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Crazy phantom battery drain ?

geoffdragon said:
Came across a "car reliability survey" on the net yesterday and Honda are top of the list. However, it also said that 33% of breakdowns/repairs accross all manufacturers are electrically related.
Bring back the magneto and dynamo.
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Yeah it's getting scary, and I don't believe that DTC's are always correct, no systems ****yst can come up with all the fault permutations and combinations and then expect some kind of auto-diagnostic software to be correctly implemented

geoffdragon said:
Checked the resistance of the 1 ohm resistors and they are bang on 1 ohm.
Have measured the drain using the 1 ohm resistor and the DIGITAL MM and oscilloscope using mv as ma.
Conected the DMM up first to get an idea and not to risk my o'scope. Fluctuating between 22 and 48 ma.
Connected o'scope and after playing with mv and time scales get readings showing 21ma for 4 seconds going to 50ma for 600ms, then back to 21ma. The maximum reading was 50ma.
Reconnected the Wattmeter and it shows 126ma draw in an hour, peaking at a 150ma spot reading.
How do I reconcile these tests ?
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Did you connect a jump-cable from battery -ve to chassis, then put the 1 Ohm resistor from battery -ve to chassis, wait a while, then remove the jump-cable ? The reason for that is that the initial current surge is around 10 Amps, and a 1 Ohm resistor will drop 10 Volts for 10 Amps i.e. the full voltage will never get delivered across the car system, so it won't be able to actually pull the 10 Amps, so the system might be in some weird state.

If you did do that, then put the Watt-meter in series with the 1 Ohm resistor (wait a while, remove jump-cable) then cross-check the Watt-meter mA readings against the mV readings across the 1 Ohm resistor.


geoffdragon said:
Just spent an hour removing the Parrot wiring, and found what I think is a "mute" box.
The wiring had been cut going into the SRS control box, looping into the Parrot module and then back to the SRS box.
Wonderful sparky did that job, all connections crimped.
I've removed it all and repaired the original loom. So thats gone.
Still no difference in the Wattmeter readings.

I'm ***uming its the SRS unit. Its a black box with 2 plugs in the side of it, bolted to bracket below the satnav dvd unit, in front of the ashtray.
Anyone confirm ?

Or it could be the ECM/PCM ? Whatever that is.

Sweat over, it's the premium sound system amplifier ***embly.
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It sounds to me like someone has been really messing with the wiring in there :eek:

btw ECM/PCM = "Engine Control Module / Powertrain Control Module" = engine ECU (in the days when cars only had one ECU and ECU stood for Engine Control Unit)
 
adam123 said:
I was parked in my 2.4 tourer for 25minutes with the radio on and killed the battery!!! (Apologies for it being slightly unrelated)
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it's not entirely unrelated, you'd expect a 45 Ah battery to last for 25 minutes with the radio on, but to have the radio on you have to have the ign at position 1, which also turns on all the other junk on the B-CAN, and then they have a private party LOL

I'll check it out with my Watt meter
 
Thanks mate. Looked a right plonker in the nursery car parked surrounded by mums!!
 
adam123 said:
Thanks mate. Looked a right plonker in the nursery car parked surrounded by mums!!
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same thing happened to me in a McDonalds, I think I got the better "deal" out of you and me LOL
 
Hi. Started with the wattmeter connected Just ma showing. Clipped resistor in parallel then removed wattmeter leads Readings as above.
Good explanation about the radio having effect on canbus system but strange going flat so quickly.
 
adam123 said:
Thanks mate. Looked a right plonker in the nursery car parked surrounded by mums!!
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with key in position 1, radio off, satnav not on, current drain is 1.3 Amps

with radio on, current drain is anything from 3.5 Amps upwards, depending on the volume setting.

after 30 minutes with radio on, it had used nearly 2 Ah, and my car started ok

the battery in your car might be getting old :(
 
Oh no!! I'm now hoping I had the AC on. I always just have it on auto set at 20 degrees. Might experiment next weekend :-(
 
geoffdragon said:
Hi. Started with the wattmeter connected Just ma showing. Clipped resistor in parallel then removed wattmeter leads Readings as above.
Good explanation about the radio having effect on canbus system but strange going flat so quickly.
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I suspect that there is something turning on and off, that normally draws a spike of around (say) 10 amps when it first turns on.

My reasoning is that a spike of 10 amps will not be possible with the 1 Ohm resistor there, so whatever it is that turns on, cannot come on properly and hence you only see the 50 mA instead of the 150 mA.

To check this, I would use the DMM as follows

1. connect a jump-cable from battery -ve to the battery chassis cable
2. connect the DMM in parallel with the jump-cable (with DMM set on mA range)
3. wait a few minutes then remove the jump-cable
4. look at the DMM mA readings
5. disconnect

then
1. connect a jump-cable from battery -ve to the battery chassis cable
2. connect the DMM in series with the 1 Ohm resistor, then place them in parallel wit the jump-cable (with DMM set on mA range)
3. wait a few minutes then remove the jump-cable
4. look at the DMM mA readings
5. disconnect

If there is a difference, then there is something that draws a spike in current when it comes on
it could be
A. the MICU directly doing this
B. the MICU causing something else to do it
C something other than MICU doing it regardless of MICU
 
adam123 said:
Oh no!! I'm now hoping I had the AC on. I always just have it on auto set at 20 degrees. Might experiment next weekend :-(
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if you had the AC on then yes that will flatten the battery in half an hour :eek:
 
geoffdragon said:
Hi, just an observation. My satnav comes on at ACC position on the key.
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mine does, that's why I put "satnav not on" rather than "satnav off", but I didn't check the current until it was "not on" ....I presume it's less when it "clears off out of the way" LOL
 
Hmm I hope so. It's never failed to start or even struggle. Even after just a 3 mile journey home the battery is full up again :)
 
Just a quick update. Waiting for fusebox to arrive. Bought from Bournemouth but it is being sent from Poland. Hope it makes a difference.
 
