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DeLorean Battery drain
#1
Hi, I am just looking for a bit of advice as I have just returned from holiday to find that my battery has drained over the last fortnight due to a 0.15 Amp drain which was present whilst the ignition was off.
I have traced the source of the drain to the dip beam relay being energised although the ignition is off and the lights are not on.
Can anyone advise if this is correct for this relay to be always energised as it doesn't seem correct to me?
Any advice would be much appreciated. Smile

Mike
Mike Knowlton DOC #761
DeLorean DMC-12, VIN#4208,
Black Interior, Automatic. Grooved bonnet, Gasflap
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#2
Hi Mike

By 'energised' do you mean there is voltage across the coil terminals?

It is normal for there to be 12v present on one of the switched contacts. The headlights can be operated with the ignition off.

Your power drain is most likely due to the central locking module. It is a poor design and draws quite a lot of current all the time. Try unplugging it...
Richard H. DOC 365 VIN 1274
http://www.deloreans.co.uk
In theory, theory and practice are the same. In practice, they are not.
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#3
Mike,

I would recommend you invest in one of these: http://www.ebay.co.uk/itm/UNIVERSAL-CAR ... 35be3ed62a

I always have my battery isolated when not in use, and I've never had any problems with flat batteries.

As RichH mentioned, it is most likely the central locking module that's the cause of your issue. If you are handy with a soldering iron the central locking module can be modified to significantly reduce the current draw.
VIN# 04708, Grey interior, 5 speed, October 1981
DOC 649
ex DOC 562
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#4
Thanks for your replies Rich & Mike

It is definitely not the door lock module as I have measured the drain and it reduces to practically zero when I remove the dip beam relay.

Just to clarify that yes, when I say the relay is energised with the ignition off I mean that there is full 12 volts across the relay coil thus energising it and closing the contacts but the lights are not on.

It is the relay coil alone that is giving the discharge current of 0.15 Amps

Thanks

Mike
Mike Knowlton DOC #761
DeLorean DMC-12, VIN#4208,
Black Interior, Automatic. Grooved bonnet, Gasflap
Reply
#5
I agree with Mike,

fit a battery isolator....also acts as an additional ant -theft device.
Chris Parnham

Ex RHD Auto's etc.etc

Main Car.. Kia E Niro 4+
Toyota Vitz 4X4 1999 (the smallest 4X4 by far!)
Toyota RAV4 EV 1999.
1970 Jago Jeep.

DOC Club Historian 
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#6
The dip beam relay coil is fed from the headlight switch via the indicator stalk flasher.

If there is a voltage across the coil, but not quite enough to pull it in and turn on the relay, then that suggests there is a partial short circuit somewhere. Alternatively a good old bad earth is responsible for most weird faults...

A schematic will help a lot if you don't already have one

There's an excellent one here:

http://www.cortex.biz/schema/schema_V1.31.pdf
Richard H. DOC 365 VIN 1274
http://www.deloreans.co.uk
In theory, theory and practice are the same. In practice, they are not.
Reply
#7
That's great, many thanks for your advice guys, much appreciated.

Mike
Mike Knowlton DOC #761
DeLorean DMC-12, VIN#4208,
Black Interior, Automatic. Grooved bonnet, Gasflap
Reply
#8
Hi,

Just to let you know that I located the fault with the battery drain.

Referring to the wiring diagram it was apparent that the dip beam relay socket base had been incorrectly wired into the loom (probably during a restoration under a previous ownership). Despite this wiring fault, everything worked OK because the relay was energised at all times and the headlamps were being powered directly via the Headlamp switch and stalk on the steering column rather than through the relay contacts!

I have corrected the wiring as per the diagram and everything works fine and there is no battery drain as the relay is not energised with the ignition off.

Thanks again for all your help on this guys.

Mike
Mike Knowlton DOC #761
DeLorean DMC-12, VIN#4208,
Black Interior, Automatic. Grooved bonnet, Gasflap
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