Parasitic Battery Drain - Help!

[Jonesey]

Firstly, hello to everyone as this is my first post. Some great stuff on here, so thanks for letting me on as a guest.

I have looked-up all the posts and trawled the internet for advice on how to trace a parasitic battery drain, have tried what I can but am now stumped. So, looking for your help to see what I can try next.

I have a 1989 2.7 Lux, I bought it 6 weeks ago and have been very pleased with it BUT it does have one or two electrical gremlins. This is really my fiddling and fettling car, I am fine on bodywork and some mechanicals but I'm no electrician! Whether I leave it locked or unlocked, the battery will drain in about 3 days. I have fully charged the battery (tested at 12.6v) and left it standing disconnected .... holds its charge no problem. The battery is only 9 months old so I have ruled that out as the cause.

I have done most of the obvious stuff like checking for glove box light being on in the dark, the connecter on the rear hatch strut etc. The interior and boot lights don't work, have changed the bulbs (still don't work) and set the switches to the middle position for "off". Used an ammeter setting on my multimeter and get a reading of 0.28 drain. Went through pulling all the fuses and relays in the engine bay but the reading stayed pretty constant. I would have thought that if the interior lights circuit was grounding that this would have disappeared when I pulled the fuse. I knew the intermittent wiper relay was duff and I have taken that out but I am still getting the constant reading on the drain.

Any ideas what I can try next? Thanks.

 

[Mark_Bennett]

I had an intermittent drain on my old 944S when the ignition switch would make contact - without the key in. This activated the passenger compartment fans and could drain the battery very quickly.

 

[944 man]

Have you established that pulling circuit fuses one-by-one doesnt stop the drain? Assuming so Id be looking at the alternator first, but this is more tricky than normal (because using a blade fuse type meter, replacing each fuse; youll usually find the culprit).


Simon

 

[Jonesey]

Yes, that's what I was doing this morning, pulling each of the fues and relays one by one, going backwards and forwards between the bonnet and the boot to take a meter reading. Most exercise I've had in years!

I remember seeing somewhere that the electric windows shouldn't operate with the doors open, something to do with the door switch. Mine work with the door open. I wonder if that could be the fault...also linked to the courtesy lights not working. Does anyone know if that is correct about the operation of the electric windows?

I'm going to take those switches out now, it's only one screw and have a look.

Thanks, Alan.

 

[ukmastiff]

I realise you have done the fault fiding thing and quite rightly but I would consider this possibility. The battery doesnt drain when disonnected from the car so you have ruled out a duff battery. It 'may' and im not saying it is still be a duff battery and that it loses charge when on the car because of the drain of an alarm or whatever effectng it more thsan it would a healthy battery , batteries are funny things.

One thing I would do is get a cheap CTEK battery conditioner for 35 pounds to leave permanently connected and that way you wont have to worry about a flat battery , drain or not. You can still try and find your problem and the 35 pounds will never be wasted as it is a fantastic gadget and will look after any future battery you get.

Best of luck

Mas

 

[Fred Hindle]

Battery conditioner is a good idea but won't solve your problems if you are away from home with the car.

My old 1984 944 has a battery drain (intermittent, some times OK, sometimes dead). One possible cause is the switches in the door pillars for the courtesty lights. Disconnect the switches, wrap insulating tape to the spade connection on the wire and tape the wire to the door pillar so you can get to them.

Hope this helps.

Cheers,

 

[944 man]

OP, theres nothing wrong with what youve done so far - quite the opposite in fact, but Im going to recommend a tool thatll make accurately testing each circuit easier and far more accurate (and you can do it stood still).

This Bad Boy should make identifying or certainly ruling out circuits far easier and more accurate.


Simon

 

[rcsalmons]

Check the drain from the immobiliser (if it has one?) If it has an oe Porsche one you will find 2 fuses under the dash below the steering wheel. Pull these and check the drain.

Rich

 

[Mike_Pollock]

Just 'cos the battery is only 9 months old, doesn't make it ok!
The winter we've just had killed mine, and got it replaced under warrenty.
They lent me one whilst mine was sent for testing, with nearly 20 others that week!
Mike

 

[FistsOfHam]

My last Passat did this, traced it to the alternator in the end. The diode had died and it was just constantly draining the battery (to the point of leaving me stranded with no battery power whilst on my way to replace it).

