Now you mentioned that he is often jump starting his van and his heater runs from the starter
battery I believe. Wonder if that may have caused it.
Oh dear. Does he know how to properly jump start ? And why is he having to do it often ? Time for a new starter
battery I suggest, cheaper than an Eberspacher ECU, and it's not going to get any better, far from it.
Because if you do it in the wrong sequence there is a phenomenon called alternator load dump that can cause spikes of 80V or more, for quite a long time.
Same thing possible on a boat installation with the usual big
battery changeover switch that either isolates, connects starter only, or starter plus habitation batteries, or hab only. Turn that around whilst the engine is running and bad things might happen. The good thing about this arrangement is that you can still start the engine from the hab. batteries if the starter has died.
Proper automotive electronics are protected by circuitry on every ECU to block this, along with reverse polarity, I used to design them myself at a very high level for motorsport. Our standard protection circuit was quite simple but very strong, which cost maybe £2 for the components.
But by the time you have actually manufactured the ECU that adds perhaps ten times that much to the real cost. Which has to be passed onto the customer.
If eberspacher are good they should also have something like this to protect the ECU and make it bombproof. But that costs money. And, cynically there is profit in selling expensive ECUs to replace failed ones, name your price, the customer has no choice but to pay it. Do they ask for those back to do their own fault investigation, learn lessons and constantly improve them ? That would be difficult because they pot them up to make them almost impossible to take apart, never mind make it possible for other people to provide a repair service.
And will they still keep making them for the older models, or will they become unavailable, time to pay again for complete new one, start again. Well that's one business model.
Bad jump start scenario: Connect external
battery, maybe not itself fully charged, with jump leads.
Crank over vehicle and get it started and running. Alternator is now running hard to recharge both starter and the jump
battery.
Great, take off jump leads with engine running. Massive load dump possibly ensues.
Proper method, get it started then run engine for say 15 minutes with everything still connected together. Turn off engine. Take off jump leads and re-start with the charge that should by now have been put back in to the starter and take it for a good run.
There are other bad scenarios that can happen, e.g. connect another vehicle to jump from it, maybe a petrol car with a
battery that is not capable of cranking a big diesel. So you start that one's engine to add the alternator output that might add up to enough to do the job. So you got the dead vehicle started, great, then you take off the jump leads from the donor with it's engine still running. Load dump to the donor.
Try never to disconnect the leads with either engine still running. If you do have to jump a big diesel from a modest petrol car, connect them together, start up the donor, run it for say 15 minutes to put some charge into the big diesel, maybe keeping the revs up to get decent output, not just on tickover, tun it off, disconnect, then try it again.
