battery drain

[Goran]

Are you sure your resistor in series method is accurate? What's your multimeter's resolution/accuracy when measuring voltage and resistance.
Seems to me you are multiplying error bars of several different measurements (battery voltage, voltage accross resistor, resistance, etc) and your R2 (the resistance of the whole car) is an unknown? Have a go at calculating your error bars for fun

The meter I bough claims 0.01A resolution and +/-2% and 5 units precision, for my measurement of 0.18A I work out the error to be +/-0.054A a bit high, true, but to get a much more accurate current reading you will need to spend several hundred pounds on a accurate meter.
http://www.maplin.co.uk/p/uni-trend-...FezHtAodmRIAhg

[oldnick]

Originally Posted by Goran

Are you sure your resistor in series method is accurate? What's your multimeter's resolution/accuracy when measuring voltage and resistance.
Seems to me you are multiplying error bars of several different measurements (battery voltage, voltage accross resistor, resistance, etc) and your R2 (the resistance of the whole car) is an unknown? Have a go at calculating your error bars for fun

The meter I bough claims 0.01A resolution and +/-2% and 5 units precision, for my measurement of 0.18A I work out the error to be +/-0.054A a bit high, true, but to get a much more accurate current reading you will need to spend several hundred pounds on a accurate meter.
http://www.maplin.co.uk/p/uni-trend-...FezHtAodmRIAhg

supposed to be accurate to 1mV , checked it against my nephews professional meter and it seemed to be about that . I suppose it doesn't matter if it is slightly out as long as it is consistant , certainly more precise than the cheap clamp meter I tried

latest development ...went to check the voltage on the battery after another 24 hours and it had dropped by .03 volts ;at this point I noticed that , with the boot open as before , the indicator lights beside the door lock buttons were illuminated even though the doors hadn't been locked and the doors hadn't been opened ...that doesn't seem to be correct , or does it ? unfotunately I tried the lock/unlock buttons on the remote without checking the doors had self locked last time I was in the car , just opened the boot which wasn't locked so I guess not

anyway , pulled the central locking pump fuse and the drain dropped by 10mA to 90 , probably because the boot lights are on the same circuit and , at a guess , they were pulling that ...can't remember what festoon bulbs are rated at ; at least I know that the pump can't be the problem

looks like I will have to pull each fuse to see if anything is giving a serious drain , seems crazy that you couldn't leave the car at the airport for a couple of weeks and be sure it will start even with a good battery

[Goran]

If you are coming to the meet you are welcome to borrow my clamp meter to confirm.
A 0.1A drain will in theory drain 16.8Ah capacity in 7 days, so a healthy 95Ah battery fully charged should be able to cope with this for a couple of weeks.

I can roughly correlate my clamp meter reading. I am now using a 31Ah LiFePo4 battery as my starter battery. These have a fairly flat & linear discharge curve between 90% and 10% SOC so state of charge and voltage correlation is fairly accurate.
For example, Sunday evening 9pm after driving around at the weekend the battery will read 13.27V in circuit after resting (I know I should be reading open-circuit, but these batteries have a very low voltage sag under light loads).
13.27V nicely correlates to 80% SOC. Not driving the car for 5 days or roughly 110 hours on Saturday morning the battery in-circuit voltage is 13.07V, roughly 35% SOC
This roughly equates to 14Ah drained over 110hours, or an average sleep mode current draw of 0.127A, so the clamp meter is not too far out.

http://smg.photobucket.com/user/o0ps...yLg-1.gif.html

[oldnick]

thanks for the offer ...but as I live 800Km south of Calais I hadn't considered attending !

[oldnick]

PROGRESS !

in the boot fuse box is a fuse for what is described as radio telephone loudspeaker ; remove that and the drain drops to under 50 mA !!!
don't have a telephone , might have been an analogue fitted as OE I suppose , now removed

not quite sure what runs from this fuse , so checked radio , doesn't work without fuse , so put fuse back .......CD stack in boot resets as it always does when you connect the battery ! so clearly that is included ; so unplugged that , not the problem because the drain figures stay exactly the same

so it looks like the drain comes either from something left over from the telephone days [ if there were any ] or something powering loudspeakers [ which I don't understand ]

m'aidez or mayday if you prefer

[HPsauce]

Originally Posted by oldnick

PROGRESS !in the boot fuse box is a fuse for what is described as radio telephone loudspeaker ; remove that and the drain drops to under 50 mA !!!

Can you be explicit on which one and exactly where please.
I know my car did once have a phone car kit (partly removed, keep finding stray cabling), though it was most likely separately fused via a piggyback that I haven't found yet.

[oldnick]

the boot fuse box on my FL has the facility for 6 rows of fuses although all I have is [ from left to right ]

a jumbo fuse for ABS in row 1
a 20 amp fuse above a 25 amp fuse in row 3 , the upper fuse being the radio fuse referred to ....but don't you have a diagram inside the cover ?

incidentally , the radio aerial also seems to be fed through this fuse , mine appears to have the famous broken plastic cog ...the motor turns correctly but it doesn't move

a little research suggests that the radio amp is underneath the CD stack , no idea how I test for a fault if I take it out , my rear speakers don't work [ unless there is a control somewhere ] which could be connected ; the sound quality from all the front speakers is just fine

[HPsauce]

Originally Posted by oldnick

my rear speakers don't work [ unless there is a control somewhere ] which could be connected ; the sound quality from all the front speakers is just fine

That could be simply down to Bose/non-Bose coding in the head unit.
Do you have a Bose system or not and what is the head unit, e.g. RNS or Symphony?

My radio aerial is built in to the rear screen.

PS The BOSE amplifier (if present) is located below boot floor level, beneath the CD changer.

[HPsauce]

Originally Posted by oldnick

the upper fuse being the radio fuse referred to ....but don't you have a diagram inside the cover ?

Yes and I have some additional fuses too - rear seat adjustment for example.
BUT that fuse I'd always assumed was for the amplifiers in the rear speakers, so that's probably why you have no sound from the back.

With Bose, there's a separate amplifier (as described under the CD changer) but with non-Bose the amplifiers are less powerful and are attached to the rear parcel shelf speakers. Take the covers off beneath them and you'll see.

In both cases these also drive the speakers in the rear doors, which are the MAIN rear sound, the parcel shelf ones are purely for bass notes.
The front speakers are driven directly from the head unit, I think maybe even with Bose installed.

[oldnick]

the box under the CD stack turned out to be reversing sensors !

so thanks for the gen on the rear speakers , will look there ..maybe the source of the current leak !