Parasitic battery drain

[p2roverman]

Originally Posted by SD1too

According to the link you've posted Mike it's not even a few millivolts, it's tenths of a millivolt. You would need a very sophisticated and expensive voltmeter to read that accurately.

Measuring the draw from the battery as suggested by macafee2 is actually a very practical solution. If you start by isolating the major culprits, such as the navigation computer and the BCU, you will narrow down the possibilities without having to remove a large number of individual fuses.

Do you have the RAVE writing diagrams Mike?

Simon

Thank Simon. I do have the RAVE dvd.
I checked the table, the readings are in the main expected to be in the 1 - 10 mV.
However, I have ordered an Amp Hound which give a direct reading of the current through each fuse. I do know that some are passing current because my existing old multi meter would ocassionally flick up a minus sign but without being able to register the small current. Delivery expected tomorrow so should have a result to report by Monday


Incidently my car does not have a satnav, and while I expect the issue to be somewhere in the BCU I'm expect the individual circuit to be fused.


I mentioned a cover preventing access to the air bag fuse, what's the reason for this?

[p2roverman]

Originally Posted by stocktake

Apparently you only need an multimeter that measures millivolts

https://autonerdz.com/yabbfiles/Atta...crossfuses.pdf

Thanks Dave.

That's a very much abbreviated version of the table I have, mine runs to 3 A4 pages. So a meter capable of reading down to 1mV is required, however I've ordered an Amp Hound which will give a direct reading.

[p2roverman]

I've bought an Amp Hound, showing 110mA on fuse 5 which, according the Hayes feeds the body control unit then has something to do with the wash wipe circuitry. I have pulled the fuse yet the wipers still work, (but not the intermittant wipe which wasn't working before). No other fuses were showing any current flow, which surprised me as I expected the one feeding the clock to have a current flow.


Have I cured the battery drain problem. I don't yet know. Is Hayes correct on the information I've reported?


Separate test - on connecting the battery there is a 500mA flow in the main battery connection, within 15 seconds this quickly drops the 350mA. I have not monitored this flow any longer to see if it drops further. Is this what would be expected?

[SD1too]

Originally Posted by p2roverman

I've bought an Amp Hound, showing 110mA on fuse 5 ...

Hi Mike,

Mentioning fuse 5 suggests that you have the early design of passenger footwell fusebox.
According to RAVE this is a "logic power" feed to the BCU so I'd be surprised if that is specific to any one circuit.

Originally Posted by p2roverman

... on connecting the battery there is a 500mA flow in the main battery connection, within 15 seconds this quickly drops the 350mA. I have not monitored this flow any longer to see if it drops further. Is this what would be expected?

You need to monitor it for longer Mike. The official data is a draw of 1 to 2 amps for up to 18 minutes. After that (sleep mode) it's 30 to 45 mA.

However it's interesting that you suspect the wash/wipe circuit. My car has an intermittent draw in sleep mode of 100 mA every few minutes. If I disconnect the wiper motor plug this decreases to 60 mA which is still unsatisfactory. It would be helpful to know if you experience the same if you leave your ammeter connected for over 18 minutes.

Simon

[p2roverman]

Originally Posted by SD1too

Hi Mike,

Mentioning fuse 5 suggests that you have the early design of passenger footwell fusebox.
According to RAVE this is a "logic power" feed to the BCU so I'd be surprised if that is specific to any one circuit.

You need to monitor it for longer Mike. The official data is a draw of 1 to 2 amps for up to 18 minutes. After that (sleep mode) it's 30 to 45 mA.

However it's interesting that you suspect the wash/wipe circuit. My car has an intermittent draw in sleep mode of 100 mA every few minutes. If I disconnect the wiper motor plug this decreases to 60 mA which is still unsatisfactory. It would be helpful to know if you experience the same if you leave your ammeter connected for over 18 minutes.

Simon

Hi Simon
Using the car today with fuse 5 out I found the windows wouldn't operate neither would the other doors lock when I turned the key. I locked them manually; after starting the car the three door locks automatically unlocked!
So Haynes is apparently wrong aboue fuse five being realated to the wipers but it does apparently have some effect on the logic of the body control.
I take your point over leaving the ammeter in circuit longer. The current of 0.5 diminishing to 0.35 was on first connecting the battery which would presumably be different to the current drawn while the system is shutting down. However if it does prove to be an abnormal flow through fuse 5 then finding it from then on might be an issue.
One more question, I know I need a new battery. The new Lucas was a dissapointment, do you have a recomendation - I've heard Tanya are good.
Mike

[SD1too]

A PM is waiting for you Mike.

Simon