I did a search for this but my question is a bit more specific than I can find. My 03 dodge cummins has failed to start twice in the last few weeks after sitting outside for 8 hours or so in 0 and below weather. I plug it in at home and haven't had a problem there. I had the batteries tested and the computer printer indicates a rating of 750 CCA each and a measured CCA of 636 and 651. The printout says "good battery" but I wonder if it's good enough. Any thoughts on whether or not I should replace these? Thanks for any input.

 

check to make sure your connections are good at the batteries, if thats the case, replace the batteries, even though they might show good on a test right after a charge, doesnt mean they can hold a charge for a period of time, and the colder the weather is, the battereis will put out less power

 

I cleaned things up a bit after the last failure to start. Do you think I have enough amps on hand to start the beast?

 

the only real way to tell would be to give the batts a good charge, then let them set about 8+ hours (seperatly) then test them, even better to test when cold to get a more accurate reading, you may have just one batt failing which will drag the other one down, but i would say if it happens again, i would replace them both