Battery Problems E320 1999

I have a E320 petrol mercedes and just recently the car will not start without a jump even after driving 100 klms the next day it sometimes needs a jump then sometimes i can use it for short trips 1klm 2klm and its fine... there is no warning light coming on about the battery being flat i did have a new tow bar fitted and was wondering if it has been wired up wrong and draining the battery over night... any help would be appreciated Regards Steve

One important piece of missing info. How old is the battery? If it's

5+ years old, I'd just replace it as a first step. Do you have a charger? If so, did you try charging the battery and see if it holds a charge that way? If so, then something is wrong with the charging system in the car. Did you check that cables are tight, no corrosion, etc? If you're worried about a drain, you can disconnect the battery lead and measure the drain with no load. Or if you don't have the tools/skill, take it in. There are auto parts places here in the US that will do a battery load test for free.

Thanks for the information I dont know how old the battery is but i assume its as old as the car... I read the manual and it said i had to disconect stuff before i could charge it so i didnt as i thought it may affect the electronics... please bear in mind im a plasterer and car stuff is beyond me... all the leads are clean and tight (no rust etc) I will do as you suggest and take it to a garage to test the battery for a possible drain when i get back to th UK in 5 weeks time... but in the mean time would it be possible for me to just connect a charger whilst the battery is in the car Regards Steve

Batteries older than four years are suspect.

It'll work, but not well. I'd go higher, but never lower.

Of course it's OK, why would you even worry about it..... unless that is you are located in arctic areas where it get's very cold and/or your car has extreme difficulty in starting so that you need lots of reserve cranking ability...... but then you should get it fixed.

cheers, guenter

- have specific gravity checked - top off with distilled water and trickle charge at 5-10 amps for several hours - check specific gravity in each cell to see if any cells are dead

- car charging via driving is almost never successful if the dead battery was well discharged. car charging systems in modern cars were never designed to pull a deep discharged battery back into full charge. they can only surface charge a battery, no matter how long the car is driven

- if ill maintained, sulfation can short out the plates and cells. nothing can be done but to purchase a new battery

Auto alternators AFAIK, are rated at upwards of 60A, so why are they not capable of fully recharging a battery, provided the car is driven far enough and assuming the battery is good? Also, I think at 5-10 amps, your definition of trickle charging is way off. That is the charge rate of a regular charger. A trickle charger is more on the order of 1 amp.

- if ill maintained, sulfation can short out the plates and cells.