The fusebox arrived eventually, fitted it this morning. That's a tricky little job.
Everything working as it should, Battery draw has dropped a bit but still recording 120ma over an hour period.
Noticed the alarm led is flashing much slower now, so that could be the difference I suppose.
DMM across resistor still showing 23 - 48ma
Checked the drain with the car locked and the ultrasonics off - no change.
Just done the self test on the gauges and their comm lines - no faults.
I have now tried everything connected to fuse 7 except the combination switch control, immobiliser control receiver and the immoes unit.
Have no idea how to check those, can't find any info in the manual other than testing the wiring.
Maybe I'm going to have to give up and live with the fact that the car will have to be used every few days, and it won't last a fortnight for holiday parking.
:wub:
 
:( sadly it's looking that way, it could be anything .....imoes, ultrasonics, rain sensor ....

look on the bright side ...you didn't waste money on a new battery, and it's still a reliable car except you can't leave it at an airport

Is the Passat laughing ?
 
True, and the wife says her car is smirking.
Just tried disconnecting rain sensor - no change.
On the bright side, I now have a workshop manual and a wattmeter.
Ce la vie.
Thanks for all the help, encouragement and ***istance in my quest.
Just a shame there wasn't a better outcome.
Regards, Geoff
 
Well I wouldn't be surprised if there are quite a few other 7th gens (and even 8th gens) with a similar problem, but the owners haven't noticed it yet.

The same reasoning applies to other Honda's, and other marques too. I might buy loads of those Watt meters in bulk and start a special website www.your-car-drains-its-battery.co.uk LOL

As I say, I'm sure that mine must have done something like that in the past, but I now know for a fact that if it did, it doesn't any more.
 
True, I wonder how many call outs the breakdown services get for cars parked up in the airport ?
Glad yours is ok now. Maybe mine will mysteriously cure itself. One can only hope. Lol. Think I may contact the hotel that we are parking at and see if I can self-park it. Then I could take the earth lead off the battery. If I explain the problem they may oblige.
All the best with the wattmeter venture, though I don't think there are many owners who would go through all I have.
Geoff
 
That's an interesting question about the call-outs :eek:

Good idea to ask the hotel, I can't see why they wouldn't let you go with the car to disconnect the battery (the valet driver might have to drive because of insurance). On the other hand, they might come up with some weird logic that the car might need to be moved at any time ?

Website venture would go on Dragon's Den, with franchises all over Europe, run by science students equipped with Watt meters and DMMs LOL
 
I sense a little of the "Del Boy" in you Brian.
The hotel are happy to let me disconnect the battery as long as I leave instructions how to reconnect in case they have to move it.
Have ordered one of these to make it easier for me and them.
http://www.ebay.co.uk/itm/291050635008?_trksid=p2060353.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT
May be handy another time and easily removable if I decide to change the car at some time.
I know I'll have to wait about 10 mins for the satnav to settle down when I reconnect but thats a small price to pay.
 
I'm sure that more than one Del Boy got onto Dragon's Den :lol:

I like that "Quick Release Battery Terminal Isolator Universal", very good idea.
I wonder if there's something like that with a solenoid, if so then you could fit a "hidden" switch in the glove compartment and isolate the battery without opening the bonnet :eek:
 
I have seen a remote control solenoid arrangement but that was about £80. Bit over the top for what I intend to do.
 
£80 is definitely too much, that one for £5.95 free-post should be simple for any valet driver ;)
 
Been having a look at the manual, and the immoes is a small relay type box behind the glovebox. As I understand, it links with the immobiliser. If it's changed, the car and keys need reprogramming. So I don't think I'll bother with that one. Also came across a bulletin saying if the keys are lost, honda can give you a blank key and a code that's activated by pulling the handbrake up and down. That's only good if you have spare keys at home.
Live and learn. The Internet is a mine of info if you know how to look.
 
there's also an Imoes test procedure, but I can't see any conditions that would lead to it needing testing, but by the looks of it, it can be unplugged for a test

same applies to the ultrasonics
 
Is it just me, or has the car been built in such a way that it has to go to honda for everything ? Noticed a number plate bulb out, so had a look in the manual and it says press in clip on one side and pull out. That's fine but the hole in the trim over the lights is to small for the light unit to come out through. Bad or deliberately bad design ?

OK it's me getting frustrated.
The handbook gives a far better explanation than the manual.
The trim has to be removed to gain access.

Dum dum.
 
Same guy who designed the current f1 engine. Lol
Had a quick look for the imoes unit. No sign of this mythical box behind the glovebox. I wonder if that description is for a lhd car and it's actually under the drivers dash on ours ? I'll see how I feel over the weekend and if I have time I'll have beak and see if I can find it. Was a bit iffy about unplugging it but I've already had the fuse out for the circuit it's in so it shouldn't have any effect. Will see then if discharge figures change.
 
It's annoying that the pictures on the DVD are mostly LHD.
But I would have expected the IMOES to be near to the key ...not in the glovebox anyway
 
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