Battery Booster Packs

Agreed - it is best avoided, if possible. There are some situations where it just isn't avoidable (e.g. dead battery on the side of a fast road, which should be very rare), but it's better to remove, recharge and replace if you can, or recharge in situ. If you have to recharge with an industrial fast-charger it's best to disconnect the battery from the vehicle electrics as well, as they can apply much higher than normal charging voltage.

Some parts seem to be more vulnerable than others - on a VW T5 it's the ABS brake controller - and that no doubt varies from make to make.

Tinwheeler wrote:Dealers do it all the time to the vehicles sat on their forecourts. They can’t keep every one of them connected to smart chargers.

Probably true, and the chances of causing a failure are probably very low indeed - but the parts are so ridiculously expensive if you do cause one to fail that it is worth avoiding. On a T5, the ABS controller is roughly a £2000 part, and that's before it's been fitted and coded...

Are the jump starting points under the bonnet provided for just this purpose??

Molly3 wrote:I was told not to jump start a modern vehicle  with the doner vehicle engine running, as the engine starts it is hit with the output of 2 alternators,

MB instructions include "run the donor vehicle's engine at idling speed", which has been my understanding for all vehicles.