Just picked up my rig the other day, and was looking under the hood this morning at the AFE magnum, to try to find out if I can get an outerwear for it, when I spot the second battery in the back of the engine compartement, on the passenger side


WTFCensored

What on god's green earth is it for???

because these diesels have almost 20 to 1 compression and you need the Cold Cranking Amps of both to turn it over to start!

BIG compression buddy all diesel have 2 as far as I know

If they are the original batteries, keep an eye on them. I just had one go bad on my 03. You should replace both at the same time if one goes down.

you have the two batts for the cranking power and reserve capacity. If you ever have one go bad, you should replace BOTH at the same time. Make sure you use the same type of new battery for both.


start reading up here... there is a TON of info here):h

The engine will crank fine on one battery. Two are needed to run the glow plugs, fuel and inlet air heaters. Later! Frank

You can also get one with two alternators, to go with the two batteries.
11061

A previous message alluded to it, but it is really important to replace GM original batteries proactively. The GM OEM batteries have been having problems for years. I replace mine at 36 months of service to be safe.

Reality is the posts corrode internally and can actually separate. If you can find any hint of moisture around the positive post, replace it. In the case of our diesels, that means replace them both.

My five previous GM vehicles have not only leaked acid around the post, the acid damaged the battery cable ends. It is much cheaper to replace the batteries before they fail.

If they are the original batteries, keep an eye on them. I just had one go bad on my 03. You should replace both at the same time if one goes down.
Same here. They actually went out while i was parked infront of the diesel performance place by my house, thank god. I Jus walked back in the front door and had them put two new ones in.
I was also suprised to learn i had 2 batteries too

I spy a gasser convert. :rolleyes:

):h

Just kidding, but you do have much to learn, Grasshopper. All in due time...

In the meantime, enjoy your awesome machine!

guys......why replace both at once?I only replaced one....about 112K miles ago....And i have 215K on the one stocker

I believe it is because of the way that they are wired together. You need to replace both at the same time.

guys......why replace both at once?I only replaced one....about 112K miles ago....And i have 215K on the one stocker

Well, without getting too technical about it... Basically since they are tied together as "one" the alternator charges them as such. If you have one that is old and one that is new... their capacity will be different, even if they are the exact same brand and model.

Now where this comes into play is, as they discharge, it is at different rates - when they charge, it is at different rates. This can cause one battery to overcharge (and worst case, blow up!) and one will not be up to par. It also can cause something with the alternator that can cause it to go out as well...


I hope that makes sense.


Vic

Hey,

And if you replace only one, it is only as strong as the other one you did not replace. The older battery once it starts to weaken will draw the new one down to the capacity of the old one. So in a sense one new battery will have its life shortened by the older weaker battery when it finally gives up the ghost!!

I hope I did not confuse you.

Take care and good luck!!

Will

what do the oem batteries look like?
robert

Mine were black AC/Delco "service free" sideposts with a clean top and green status eyes.