Electrical Gremlin ('68 220)

[aircap]

Hey again:

The other day I came out in the morning to drive the Benz, and when I turned the ignition key to the "on" position, I got nothing. No idiot lights, no juice at all. I think I may have accidentally left the headlight switched turned to one of the weirdo "parking light" settings by mistake (though I'm not even sure of that...I think I would have noticed when I was outside the night before messing around with the car).

Anyway, I connected it via jumper cables to another car, but even then (at first), there was nothing. After I futzed around with the cable connections, making sure they were really tight, the idiot lights blazed. Then I tried to start it and CLICK. The idiot lights went out again, even though the car was still hooked to another car's battery.

I got out and jiggled the cable connections around some more, looked back at the dash and once again the lights were on. This time it started right up, as though the battery hadn't been low at all.

Later the same day, after I drove around a long time to make sure the battery was up, the car did the same thing again. This time I just went straight to the battery cables, and the car started right up.

I thought, "Well, maybe the battery was still just a little bit low." Since then (that was Tuesday) it's been fine.

Until this morning! I started the car just fine and dandy in my driveway, but after stopping at a convenience store on the way to work, it did the same thing once again...and again, after jacking around at the battery connections a couple times, it started right up.

So...I guess now that I'm telling this story, it's starting to seem more obvious to me that I should at least totally clean (and at best replace) the battery cables. Anything else I should inspect while I'm doing that? Things I should look out for? Special weirdnesses associated with MB cables? I'm a clueless noob to the marque, and appreciate any guidance you more experienced folks can provide.

Thanks...
MC

[carnut]

Yes, clean and/or replace cables. By cleaning I mean remove and clean and reinstall. Then charge the battery overnight on a slow charge. Simply jump starting then driving will not always recharge a battery. Driving will provide a "surface" charge in the battery. How old is the battery? 3 to 4 years old and being severly discharged could cause early failure of the battery.

[230/8]

MC:

Go to the Autozone, or NAPA, and get yourself a battery terminal brush, the kind the cleans the post and inside the cable terminal end. Clean the bejabbers of both + and - terminals and posts. Re-attach and then remove the chassis end of the ground cable where it is attached below the battery tray and clean it.

Once you have done that go to the opposite side of the engine and locate the engine ground strap. It should be located near the firewall and attached from the block to the chassis. Clean both ends of the cable and the surfaces on the block and chassis. If you are still feeling frisky after all that, disconnect the battery ground again and chase down the positive end of the battery cable where it attaches to the starter. Clean that end of the cable and the terminal on the starter.

Reattach all the terminals, slow charge the battery (there is a good cheap solid state unit out at WallyWorld, the Schumacher brand, no, not Michael, for only $18) and you should be good to go. If you really flattened out the battery you may need to use a regular boost charger to get the battery to begin taking a charge. These are available from Sears/CSK/Autozone/NAPA in the $100 range and will last forever. They may even loan you one. Hit the battery with about 5 minutes of charge on the 12V boost setting then switch over to the 12V slow setting until the charge rate falls to less than 4-5 amps. Usually the timers will only allow 90 to 120 minutes of charge time, which should be enough bring a good battery back from the dead using fast charge; slow charge may take longer. If you buy the little cheap charger just put it on overnight...it has a regulator so you cannot overcharge the battery.

Worst case is you need a new battery, best case is no more trouble from your existing equipment.

230/8

[aircap]

I'm not even sure the battery was ever low now...but I'll definitely clean the dickens out of all the pertinent connections this weekend, and throw the battery on the charger as well. (I have a good charger already.)

Thanks for the $.02, everybody. If I continue having weirdness, you know I'll share with the group.

[250 Coupe]

If cleaning the posts and charging the battery don't help, replace the cables.

The copper can rot inside the lead clamp and look fine and resist a good pull but won't conduct well enough to handle the high current at start up.

Also, it might be a good idea to watch the battery posts as you tug on the cables. If a post looks like it turns a bit, the battery has failed internally and needs replacing.


Michael

[michaeld]

Most electrical gremlin issues result from a bad ground.

You might have bad wiring either from the battery to the starter, OR from the starter to the ignition.

Now, this doesn't deal with the sentence immediately above, but one thing that one can do OVERALL to restore the best possible ground is to make sure that one has a good ground strap from the engine block to the frame, and then to wire a large wire connecting the engine (I just chose a spot on the cylinder head) to the firewall. I also have two ground cables on my car; one from the neg bat to the frame, and one from the neg bat to the alternator.

As these cars age, rust and old, calcified wiring reduces the return path and cause increased resistance.

[Tomguy]

I've had this happen so many times, what you are describing is a corroded battery connection. Either where the terminal connects to the battery, or the wire connects to the terminal as Michael #1 suggested. If this does happen on a fully charged battery eventually it will go dead - because it's not actually charging enough through those poor connections! Seen that, too.

Ah, the joys of having a tractor that was constantly exposed to harsh conditions. The battery connections got so corroded I needed to clean them biweekly.

Edit: as for chargers, picked up one of these babies on clearance for $60 about 6-7 years ago, haven't looked back:
http://www.sears.com/sr/javasr/product.do?cat=Batteries+%26+Chargers&pid=02871230000&vertical=AUTO&subcat=Battery+Chargers+%26+Boosters&BV_UseBVCookie=Yes

[t walgamuth]

also check your ground connections. this would include the mounting place where the negative cable attaches to the chassis and the strap that connects the motor to the chassis.

good luck

tom w