CL55 Battery flat in 7 days How long should it last?

[television]

When using meters, a clamp meter is fine for seeing that you have a leak with disconnecting the battery in the first place, but it is a miserable thing to work with as it has to be reset, to get an update or change.

This leaves the simple multirange meter as being the best all round tool. Ideally a 20 amp one is the best, but a 10 amp would be fine. If the car is cold and gone to sleep that will do the job well. one can always put a shunt on the meter to increase its range.

I am going to do a DIY on this over the next few days, to save keep writing it all out.

Your car does not have an OVP relay, and even if you would they do not cause leaks or current drains

 

[Cole@MBS]

We did a drain on a S55 the other day. once sorted the currant pull dropped to 00.07 ma!!!

This was pretty good

 

[Cl_a_55y]

We did a drain on a S55 the other day. once sorted the currant pull dropped to 00.07 ma!!!

This was pretty good

What was the cause of the drain on the S55?

 

[Cole@MBS]

Battery was shot, kept dropping the voltage and waking things up, new battery, sat 3 days with a volt meter on it, pulsed between 00.08-00.07ma,

No problems since!!

 

[Alex Crow]

0.07 ma? your meter must have a low range. could that possibly be 0.07 A colin?

i should point out again, for the O/Ps benefit, that these modern cars will take extra current until the electronics go to sleep, leaving just the alarm monitoring and one or two other modules half awake (eg seat controller). JUST OPENING A DOOR WILL WAKE THE CAR UP AGAIN!! sorry for shouting but it is so easy to think you have found a drain and it is just because of unplugging/plugging in a module and it waking up again, or disconnecting/reconnecting a fuse or circuit, or even opening/closing a door. all in all an absolute pain to do, and best to have the car for a whole day and do something else in the workshop at the same time.

plugging in an ammeter in series is also a total pain as you need to connect it before disconnecting the batt lead, otherwise it will blow even a 10A fuse sometimes. i disconnect the batt lead, connect the crocodile clip to batt terminal and touch the batt lead to the terminal while i connect the clip to the batt lead, then isolate the batt lead from the terminal. if doing this i connect a 60w bulb in series with the meter to stop blowing ammeter fuses - remember if you use this method, that measuring high current draw will be inaccurate, also the bulb will lower the voltage supplied to consumers. however using the bulb technique will work fine for measuring low ma values, with the effect of the bulbs impedance making almost no difference when you get down to 40ma.

when doing battery drain and AH calculations i work on the basis of the battery being able to supply 1/2 of its rated AH before it fails to start the engine, an good rule of thumb for new batteries but old batteries will never reach this level obviously.

ie 100AH battery will supply 42ma for approx 50 days before the battery will fail to start the engine.

 

[Cole@MBS]

0.07 ma? your meter must have a low range. could that possibly be 0.07 A colin?

i should point out again, for the O/Ps benefit, that these modern cars will take extra current until the electronics go to sleep, leaving just the alarm monitoring and one or two other modules half awake (eg seat controller). JUST OPENING A DOOR WILL WAKE THE CAR UP AGAIN!! sorry for shouting but it is so easy to think you have found a drain and it is just because of unplugging/plugging in a module and it waking up again, or disconnecting/reconnecting a fuse or circuit, or even opening/closing a door. all in all an absolute pain to do, and best to have the car for a whole day and do something else in the workshop at the same time.

plugging in an ammeter in series is also a total pain as you need to connect it before disconnecting the batt lead, otherwise it will blow even a 10A fuse sometimes. i disconnect the batt lead, connect the crocodile clip to batt terminal and touch the batt lead to the terminal while i connect the clip to the batt lead, then isolate the batt lead from the terminal. if doing this i connect a 60w bulb in series with the meter to stop blowing ammeter fuses - remember if you use this method, that measuring high current draw will be inaccurate, also the bulb will lower the voltage supplied to consumers. however using the bulb technique will work fine for measuring low ma values, with the effect of the bulbs impedance making almost no difference when you get down to 40ma.

when doing battery drain and AH calculations i work on the basis of the battery being able to supply 1/2 of its rated AH before it fails to start the engine, an good rule of thumb for new batteries but old batteries will never reach this level obviously.

ie 100AH battery will supply 42ma for approx 50 days before the battery will fail to start the engine.

