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Discussion Starter #1
Ok, i picked up my 07 lbz duramax about 2 weeks ago. Right before i purchased the truck the previous owner told me it started kinda hard one day so he had the batteries checked and one was bad other was good. The good battery would be the original AC delco battery.

He replaced the battery on the passenger side with a battery from the store that is 700cca 875ca. the ac delco is 770cca.

So, i went to the store today to replace the other battery on the drivers side...just more for myself to keep them replaced at similar time. They offered a battery for just $10 more that was 800cca 1000ca. I was on the fence with the idea of having matching batteries that were actually under rated for what the stock size was...or was it ok to have mismatched cca batteries in the truck.

I ended up buying the 800cca battery and installing it on drivers side...and left the 700cca battery he had bought on the passenger side.

Being new the diesel world... is this a NO NO...or does it really matter they aren't the same batteries?
 

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Depends on who you talk to.
Some claim they have to match and replacing only 1 battery would make the new one go bad quick.

I use to own a fleet of peterbilts and we used to test batteries with a load tester and a hydrometer as part of our scheduled maintenance and we only replaced the batteries that tested bad. Those trucks all had 6 batteries each.

Never had many battery problems.
 

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i might be wrong but it has happened before. ha ha. the battery's are wired in series. meaning the positive leads of both battery's go to the same place. the electrical draw load is shared by both battery's. so you have 1500 cca given you have a 700 and an 800 cca battery. they are not used independent of each other. so in other words there is nothing to worry about.
 

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what they said. dont worry about it
 

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Discussion Starter #6
All makes sense to me now. I tried to talk the autostore into letting me return or exchange the 700 he bought for the difference in cost to get the 800. i even had his receipt...but they couldn't do it.... oh well...i tried.

thanks for the help
 

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i might be wrong but it has happened before. ha ha. the battery's are wired in series. meaning the positive leads of both battery's go to the same place. the electrical draw load is shared by both battery's. so you have 1500 cca given you have a 700 and an 800 cca battery. they are not used independent of each other. so in other words there is nothing to worry about.
When both positives go to the same place, that's parallel.
 

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Different batteries

Depending on brand/age/size/discharge cycles, each battery is different with respect to accepting a charge. If you have two batteries that are not the exact same, there is a high chance that one will charge differently from the other. In a truck this just means keeping an eye on the water levels a bit closer until you get to know your batteries.

In the marine world a lot of charging systems are designed to decouple the batteries during charging, for this exact reason.

-W
 
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