95 e300d. The battery in the car now is a duralast purchased new in Jan., 2006. Yesterday, I left my primary headlights on for around 75 minutes. It wouldn't start. I've left my lights on before, not for that long, but an hour and 15 minutes doesn't seem long enough to prevent starting. Am I wrong? I checked voltage a couple of weeks ago and alternator is working and battery is strong.

So, sitting there in Charlottesville, 100 miles from home, I called MB roadside assistance. I got a call back after 5 minutes saying a tow truck was on the way. 1.5 hours later, a guy in a wrecker comes by, barely touches the jumper cables to the battery and it starts. Guy says MB Roadside covers the cost of the jump. I tipped him and drove home. Even though we waited a while, I was really surprised the jump was free. My insurance would have covered it anyway, but still it was cool.

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2009 E320 Bluetec 117,000
1995 E300D 306,000 Sold
1996 Ford Taurus LX 130,000 Sold
1985 300TD Still 225,000 Sold
2016 Ford Fusion 24,900

IF you add up the wattage that the headlights & parking lights use..then subtract that from the battery's rating you can figure how long it will last.

Each headlight uses 45-55 watts.
Each parking bulb uses 10 watts, side markers & tag lamps as well.
2 headlights = 100 +- watts
8 parking lamps = 80+- watts
Almost 200 watts including the interior lighting....divided by 12V =16+ amps on a battery rated at 80-100 amps.

I would think a good battery would last 2 hrs at that rate before not having enough power to start the car!

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MERCEDES Benz Master Guild Technician (6 TIMES)
ASE Master Technician
Mercedes Benz Star Technician (2 times)
44 years foreign automotive repair
27 Years M.B. Shop foreman (dealer)
MB technical information Specialist (15 years)
190E 2.3 16V ITS SCCA race car (sold)
1986 190E 2.3 16V 2.5 (sold)
Retired Moderator

Thanks a lot Doc. That's very helpful.

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2009 E320 Bluetec 117,000
1995 E300D 306,000 Sold
1996 Ford Taurus LX 130,000 Sold
1985 300TD Still 225,000 Sold
2016 Ford Fusion 24,900

While you had him there I would have paid (tax and install free) for a new MB battery. I will trust a quality MB battery 4 years (maybe 5) in this hot climate, but 3 years for any other brand and 2 years for a battery in a new car. Optima is the only other battery I've had (not saying there aren't more, just haven't found them) that lasts 4 years of abuse in the South. The off brands may still be starting the car after 3 years, I just don't trust them after that amount of time....

My .02 cents FWIW.

John in San Antonio
(who hates dead batteries worse than running out of gas)

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John Hughes, was in Landstuhl, Germany but currently in San Antonio, TX


1978 280CE Astral Silver now 59,xxx miles and counting "Silber-Kugel"
1986 300E Black Pearl Metallic 143,xxx miles 5-spd daily driver w/ blk leather "Schwarz-Schönheit"
1989 190E 2.6 (euro) 5-spd Desert Taupe 112,xxx kms Had to leave behind in Germany!!! "Helga"
1983 300D Pastel Beige now 312,xxx + miles SOLD

OBK#24

My car beeps at me if I leave the lights on. Very helpful!! It also doesn't like me to leave the key in! It also likes me to wear my seat belt! It is a very thoughtful car!

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1998 C230 330,000 miles (currently dead of second failed EIS, yours will fail too, turning you into the dealer's personal human cash machine)
1988 F150 144,000 miles (leaks all the colors of the rainbow)
Previous stars: 1981 Brava 210,000 miles, 1978 128 150,000 miles, 1977 B200 Van 175,000 miles, 1972 Vega (great, if rusty, car), 1972 Celica, 1986.5 Supra

Battery

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'84 300SD sold
124.128