DYI_mb_fun

I get the message about the battery and hear this noise (see attachment). Does anybody know what that could be and if they are related?

sn202020

"Low battery" warning.

See
System button. - Dynamic - Engine voltage
engine run 13.5volt ~ 14.9 (alternator good)
/ engine off 12.2 v ~ 12.5 (battery)

If the original battery never been changed 8 years, it's time anyway to
get a new AGM battery.

Check
alternator & Serpentine belt

DYI_mb_fun

Voltage is within range when engine is off and when it’s running

Very confusing

sn202020

Voltage might be in good range but amperage might not.

Again, the cheapest thing to do is,

If the original battery never been changed 8 years, it's time anyway to get a new AGM battery.
H7-AGM type at Costco about US$250

Or

Wait until you see more obvious symptom.

DYI_mb_fun

Thanks for your help! Replaced battery and that took care of message..

Have to figure out the whining noise now

sn202020

Your noise at 1500rpm sounds might be

- Serpentine belt
- pulleys - idler, AC, alternator, tensioner
- turbo bearing - not likely.

1. Hear and find noisy location under the hood at 1500rpm

2. Remove Serpentine belt and turn all the pulleys by hand and hear if any bearing is noisy. If possible, add some bearing grease into the noisy pulley bearing to see if it fixes. (My alternator pulley, OAD, was noisy and replaced)

3. Remove turbo intake hose and feel the fan blade bearing's play. Less than 1mm up/down and side/side is normal, I belive.

DYI_mb_fun

Ended up replacing the Alternator, Idler pulley and tensioner and that took care of the whining noise

thanks for your help!