Jumper leads or lithium jumper pack?

[Plasnart]

For what it's worth, I have one, that started a long stroke Diesel motor on a water pump that hadn't been started in a number of years and it had enough grunt to get the thing started and I'm pretty sure the battery it was"jumping" was dead flat. I think that's sold them for me

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I was there that day. First attempt on that pump was with jumper leads. No luck. You suggested your tiny little jump pack. I thought no way. Your tiny jump pack kicked its arse. My eyes fell out. Game over!