I just replaced the alternator. I had the battery and alternator scanned before and after to make sure there weren't any other charging system issues. Both times (at different locations) they seemed surprised the battery was reporting more amps than it's rated. It is rated at 750. A few days ago they said it was reading over 800. Today, after charging and a new alternator they said it was reading well over 900 amps.

I certainly don't mind having the extra power, but is having that much over the rated capacity an indication that there's something inside starting to wear out? (Or were the two people who tested it as clueless as I am?)

I charged it last night. Before I replaced the alternator this morning I checked it again and the charger said it was only reading about 65 percent again. I charged it up again before I started it and it seems to be OK.

 

If they are comparing their discharge reading (900 amps) with the CCA rating on the battery, then that would be basically normal.

The CCA rating printed on the battery is the amount of current that a battery can deliver for 30 seconds at 0° F. A battery does not deliver current as well when it is cold.

If they tested the battery capacity at say 80° F, then it would deliver more current than the rating label.

 

I just checked it first thing this morning, and it's reading 12.3V/70%. I'm sure it will start just fine, but is it typical to drain that much overnight?

 

i would say sounds like a dead cell. had the same thing that ahppedn to me on a ga battery. ran fan for a few days then it just refused to start. replaced it wit a new one. problem solved

 

It always seems to start just fine, unless I run the dome lights or radio for any amount of time. It has checked out on testers at both Advance Auto and Walmart and both said it was good but with low voltage and high amps.

 

id still throw a new one on. thre might be a slight draw in the sytem tho

 

If that battery is over 3 years old just get a new one.