About to go to Autozone for a battery, quick qs
 

My battery is about dead (but not quite!) and suffering due to the cold temps in western mass right about now. Time for a new battery.

Last time I tried to replace my cables I couldn't get them off, the neg cable in particular is so corroded. Is it ok to cut the cable just before removing the battery if I'm going to get new cables anyway? Or will this blow my arm off or something?

Also: how do you disconnect the cables on the other end, i.e. not the battery terminal ends (Haynes manual says the neg cable is grounded (don't know where) and the pos cable hooks to the starter, beyond that it offers no guidance)? Last I looked, this wasn't self-evident, but maybe I'm not looking hard enough. I'm sure this has an easy answer :)

Thanks,

No, cutting the cable won't kill you.. as long as you don't short out the battery in the process. If there's enough slack in the cable, a new end can be attached, so you may not need to replace it -- usually much easier to do in cold weather. Autozone should have a selection.

Incidently, the corroded cable may be the problem with your battery or contributing to it. So, also get a cable clamp cleaner and clean the mating surfaces of battery & cable for both cables. You want bright shiny metal on both contacting surfaces. Slather the cable with grease after attaching to keep the future corrosion problem down (I've used everything from axel grease to vaseline, whatever was handy).

Yeah, I agree. If your cables are that corroded, then you really need to clean up the contacts. Have them test your battery to be sure that it is on its way out before paying for a new one. I don't know your model, but I wouldn't think you would have to trace the negative cable very far to see where it is gounded. Be sure that the ground connection is also very clean. You can buy some battery cleaner spray to help clean up acid and corrosion, and it never hurst to undo the connection and go over it with a wire brush.

OK I'm off, thanks guys--always helpful.

Best to use dielectric grease - it won't "insulate" the clamp/post connection. Another trick I learned back in the day to prevent corrosion build-up on the posts - epoxy a penny about 1" away from each post. This "draws" the corrsion towards the copper and is much easier to monitor & clean than build-up on the posts. Good luck.

Battery
 

1984 300d Turbo 147k
Buy A Battery Post Cleaner It A Wire Brush The Cap Pull Off Its A
Post Cleaner, Pull It Apart Its A Inside Battery Cable Wire Cleaner
At Autozone, Buy A New Battery $90.00 A 49 Series, Take The Neg -
Cable Off First And Install Neg Cable Last, Use Battery Post Paste
After Replace Battery

JBG,

Be careful before U cut the positive terminal. Some MB models are a real bear to replace the cable on the solonoid.

Why not let the people at AZ replace the battery? They should have terminal pullers to remove the cable terminals from the battery. Make sure they clean the holes in the cable terminals real good.

P E H

Yeah, AZ will take the old one out and put the new battery in for free. If you still want to replace the terminals, the ground cable on the W123's is short. It connects to the fender right next to the battery. The Pos cable I'm not sure about if it goes directly to the starter or to the small terminal block on the fender first. It's not too difficult to trace where it goes, but if it goes to the starter, it's more than a five minute job to replace.

battery is stong
 

Had them run a test, battery was great (12.3 amps). Guess I jumped the gun a little.....glad I didn't have to buy a battery though as after reading the posts here I was expecting to pay $65 for the AZ group 49 duralast. It's now $90, fyi, as mentioned above. That is correct.

Luckily, I didn't have to buy one....yet.

Neg terminal corrodes consistently. Guy told me to put some baking soda on it, which I did. Won't stop the corrosion, though. Whatever.

Got some 21" and 19" wiper blades while there--my windshield is much happier now as the blades don't hang off the pass side. The blades are thin and "iffy" but whatever, they were 6$ each. If they last 6 months to a year I'm golden.

Thanks again,

.

I think I will try this one.
Just to make sure you are epoxying the penny to the plastic casing of the battery, correct.
And not to the battery cables or somewhere on the car ?

Thank you
Have Fun
RichC

.

If the post is corroded put oil on it.

If the cable corrodes the battery is leaking gasses and the corrosion will keep coming back. Doesn't matter if you coat it with stuff. Battery is OK in that it holds a charge. Battery is not OK in that it is seeping gases.
You either need a new battery, or just keep cleaning this one.
BTW, I just keep cleaning the terminal on my wagon {negative} and on my tractor {positive}.

I went to Autozoo yesterday, looking for a group 49 battery. The one Autozoo had was not the good old Johnson Controls battery that they used to have. The one they have now is hecho in Mexico. No thanks.

Went to Pep Boys. They have the good Johnson Controls battery, with a Bosch label, but at 50% higher price than Autozoo. Looks to me like they might be discontinuing it, as they only had one left among 3 stores.

Looks like it's time to find a new default for buying replacement batteries. Can you still call the MB help line and get a new one installed for $118, like the battery thread on this site says? Anyone know???

Either that or buying an Interstate for about $100 seems like a better idea than going to either Autozoo or Pep Boys, assuming the Interstate has a comparable warranty.

The best battery for MB diesels is the Interstate Megatron, 850 AH. when you put a new battery in , add the little felt black and red washers that you can get a Sears and other auto parts places. They are chemically treated, don't look bad and do the job.
If you ever have corrision on your battery terminals, pour a little Coke or Dr Pepper on them - it will fizz and bubble and clean them up nicely - then think about that the next time you drink a Coke or Dr Pepper.