Sorry A/P, 0.07-0.08.

Your so fussy at times

 

[television]

Sorry A/P, 0.07-0.08.

Your so fussy at times

Thats better,, the main trick is getting the ammeter in series with breaking the circuit,,and I will show how to do this in the DIY article that I am doing

 

[Alex Crow]

Thats better,, the main trick is getting the ammeter in series with breaking the circuit,,and I will show how to do this in the DIY article that I am doing

anything like my method? sometimes i use a switch in series with the ammeter, still using that bulb as a safety though, have to take the meter apart to change the fuses.

 

[television]

anything like my method? sometimes i use a switch in series with the ammeter, still using that bulb as a safety though, have to take the meter apart to change the fuses.

Yes,,just have 2 leads on the same terminal on the meter, 1 with a probe, the other with a crocodile clip, just put the crocodile onto the connector, and put the probe in the center of the battery post. slacken the bolt and slide the clamp up the probe an hold it, join the second lead to the battery post

 

[Alex Crow]

another thought, should that glove box light circuit be live with the ignition off? on older vehicles they were only live with the ignition on position 1+2. there was a problem with front sams flattening batteries on some earlier s-class cars too.............

 

[television]

another thought, should that glove box light circuit be live with the ignition off? on older vehicles they were only live with the ignition on position 1+2. there was a problem with front sams flattening batteries on some earlier s-class cars too.............

Poor old SAM should have chosen a different name

Yes SAM's,seat controllers, OCP all known,boot lamps another,,they take about 3 days to kill the battery

 

[Cl_a_55y]

another thought, should that glove box light circuit be live with the ignition off? on older vehicles they were only live with the ignition on position 1+2. there was a problem with front sams flattening batteries on some earlier s-class cars too.............

Yes I thought it was strange that the glove box light had power 15-20 mins after everything was switched off, locked and alarmed. On every other car I ever had, the glove box lighting came on only when the dash panel lights were on and/or if ignition set in the accessory position. In my case the dash panel lights were off, ignition key out, keyless go card well away from car and the main light switch was set to off (not auto)

Something even stranger... When I checked next day in daylight the glove box lamp did not come on at all but after dark it did again so I guess it works off the daylight sensor circuit somehow irrespective of other light settings?

Anyway I did DEFINITELY fix that switch problem and now the light only comes on when the box is opened at night irrespective of light switch settings. Not when the box is closed like it did before. Damn I was so sure that would fix the problem once and for all!!!!

All these abbreviations are fine for you experts but please, at least the first time, can you give them their full name?

So pray tell what is a front SAM?
Also what is an OCP? Over Current Protection relay perhaps?
As opposed to OVP, Over Voltage Protection relay?... of which Malcolm (Television) at first said to check, later to retract, saying a CL55 doesn't have one and they don't cause leaks or drains anyway! All very confusing.

So for final clarification, apart from the seat controllers, what else is a likely suspect to cause this problem and IS fitted on a CL55?

Thanks everyone for your help and input.

 

[television]

Yes I thought it was strange that the glove box light had power 15-20 mins after everything was switched off, locked and alarmed. On every other car I ever had, the glove box lighting came on only when the dash panel lights were on and/or if ignition set in the accessory position. In my case the dash panel lights were off, ignition key out, keyless go card well away from car and the main light switch was set to off (not auto)

Something even stranger... When I checked next day in daylight the glove box lamp did not come on at all but after dark it did again so I guess it works off the daylight sensor circuit somehow irrespective of other light settings?

Anyway I did DEFINITELY fix that switch problem and now the light only comes on when the box is opened at night irrespective of light switch settings. Not when the box is closed like it did before. Damn I was so sure that would fix the problem once and for all!!!!

All these abbreviations are fine for you experts but please, at least the first time, can you give them their full name?

So pray tell what is a front SAM?
Also what is an OCP? Over Current Protection relay perhaps?
As opposed to OVP, Over Voltage Protection relay?... of which Malcolm (Television) at first said to check, later to retract, saying a CL55 doesn't have one and they don't cause leaks or drains anyway! All very confusing.

