I'm on the original batteries.

[Crank]

My truck is 2004.5 2500 with 33,000 miles and on the original batteries still. How long or when should I replace them?

 

[DavidC]

Load test them, that will tell how good they are. Being 15 years old I would think you are due.

 

[Crank]

How do you load test them? I have an ohm meter.

 

[DavidC]

It requires a load tester like this at Harbor freight, Auto zone or Oreilly's can probably test also

#ad

 

[DavidC]

Harbor Freight load tester
https://www.harborfreight.com/500-amp-carbon-pile-load-tester-91129.html

 

[GrantP]

Load testing is the correct answer, but I'd just replace them regardless. You are on borrowed time.

 

[petersonj]

I agree with @GrantP . CR engines are very dependent on good cranking speed.

- John

 

[12LaramieHO]

Load testing is the correct answer, but I'd just replace them regardless. You are on borrowed time.

Crank, I agree with GrantP.
You're on borrowed time. They've given you good service, just go ahead and change them out.
My 12' CTD had 33,000 miles on it and they were done in 17'. I have no complaints on a set of batteries that went 5 years and saw service on Donner Summit through 3 winters and 3 summers in Palm Springs/Mojave area.
~C

 

[handtools]

My truck is 2004.5 2500 with 33,000 miles and on the original batteries still. How long or when should I replace them?

About 5 or 10 years ago!!!

 

[Shiner]

Living right...…..but on borrowed time......buy a lottery ticket!

 

[p-Bar]

Run em' till they start cranking slow best load test. then replace

 

[Ozymandias]

Keep them as long as possible, no batteries like this can be bought for money.
Awesome quality they used back then.

 

[Crank]

I'm in Mn and it is pretty much my garage queen. Bought it new Forest Lake Dodge. No winters, just summer camping to up north and once to Iowa. Trickle charge it in the spring at 2 amps. Original everything. When I retire I will head south.

 

[04blackcherry]

Low miles on the truck, so it seems like it might sit unused a lot. I didn't see any crust on the terminals. Do you keep a trickle charger on it? I just replaced my original batteries on the '04 last September, but mine is a daily driver. Batteries don't like to sit with all the parasitic draws on them.
(Sorry, I posted just after you said you had the charger on it.)

 

[Crank]

The only parasitic is the radio and dome lights. Cd cassette player.