OEM leisure battery not charging [Resolved]

[ADub705]

Hi All,

I recently wired an aftermarket stereo and power amp (nothing huge) to the OEM leisure battery, in the case of the stereo to stop it power cycling on stop-start. The devices all work fine but the battery doesn't seem to be charging, I'm pretty sure all the wiring has gone back correctly but before pulling it all out again I wanted to check if there are any other checks to carry-out. For example:

1. Does the alternator only charge the leisure battery once the main battery is fully charged? This could be an issue with shorter trips.
2. My airbag warning light is on (because I switched the ignition without the seat cables connected) presumably this won't have an impact?
3. There's an 80 Amp fuse under the passenger seat that the charging cable connects to which is intact, do I need to check other fuses?

Thanks in advance for any help.

 

[Deaky]

If you're only doing short trips the OEM split charge relay will not charge the battery sufficiently. There is another fuse in the Ebox under the starter battery. The airbag light it not connected with your issue in any way.

Ideally you need to fit a battery to battery charger in place of VW's relay. If you've got a multimeter can you remove the 80a fuse and test for 12v? I'm assuming you can hear the relay click when you start the engine?

 

[ADub705]

Hi, thanks for your quick response, I couldn't hear the relay click upon engine start and checked the input voltage to the relay (the one in the picture with '100' on it) with a multimeter (with engine running) and there's nothing. Alternator is producing over 14 volts.



Can I confirm which other fuse you are referring to? Is it in this box next to the starter battery (all the ratings seem too low) shown below?

 

[t0mb0]

Hi, thanks for your quick response, I couldn't hear the relay click upon engine start and checked the input voltage to the relay (the one in the picture with '100' on it) with a multimeter (with engine running) and there's nothing. Alternator is producing over 14 volts.



Can I confirm which other fuse you are referring to? Is it in this box next to the starter battery (all the ratings seem too low) shown below?


View attachment 95158

View attachment 95159

Is the voltage 0v on the signal wire into the relay or the actual power feed from the vehicle battery or both? To put it another way, big wire or little wire?

 

[ADub705]

I tested the power feed but just gone and tested signal wire and that reads 13.9V when engine running (0V when off).

 

[Deaky]

I tested the power feed but just gone and tested signal wire and that reads 13.9V when engine running (0V when off).

Sounds like a faulty relay then if you can’t hear it clicking. The fuse box I was referring to is underneath the battery.

 

[t0mb0]

Sounds like a faulty relay then if you can’t hear it clicking. The fuse box I was referring to is underneath the battery.

Could be, but the power feed going in is 0v by the sound of it so that fuse box is probably the first port of call.

Unless the power feed measured was the relay output, not input,of course, in which case, back to the relay!

 

[Loz]

Can I confirm which other fuse you are referring to? Is it in this box next to the starter battery (all the ratings seem too low) shown below?

 

[ADub705]

Thanks for that, not the easiest fusebox to access...think I found the culprit though. None the wiser why it blew though.