Bad Battery? Bad Alternator? Other?
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Super Member
Joined: Jun 2012
Posts: 919
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2009 c63
Bad Battery? Bad Alternator? Other?
Every few weeks, my car won’t start, No electrical evidence at all. Then it’s fine after the third attempt or so. Once running, everything is fine and there are no codes.
Tonight after a one hour drive, I turned the car off, read my phone a minute, the tried to open truck, nothing. No electrical, not even the gauges.
An hour later, I tried again. This time the center gauge only lit up and the car started. Three hours later, all three gauges lit up, but it didn’t start right away. Second time it started.
🤷♂️
Before I take it in, is this symptomatic of a bad battery? It’s maybe 4 years old.
Tonight after a one hour drive, I turned the car off, read my phone a minute, the tried to open truck, nothing. No electrical, not even the gauges.
An hour later, I tried again. This time the center gauge only lit up and the car started. Three hours later, all three gauges lit up, but it didn’t start right away. Second time it started.
🤷♂️
Before I take it in, is this symptomatic of a bad battery? It’s maybe 4 years old.
MBWorld Fanatic!
Joined: Dec 2005
Posts: 4,058
Likes: 342
From: NJ
2009 SL63 AMG
Sounds like a few different things could be going on here.
You can test a battery and measure its health pretty easily either at home or at your local auto parts store.
After testing the battery, I would start checking ground connections.
You can test a battery and measure its health pretty easily either at home or at your local auto parts store.
After testing the battery, I would start checking ground connections.
Super Member
Joined: Apr 2014
Posts: 682
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From: SC
2010 C63 AMG RIP. 2021 Toyota Tacoma TRD Off Road, 2013 C63 coupe
I had a similar issue with a 5 year old battery. I took two or three attempts to get the car cranked. It was the battery not holding the charge very well. I ended up replacing the battery.
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Joined: Oct 2023
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Red light means the battery is fine. When the red light stops flashing when you press a button is when the battery in the fob is dead. Did you check and see if your ESL is okay? If you have a higher end scan tool or Xentry you can scan for ESL faults, which could cause some of the symptoms you're describing. When you had AutoZone check the battery, did they do a load test? It usually involves putting a several hundred amp load across the battery for a few seconds to see how much current it can provide during startup. If you need a replacement, batteries that fit the car can be found at Wal-Mart for $180 and can be a cheap maintenance item to replace anyway while you're in there. No coding is required to swap out the battery.
Since my W204 is new to me, I've noticed that on these cars you must keep the brake pressed for the entire duration of the cranking. If you let go of the brake while the engine is cranking, it will stop. My Volvo doesn't do this, it only requires the brake to be pressed at the same time as the start/stop button. Something to keep in mind.
Since my W204 is new to me, I've noticed that on these cars you must keep the brake pressed for the entire duration of the cranking. If you let go of the brake while the engine is cranking, it will stop. My Volvo doesn't do this, it only requires the brake to be pressed at the same time as the start/stop button. Something to keep in mind.
