intermittent battery drain problem

[nickgardner]

I'm still struggling with intermittent flat battery problems. the story so far:

its got a 6 month old top spec yuasa battery and testing with a proper intelligent battery tester (not just a voltmeter) confirms its good

it occasionally goes flat. I came back from a month away and it was dead as a dodo despite being on an intelligent trickle charger

alternator is charging at 13.8 v when engine running so thats ok

It can go for a week or more with no problem then suddenly overnight a flat battery occurs. Its being used pretty much daily at this time of year. yesterday it didn't have enough in it to turn over the engine despite having been used well the day before. I'm being careful that interior lights are not left on. I've checked the trunk light switch and thats working fine.
Could it be an alarm issue? I doubt it. My car was collected directly from the factory when new so doesn't have the remote central locking/alarm which was a dealer fitment in the UK. I confess to not being sure exactly what if any alarm systems it has - red leds in the door caps flash once its locked manually with the key. but I doubt the alarm is the problem - when I was away and the car was on a trickle charger it wasn't locked as it was in a secure garage and it ended up completely flat.

A few weeks ago I had a mysterious event when I realised radio was on and playing despite car having been turned off some hours before and no keys in it. Haven't been able to replicate that since

I have put an in line ammeter onto the battery which shows negligible current draw - but not zero - from memory .1 or .2 of an amp if I make sure interior and trunk light are off but car is not locked

I don't believe its the battery and I'm thinking there must be some quite significant intermittent current draw to drain it overnight. Given the radio episode I'm suspecting the main ignition switch possibly but any thoughts would be welcome. thanks

 

[noblewilson]

What is the battery reading when it wont turn over? Just want to make sure it is not earthing/connection issues.

 

[clyde]

It sounds very much like the engine wiring loom is goosed Nick. I had all sorts of electric issues, including battery drain until I eventually sussed that it was the loom. The sheathing disintegrates allowing various nasty things to happen.
It’s impossible to see without cutting back the outer loom plastic.
I was lucky and convinced Porsche that they should replace it as it should have been covered by a recall but wasn’t - too long a story to go in to here.

 

[vic cohen]

might sound silly but if its of any help , my electric window switch produced a very similar scenario....passenger side , only used occasionally ..........its easy enough to pull the wires off and see ......

 

[Gordon Attar]

Please remember that your alarms were in the main OPC fitted not factory fitted and don't have to be active to drain the battery, likewise an aftermarket radio cd or any other fault, even out of use trackers
Ref ammeter if it hasn't an inbuilt data recorder you will need to sit and watch it for an hour or two. Or take it to a specialist.
I would have the earth strap checked as well before going wiring loom root.

 

[davepaul993]

mine got flat once it was the bonnet switch leaving int lights on so swapped all outside n centre console bulbs to led`s
i still keep an eye on things but that was that
most of the time mines on battery master charger in between use.

 

[lindsay39]

My alarm is misfiring and generally when car is locked can discharge the battery in less than 3 days. (See my forum thread on this issue)