 

[Jonesey]

Thanks "944 Man" for the recommendation on the fuse spade tester - that would save a lot of time. It also took me ages to work out how to set to amps measurement on my Multimeter - it's not auto ranging. Well, you learn as you go on.
Interesting about the fuses on the Immobiliser, after using the remote to unlock the car, I get a clicking noise from under the dash after a few seconds and have to press the remote again before I can start it. I'll see if I can find the fuses. Are there any other fuses or relays I should check that aren't in the main box in the engine bay?
I took out the door pin switches as suggested but these looked in fine condition, no corrosion, operated ok and did not make any differnce to the battery drain
Hear what you say about the battery, I dont think Lion Brand from Europarts is the "topper of the toppers" in terms of quality. I think i'll have it load tested before shelling out for a new one.
Thanks to everyone for your advice so far.

 

[peanut]

the easiest way to test is to remove all the relays and fuses and see if there is still the same drain present.

If there is still a drain you are looking for something that is wired directly from the battery or ignition switch and is constantly live (ie not switch live)
Have you removed your door interior light switches and tested them with a multimeter ? also look at areas most owners do their DIY
CD player sound system, Alarm and Immobiliser etc

The clicking relay when entering the car is a classic sign of dodgy interior light switches. Try sitting in the car and opening and shutting the doors to see if the relay chatters

 

[944 man]

If youre going to leave it for three days, then fully charge the battery and unplug the alternator, leaving everything else as it should be. If it starts as it should then youve saved days of trouble - and if not then you now know where you should be looking.

 

[944Turbo]

12.6 is maybe a little low for a fully charged battery with no load. Windows should work with doors open, saves putting the key back in if you forgot to close. Blade current testers also available in maplins.
Good luck
Tony

 

[peanut]

jonesey I've re-read your first post and I missed the bit about the interior and rear hatch lights not working. I should say the problem lies with these circuits. Its the most logical place to start

I would download and print out the electrical schematics and isolate those circuits and do some continuity checks. I'm sure you will find a short somewhere ,possibly in a bulb holder or a door switch.

let us know how its going[]

 

[Jonesey]

Had the battery load tested and it's fine. Also confirmed that it's charging at the correct level with engine running. The mech did say that 0.26 was very high, he'd expect it to be 0.0something.

Took out the door switches and they look fine, i've had a look at the bulb holders but will give both the cabin and boot lights another once-over tomorrow and try to follow through the wiring.

After that, I think it's going to be handed over to an auto electrician. Anyone know a good mobile one in the Berkshire/Surrey area?

Thanks for all the suggestions and help. Will keep you posted with what I find.

Alan.

 

[944 man]

Did you leave it with the alternator unplugged?

 

[Jonesey]

Had the auto electrician out today and it's sorted. It was the aftermarket Scorpion alarm causing the drain. So, that's now been stripped-out and its running at 0.024 with the Porsche immobiliser set. Have lost the central locking capability but it's no big effort having to use the key.

The courtesy lights also now work. The rear one had its link to the strut switch disconnected for some strange reason and the door pin switches just needed a bit of w&d as they weren't making good contact. He also rewired the radio and the power line to the window aerial. Apart from the sunroof not going down without manual help, everything electrical is now working fine.

So, thanks for all your advice and help. Am now confident enough to take my very tidy machine out for journeys involving stopping for a few hours and it starting when I get back to it[]

 

[peanut]

sounds like he knows his stuff ! Perhaps you could recommend him so that others can use his services?

Glad you got it fixed and thanks for letting us know the outcome.

 

[Jonesey]

Yup, certainly does know his stuff.....broad experience on all Porsches. If anyone one is looking for a good auto electrician, he gets my recommendation. Came out next day and rate was very reasonable. So, for anyone in the Berkshire, Hampshire/Surrey borders, his name is Eddie and can be contacted on 07767 887477.

On the Jaguar forum there is a sub-forum for garages and indies. I don't see one here, so if one of the moderators wants to put this post in another, more relevant area (such as "Electricals") then please do so.

Trust this helps,

Alan.