Mechanics

BATTERY

1999 BMW 740

Electrical problem
1999 BMW 740 V8 Two Wheel Drive Automatic 70k miles

just bought 99'
Seller said battery is brand new. Went to start when I was leaving work and nothing. Got a jump and started instanly. Parking sensor, abs sensors stayed on while driving home. During acceleration the sensors sometimes disappeared and came back on as I slowed the vehicle. This sounds like an alternator problem? The car is dead in my garage. Should I jump it again to get to a service center or would that cause more damage. Which type of service center is best. Strictly BMW centers.
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No Qtr
May 11, 2008.




Let's take this a step at a time, first, remove the negative battery terminal and charge the battery, reconnect the battery and start the car and observe the voltage at the battery. It should be about 14 volts. Then check for a key off draw by installing an ammeter in line with the battery and checking the draw at the battery with all the doors shut and the key off. It should not exceed 50 MA. Let the battery sit for a few hours and watch the voltage, it should not go below 12.5 volts. If it does replace the battery. Repost with your findings, I will be here for you.
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Dr. Hagerty
May 11, 2008.
Probably an alternator problem. You need to check if alternator is charging your battery. Just my 2 cents.

Tiny
KarenCaren
Sep 11, 2008.

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