2nd Gen Non-Engine/Transmission Single battery replacement

[PVanderlugt]

Hello all,

Bought a set of Interstate batteries 2 years ago to replace the factory ones 2 years ago. Noticed a little slower cranking now that the weather is getting colder, looks like the drivers side one went bad. Dealer says he can only warranty the bad one, since the other one test better then new spec. I was always under the impression that you have to replace these batteries in pairs? due to the memory they develop? any mayor issues with just replacing one?

Pete

 

[seafish]

AFAIK it is not a "memory" problem (lead acid batteries don't have that issue) but instead a problem of age and wear of the plates inside the older battery that can lead to different charge rates needed BETWEEN the new replacement and the old battery. And since the truck charging system charges ONLY at one rate determined by a COMBINED voltage reading, then maybe one battery will be getting overcharged while the other is getting undercharged, which can certainly lead to MORE problems down the road.
For that reason, it is always better to replace both batteries at the same time.

 

[Road Dog]

Batteries (of all types) have an internal resistance. When you're running batteries in parallel then you want the resistances to match so that they discharge and charge at the same rate. If you replace it with an identical battery (same CCA and reserve capacity) then it won't matter. The existing setup has been unmatched for a while. I don't think 2 years is very old for a lead-acid battery.

(The internal resistance is what limits the maximum current that the battery can produce. If you shorted a battery with zero resistance you'd get infinite current for a brief period. That doesn't happen because there's a small resistance restricting the flow of electrons out of the battery. )

 

[PVanderlugt]

Thanks guys that makes kinda sense, the "bad" battery would be replaced with an identical (to the other side, ) new battery, same AMPS and reserve, etc.
just wondering, even if I can not talk them into replacing the other "good" one if it would be worth the $130 to just throw a new one on my own dime on the other side, as much as Dodge has problems with there electrical systems, wondering if it would not prevent gremlins down the road. Might be able to use the other "good"battery in something else.
Pete

 

[Road Dog]

There's no way to know how long a battery will last. If the old battery is significantly weaker then it'll fail in a year or two and get replaced under warranty too.

 

[hsmith]

Remember this rule. You are only as strong as your weakest battery. ALWAYS!!

 

[JKosten]

While you are doing this check the condition of the cross over cable. Mine had corrosion under the insulation back from the ends. I could feel the difference.

I ended up replacing every battery cable with OO gauge and have not had any problems since.

 

[Bob4x4]

Internal battery resistance DOES change with time and use,however it would be hard to find a shop that could measure it directly. There are some very high tech battery testers being used today and if they say the battery is good you are pretty safe they are correct.