Stereo battery drain

[a8rnx]

Hi guys, hope you’re all well.

I was wondering if anyone can help with a battery drain issue I have been having for the last two weeks.

Recently purchased a 2005 5 door gti. Seller fitted a new battery prior to collection, two days later the vehicle was flat. Numerous days of jump starting, no luck drying straight away.

I then removed the battery and charged this 100%, to which it died again the following day.

I then had the vehicle looked at as there was clearly a drain but this could not be resolved.

In the last few days, I removed the MFD2 sat Nav the vehicle came with and replaced it with a normal mk5 CD player, the car then died again the following day.

As of Wednesday this week, I stripped the CD player out and left no stereo in the vehicle at all. The car has been fine in the last 2 days and has fired up every single time.

What can be causing this drain as connecting both head units still drain the battery.

I didn’t think a new gateway module would be required if the original head units are draining the battery and I haven’t fitted an aftermarket system?

Any help would be really appreciated

Cheers

[pudding]

Early RNS510s could flatten the battery, but later ones (Revision P onwards) could have a firmware flash to fix that problem.

I have no idea what an MFD2 is, but could be a similar problem.

I agree, a newer gateway shouldn't be the fix as it can create other problems.

You will need to perform a parasitic draw test if you have a decent multimeter.  Plenty of info on Google on how to do it, but it basically means connecting an amp meter to the battery and pulling each circuit's fuse until you see the parasitic draw drop.  Normal draw is around 10 milliamps.  You should be able to leave the car standing for at least 2 weeks without the battery dying.

What quality/brand of battery?

Might also be worth checking the integrity of the main battery to body/engine ground straps.

[a8rnx]

Hi mate, thanks for your reply.

The unit in the car at the moment is a very early factory sat nav unit, also known as a MFD2.

I have tested & charged the battery even though it’s brand new. The battery itself is a Banner 12v 60Ah 480A & is two weeks old.

I don’t believe it to be the battery as I tested that tonight and is pulling 12.7v with the car off and 14.6v with the heaters, lights, heated seats etc all on so I know the battery and alternator are good.

Seems very strange for two stereos to be draining the battery within hours. Even when the car died with the MFD2 fitted you could see the red power light on the unit itself still being lit with no power in the car to be able to even unlock it via fob, this had to be done using the key hole.

[colesey]

Think it might be the can bus which needs updating. I had that problem with my 2006 car about a dozen years ago.

[LC5F]

Have you checked that the alternator is producing enough charge? - engine on, you should see around 14v at the battery terminals

Temporary fix + confirmation radio & canbus are not getting along do this:
https://www.mk5golfgti.co.uk/forum/index.php?topic=37977.0
It switches the radio always on power over to ignition on, takes longer for the radio to boot up... but if your battery stays alive with this, you know it's canbus not putting car in sleep properly.

The battery supplied by the seller looks quite low 60Ah & 480 crank amperage, it has a lot less headroom for drainage before the Golf wont start - even the basic Halfords one is 75Ah / 680ccA

[LC5F]

They are just your standard blue crimp connectors, easy to find - most car folk have have them lying around.

You need 2 male / 2 female, the terminals of the fuse fit into female connectors and male connectors into engine bay fuse board - bit of insulation tape between the female connectors going onto the fuse to stop them touching.

[a8rnx]

Hi guys,

So I completely removed the stereo leaving the a hole in the dash & the car stayed alive starting every morning without fail for a whole week. I used the car most evenings and it’s been completely fine.

I then used the car on Monday evening and now just popped out to it and it is completely flat, dead as anything.