Is there an auto-electrician in the house?

[swee'pea99]

Disconnect battery leave for a week, see if battery drains when not connected it's battery. if not then start looking for problems.

Interesting. Definitely worth a try. Thanks for that.

 

[swee'pea99]

Have a Google at "parasitic draw test" you could give it a go yourself if you feel confident enough.

I did. I don't.

Fingers crossed nothing to serious.

Thanks.

 

[Smokin Joe]

Put your phone on video and shut it in the glovebox and then the boot. That will either confirm or eliminate them as the problem.

 

[swee'pea99]

Put your phone on video and shut it in the glovebox and then the boot. That will either confirm or eliminate them as the problem.

Another Top Tip, ta. I'll definitely try that when I put the battery back in the car.

 

[bruce1530]

Do you have a dash cam or phone charger plugged into the lighter socket?

 

[swee'pea99]

Do you have a dash cam or phone charger plugged into the lighter socket?

Nope. I also discovered earlier in this saga that mine lighter socket is one of the ones that goes dead when the ignition's turned off, regardless of whether anything's plugged in. But thanks for the thought.

 

[DRM]

Yeah could be one dead cell

even though the OP says it’s been on 6 months, how long was it on the shelf before being fitted, this could lead to a dud new battery as they don’t like been left for along time without being charged, also I’ve heard of people that live near mobile phone masts, the radio signals can wake the engine management pcb causing faults such as this as it should sleep when the ignition is off and car locked

 

[swee'pea99]

Disconnect battery leave for a week, see if battery drains when not connected it's battery. if not then start looking for problems.

Couple of days ago it was reading 13.4v, 48 hours later it's on 13.27. Would I be right in thinking that pretty much rules out a battery problem?

 

[CXRAndy]

You need a digital multi meter, ideally two to make the job easier

. Lock the car and remove remote from vicinity. leave bonnet open obviously.

Disconnect the negative battery lead, place meter in DC amps reading setting. connect between battery and measure current. The current will be several amps, but quickly drop down to milliamps, then after 10-30 mins go down to less than 20mAmps if car is working properly.

If current remains in high mAmp range then something is not going to sleep or there is a current leak.

Next step. reconnect battery lead. let car go to sleep for 30 mins

Use you meter in DC millivolt range. Measure across each fuse noting any that have a few millivolts measurement. Note down the circuit the fuse feeds. Then one by one remove fuse and see if current draw from battery drops down to less than 20mA after a period. Once you've isolated offending current draw. Its a case of aquiring a wiring diagram or get auto electrician with your found diagnosis to delve further.

 

[swee'pea99]

You need a digital multi meter, ideally two to make the job easier

. Lock the car and remove remote from vicinity. leave bonnet open obviously.

Disconnect the negative battery lead, place meter in DC amps reading setting. connect between battery and measure current. The current will be several amps, but quickly drop down to milliamps, then after 10-30 mins go down to less than 20mAmps if car is working properly.

If current remains in high mAmp range then something is not going to sleep or there is a current leak.

Next step. reconnect battery lead. let car go to sleep for 30 mins

Use you meter in DC millivolt range. Measure across each fuse noting any that have a few millivolts measurement. Note down the circuit the fuse feeds. Then one by one remove fuse and see if current draw from battery drops down to less than 20mA after a period. Once you've isolated offending current draw. Its a case of aquiring a wiring diagram or get auto electrician with your found diagnosis to delve further.

That's very kind of you, and thanks for taking the time to really make it clear. But it's not going to happen. This is just not a kind of thing I feel confident in/have a feel for/any experience of. It's like detailing a wheel hub rebuild to someone who can't fix a puncture. I do need a chap. But like I say, thanks, seriously.

 

[swee'pea99]

Couple of days ago it was reading 13.4v, 48 hours later it's on 13.27. Would I be right in thinking that pretty much rules out a battery problem?

After a week (out of the car - just sitting here in the corner of the room) it's fallen from 13.4 to 13.1. I'm guessing that's normal, and no sign of anything amiss. Or am I wrong, and it should read the same as it did a week ago? Thanks for any advice.

 

[CXRAndy]

After a week (out of the car - just sitting here in the corner of the room) it's fallen from 13.4 to 13.1. I'm guessing that's normal, and no sign of anything amiss. Or am I wrong, and it should read the same as it did a week ago? Thanks for any advice.

Yes battery is fine if its only dropped 0.3V .

Ambient temperature can affect the battery voltage slightly.

 

[swee'pea99]

Yes battery is fine if its only dropped 0.3V .

Ambient temperature can affect the battery voltage slightly.

Thanks. That was my gut instinct but nice to have it confirmed.