Qustion on alternator output 190e 2.6 - PeachParts Mercedes-Benz Forum

moonshine · #1 02-20-2007, 01:33 PM

Checked my cold battery at 12.45 volts, started car, waited 5 min. then checked with car at normal idle, volts were 14.45, Question, is this a sign of a well or sick alternator.

#2 02-20-2007, 01:35 PM

The alternator appears to be healthy by those numbers. I would have just a little suspicion of the battery condition, however. Had the battery run down a little before this test?

moonshine · #3 02-20-2007, 04:28 PM

Tanks for the quick reply, battery is 3yr old with only 12,000 miles driven, car starts well in 0 weather, as long as its over 12.25 feel its good as this was tested after a 3 day rest and about 25degrees (F), I will keep and eye out for it tho.

david s poole · #4 02-20-2007, 04:37 PM

a fully charged battery at rest should read 12.65v.yours at 12.45 is about 50%.it is also 3 yrs old and this is it's last year.check the electrolyte level in the cells and make sure it's up to snuff.

moonshine · #5 02-20-2007, 06:30 PM

@ 20-25 degrees (F) should not the battery test a little lower than when nice and warm, I thought a battery would loss about half its power at 0 degrees this should relate to lower voltage or just cranking power. thanks for the replyl