zcct04

I have had to jump the car a couple times in the last couple months. Battery has been replaced, so I'm assuming alternator. Probably need to get it replaced but am still in denial (voltmeter shows 14+ shortly after starting) and also in sticker shock over the price.

My question - with every other car I've had, the battery shows signs of loss of charge - slower cranking being the primary clue. I don't get any warning on the C63. One minute it's fine, the next I just get a single 'clunk' sound but absolutely nothing else. Voltmeter is still showing 11-point-something volts.Is this similar to what others have experienced?

deadlyvt

Loose terminal connections?

bhamg

For an AGM battery like yours:

skratch77

I changed my battery to a new Bosch from pep boys and the car would need a jump every other day after about 6 months.

I too thought it was my alternator but I decided to put the old oem battery back in and the car has been fine for 2 months now.

Go figure, so maybe the battery is gone and I would replace with an oem from the dealer after what I went through buying from pep boyz.

bhamg

Bosch AGM batteries have a 4 year exchange warranty which is as good as it gets. I had to replace mine also, in its 27th month.

Dogtag114

I have 7 years and over 80k miles on mine, maybe more if the first owner never changed it (or the dealer as part of CPO), should I replace it proactively?

Jasonoff

Have it tested.

icantthnkof1

My original battery died this Feb and replaced it with a Bosch. I had the same issue with no warning last week. I thought I may have had a parasitic drain, but tested the battery first. I was told it had a dead cell. They would have replaced it with the same brand, but they were out of stock so they replaced it with a Champion AGM. I believe the Bosch batteries are junk.

chrisridebike8

I agree about Bosch. My OEM battery lasted 6 years. Replaced it with a Bosch AGM and it barely lasted a year and a half.

Dogtag114

AutoZone did yesterday and said it was fine... tech didn't look particularly savvy and just said is meter said good or not when I asked for details.