2004 S10 Blazer battery draws down, wont start after about 5min. with the rear hatch open/dome light on. Battery test shows good.

 

That would take a major short to kill a good battery that quick. One that could cause a fire. How are you testing the battery? When you disconnect/connect the battery, is there a large arc?

 

Agree with Walleye Hunter.

A proper battery test:

Charge fully, knock off the surface charge and hold 12.65V min
Electrolyte measures good and balanced if access to cells
Load test at 1/2 CCA for 15 sec (100's of amps), voltage never goes below min (9.7V at 80F)
Battery bounces back to above 75% charge (12.37V)

If you have an amp clamp meter measure one of the battery cables during the draw down.


George

 

I had it tested at the same place I bought it from, the local battery, tire, brake, ect. store.

 

What is the voltage at the battery posts after its charged up and while attempting to crank?

George