Just had to replace both Interstate batteries yesterday morning. Each battery had more than one bad cell. The good thing is they were still under warranty.
My question, since I am not of the "electrical" type is "why do our diesel trucks have two batteries? Could there be one larger battery to replace these two existing ones?

Thanks

 

Two words here: Glow Plugs. They draw a ton of current to heat up the cylinders in mere seconds. You can start on one really good battery, but not reliably. The second battery makes starting very reliable in cold weather.

 

That one larger battery would be more expensive than the two you currently use, and would likely have to go in the bed of the truck.

 

You should have been watching trucks on the power block this last weekend. They did just what you're wondering on project super dually.

 

That battery retails for $780. I will stick with my $180/pair Duracell Sam's Club specials.

 

I wasn't paying attention when they said price.... That's just stupid

 

I don't pay attention to ANY of those extended info-mercials. That's really what they are.

You want "How-To"?

Television isn't even a close second, and a waste of time.

My absolute BEST source of information about these trucks is right here, FTE!

Pop

 

Can't argue with that statement one bit.

 

I can start on one battery almost as if the second one was still connected.

Granted at 75*F thats probably not all that hard

 

same here.

 

Not only do the glow plugs draw alot of juice when there on but the compression of these engines need alot of juice to turn them over.

 

In colder weather it helps with the thicker oil our diesels have. Gas engines have between 9:1-10:1 compression ratio. Diesels have like 20:1 and that requires more cranking power.

 

High compression and big displacement combine to challenge the battery without glow plugs and cold oil. Winter flat kills a single battery on these trucks.

 

How do the Duracells last? I just put 1 in my Wife's car.

 

Almost a year down and they are still testing like they did new. 3 year warranty and you can't beat the price.