On Sun, 09 May 2021 13:31:57 +0100, "Dave Plowman (News)"
wrote:

In article ,
newshound wrote:
On 07/05/2021 22:26, RJH wrote:
Would it be OK to charge on of these:


https://www.walteronline.com/en/tool...mpressor-p3155

(jump starter/compressor/light/USB) by connecting the jump leads to a car
battery charger, rather than use the supplied AC adapter?

IME these are pretty indifferent products, they don't contain much of a
battery, and the compressors are feeble too. Being lead acid you do have
to keep them charged regularly.

Eh? Lead acid self discharge very slowly.

But maybe they discharge quicker than lithium?

I have a couple of Lithium Ion car starters, and they are brilliant. The
smallest is literally pocketable, about half the size of a standard
paperback and will still fit in a jacket pocket with the leads and big
croc clips. This is more than enough for a 1.3 petrol engine.

Interesting. The Lidl jump start pack I mentioned which has an 18 amp.hr
gel battery has been used to start my 3.5 litre V8 Rover. Recently. The
Li-Ion one I also have says up to 2 litres and this was certainly true, as
it wouldn't even attempt to turn the engine.

But those results don't seem to match the general experiences of
others. I have at 2 'shells' of LA based 'booster packs' that used to
contain ~17AH sealed LA batteries that were written off because the
batteries died, often from lack-of-use and you could generally buy a
complete new unit for less than the price of a replacement battery. I
did re-battery one once then when that was found dead, never bothered
again.

The larger is about 20x10x6cm and I am sure would do a large petrol or
small diesel engine.

I'd want to be certain, rather than sure.

I've started daughters 1800 diesel Connect with my Lithium pack and it
did so easily? That said, as long as it can spin over a couple of
times at a reasonable rate it does seem to start fairly easily.

Check the specs for starting
current, not so called peak. And the capacity of these Li-Ion packs (at a
reasonable price)

I'm not sure they are Li-Ion but Li-Poly?

are much less than the equvalent lead acid types. Oddly,
they all seem to quote in mA.hr. Wonder why that would be, since car
related batteries are always amp.hr.

I think it's because they have come from an environment (RC Models
etc) where batteries were generally rated in mA. shrug

However, a pocket sized LiPo could have the same CCA as a LA battery
10x the size.

Cheers, T i m