battery keeps going flat

[striker600]

Hello to u all.Just gone in garage to start car & click! battery is flat.Battery is a new bosch 95 amps Bought new on 20/12/08.car was stood 4 a week at new year whilst on hol.when i returned it was dead!not enough to operate C/L. I exchanged battery for another bosch on 07/01/09.I charged it 4 a few hours just to make sure it was fully charged.Had alternator tested & it producing over 14 V with elec consumers on.For last Week i have been doing short journeys & for last 2 days engine cranks slower & lazy when stood overnight.When i leave car unlocked in garage overnight (no alarm on) the engine seams to crank faster & more lively.is there a known problem with the alarm draining the battery or any other drain on battey?Just jump started car & going 4 a drive.

 

[Brian WH]

Hello to u all.Just gone in garage to start car & click! battery is flat.Battery is a new bosch 90 ish amps Bought new on 20/12/08.car was stood 4 a week at new year whilst on hol.when i returned it was dead!not enough to operate C/L. I exchanged battery for another bosch on 07/01/09.I charged it 4 a few hours just to make sure it was fully charged.Had alternator tested & it producing over 14 V with elec consumers on.For last Week i have been doing short journeys & for last 2 days engine cranks slower & lazy when stood overnight.When i leave car unlocked in garage overnight (no alarm on) the engine seams to crank faster & more lively.is ther a known problem with the alarm draining the battery or any other drain on battey?Just jump started car & going 4 a drive.

Charging the battery for a few hours may not have been enough.

Check battery connections are clean and tight. Charge battery overnight at least. Don't forget you need at least 10 miles of running to replace the start charge taken, so short runs will kill your battery anyway even if new.

 

[striker600]

Battery contacts are clean&tight.Im going to charge the battery overnight
.As i said, the last week I was only doing 2 miles to work&back so its not enough time to put sufficient charge back in the battery.I have just coverd 18miles with 2 stops on/off with engine, which sounded lively and fast when cranking.
I have just read the handbook which states "Have the battery charged checked more frequently if the vehicle is used primarily for short journeys,or left parked for lengthy periods." Its an inconvienence to keep charging the battery every few weeks,but i dont see what else i can do bar driving the car for longer periods.
I have a friend who bought a new audi A4 TDI who after a month of ownership,suffered a flat battery after a week of car being parked.
Is anyone aware of the alarm or any other issues that can drain the battery?

 

[PJH]

If the security system has Internal Movement sensors then that could be the cause. Can you disable that function on your system so that the alarm will only activate if the doors are opened?

 

[Dec]

You should get a Volt Meter that can be plugged into the cigar lighter, not strictly accurate but will give you a good indication of the condition of your battery when you turn the key to position 1 before you start the car in morning it also let you monitor the rate of charge going into battery as you drive.

Like yourself, I do a lot of very short runs and need to keep a close eye on my battery condition so I went a step further and converted a smaller type of volt meter and put it where the temperature gauge should be. See post #8

Not sure about your car but some alarms will draw about 40ma, this is nothing to a healthy battery but if the battery is run down due to too many short trips then this current drain becomes very severe on the battery.

Dec

 

[gbjeppm]

More than likely you have got a battery drain somewhere, classic symptoms of this, and the early 203's are renowned for it.

Changing the battery is a delicate operation in the W203, and could have blown something which is now causing the drain.

This thread is worth a read, I have been there before!! The last post shows common potential causes.
http://www.mbclub.co.uk/forums/showthread.php?t=44052

I agree that short journeys are not great for a battery, but going completely flat, suggests that it is not the underlying problem.

Edit: If you have comand, then the diagnostic mode will also tell you your battery voltage, which also might help/

 

[Stan the Man]

If possible use a ammeter in series with the battery to measure quiescent current, should be less than 30mA with all systems shut down.
If it exceeds this you have excessive battery drain.
Possible culprits include the boot lamp, overhead control panel, comand and memory seats (if fitted)

 

[striker600]

yes the alarm movement sensors can be turned off

 

[striker600]

I have a ammeter but not sure if i have used it correctly.Anyway this is how i used it-With the battery fully charged (charged overnight)& reconnected to car. I set the meeter to the A setting on the 200mA scale.I put the red + probe to the +battery terminal,& the black - probe to the earth strap point (strut plate) I didnt get any reading(all systems shut down).I also tried+probe to batt+ and -probe to batt - an got no reading,but i think that is in paralel.If i had the ammeter connected wrong can you tell me how to connect it correctly so i can perform a current drain test.
Other info,My car dose not have command and all interior lights including boot go out.It has the OCP, & elec memory seats which as far as i am aware work correctly.

If possible use a ammeter in series with the battery to measure quiescent current, should be less than 30mA with all systems shut down.
If it exceeds this you have excessive battery drain.
Possible culprits include the boot lamp, overhead control panel, comand and memory seats (if fitted)

 

[striker600]

just had a read at this web page http://ponderingfools.blogspot.com/2008/03/car-battery-myths-part-3-of-4.html Scroll down to paragraph 10.2

Following the instructions in 10.2, i Connected ammeter as follows.selected 200mA scale, Disconnected -terminal clamp, put-probe to batt-terminal,put+probe to disconnected -terminal clamp.The meeter reading was 0.00. All elec consumers were off.Is this the correct way to connect a ammeter to perform a battery drain test, and dose this meeter reading indicate no current drain?
Any comments would be appreciated.

Andy.

