Power drain!!!!

[daveyb]

This is starting to drive me nuts! I seem to have a 1 amp constant drain. I disconnect the battery after I have used the Jag and not lock it! I do this to save the battery and open the door as bizarrely turns into an 8 amp drain and ends up killing the battery if left connected. It has chewed up and spat out 2 new batteries so far.

I have had it to my local garage and an auto electrician, no joy from either.

Doesn’t help I have the electrical knowledge of a five year old girl! I do expect some electrical problems but this is ridiculous.

Anyone got any ideas?

I have a box of matches that look very tempting at the moment!!!!!!!!!

[Mr.Ian]

A few thoughts

1 - throw matches away
2 - has the car got an alarm system? might be a fault there.
3 - I think the electric aerial/relay can cause a drain if faulty, try to disconnect it too.
4 - I'm sure through a sequence of deduction an auto electrician would be able to test for and find a current drain by disconnecting items.

[Mr.Ian]

Just reading your post again, where are you getting these current drain figures from?
You will have a permanent drain from any permanent live items eg:- clock / alarm / computers if any and battery should cope with these if they are drawing what they should.
As I said in my previous post I think the aerial / relay are prone to current drain as it can think it's not retracted and keep power onto the motor.
There will obviously be a higher drain when the door is open as it brings on the interior lighting (not sure of the figure though) but also an alarm would sense the door being opened too.

[PaulE]

A logical investigation needed here it seems. Is the charging side OK? I would check that first. Is the alternator doing its stuff? Then a careful look at where the problem lies by a methodical electrical engineer.

When you have solved it (which you will - don't give up hope and reach for the matches) get yourself a conditioner which will keep the battery on top form. The Club Shop stocks C-TEK ones which are excellent. Suggest the 3600 model. Give Annie a ring on 01909 733209. C-TEK also have a website. Paul.

[daveyb]

Hi Guys

I have a toad immobiliser that is working ok? No alarm fitted. My electric aerial would only go half way up but retracted ok. Doesn’t raise at all now! Could it still cause a drain?

The garage and auto electrician had my car hooked up to computers to fault find, an 18 year old Jag not totally compatible?? I am only repeating what I have been told!!!!!

As I have said I am pretty useless with this elastic trickery stuff. I have been told that if I connect my multimeter to the neg on the battery and to the earth lead, I should see if I get a drop in amps if I pull the fuses out one at a time. Someone else said I can’t do that as my electrics are more complicated and gave me a load of jargon I did not understand!

My meter is fused to 10Amps and see in the big green book some circuits are 15Amps, can I hook my meter to the battery and pull the fuses avoiding the 15A fuses?

How do I test the alternator? Yet another person said it is probably diode leakage!

Your advice is greatly appreciated

Dave

[MARKPEARSON]

Hello davey b

Any advice given without seeing the car will only be a suggestion but as you said the electric ariel is not working properly that is where I would start.

As mr ian says these can keep the power on if they think they are not fully retracted so I would disconnect ariel and then see what the power drain is.

If that does not cure it then it is a case of pulling fuses out one at a time checking power drain each time untill you find what is causing the drain.

As you are measuring the power drain with the boot up you will also have the two boot internal lights on and this will give a false reading as these will draw current from battery remove the bulbs to get accurate reading.

I took a few readings from my 1993 4.0 the car is totally standard no modifications and the car will stand over three weeks and start without being on trickle charger.

1, Nothing on boot lights off .2A (200MA).
2, Boot open boot lights on .64A(640mA).
3, Door open all internal lights on and boot 3.2A.
4, Electric ariel 13A to lift 2A to retract.

Hope this is of some help.

Best Regards Mark.

[daveyb]

Hi Mark

Thanks for the extra advice. As I have said the aerial is fully retracted and does not even attempt to rise, seems dead. I have had a poke around the aerial today and a previous owner or someone has fitted a 15amp fuse to it when it should be a 10amp fuse. There are a lot of screwdriver scratch marks on the black box I assume holds the aerial motor.

This is probably a silly basic question you will laugh at, but how do I disconnect the aerial?


Dave

[SimonR]

This is probably a silly basic question you will laugh at, but how do I disconnect the aerial?

Don't worry about asking silly questions - other people asking fundamental questions is how the rest of us learn!!!

[almcl]

This is probably a silly basic question you will laugh at, but how do I disconnect the aerial?


There should be a bundle of three wires coming out of the aerial box. Depending on your model year these should have plug which can, with a bit of dexterity, be undone.

A little further back along the wires is the delay relay (stops the aerial retracting for about 15 secs when radio is switched off, no one seems to know why.) Coming out of the relay and heading forward should be a brown/purple wire. This has an in-line fuse. Disconnecting this fuse removes power from the relay and the aerial.

Finally, there should be 15 amp fuse on the main panel at no3 position which feeds the aerial (and several other things.) Pull this and see if the current draw drops.

[daveyb]

Thanks for that Al

I will give that a go tomorrow, looks straightforward. The fuse listings in my handbook and the green manual have the aerial on the middle fuse at 10 amps and doesn’t feed anything else. I assume this is the fuse I pull?

Had a look at your website, you have got some excellent pictures on it, I especially like the estate prototypes!

Dave