Notices
Mercedes Tech Talk Discuss general technical questions and issues about your Mercedes-Benz. Moderated by a certified MB Tech.
Sponsored by:
Sponsored by:

Help- voltage swing issues

Thread Tools
 
Search this Thread
 
Rate Thread
 
Old Sep 20, 2017 | 08:28 AM
  #1  
dkwilson's Avatar
Thread Starter
Newbie
 
Joined: May 2017
Posts: 3
Likes: 0
2006 SLK 350
Help- voltage swing issues

Hi all,

I've been having voltage issues with my 2006 SLK 350. First, i must say that there is a brand new battery in the car (<1 year). Also, i just replaced the alternator ~3 weeks ago (refurbished from JC Whitney), which has since made the not-starting issues go away, and the car starts every time now (before the battery would die in a single day). When i put a voltmeter across the battery with the car off, the reading is ~12.4V. When i start the car, the voltage across the battery builds up to ~13.5V or so, then drops down to ~12.3V. While it's sitting there doing this, you can hear the car kind of "rev up" (but not with anyone on the accelerator), then hit a point where you can hear it drop and get quieter- then it just does this over and over. (Slow build up, louder, louder, then hits a wall where the voltage falls and you can hear it do so.)

The other issue we are having is that the radio won't let you change the 'source'... it is stuck on the CD mode. I have read through some forums about guys saying this is a battery feature that if the voltage is not sufficient enough, it will disable car features like this. So i'm hoping it is just related to the voltage issues that i can hopefully easily resolve together.

Please help, this is such a pain.

Thanks!
Reply

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 


You have already rated this thread Rating: Thread Rating: 0 votes,  average.


All times are GMT -4. The time now is 07:32 PM.

story-0
6 Mercedes Models That Did NOT Age Well (But Are Somehow Still Cool)

Slideshow: Not every Mercedes design becomes timeless, some feel stuck in the era they came from.

By Verdad Gallardo | 2026-05-12 18:09:07


VIEW MORE
story-1
Manual Mercedes? 6 Times Sindelfingen Let Drivers Have All The Fun

Slideshow: Yes, Mercedes built manual cars, and some of them are far more interesting than you'd expect.

By Verdad Gallardo | 2026-05-02 12:36:58


VIEW MORE
story-2
Mercedes SLR McLaren 722 S Is Extremely Rare Example Modified by McLaren

Slideshow: A one-of-one U.S.-spec Mercedes-Benz SLR McLaren Roadster became even rarer after a factory-backed transformation at McLaren's headquarters.

By Verdad Gallardo | 2026-04-29 11:19:28


VIEW MORE
story-3
8 Classic Boxy Mercedes Designs That Have Aged Like Fine Wine

Slideshow: Before curves took over, Mercedes mastered the art of the straight line, and some of those shapes still look right today.

By Verdad Gallardo | 2026-04-25 12:05:49


VIEW MORE
story-4
Flawlessly Restored Mercedes 190E Evo II Heads to Auction

Slideshow: The 190E Evolution II shows how a homologation necessity became a six-figure collector icon.

By Verdad Gallardo | 2026-04-22 17:53:47


VIEW MORE
story-5
Electric Mercedes C-Class Unveiled: 11 Things You Need to Know

Slideshow: Mercedes is turning one of its core nameplates electric, and the details show just how serious this shift is.

By Verdad Gallardo | 2026-04-21 13:58:06


VIEW MORE
story-6
Mercedes EQS Gets A Major Update: Everything You Need to Know

Slideshow: Faster charging, longer range, and a controversial steer-by-wire system define the latest evolution of Mercedes-Benz EQS.

By Verdad Gallardo | 2026-04-15 10:35:34


VIEW MORE
story-7
5 Underrated Mercedes-Benz Models That Don't Get the Love They Deserve

Slideshow: These overlooked Mercedes-Benz models never got the spotlight, but they quietly delivered more than most remember.

By Verdad Gallardo | 2026-04-13 19:35:45


VIEW MORE
story-8
Mercedes 300D Has Pushed Well Past 1 Million Miles and It Ain't Stopping

Slideshow: A well-used 1991 Mercedes-Benz 300D with more than one million miles is now looking for a new owner, and it still appears ready for more.

By Verdad Gallardo | 2026-04-10 10:05:15


VIEW MORE
story-9
10 Most Reliable Mercedes-Benz Models You Can Buy Used

Slideshow: From bulletproof sedans to surprisingly tough SUVs, these Mercedes models proved that the three-pointed star can go the distance.

By Verdad Gallardo | 2026-04-08 09:55:49


VIEW MORE