On Mon, 10 May 2021 11:15:57 +0100, "Dave Plowman (News)"
wrote:

snip

Whilst it may start off with less Ah capacity, it may well have a
greater cold cranking current so more likely to start a car, assuming
it's willing to start easily.

Cold cranking is the one to look for.

Yup.

Looking at specs for these Li-Ion
packs,

Are they Li-Ion though? Mine is Li-Po?

If you don't know they are actually Li-Ion I'd just call them
'lithium' fir these purposes.

they seem to do anything other than quote in the same way as you'd
expect with a lead acid battery. I'm sure it's not a problem with a small
engine, but can be if looking for one which will cope with a bigger one
and maybe diesel.

As mentioned elsewhere, would you count an 1800 diesel in a Transit
Connect that wouldn't even start to crank it over to be a suitable
test? If so, my cheapo (well, free to me) Lithium pack started it
easily. ;-)

- is
going to be fine after 6 months, like for like?

Yes.

I'd say most Li-Ion jump
start packs ain't got the finest either, by the price.

But I'm not sure they need to, given what sort of CCA even low spec
ones can output.

But for how long?

Long enough to start a car that won't on it's own (probably several
times on one charge)?

They all seem to be much lower capacity than the older
lead acid jump packs.

Yes, but they aren't the same thing so you can't easily compare that
particular value. It's like trying to compare the performance of an
old design 1300 with a modern, fuel injected and turbo'd 1300.

Not a problem if the engine starts instantly, but
this may not be the case with an engine where a start was attempted with a
very low battery and failed - hence needing the jump start.

Nope, still not really a problem, as long as it isn't 'too' long.

I would say my (pocket sized) battery can spin an engine over faster
and as long as any portable LA based 'Jump start pack' I've ever owned
did. The big difference is I can't get the old one in my pocket and
the battery is usually shot by the time I dug it out to use again (and
so generally using an old car battery I've kept and some std jump
leads). Now, part of that may well have been because they were only
'cheap' packs (often on special from the local Car Parts place or
Maplin etc (but still with a 17AH sealed LA battery in it where the
spec suggests it was never meant for a SLI role).

Cheers, T i m