I have an 85 tdt wagen with 150k on it. I bought it in Florida hence no rust and very nice car. I live in the Metro Boston are and as some of you may know we had a Freezing single diget spell of weather recently. I bought a brand new MB batery for it last February 2004.
It had been starting fine on these cold mornings roughly 8 degrees to 18 degrees. One morning it did not and I killed the batery. So I left the car on a charger at a rate of 2amps trickle charge and also had the engine plugged in. Came home that night it started right up. I then left it on the tricle charger over night and engine plugged in again.
Heres where it gets fun.
The next day I decided I would not need to use the car and simply shut the power off to my garage instead of going out and unplugging everything. I'm lazy and it was cold. The next day I went to use it, the interior light would not even come on. Totally dead. Well I think I know what happened. The engine heater actually drained the batery. It was hooked up to the same extension cord as the batery. Both connected to a connector for 3 plugs hooked to a single extension cord. So the engine heater took power from the batery back through the non working charger and into its own cord. The big problem is that this batery sat this way for at least 24 hours in zero degree temperatures.
Well, I hooked it up to a charger at 2 amps again for around a day up to a full charge. I did plug the engine in as the weather was warming up. Again it started right up. So I just parked in inside my garage. The weather is now 30 degreees so no problems. Or so I thuoght.. About 3 days later went down opened the door, no interior light dead. no headlights nothing. That was last night so I hooked it up to the charger again.
My question is why did a fully charged batery go dead when not hooked up to anything -and yes all my doors were closed and lights off. Very strange. Am I guilty of murdering a very good new batery?

When a battery is fully charged the specific gravity reading is high, because you have electrolyte in the cells. If the battewry is allowed to drain to a low state of charge, the electrolyte becomes water which can freeze in freezing weather. You may have frozen and killed the battery. The only thing to do is charge it on a regular charger and keep checking the spec gravity in each cell. If the readings all come up evenly, load test the battery and see if it holds up.

Good luck,
Peter

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Auto Zentral Ltd.

I've had it on the trickle charger for 10 hours last night. My timer will kick on the charger again toody for about 5 more hours. Assuming the car starts -I'm almost positive it wil. Will driving it on the highway tomorro help. My work commute is 23 miles one way. I don't want to get stuck at work in the evening though.

A lot of places will load test a battery for free these days, especially the big auto-zoos.

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'82 300SD - 361K mi - "Blue"

"Good judgement comes from experience. Experience comes from bad judgement."

listen, look, .........and duck.

If the battery is an extremely low state of charge, the trickle charger will take forever if it is able to do the job at all. If you do get it started that 80 amp alternator on the car should finish the job in 23 miles although that is not what an alternator is for. once you do get the car going and drive it, you need to do a spec gravity test and load test to determine condition of the battery.

Peter

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Auto Zentral Ltd.

It sounds like he has something draining the batery when the car should be off. And the trickle charger is enough to satisfy that drain...........is it charging at the correct level when its running. I have had a bad regulator intermittantly drain my batter the first year I had it.....killed that battery sure as anything.

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Proud owner of ....
1971 280SE W108
1979 300SD W116
1983 300D W123
1975 Ironhead Sportster chopper
1987 GMC 3/4 ton 4X4 Diesel
1989 Honda Civic (Heavily modified)
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Section 609 MVAC Certified
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"He who fights with monsters might take care lest he thereby become a monster. And if you gaze for long into an abyss, the abyss gazes also into you." - Friedrich Nietzsche

I don't think a 2 Amp overnight charge will do much. It's probably a 100Amp/Hour battery, it would take at least 50 hours to charge it (2 Amps times 50 hours equals 100 Amp/Hours). 10 Amps over night (appx 10 hours) would be a better charge rate.

I don't respond to people who have nicer wagons than mine. I think you should sell it to me immediately and buy a nice reliable Toyota....

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Bill Reimels
Now down to one:
1972 300SE 3.5 W109 (Euro delivery)

I suspect a load somewhere drawing off the battery, and the trickle charger is giving just enough juice to keep it from dying over night (you said it was a new batt right?)

I would look for your drain somewhere in the system (trunk, some random interior light, seat motor swtich stuck in the on position, window switches, heated seats, etc..

See if you can find what is drawing your goods...you may need to purchase a few dollar multimeter (the ones with probes) and start pulling out fuses and putting the meter across them, car off, batt in, and see what sort of amps are going through the meter (use the 10amp setting on your meter and make sure the probes are right).

ALso check the radio and power antenna...these goodies get power when they are off

The trickle charger, unless archean and cheapo beyond belief, should atleast have diode protection circuitry
As an FYI..you can't make AC from DC (plugin power from battery power) through a DC power supply (your trickle charger) in reverse...so no worries there.
Transformers don't work so well on DC, unless of course you are trying to make some sparks

Anywho, get a meter, do some checking, listen, test, report back

How much did that battery run you? ($$$?)

EDIT: Don't forget to see if the alternator is drawing a lot when its off...