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Battery issue


ShootingEgg
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11 minutes ago, ShootingEgg said:

My battery is getting charged when on. So not pointing at alternator but who knows.

If the battery is draining back through a defective alternator it will show up as a parasitic draw.

You've already said there is no draw.

So, does the battery discharge when disconnected? if so it can only be the battery, if it only flattens when connected you must have a draw.

If you're confident you're measuring it correctly and it's below 0.05amps then there is a possibility something is repeatedly waking up the BCM.

I don't know if FL2s suffer from this, but the old P38 Range Rovers certainly did and I've seen it on a few other makes as well.

This is going to be interference from something electrical, phone mast, cctv, some outside lights can do it, that sort of thing.

The car will think you are approaching with the keys and gets ready to activate various systems when you get in, while it's in this state it may draw around half an amp, it then goes back to sleep when no one unlocks the car, repeat this often enough and you have a flat battery.

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25 minutes ago, Wymondley said:

the battery is draining back through a defective alternator it will show up as a parasitic draw.

I put the tester on the earth lead, and saw 0amp then saw a draw when turning lights on. This was when the engine was off but car unlocked.

 

I've not done much more recently due to work and other things I have on. 

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Like I said earlier, you need to lock it with the fob and watch what happens on the meter to get a true reading, amps peak, then drop off gradually to around 0.05 amp, it can take several minutes to do this.

It may need the bonnet closed to lock and arm the alarm so just extend the meter wires if necessary. 

Keep an eye on it for as long as possible.

All this assumes the battery is good and doesn't go flat when disconnected.

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  • 2 weeks later...

I had one - I would park the car up at the train station, and on return it would be flat - necessitating a call out to whichever breakdown I was with - eventually traced to the boot light not switching off... It was funny as I never had problems with it setting off from home after being parked overnight....

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On 20/12/2022 at 08:13, discobob said:

I had one - I would park the car up at the train station, and on return it would be flat - necessitating a call out to whichever breakdown I was with - eventually traced to the boot light not switching off... It was funny as I never had problems with it setting off from home after being parked overnight....

I removed the bulb ages ago thinking it was that

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