dead battery
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Joined: Aug 2010
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1990 300e 2.6ltr
dead battery
i replaced the battery in my 90-300E w/a new one and it's dead with in 6 to 8 hrs 
same case with old battery and installed battery shutoff seitch
but getting tirerd of popping hood all the time.
same case with old battery and installed battery shutoff seitchbut getting tirerd of popping hood all the time.
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300E a couple 1994 w124wagon E320 Wagon/,1971MGB Track/Rally, MG Midget Autocross ,2000 E320 wagon.
OBvious
question,but have you tried testing the alternator output?
Or is it draining without even running the car?
Or is it draining without even running the car?
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300E a couple 1994 w124wagon E320 Wagon/,1971MGB Track/Rally, MG Midget Autocross ,2000 E320 wagon.
Get out
the multimeter and start testing circuit drain.via the fuse boxes.
Something is pulling a massive load.
Something is pulling a massive load.
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From: Massachusetts
2018 GLE350, 2014 G550, 2000 SL500, 1980 TR8, 1995 E320 Cabriolet
Connect a the ammeter function from a multi-meter in series with the negative terminal of the battery (the + lead of the ammeter to the battery and the - lead to the chassis ground lead). Start on the highest current setting (usually 10 amp for most digital multi-meters). Note the reading - normal is less than 50 milliamperes (0.050 Amps) or so. If your battery is draining that fast the current reading should be very high - 5 - 10 amps! Start pulling fuses one at a time until the reading drops significantly. Don't forget the big fusible links under the hood. If you can't find the draw via the fuses, you may also want to disconnect the alternator - a bad alternator diode is a common cause the sudden high current draws.
Good luck.
- FD
Good luck.
- FD
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Joined: Jun 2006
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From: Northern California
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FD has just explained one of the two ways to determine if you have a key off current drain. The other way which I prefer is to measure voltage instead of current. I disconnect the negative lead to the battery and install a wire wound 1 ohm 10 W resistor between battery terminal and cable. Then I measure the voltage drop across the resistor. Anything over .05 V is excessive. I prefer this method, because it is safer for the meter. Both FD's method and mine are the professional approach to solving your problem. Good luck.
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