Car battery is always empty. every time I park the car and leave it for a day, the battery is empty. I can just start the car, but that is after a few tries. I really do not know what the problem is. Battery is completely new. is this a known issue for this model? and how do I find out what the problem is.

 

Can you confirm that the battery was fully charged after installation? Batteries often sit on a shelf for a long time and therefore are never at full charge when purchased.

 

The battery was charged but already have this battery for a 3 months. I drove with this battery for 5000 km. Its a mercedes batter. but for some reason its always dead now

 

Charge the battery fully with it disconnected from the car. Check the voltage over a couple days, should stay above 12.5 vdc. If it dies on it's own, it's the battery.

 

If after that the battery is no longer suspect check the voltage output from the charging system. I use an ELM 327 device along with the Torque app on my phone to monitor that voltage.

 

I hope its the battery. if its not the battery. how can check ( with no device 3247) where the problem is of the leak.

 

That is more pain - see if you need to suffer it by checking battery & alternator first!

 

You can put a digital volt meter across the battery posts with the engine running.

 

Not that this is the single most reason, but, can add to it. Do you lock it, even when garage? Any cell phone chargers left plug in?
I recently had a situation of looking for a 6.5 V drain in a Suburban. Part of it was two, chargers were left plugged into the CIG lighter. Their LEDs only visible at night when I happened to be entering the vehicle for other reasons.

 

I did have a telephone charger in it, but I have been doing this for 2 years. this is really something of the last time. I put a volt meter on it and the battery gave 11.3 va. Now I turned on the engine and then he gave 14 va. I assume that the aletnator is just right, but not the battery. while it is a new one. I do not understand. Now charging at the moment to see if the battery runs empty after charging.

 

After you've fully charged the 12V battery, the next step would be to measure quiescent current draw when the car is IG-OFF and doors locked. You will need to position the meter where you can see it with the hatch closed and locked. If you see that the current measurement is much more than 0.02A, you may have a relay that is stuck closed, allowing some circuit to continue to draw power from the battery.

 

Hi, Thanks for your answer

If I understand that everything must be closed (except for the trunk) without a battery and then measure on the outputs on the cables (as in the picture?) If it is more than 0.02A, then a fuse is broken?
I would have to go after all the fuses behind the seat? is that what you mean?

 

No. You would need to reinstall the battery.
The meter would be set to measure DC current, not DC volts.
The meter would be inserted between the negative cable and the battery negative terminal. That allows you to measure the current flow from the battery to the vehicle.

So you have to figure out how to connect the meter to the battery and to the battery cable securely, and then close the hatch and lock the car, all while the meter remains in view.

 

This attachment should help with the quiescent test:

 

if drain is too high you are looking for a "stuck relay" not a fuse. Remove one relay at a time & repeat the current draw test. Make sure to note where the realy goes and only remove one at a time so as not to get lost.

 

Thank you so much. Why not also the fuses?

 

Fuses conduct current all the time. Relays are switches.

 

If relays don't check out as the problem, fuses would be the next step in finding which circuit is causing excessive current drain. Generally, as Ranchero suggests, a blown fuse would make a circuit open thus not able to draw current at all.
For right now though, relays are the most appropriate area to look into.

 

Latch the trunk latch leaving it open so you can measure. You dont have to close it just latch it so the car think its closed. Need to know when the car is asleep without knowing how long to wait? Leave a sunvisor mirror open for the vanity light. When the light goes out the car is asleep and you can check the draw which should be less than 28 milli amps. Another thing to remember or know is that your battery was low at 11.3v. This is often the reason the car either wont go to sleep or wakes up running the battery all the way down. Its not a drain its a weak battery making the modules act up and wake up. Everytime you run a battery down you significantly reduce its reserve power capacity.

 

Any chance the battery simply isn't the right one for his car?