Auto Parts: Battery starting issue, auto parts stores, volt meter

Question
My battery has recently had trouble starting our van.  When starting today the solenoid clicked several times before the car started.  When I measured in with a voltmeter I got 12.84V before starting - it then dropped to 6.5V when cranking - then went to 14.4V at idle.  Battery is 3 years old out of 6 year prorated Diehard warranty.  Should I take it to Sears and let them diagnose further and hopefully replace.  We live in a cold weather state and doubt it will survive winter unless cleaning terminals and battery top would fix the problem.

Answer
It would surprise me if your Die Hard is on its way out at this point in time, but anything is possible.  

If you suspect your battery is dying on you, many auto parts stores will test it out for free.  You can measure voltage with a plain volt meter, but the best way to test for dead cells is to hook it up to a battery tester.  These will properly test a battery through a full range, and put a load on it.  Again, this can be done for free if you call around and find a parts store that would be willing to do it.

Another thing to do would be to pop the caps off the battery and check the water level (if possible).  If it's low, use distilled water to refill.  Charge the battery up overnight and see where you're at from there.

Clean terminals is always good to have, and help eliminate any problems or questions in that area.

If this is not your problem, the next area I'd look is the starter.

Hope this helps.

- Brent