battery reads 0 v when running ?!?
 

today my 190e 2.3 died while driving after hard braking for the traffic light. I couldn't restart the car (the battery was dead) so I took it 2 blocks furder and they recharged it (it was empty). after that the car runs fine (propably until the battery depletes again in next 5-6 days.

when I got home I connected the multimeter to the battery (engine off ) and it was reading 11.56
then I started the engine and it was reading 0 ????
what is the problem. (I have replaced the regulator few days ago and the and the alternator belt was tightened.
do I have the short somewhere?
do I need to replace the alternator?

On my other car (mazda) the batery reading is 12.55 (engine off) and 14.35 with engine running sosomething is weird with my benz...

Any Ideas?

if there is no short, i would be banking on the alternator. Some car places will do free testing on alternators, so if I were you, I would take the alternator off and take it in to get tested.

Even if your alternator was dead you still should get a reading on your multi meter, should read what ever your batt is, 12 volts or less not 0 volts, try removing both terminals, clean up batt posts and terminals with a wire brush, refit and check again. :)

did the cleaning already
 

the thing i that when the engine is off it reads the voltage immediately and when I start the engine it reads 0 (tried 10 times every time it's the same thing)

could be your multimeter, check another car to make sure?

Check if the cable "+" is connected to terminal "+" on the battery. 0 volts at the engine running will indicade that terminals on the battery are reversed.

I have checked my mazda and it reads perfectly every time
 

I have checked my mazda and it reads perfectly every time so it must be some weird thing with my mercedes.
Anyone knows what would cause such a behaviour?

cheap multimeter...
 

that happens when you buy a $9 multimetar from e-bay...

anyways I tried different multimeter and it was showing that when car idles on 750 rpm the voltage is dropping down constantly...
before i started the engine the voltage was 11.55
after 3-4 minutes of idling the multimeter was showing 10.7 v (engine on)
after I switched the engine off the battery started recovering slowly.

I couldn't start the engine again because the there was not enough power so I conected it to the charger

So what do you guys think:
is it a short somewhere that is draining the battery when the engine is on
or is it the alternator not charging the battery?
thanks...

Ion Gremlins
 

S.S.,

You are either running "on the Battery" or the "ALT" is not producing power

[SAME THING]
,
(for whatever reason: poor ground(s) , poor + connections , bad regulator)

Start with the basics, CONTINUITY on your cables.Then connections
Ozzy is putting you on the TRACK!
You have a Multimeter, So the rest is A.B.C.'s


Good Luck!

Question: Are you putting the multimeter probes on the posts or on the clamps? Measure directly from post-top to post-top. When you measure with no load from clamp to clamp, even very corroded connections will show an insignificant voltage drop. Add in 100A of current while starting, and you will see about 0V, while the battery posts may still register 10V or so.

Steve

thanks guys...
 

first problem (0 voltage) was solved by replacing multimeter with another one but my main problem still remains -the battery is not charging when the engine is on...

I asume that my alt is bad (I will take it out and take it to the autozone for testing...)

regulator was replaced several days ago...