Initially, I'd go for the cheap test of getting a battery tender and leaving it on all the time it is not in use to see if matters improved. (Aldi/Lidl ones are cheap and effective). Assuming it is garaged or has power available.

Other than that, I find modern batteries cause problems at around 5 years old, so it may be worth him putting some pennies aside for a replacement. It is usually at this time of year with cold batteries that problems start up.

Does the radio data and clock data seem fine when switching the ignition on and disapear when starting?? I would guess so and indicates volatge dropping too far when starting up.

I have just repaired a BMW (different model) of similar vintage with charging problems, giving very similar symptoms.

Firstly check that the alternator is made by Bosch - Valeo machines are not suspect. A batch of Bosch regulators made in the UK (S. Wales) are suspect, and fail due to a water soluble adhesive being used to cover the hybrid chip. The water boils and steam blows the lid, destroying the sealing integrity.

Replacement regulators (the part number changes) are made in Mexico and do not exhibit this fault.

Changing the regulator/brusbox assembly is completely straightforward. On some installations it can be done in-situ. Any vehicle of this vintage (M-B, VAG etc) will exhibit this problem if this regulator is fitted. Genuine Bosch Mexican regulators are available online more cheaply if bought under the "cargo" label. You will need to enter the original part number (FOOM....) and get the updated part. There are lots of configurations and termination options to suit different vehicles. BMW use +15 and 61 on the 2 pin connector.

Bosch have closed the S. Wales factory.

659.

Edited by 659FBE on 30/01/2014 at 11:28