Hey, I just tried to start my 88 300e but it won't turn. I checked the voltage on the battery and it was hovering around 5.5 volts. I then trickle charged it for several hours until the charger said it was ready and disconnected the charger. My voltmeter read 11.2 volts across the posts, but I watched it quickly fall to around 8 volts. Could this be anything other than a dead battery? It would be hard to imagine that big of a load with the engine off...

Any help would be appreciated.

Thanks.
Peter
88 300e
88 420sel

Sounds like the battery is toast, but have you checked the water level in the battery lately?

__________________
Mike Tangas
'73 280SEL 4.5 (9/72)- RIP
Only 8,173 units built from 5/71 thru 11/72

'02 CLK320 Cabriolet - wifey's mid-life crisis

2012 VW Jetta Sportwagon TDI...at least its a diesel

Non illegitemae carborundum.

If you have a short somewhere outside of the ignition, the battery won't charge properly connected. I would recommend disconnecting the vehicle from the battery and then charging it (and if it is not a maintenance free battery check the levels first). Trickle chargers take an easy 12-24hrs to charge a battery, depending on their amperage. It should end up 12.75V+ charged.

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1982 Mercedes-Benz 300CD
1982 Mercedes-Benz 240D - stick

wow - you guys are right on once again. I just checked my water levels and they're extremely low - hopefully I can still salvage my battery. Any tips on filling? I might do it a little later tonight so any ideas would be appreciated.

And thanks again.

Peter

i gotta believe mike is right on with this one.my car would trickle up and then would lose it's charge after a few starts.being an idiot i would continue doing this(recharging) until i was trickling every other start.hmmm..this doesn't seem right,so i checked my battery fluid level and ,yup,level was LOW.too low to bring it back.take your battery to a shop,check it out and maybe you'll be lucky to get away with only adding some electrolyte.i'm not exactly sure but i think battery life is around 8yrs

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'95 s500 (bought for wife but can't bear to share!!!) 125kms
'92 legend 180kms
'88 tbirdturbo(fantastic car-only regular maint.)120kms
'87 mustang gt(gone)
'86 tbirdturbo(gone)
'85 mustang gt(gone-but not forgotten)

To fill just carefully pour in some pure water. I have taken a shine to the Prestone radiator and battery water, it is purified and demineralized. Do not fill above the bottom of the neck as it will overflow once it starts charging. You don't want acid running down the battery and all over the tray. You might be able to save the battery, but the life has been severely shortened. When you do replace the battery, be sure to check the water level on a regular basis.

__________________
Mike Tangas
'73 280SEL 4.5 (9/72)- RIP
Only 8,173 units built from 5/71 thru 11/72

'02 CLK320 Cabriolet - wifey's mid-life crisis

2012 VW Jetta Sportwagon TDI...at least its a diesel

Non illegitemae carborundum.

for the price of a dinner for two at a second rate
seafood eatery with paintings of boats tossed in the waves graceing the wall you can buy an Interstate battery an have peace of mind rather than month old fish that has been in the oven too long............
William Rogers.........

To fill your battery you need a funnel and some distilled, not tap, water. You can get it by the gallon at most grocery stores. Slowly splash small amounts into the funnel until the point that it is just visible not leaving the overflow, which is approximately at the bottom of the cap when it's in. The reason you can't use tap water is the minerals and negative ions like chlorine and flourine interfere with the chemistry within the battery. To tell you more than you probably ever wanted to know, what is going on inside your battery is the following: The battery is composed of alternating + and - plates. The + plates are composed of lead oxide (PbO2) and the negative plates of pure lead (Pb). The battery is filled with sulfuric acid (H2SO4) at a specific gravity of about 1.26 or so. When you demand power from it (discharge), the SO4 from the H2SO4 solution combines with the pure lead plate to make PbSO4, and the remaining H2 from the solution combines with the O2 from the positive plate to make water (two molecules). All of this extra water lowers the specific gravity of the solution and thus the charge of the battery. When you charge the battery, the reverse occurs. The SO4 is forced from the negative plates (back into solution), O2 back to the positive plates. Most of the H recombines with the SO4 to reform H2SO4, but some of it escapes as hydrogen gas, hence the explosion hazard and the ultimate reason batteries die eventually. The specific gravity goes back up as well. So, after you have filled it and charged it, and be careful as the faster you charge a battery, or the more charge it needs, the more likely it is to release the hydrogen ( which is why you have shaved some time off of your battery's life) so make sure it's charged in a ventilated area and there is no ignition source (smoking, sparks from charger leads, etc). Once you have it all charged up, you can check the specific gravity of the solution and see that it is OK. You can get a tester anywhere that works a lot like an antifreeze tester. As far as maintenance free batteries go, I don't like them. They last half as long as these batteries (periodic addition of water replenishes some of the H's lost), and they have shorter reserve times. The only reason to use one is if it's buried under other components as in new cars. Plus, these batteries serve as a little reminder that your car needs you and your diligent maintenance to survive. You haven't harmed your battery as much as you might think.

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1982 Mercedes-Benz 300CD
1982 Mercedes-Benz 240D - stick