Parasitic Battery Drain (?)

[Jamie1991]

Hi! Thanks for any help answering this question. In my 2011 Scout I have had a problem over the past few months with battery drain. The battery was replaced in November last year (when I got the car) with a new one and ran fine until this winter where I have found a need to jump start the car 4 or 5 times already. Once jump started and running the car seems to start without problem as long as it is used every day (so imagine alternator / starter are fine) but if not used for a few days I find the battery flat. Following advice from online I plugged a multimeter between the negative terminal and cable today and (assuming I'm reading it right) got a reading of 0.8-0.9 amps at rest (key out the engine etc). The biggest contributor to draw seems to be the stereo - removing this fuse causes the draw to drop to 0.5 amps. Removing additional fuses (headlight, central locking and a fuse for some reason in a 'reserve' slot) gets the draw to nearly nothing. I've a couple of queries if anyone is able to answer. I've uploaded a pic of my multimeter reading - for those more experienced than me - am I right in thinking this is reading amps? (I wonder as I've read normal draw is in the region of tens of miliamps so this seems very high and suggests at least four circuits are contributing to draw). Thanks in advance.

 

 

[JulianS]

Is it possible that the boot light is remaining on? Had it once on a Morris Marina. Get your smallest child in the boot and shut him in. (for a while!) It looks like you've hooked it up correctly. 820mA is certainly too much although I understand that some modules take a while to  go  to sleep so maybe you need to monitor for a while.

[Jamie1991]

Will check out the boot light - thanks! 

[Guest]

Just leave the cargo cover retracted to see boot lights, no need for child labour.

[Golf-Fiend]

40 minutes ago, MicMac said:

Just leave the cargo cover retracted to see boot lights, no need for child labour.

 

Or just fold rear seat back down.  However, locking kids in the boot is much more fun, however this might be illegal in several countries

[Jamie1991]

Car boot checked (without use of child labour!) and all looks ok. Will continue my search for the culprits 🤣 Hadn't realised some modules will take a while to power off so will maybe leave a couple of hours then re-check next time. Thanks!

[Breezy_Pete]

@Jamie1991 grab a helper to make it easy, then try this method: https://www.briskoda.net/forums/topic/495243-quick-and-dirty-parasitic-current-measurement/

 

[nige8021]

Have a read of this VW Battery Discharged Diagnosis for Static Current Draw.pdf

[Jamie1991]

9 minutes ago, nige8021 said:

Have a read of this VW Battery Discharged Diagnosis for Static Current Draw.pdf

 

That's brilliant - much easier than what I was doing (pulling fuses and checking the current drop). Thanks. 

[J.R.]

On 23/01/2022 at 18:42, Jamie1991 said:

 Following advice from online I plugged a multimeter between the negative terminal and cable today and (assuming I'm reading it right) got a reading of 0.8-0.9 amps at rest (key out the engine etc).

 

 

You are getting a false reading as the comms network has not shut down as witnessed by the radio consumption.

 

To get a true reading first you must trick the vehicle into thinking the bonnet is closed by closing the latch with a screwdriver or similar, then  switch off ignition and lock vehicle leaving drivers window unwound as a precaution, disconnect battery and make your multimeter connections but do not take the reading for 20 minutes, it will probably have fallen to the quiescent current after 10 minutes but if it looks high wait for the full 20 minutes.

 

I would expect 20-40 milliamps current draw unless you have accessories like a dashcam or a towing relay.

 

If it is higher then use the procedure linked to by Wino but in that case its both the bonnet and door catches that you will have to fiddle.

[Breezy_Pete]

You may not have read the link I posted, or confused me with Nige?

[Jamie1991]

Thanks all. Will recheck the total current raw this weekend using the method suggested by Wino and JR, and if higher than normal will check circuits per Nige 👍