I have had something not dissimilar for more than 20 years. It was worth it’s considerable weight in gold when my MR2 developed an unexplained habit of sounding the alarm but only in the middle of the night - hooking up the booster silenced it again. If I remember right it had a new battery and a new alternator, but still persisted. It mysteriously stopped and never returned, anyway I digress.I have this one:
It's the cheapest Halford's do... so not suitable for any gadget-lovers on here.
It's a bit heavy (being a traditional Lead-Acid battery and not some fancy Li-ion), but it so far started any 4-cyl Diesel or Petrol car I tried it on.
(Well, it didn't crank my neighbour's A4, but I suspect his battery was knackered and short-circuiting).
What do you recommend for w211 270 cdi for personal use?