I've read a few posts on this matter so just want to check I'm on the right track. A bit of necessary history first.
My brother's 330ci convertible had a flat battery about 2 months ago (it was the original battery). So he took it his local mechanic and got a brand new battery fitted - a real cheapo budget brand (the tightwad!).
A week later when I was driving it around, the new battery unexpectedly died. So two batteries dead in a matter of weeks, we suspected the alternator. Although the AA breakdown guy did say that he thought on voltmeter thingy that the car might have been draining power when the car was turned off. Anyway my brother took it to his local mechanic again and got a brand new alternator fitted. At this point I had noticed that the positive battery clamp (the circular metal part that fits round the battery post) was loose, and had a big crack in it, but it was solid enough for the time being.
As soon as the new alternator was fitted the airbag light was permanently on. The mechanic said he would get round to clearing the code/fault when my brother brings the car in next time, and not to worry about it. Also the red battery light was on intermittently. Once again the mechanic said this was just down to the cold weather. I did think it strange that temperatures of worst -7c would cause this to happen, but my bro just took the advice of the mechanic.
Over the next 3-4 weeks cars been driving fine, albeit with a constant airbag light and a constantly flashing battery light.
Just yesterday the battery completely died. I had a look at the positive battery terminal and that previously loose clamp has now just split in half. Although, arguably it was solid enough not to be displaced during regular driving, but then I can't seem to think of any other reason why battery light should be flashing on and off when driving only.
Been having a look around and it seems you can't just replace the clamp part but the entire safety battery terminal clamp, which seems a bit expensive.
My brother's abroad for 3 months so I get to drive that car but also fix the problem :(
Have taken battery out and recharged it fully and it hooked it (not safely) back up and car starts fine. Have not driven it yet.
Firstly, would a roll of insulation tape holding the two broken clamp parts together serve ok as a short term/medium term solution.
Secondly, is the safety battery terminal (SBT) the real problem here. I've read that it's got something to do with airbag deployment in the event of an accident. The car definitely hasn't been in an accident, but it seems coincidental that airbag light is on when there is a problem with the SBT. Was that the problem in the first place? Did my brother's mechanic just replace an alternator for no reason?
Have found a pdf which details how to replace the SBT part, and have found the part on ebay
Any ideas suggestions on how can I found out the exact problem without an error/code checker tool. As I don't want to fork out for the part if the problem is elsewhere and/or if a bit of blue tape and solder will do the job.
Will post picture's of the broken clamp shortly.
Thanks for your help.