So, it finally happened. My lovely old car will not start. I got in it this morning to fire it up and all I got was a slow, low cranking that went on (slowing the whole) time for 5 or 6 seconds. I have dash lights, interior light, even the glow lights, but while the slow crank happens the battery light is lit (faintly).

I'm sure it's a dead battery because monday last week it was a difficult start. I drive to and from work each day, so I am sure the constant driving is what kept the battery viable all week. I didn't drive it at all this weekend, so I am guessing the battery failed to hold a charge since Friday.

Anyhow, I am going to be picking up a new Mercedes White battery - anything special to know? Let's hope I can get it wedged in there -- it looks heavy!

__________________
1984 300D Turbo, 326000 Km, Thistle Green Metallic

Go to autozone or what ever you have around you. Have them test the battery. Bada boom Auto zone will replace the battery for you. You don't have to get your hands dirty. It's only a battery......(I've got my flame suit on) LOL
Bobo

__________________
92 300D 2.5L OM602 OBK #59

Removing the air filter housing lid will provide a little extra room. Clean up any corrosion that might have occurred under the battery while it's out. Removing the tray might be necessary.

Good tip on the clearance issue. I'm actually just going to go to Lordco here (my local autozone equivalent) and pick up a battery. A pal brought his battery tester and we solved the issue, I was down to 258 amps (ouch!) so it's trickle charging overnight. As long as it can make it through the day tomorrow I should be just fine. Also verified that my charging system is good and the alternator is putting out sufficient voltage (I saw 13.77V).

Now then - the stock mercedes batter I have claims 450A which seems awfully low. I'm thinking higher is better - what about 850? Is there such a thing as too high a figure (within practicality) ?

__________________
1984 300D Turbo, 326000 Km, Thistle Green Metallic

The higher CCA's are achieved at the expense of durability. Be careful what you wish for.

Noted I'm sure that some figure more than what I have now might not hurt, though.

__________________
1984 300D Turbo, 326000 Km, Thistle Green Metallic

I have similar symptoms about every 4-5 years. Cured my a new Interstate battery.

__________________
Charles
1983 300D, bought new, 215k+ miles, donated to Purple Hearts veterans charity but I have parts for sale: http://www.peachparts.com/shopforum/mercedes-benz-cars-sale/296386-fs-1-owner-83-mb-300d-turbo-rebuild-parts.html

Yep - looks like Interstate MT49 is the one that's do it. 750CCA sounds nice too, especially with winter on the way.

__________________
1984 300D Turbo, 326000 Km, Thistle Green Metallic

It is worth noting that if you don't drive with the lights on for long periods or use the vent fans a lot, that your battery could still start your car several times even if the alternator has died.

So what I am trying to say is don't rule out completely that it might be that your alternator is not charging your otherwise ok battery (you can test this by checking the voltage at the battery and seeing if it rises with engine rpms). Worth testing before buying a new battery. - Oh yea, but how to start it without a good battery to test with

__________________

Depending on how many miles your alternator has on it, it could very well need the regulator replaced!!! What happens to these beauties is the brushes wear over time, and do not make contact all the time with the commutator inside the alternator. You may charge fine for a while but then stop charging or have a reduced rate. The charge light on the dash may only glow faintly. Had this happen on my 300TD with over 300K on it. The regulator is cheap,, round 25.00 from ******** AZ. It is a simple install and doesnt even require removing the alternator from the car! Did mine from the bottom, two screws and out it came.

DO not overlook the belts as a culprit in your charging fiasco.
the alts in these cars are not stellar, and a slightly worn belt will allow the battery to discharge. 13.77 sounds OK, but once you drive with your blower on and the headlights going, a slipping belt, can discharge a battery. ask how I know... two different cars, bad belts both times!

__________________
John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread
"as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do!

My drivers:
1987 190D 2.5Turbo
1987 190D 2.5Turbo
1987 190D 2.5-5SPEED!!!

1987 300TD
1987 300TD
1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere!

Good to know. I will check the state of the belt and probably will just pick up a new regulator for good measure anyway.

Thanks guys!

__________________
1984 300D Turbo, 326000 Km, Thistle Green Metallic

check for a drain somewhere. I am chasing one on mine. Drains the battery in 1-2 days, or if you drive with the lights on for a long period, it will not start the next day. Battery and charge system tested fine.

__________________
83 300SD Dark Silver Dark brown inside

Batteries Plus is a great place to get a quality battery and great service.

__________________
1985 Mercedes Benz 300SD, TMU
2015 Chrysler 200S

Have you got a volt meter to check and see if the charging system is functioning? If you do, that'd be a valuable piece of information.

And as for the battery CCA debate, I'm running an 850CCA battery from Advance that's going on four years old, has been deep cycled once by leaving interior lights on, and hasn't given any trouble yet.

__________________


~Michael S.~
Past cars:

1986 300SDL
1987 300SDL
1982 240D
1982 300SD


Current:

1987 300SDL