Hey guys,

Got a wierd problem with my old girl and I am hoping you can help out.

The problem:
Battery seems to never get charged / runs down.

If I charge the battery with my battery charger, battery seems to be at 50-60% after about a week of the car sitting. Dosen't seem to get charged to 100% even after a 15 minute drive. Battery ran down twice over the winter and I had to get it boosted. Seems better with the warmer weather.

The Battery is about a year and a half old, so it should be ok. So I figured the alternator was going, so I took it to a good mechanic near me and had the charging system checked. (alternator / voltage regulator / battery).

Car passed with flying colors. Alternator ok, VR ok (I asked specifically), battery holds charge. But, surprise surprise they said the battery was low and that I should charge it.

So ... they figure I might have a parasitic draw ... from what I read on these forums I might just have bad battery cables.

Do you guys have any suggestions / tips / ideas on what I can look for or try?

Not sure where to go from here besides getting new battery leads (seems like a shot in the dark solution)

__________________
Name:
Daisy, or Bertha ... depends on the day.

Details:
US 1985 W123 Mercedes 300D Turbo.
227,000 Miles, and still strong.
Runs on Diesel in the winter, and B20 in the summer.

History:
She was run on French Fry Oil by a previous owner, which really borked the fuel system. Now fixed.

Previous owner held the car together with Duct tape, spit and whatever he could find at the local pepboys for under $5. I am now paying for his lack of caring for the car.

Ottawa Ontario Canada

Just because the battery is only a year and a half old, does not mean it is not getting weak. That is why most good batteries come with a 3+ year warranty. If your cables are clean and tight and the charging system checks out, Replace the battery.

__________________
Dave
1983 300D Daily Driver

You should at least check the water level in the battery first. Following that you should check to see if there is a drain with the key off.

__________________
http://superturbodiesel.com/images/sig.04.10.jpg
1995 E420 Schwarz
1995 E300 Weiss
#1987 300D Sturmmachine
#1991 300D Nearly Perfect
#1994 E320 Cabriolet
#1995 E320 Touring
#1985 300D Sedan
OBK #42

Disconnect the negitive lead and put a meter in series with that and the battery terminal.You should only see a few millvolts for the clock and radio memory and that sort of stuff. If its more than that you'll have to pull fuses one at a time till you find the circuit that is open.

Common on that car to have a loose alternator belt. The alternator will spin ok for a test but slip at higher RPM's, eventually discarging the battery. So, check the belt, glazed? loose? to confirm if too loose, try rotating the alternator pulley the opposite of normal rotation by hand ( ENGINE OFF!!) if it moves at all, its too loose.

__________________
81 300CD (sold) 1972 280 SEL 4.5 (sold) 1966 250 S 4 spd (sold) 1974 450 SL (sold) 86 BMW 325ES (sold), 1973 280C (sold) 1988 300 SE.

I suspect that one loose alternator belt on a 1985 300D would be extremely uncommon.

Is the charger on the battery for a week? If so, is an automatic charger that drops to a trickle charge after full charge is reached?

__________________
Sam

84 300SD 350K+ miles ( Blue Belle )

This is a long shot for sure but ---- a buddy of mine was having much the same sort of problem on his Dodge truck. I checked the current draw with the key off and found a small drain. We never got around to tracking it down. Eventually found that the light in the glove box was staying on, thereby slowly draining the battery.

__________________
John Schroader
bio burnin' 83 300D, '83 300 SD, '79 240D
"I've never met a man who was good at making excuses who was good at anything else" Ben Franklin
"You cannot permanently help a man by doing for him what he could and should do for himself" Abraham Lincoln

Think your right Blind. I pretty much dismissed the battery because it was brand new, and that the garage told me it held a charge.

BUT! *cue dramatic music* (duhn duhn duhnnnnnnn)

I pulled out the charger last night and plugged it in. (figued if I had a draw that drains it to 50% over the course of the week, then it should be at 75% mid-week, was trying to see if that was a problem). The charge read 50%.

So I thought what the hell! So I charged it to 100% and started to think about what could be going on. Once it was finished I unplugged the charger.

About a second later, I thought hmmm ... wait a sec ... and plugged it back in ... charge read 70%.

Bizzare no? so I sat there and watched the charge % with it the charger plugged in, (not in charging mode just watching the charge % level, cool charger I purchased btw) and over the course of 5-10 minutes the charge level dropped to 50% and stayed there.

So ... garage told me the batt holds a charge ... well it does, only 50% of it.
Which means, the charging system does charge the battery, but the batt only can hold a 50% charge. Which is ****ed up.

I don’t know why the garage dident spot that.

Luckly the battery is still under warrenty so hopefully they will get me a replacement.

Once I get a new batt in, I'll see if that fixes the issue.


P.s thanks for the suggestions guys.

__________________
Name:
Daisy, or Bertha ... depends on the day.

Details:
US 1985 W123 Mercedes 300D Turbo.
227,000 Miles, and still strong.
Runs on Diesel in the winter, and B20 in the summer.

History:
She was run on French Fry Oil by a previous owner, which really borked the fuel system. Now fixed.

Previous owner held the car together with Duct tape, spit and whatever he could find at the local pepboys for under $5. I am now paying for his lack of caring for the car.

Ottawa Ontario Canada

The charger I purchased is a Float / Multi mode charger. It has two charging modes, a 2 amp trickle charge and a 15amp quick charge. I have been using the 15amp quick charge. Once it reaches a 100% charge it flips to a float charge mode.

__________________
Name:
Daisy, or Bertha ... depends on the day.

Details:
US 1985 W123 Mercedes 300D Turbo.
227,000 Miles, and still strong.
Runs on Diesel in the winter, and B20 in the summer.

History:
She was run on French Fry Oil by a previous owner, which really borked the fuel system. Now fixed.

Previous owner held the car together with Duct tape, spit and whatever he could find at the local pepboys for under $5. I am now paying for his lack of caring for the car.

Ottawa Ontario Canada