Brilliant synopsis as usual elekie doc.

So would you advise recovery to Main dealer for any modern car ?

Alarms me when motorists are persuaded to offer a jumps start by stranded motorist.

Just read the handbook-gives you the order to connect!

Exactly. That's one of the first things it tell you about in most handbooks. I suppose it may be that as many go electronic (pdf) only, perople forget to bring a copy with them on their smart phone, or at the very least print out and keep a copy of relevant pages (such as this, tyre pressures, other issues they may need to know about) in the glove box or car side pockets.

It also makes a lot of difference if the car is to be the one giving the jump start for another, including what order you do what.

The Mazda3 forum I'm a member of may well have the handbook for each generation of the car (perhaps not the gen-4 car yet) in electronic form for anyone wanting to check. Unfortunately I cannot exactly remember where it would be - the site does have 'workshop manuals', which aren't the same thing.

www.mazda3forums.co.uk/

I also read an article in Autocar about lights left on and a jump start but not sure if the OP found something else.

www.autocar.co.uk/car-review/mazda/3/long-term-rev...w

Its their long term test of the new Skyactiv X and the tester did indeed leave his lights on and call Mazda assist. But it was the parking lights not the dashboard lights which on mine at least are impossible to leave on in a parked car. Also no mention of "recovery firms have allegedly resulted in dashboard meltdown" which seems odd as every mechanic knows most modern cars have a problem if you connect jump leads wrongly.

Would be interested if the OP feels like posting the correct link.

Interesting thread. I am aware of the dangers of jump starts on newer vehicles and would always seek advice or guidance from the handbook. My Volvo does not have a handbook. It has a screen with My Volvo section that has all the information contained in a handbook but electronically. I wonder if the battery discharged fully then I could not access the computer screen for advice. Could be a problem. Need to look it up and take note. Coincidentally, yesterday I was parked next to Mazda 3. When I returned to my vehicle the dash lights of the Mazda were on. Which suggest it was parked in daylight and the owner didn't notice. I hope his battery had enough charge to sustain itself until his return. Cheers Concrete

My son got a work Berlingo van a few months ago which has resulted in him using his Fiesta once a week at most. The battery in the Fiesta was going flat, despite it being a relatively new 5 year warranty one. I checked that the interior light was off and told him to switch off the radio before the engine to eliminate that a cause. It turned out that he was accidentally using the Fiesta remote on occasions where the boot button is the unlock button on the Berlingo (why aren't these standardised?).

Anyway, the point of posting was the first time I had to jump start the Fiesta I used our old Panda, but the last time (before we realised what he was doing) I had to use my Astra with start stop and ATM battery. I was concerned that I didn't fry it and despite being fairly sure of the correct procedure, still read the handbook (paper and kept in car). No dire warnings other than to follow the instructions carefully. With the battery in the boot, there's a positive terminal under a cover under the bonnet, but it's not so easy to find anywhere to connect the negative that is bare metal and chunky enough to take the current.

Fond memories of my first car, the only one that had a starting handle. It was a much-loved 14-year-old 1955 Austin A50 whose compression ratio was so low that a gentle half-swing on the handle was enough to start the engine, first time every time. I only used it to save the battery on a cold morning, but it wasn't strictly necessary.

The handle had a useful 'barber's pole' groove at its end which made sure that it was thrown out when the engine started, rather than breaking your thumb.

Thereafter I had a run of transverse-engined cars, but in any case compression ratios were going up and most cars after about 1980 would be impossible to start with a handle. A pity, especially as nowadays there are so many more electrics that can be left on accidentally, or leave themselves on invisibly like boot or glove box lights.

If I recall correctly, it specifically says in my car's handbook that it should never be bump-started. I suspect it's the same for most, if not all modern cars.

I think the best advice we can give on this forum is: Don't provide or accept a jump start unless at least one of the drivers knows what they're doing.

One other thing I found out when needing a jump start is that the car giving the jump start must have a higher engine output (not sure if torque and/or power) than the one being started. Not doing so will damage the former.