battery testing ?

[bd1028]

I have a 2002 2500 hd duramax with Delco professional batteries installed in 2008 .the truck is a little sluggish turning over when truck sits overnight ,if I let it sit 2 days usually will have to jump it .started truck yesterday and took to garage guy put hand held tester on each battery and said they were fine .he said need to do a leak down or draw down tes tto see what is drawing them down .I think they have lost their cranking amp capacity what do you guys think?

[cowboywildbill]

Make sure cables are clean and batteries are fully charged, then do a load test. If they both test OK, then you would start looking at something staying on and pulling them down.
Like the BCM or anything that has been added or tapped in like aftermarket accessories. It is normal to have a small current draw when dormint, a repair manual would tell you the amount that is normal.
Good Luck.

[DickWells]

FWIW, also, those side terminals are not the greatest things. First thing I do to a GM with S T's is to go down to Ace Hardware and buy four, 3/8 - 16 X 1 -1/2, or 2" SS bolts and 8 SS nuts, and replace those factory bolts. You put the terminals between the nuts, so that you can come down pretty tight, without straining the internal threads in the batteries, too much. Makes a world of difference with the integrety of the connections, there. They do seem to need to be re-tightened about once-twice a year, though. Just one of the great DIY mods that I've gotten from the Diesel Page, over the years.

[bd1028]

Just checked the date code I was off a little bit I put those batteries in 2006.My how the years fly by!!

[cowboywildbill]

Yep! it might be time for some new one's!

[JohnC]

When you tested the batteries, did they remove the ground cable from one of the batteries? If not, you tested the two batteries together (twice), not individually.

[bd1028]

No they never disconnected anything and I wondered about that but figured they knew what they were doing !I quess I should of asked.Thanks for the heads up now I know .Bad thing is I let those guys have my truck today they said batteries were fine but needed alternator said there was an open circuit drawing the batteries down when the truck was parked and turned off

[cowboywildbill]

UH OH! I think I would try to get it back. Not likely that a bad altenator would pull down your batteries and especially when your not running it..