Parasitic current draw, help please.

[Lloyd Barwick]

I have a VW T5 Transporter panel van that has a 0.4 amp parasitic current draw. It has a very basic electrical fit with no heated windscreen, windows, seats or accessories. With 'all' the fuses removed from all three fuse boxes. and the alternator disconnected, its still there. Has anyone got any ideas please?

 

[ruston]

Has it got a permanent live from the battery to the radio, or some other accessory fitted direct.

PS , this is based on an old van with no ECU or Memory requiring kit.

 

[Lloyd Barwick]

Has it got a permanent live from the battery to the radio, or some other accessory fitted direct.

PS , this is based on an old van with no ECU or Memory requiring kit.

Thanks Ruston, It has an original fit radio, powered through the ignition switch and no other accessories.

 

[Bobster]

Capacitive leakage through airbag circuits, dash clock, odometer.

0.4A is nothing, is it causing a problem?

 

[ruston]

And the radio definitely has no memory , or no engine management?
Is it an old caravette type, it may have some additions that you have not found yet.

 

[Octopus]

Got a tow bar and electrics?

 

[Lloyd Barwick]

Yes Ruston, the radio does have a memory and it's a 2008 van with no aftermarket parts fitted, (not that I've found anyway and I've looked really hard). But even with the radio and ECU it seems conventional wisdom is that it should have no more than 50 milliamps parasitic draw.

 

[Lloyd Barwick]

Nope! No tow bar.

 

[Lloyd Barwick]

Of course the POS battery lead goes directly to the starter solenoid, I'm wondering if there is any way there could be a partial short there. So my next move will be to disconnect the starter.

 

[ruston]

My VW Sharan shows 0.6 standing , most are around this.

 

[Bobster]

What is it your exactly trying to achieve here?

 

[Octopus]

What is it your exactly trying to achieve here?

Not getting a flat battery?

 

[Bobster]

Not getting a flat battery?

A car battery will go flat eventually regardless of a load on it. Yes it will take ages, but it will still take ages at 0.4AH

 

[ruston]

Lately mine has been standing a lot , so I start it regularly to get the oil around . every two weeks or so I put the battery on a trickle charge to keep it up to par.
I only do this to put back in what the starter has taken out. When I use it regular I have no problems with battery performance.

Perhaps the OP does a lot of stop starts , and may not be putting the drain back in , or maybe the battery has a poor cell , and as Murdoch has said ; is going flat.

 

[HandySparks]

0.4A sounds too much to me. At that rate, a fully charged brand new 70Ah battery would be completely dead in a week. I'd expect to be able to leave a car with a battery in good condition for a month and still be able to start it.

 

[ruston]

It will , or should not draw that all the time, when the ECU goes to sleep it should drop.
Reactivating the ECU will show the draw again.

This may help.
http://grouper.ieee.org/groups/802/3/RTPGE/public/july12/hoganmuller_02a_0712.pdf

 

[Lloyd Barwick]

Trying to not have a flat battery after 4 days Rob, which is what was happening. Then after fitting a new battery I got a considerable 'flash' when connecting the NEG lead. That's what got me started on this little adventure.

 

[Lloyd Barwick]

Thanks Ruston I hadn't realised this. I'll connect it through my mutimeter tonight and check it after 30mins. Apparently all the test circuits in the ECU should have gone to sleep by then. They say a little knowledge is a dangerous thing, which is certainly true of me and electronics.

 

[ruston]

A clamp meter would be better than a multi meter in series ( if you are using it as an ammeter), as replacing the neg will power up the ecu.
The ecu needs power all the time, so you will get a reaction from replacing the leads on the battery . It should not be a substantial flash though , more a gentle protest lol.
Remember you will also be powering up the accessories that have a memory, and the likes of the alarm, central locking etc.

PS. Is the new battery holding up, and have you checked the alternator output and the belt tension?