12v battery light

[Stup]

Does anyone have experience of the 12v battery light intermittently showing when driving? Same with a new battery..

Last week we had a storm, next day i had this light and the iKey fault with a load of other crazy behaviour. I had to disconnect the 12v battery to get the car to power off! I'm assuming water in the BCM as it was a bit wet in the area. iKey and other problems are now gone but the 12v light is coming on..

Any ideas for things i can have a look at?

 

[alozzy]

Make sure the battery posts are clean, that it's fully charged using an external 12V battery charger, and that the main battery negative's ground is securely fastened to the body. That ikey fault, and related trouble codes, is most often caused by a low voltage 12V battery - either due to poor grounding, a discharged 12V battery, or a bad 12V battery

 

[LeftieBiker]

Before you do the above, turn the car off with the hood latch released and driver's door unlocked, so when you measure the rest voltage of the 12 volt battery 30 minutes later there won't be a drain on it. If good and charged, it should read 12.5 - 13.0 volts. If it's much lower than that, then you have a weak 12 volt battery or there is a 'phantom drain' on a good one.

 

[Stup]

Thanks for the ideas.

Looks like it's not charging the 12v at all. No error codes in leaf spy after reconnecting the battery and powering the car on.

Voltage drops from 12.6 to 12.3 instead of increasing to 13-14, with the motor enabled.

I've checked all fuses that i can find, in 4 plastic compartments on the engine bay and checked the ones that are on the positive cable near the 12v battery connection.

Any ideas for anything else i can check?

 

[Stanton]

I'm assuming water in the BCM as it was a bit wet in the area. iKey and other problems are now gone but the 12v light is coming on.

After everything you've mentioned the above comment is troubling; you should see at least +13v at the battery when on/charging (and more when the wipers are on, etc.). I think you're looking at a trip to the dealer.