Battery gauge shows zip, but car starts and runs

- K
- Katrina
  
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posted
15 years ago

Sat, Mar 7, 2009 8:08 PM

What the heck? My '89 740 Turbo sat for awhile due to a flat tire. It started up on the first try last week. Today we've got some nice warm weather so I put air in the tires and took it around the neighborhood. I noticed my battery gauge, the needle is all the way to the left, besides the number "11" when it used to be right smack dab in the middle between the 11 and whatever is on the right side. A 16, I think. Anyway...I drove it right back to the house, parked it and now I patiently await your thoughts and advice. Thanks in advance!

- J
- James Sweet
  
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posted
15 years ago

Sat, Mar 7, 2009 8:57 PM

Try tapping the gauge with your knuckle while the car is on, sometimes they stick when the lubrication dries up.

- A
- Andy
  
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posted
15 years ago

Sun, Mar 8, 2009 1:26 AM

Yeah, my fuel gauge ('88 760GLE) does this and will drop to completely empty from time to time. Luckily I know that I can get 500km to a tank :-)

Cheers, Andy.

- M
- MasterBlaster
  
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posted
15 years ago

Sun, Mar 8, 2009 7:01 AM

That's your voltmeter. It shows either the resting battery voltage (with the engine off, but the key on), or the charging voltage (with the engine running). A normal, fully-charged battery should show between 12 and 13 volts on the gauge when just sitting, and around 14.5 volts when the engine is running and the alternator is doing its thing. Is your gauge always sitting at 11, or does it start at zero, then pop up to 11 when you turn the key on?

Do you, or anyone you know, happen to have a pocket-sized voltmeter you could connect to the battery terminals to verify what the battery and alternator are doing? If not, a lot of places can check the charging system for you with a few simple tests. Some might even do it for free. Try the local gas station (if they have mechanics and service bays), or Autozone, or some other auto-parts stores.