[sam-able]

My 2006 e91 330D was recently without its alternator for a few weeks after a mobile mechanic failed to fix my issue and left the car stranded in my parking space.

I eventually got the car to the garage where they replaced the alternator (at that point I thought it was likely the issue and couldn't be bothered to pay for them to replace the old one to diagnose only to have to take it out again if it needed a new one. They also replaced the battery control unit and the cable connecting it.

I picked it up and everything was fine for a few days until I got the 'key not recognised' light while I was driving, and after a brief stop, it wouldn't start. I managed to get it going with the spare which was tucked away, low on battery, but working - I've unbelievably since lost the spare ).

Now the car always starts first go, but then won't always start again for 20-40 minutes, showing the 'no key' light.

I've done some reading and everything suggests that it's a battery/power/ground issue, but the garage took another brief look today and say they can't see any issues.

Has anyone had a similar issue? The fob opens the car no problem, no low battery light, starts the first time without issue, but after that it won't recognise it for a while.

Photo is my battery/bcu as it stands - something I read suggested there should be a cable connecting the IBU to the blue dotted connection? When I mentioned this they said the IBU was connected.

tldr; Can stops recognising my keyfob for about half an hour after cutting the engine, otherwise it works fine.

[sam-able]

I thought I'd worked out that holding the key in when trying to start worked, but it doesn't always.

What I have realised is though, is that the battery and alternator are only registering at 10-11v while running - I'm now assuming I should take it back to the garage that fitted the new alternator.

Does anyone recognise this at all?