Driver's side battery failed recently on my '02 2500 CTD. I had replaced stock in Oct/08 with stock batteries - Mopar 72 series - since the originals had lasted 6½ years and were still good - seemed like a good recommendation to me.

I bought the new batteries from a truck shop in Santa Fe that's done a lot of work for me and I trust his word, but now he's told me that if I replace one I should replace the other as well, since the older battery will pull down the new one and shorten its life.

I would like to do what he says, but money is a factor and I hate to throw away a good battery if I don't have to.

Has anyone here got any input for me ?? \

Thanks

Lar.

 

Generally speaking, Mr. Truck Shop Guy is right. Usually when one battery is shot, the other is already weak, because the shot one has been drawing down the other already. If only the shot battery gets replaced, the other (now weakened remember) will draw the new one down. You will not see this happening or notice it in any way in most cases - you'll just be replacing them again... sooner.
My recomendation: Test the old battery that's still "good" - if it tests good, just replace the shot one. If it shows any sign of weakness - you'd be wasting money to replace only one.
Oh, and replace it with the exact same battery as the other.

 

x2
Best practice is to replace them both.
Wal-Mart usually has good prices...

 

I replaced both batteries in my truck and kept both batteries and just set them in my shop. Had a battery go bad in my 1500 truck and then used one of the ones out of my diesel for it. It has been in the truck for 8 months and is still going. Cold weather is coming so I will soon find out how long it will last.

Sam

 

I talked to the people at Interstate Batteries, too, and they made the same recommendation so I'll go with you guys and replace 'em both.

Not sure about hanging on to one. Good idea, but not sure how the core factor will work out.

Lar.

 

I've tried to buy one a couple times and it has proven to be right to just change them both if they are over a couple years old. you may go a few month's but you be in the same place making the same decision.

 

On dual battery setups is is suggested to replace both at the same time to ensure trouble free operation down the line.


Traditionally the weak battery pulls down the good one sooner than if both were of equal age.