So for final clarification, apart from the seat controllers, what else is a likely suspect to cause this problem and IS fitted on a CL55?

Thanks everyone for your help and input.

I should have said OCP :Oops: that is the overhead control panel that houses the mirror etc, this is a known fault that can stop the car from shutting down.

A SAM is a signal acquisition module.
The car has high speed, and low speed CAN buss,,all or the component on the car send out data, the SAM picks all of this data up, and knows then what the car has got, like memory seats, mirrors, right down to things like aircon and the type of headlamps etc. Many of the cars components have a memory, and it is the memory part that fails the most.

Just like on a car radio, there is a feed that stays live at all time, and another that turns it off and on. the seat controllers work in the same way.

Now many electronic things that we own can lock up,,that is freeze,, and the only fix is a power down and start up again. As the seat controllers etc on the cars have this constant live feed they too can lock up, and a power down will some times fix.

 

[Cl_a_55y]

Please report back with what you find.

We managed successfully to connect my Fluke in series without breaking the circuit using the method you described with 3 leads. We ran the test 4 times. The first time we monitored it for 1 hour, the other 3 times for 30 minutes each. On all 4 tests, the current drain seemed to drop roughly every 2 minutes. Starting at around 15-17 Amps as the electric boot closed. It dropped down in stages for 11 minutes and then stayed the same at between 0.16A and 0.19A until we stopped the test after 60 minutes.

So with 190mA draw, I calculated using Alexander Patient's method that the battery would last at most 9 days before it failed to start the engine. As I said before, mine lasts around 7 days so it seems roughly consistent.

Tomorrow we will start working through the fuse boxes with the small current tester I bought from Maplins to try to establish which circuit(s) are drawing too much.

Any comments on the above welcome and I will update further after next batch of tests.

Incidentally the Fluke 75 had no problems. It read up all the way up to 30Amps despite being rated for 10Amps and fused for 15Amps when the ignition was switched on and aircon burst into life too. Also tested by operating Comand, electric windows, both seat adjusters, windows, sunroof and boot closing before switching off, locking and alarming the car.

 

[television]

The first thing to do is to check the seat controllers,,next the OCP,,then the comand,,this is easy as if the Comand has not gone to sleep, the CD changer will make clicking trying to load noises

 

[Cl_a_55y]

Spotted this - by the way this is NOT my battery fix!!!

 

[television]

Spotted this - by the way this is NOT my battery fix!!!

The handle of that clamp is going to short out in the other battery pole at any time soon ,,bye bye battery

 

[Alex Crow]

my thoughts exactly malcolm. have seen the entire top blown off a battery just by some muppet connecting the jump leads back to front.

 

[The Sat Diver]

I'm away for weeks at a time.. and my CL500 always had a flat battery even after replacing with a brand new one at best it would then last 3 weeks...

Too many electrical bits still running even when parked up.. eventually got rid of mine when in the Lakes approaching a tight right hander in pouring rain nearside front wheel went rhro' a puddle about 10-15cm deep and the steering just froze for a second.. simply could not turn the steering wheel and was heading for the woods... it gave me a fright.. so did it again deliberately further down the road and sure enough it happened once again.. Mercedes denied all knowledge.. but found out from my local garage that they will fit a cure for some 400 quid !? .. I loved that car but wouldn't have another.. anyone else had a similar experience ?

 

[amwebby]

This happened to me once, when fording a stream that had broken its banks and came across the road. I'd estimate the depth at 40-50 cm. As soon as I realised the depth of the water I hit the level control switch to raise the height of the car to maximum. I lost power steering momentarily. I don't know if it was a combination of hitting the water and raising the height of the vehicle at the same time but I've never had the problem again despite going through some very deep puddles. 10-15 cm is barely the height of the tyre and wheel rim so it is hard to see how water ingress could cause a problem at that depth.

My CL500 has stood for over 4 weeks with no battery problems. The only problem I had was when the faulty seat controller was causing a half amp drain as mentioned previously. This is a common fault apparently. I would always check the seat controller first as it appears this is often the cause of the problem with no visible signs, i.e. seat controls not working. If it is not that then it is a time consuming task to turn off each electrical unit to trace the source of the drain.