280SE 4.5 Battery flatens in no time - PeachParts Mercedes-Benz Forum

Hugin · #1 04-23-2006, 04:02 PM

Hi

I have just taken my 280SE 4.5 out of winter storage.
It fired just fine, I left it running for a short while, then turned the key off.
When I came back a few days later to take her for a drive, the battery was totaly flat, no sign of life.
Then I re-charged the battery and started her ok.
But, the charger-lamp was lit while driving, and even when the engine was switched off and the KEY OUT....

So, in a few hours, the battery was all flat again

I have not measured the amount of leaking current yet.

Have anyone expirianced this before?

I'm no expert, so I have ordered the service-manual by mail to seek help.

Just an idea, isn't there a rectifier diode in the charger?
If this is shortened, would I see this sympthoms then?

Any help out there

tram · #2 04-23-2006, 05:50 PM

Alternator or regulator short. Take a close look at the wiring harness between the two as well.

roberthelfrick · #3 04-23-2006, 06:55 PM

What is location of voltage regulator?

tram · #4 04-23-2006, 08:23 PM

Off hand, it should be on a "rack" of other stuff up on the passenger inner fenderwell by the firewall. The plastic connector to the regulator will look identical to the three prong plastic connector on the alternator.

Bob_Mitchell · #5 04-23-2006, 08:34 PM

Could be just a bad battery, if it was on a charger - trickle or otherwise over the winter... Check the water level. I would remove the neg terminal overnight then see if your battery will hold a charge. Most local auto part stores will check your battery for free. Be sure you charge it first because all battery test's are not equal. If there is a shorted diode on the alt. that will cause this also. Just checking the voltage is not good enough in this case. If the battery checks out good you may want to remove the wires from the alt. overnight and see if that is your bird. All the best. Bob

Tomguy · #6 04-23-2006, 10:29 PM

Bad alternator or regulator. This would PROBABLY be a viable test - someone tell me if I'm wrong: Take the cable off the alternator (careful, might cause a short!) - if the "Gen" light goes out, and goes back on with it connected, it's the alternator. If not, it's the regulator.

250 Coupe · #7 04-23-2006, 10:53 PM

I went round and round with this on my 1974 F250, changed the regulator which didn't fix it but changing the alternator did.

My .02 worth.

Michael

Hugin · #8 04-24-2006, 01:42 AM

Thanks guys, will have a look at it after work today ;-)

Hugin · #9 04-24-2006, 02:39 PM

It was the alternator that was faulty.

Now, is the alternator of the M130 6-cyl equal to the one on the M117 4.5 liter engine?

Since the V8 is very rare here in Norway, it will be easier to find a replacement if they were equal....

Regards

Tom

Tomguy · #10 04-24-2006, 02:48 PM

Some of the 6-cyl had 35 amp alternators from the look of it. You need a 55 amp one for the 4.5.

Surely there are people here with spare alternators (such as me) who could send them out if you needed, and couldnt find one locally.

Hugin · #11 04-24-2006, 04:25 PM

Thanks Tom

Let me try the sparepart shops tomorrow, I would hate to have to wait for shipping from US.
Driving season is finaly here in winter wonder land you know ;-)

If I need help, I will gat back on this thread.

Thanks again.

BTW, It seems I will be selling my 280SE Coupe now.
I'm searching high and low for a nice 280SE 3.5, so if anyone.....

tram · #12 04-25-2006, 02:54 AM

Isn't there an electrical spezialist there that can overhaul yours? There MUST be.

Hugin · #13 04-27-2006, 02:50 PM

Hi

Ok, now I have bought a new alternator.....but it turns out that the terminals are different then the old one.

The old has a B+, D+, D- and a DF-terminal.
The new one has a B+, D+, + and a W-terminal.

Now, by obviously B+ and D+ are the same and D- by ohming and scematics are ground.
The DF on the old and the W on the new is a mystery....
In my 280se-book the DF is described as the "energising coil".

Could the DF equal the + terminal on the new one?

On the data-sheet that came with the alternator it says that the W-terminal is not always used.
The new alternator is a Bosch.

Tom

Hugin · #14 04-28-2006, 02:19 PM

Help......

Tomguy · #15 04-28-2006, 04:21 PM

It's possible you bought an alternator with an internal (as opposed to external) voltage regulator - without a book, I have no way of telling what the letters mean. If this is the case, you can simply bypass the external one.