 

[Dieselman]

The method you are using sounds correct .
As long as the meter creates the link then it is correct for current.

I suspect you have no reading due to using the AC current selection as oposed to the DC selection.

 

[striker600]

Dieselman,i had the meter set to DC, on the 200Ma scale and it read 0.00

 

[Diesel Benz]

The method you are using sounds correct .
As long as the meter creates the link then it is correct for current.

I suspect you have no reading due to using the AC current selection as oposed to the DC selection.

The latter approach is right but did you read how he tried it first? If I got it right, he short-circuited the battery with the ammeter at 200 mA range. The reading would have been a few hundred amps but the multimeter fuse blew first. At least this is what I assume.

striker, try to check if the multimeter works, test a small bulb or similar where the current is not too high.

 

[Dieselman]

he short-circuited the battery with the ammeter at 200 mA range.

Good point.

 

[striker600]

Just tested meter across interior boot bulb.Got just under 12V.Across batt 12.6V,so i assume its working ok,

 

[Ted]

No, mate, Voltage reading is high impedance, Current range is VERY low.
To prove your ammeter is working, do what you did before, (on series wirh battery/battery lead) but on the 20 amp (NOT mA range). Now switch on the sidelights. You should see a reading of a about 3 amps (and see the lights on). If nothing, as the other guys say,meter is shot or (more likely, internal fuse blown)
To see 0.00 on the mA range is so unlikely as to be almost impossible.

PS dont try to start the car with the ammeter connected in.

 

[Stan the Man]

I have a ammeter but not sure if i have used it correctly.Anyway this is how i used it-With the battery fully charged (charged overnight)& reconnected to car. I set the meeter to the A setting on the 200mA scale.I put the red + probe to the +battery terminal,& the black - probe to the earth strap point (strut plate) I didnt get any reading(all systems shut down).I also tried+probe to batt+ and -probe to batt - an got no reading,but i think that is in paralel.If i had the ammeter connected wrong can you tell me how to connect it correctly so i can perform a current drain test.
Other info,My car dose not have command and all interior lights including boot go out.It has the OCP, & elec memory seats which as far as i am aware work correctly.

In order to measure quiescent current you need to disconnect the negative battery terminal. Select multimeter DC amps high range 0-20 and connect multimeter leads one to negative battery terminal and the other to the disconnected terminal clamp. Now decrease multimeter DC amps range until you get a reading, should be around 30 to 40mA on the 0-200mA range. If you get a negative reading reverse the multimeter leads.

Take care when disconnecting/reconnecting battery, you can damage the rear sam also you may need to reset windows and traction control afterwards.

My guess is that if you have excessive battery drain the culprit will turn out to be a memory seat control unit (try disconnecting each in turn, pull the plug under the seat.

 

[striker600]

Ted,you got it spot on! I have just checked the fuse on the multi meter& its blown! silly me. I"ll Get a new one then perform the drain test again in series NOT in parallel.Update you with the test results later.

 

[Autofix]

Another point worth mentioning is that to test that all systems shut down as they should then need to be woken up first. If the battery is disconnected, the reconnected this will not be the case. The method I use is to clamp the battery terminal with a long nose vise grips or similar and connect the metre. Start the car, switch it off, then remove the grips. This then allows the meter to maintain the circuit. If the circuit is not maintained the test may not be valid.
Better again, use a clamp on meter.
Also be aware, I saw a cheap metre that went open circuit for an instant as the range was changed.

 

[striker600]

In order to measure quiescent current you need to disconnect the negative battery terminal. Select multimeter DC amps high range 0-20 and connect multimeter leads one to negative battery terminal and the other to the disconnected terminal clamp. Now decrease multimeter DC amps range until you get a reading, should be around 30 to 40mA on the 0-200mA range. If you get a negative reading reverse the multimeter leads.

Take care when disconnecting/reconnecting battery, you can damage the rear sam also you may need to reset windows and traction control afterwards.

My guess is that if you have excessive battery drain the culprit will turn out to be a memory seat control unit (try disconnecting each in turn, pull the plug under the seat.

I have just done some drain tests with the muiti meter, connected in series between batt.neg terminal &earth strap.Meter was set to 10 amp DC range.All elec consumers off. 1000 milli amps (ma)=1 amp.(a)

Here are the readings-
Total current drain=1.02amps=1020 milli amps
I then disconnected the following consumers (in turn one at a time)by removing the fuses(using the mb fuse card)and took meter reading

Rain sensor-fuse 9 (is this known as OCP? mb fuse card dose not list OCP,only rain sensor) 0.93a=930milli amps.1020ma-930ma=90ma drain.

Seat adjuster(drivers)fuses 2,21,27. 0.89a(890ma)
1020ma-890ma=130ma drain.

seat adjuster(passenger)fuses 1,22,38. 0.29(290ma)
1020ma-290ma=730ma drain.

I then dissconnected both driver&passenger seat fuses,meter reading was 0.13a or 130ma.

I then disconnected all 3 together,ie.seats&rain sensor fuses.Reading was 0.05a or 50ma. 1020ma-50ma=970ma drain.

My Questions are¬
1.With all the above 3 consumers disconnected at the same time, the current drain is down from 1020ma to 50ma. Is 50ma within the acceptable tollorence?

2.Do i need to disconnect the fuse(s) of other consumers to test for current drain?If so witch ones?

3.Do i need to replace seat adjuster(drivers&passenger)and the rain sensor?

4.How much are the above 3 componants?

Any additional help and imformation would be appreciated.