I disconnected the cables from both of them and stuck the passenger side on a charger for a while. The charge came up okay. Switched to the driver side late afternoon, and this morning, the charge level is still low (1/2 - 3/4).

So my question, when replacing a battery, does DC recommend that the replacement match exactly, or just another battery with approx the same amps?

Would it be covered under warranty? I read through the warranty info and couldn't determine that it would be covered (since the mileage is just over 36K miles) even though the truck is 2 yrs, 1 mo old.

Also, just what is the (factory) battery rated at? I noticed that they are completely free of any markings indicating their strength.

[kcjayco]

As a diesel mechanic for 25 years my experience is change both batteries. The old one will pull the good down to it's level. I replaced both of my just recently. I used batteries rated at 700 cold crank amps. Group 27. I hope this helps.

[Thornbird]

I would seriously doubt you could get them replaced under warranty. I believe they're listed as a "wear" item, much like brakes, clutches, wiper blades and the like.
I agree to replace both batteries. These diesels need alot of cranking power, so don't skimp on the cold cranking amps.

[JohnC]

You need to replace both batteries. The starter requires mass quantites of current. When the voltage is low the starter tries to draw more curent which increases the heat buildup in the starter. These starters I understand are VERY EXPENSIVE!

The factory batteries are rated at 750 CCA. I installed 2 Optima's in mine and love the way it cranks.

Be ready for a shock, the cost was $264 out the door. Look around you can get them for about $120 each.

[y2kram]

I looked at the Optima battery. The warranty on those really sucked. The heat in Phoenix tends to eat batteries. I don't think I've ever had a battery last 4 years.

I ended up buying a pair of Autozone batteries (Duralast). 1000 amps, 800 cold cranking amps.

3 year free replacement, 8 year warranty.