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From: dennis on 5 Sep 2009 15:14


"Dave Plowman" <dave(a)davesound.co.uk> wrote in message
news:50961f9d90dave(a)davenoise.co.uk...


> Oh - would you encourage your missus or daughter to ask for help from a
> stranger at night - rather than calling the AA, etc?

Most murders, etc. are from people the victim knows so asking a stranger is
probably safer.



From: Clint Sharp on 5 Sep 2009 15:16
In message
<e41259f2-a71f-49b5-8d60-424e0a0c914e(a)a7g2000yqo.googlegroups.com>,
RubberBiker <dom(a)gglz.com> writes
>Do you really see a little glove-compartment sized battery turning
>over the starter motor on a car?
That's not the point, the idea of many of the booster packs and 'normal'
retail jump leads is to charge the battery to the point where it can
start the car.
>Starer motors draw around 80A.
And the rest.
>
>That's why jump leads are thick heavy wires.
Ever dissected a set? Most are just lots of thick insulation.
>
>Is that little flex and a cigarette lighter socket going to pass 80A?
>
>Still - it can probably deliver enough juice so you can listen to the
>radio until someone arrives with jump leads.

--
Clint Sharp
From: dennis on 5 Sep 2009 15:49


"Clint Sharp" <clint(a)clintsmc.demon.co.uk> wrote in message
news:BBszeUIGkroKFwjb(a)clintsmc.demon.co.uk...
> In message
> <e41259f2-a71f-49b5-8d60-424e0a0c914e(a)a7g2000yqo.googlegroups.com>,
> RubberBiker <dom(a)gglz.com> writes
>>Do you really see a little glove-compartment sized battery turning
>>over the starter motor on a car?
> That's not the point, the idea of many of the booster packs and 'normal'
> retail jump leads is to charge the battery to the point where it can start
> the car.
>>Starer motors draw around 80A.
> And the rest.
>>
>>That's why jump leads are thick heavy wires.
> Ever dissected a set? Most are just lots of thick insulation.

Depends on the car..
I tried to jump start a Merc diesel a couple of months ago.
I put on my jump leads which are 10 mm2 copper (from System X exchange power
distribution) and got sod all.
I had to fit a second set before I could start it.



From: NT on 5 Sep 2009 15:54
On Sep 5, 6:27 pm, "Fredxx" <fre...(a)spam.com> wrote:
> "Bod" <bodro...(a)tiscali.co.uk> wrote in message
>
> news:7gfl0cF2pd0kaU1(a)mid.individual.net...
> > NT wrote:
> >> On Sep 5, 5:49 pm, RubberBiker <d...(a)gglz.com> wrote:

> >>> Do you really see a little glove-compartment sized battery turning
> >>> over the starter motor on a car?
>
> >>> Starer motors draw around 80A.
>
> >>> That's why jump leads are thick heavy wires.
>
> >>> Is that little flex and a cigarette lighter socket going to pass 80A?
>
> >>> Still - it can probably deliver enough juice so you can listen to the
> >>> radio until someone arrives with jump leads.
>
> >> £40 would get you a toolkit that works. Just teach them how to push
> >> start it, and to engage gear when there isnt enough power to turn the
> >> engine over.
>
> >> NT
>
> > I thought starter motors draw a couple of hundred amps.
>
> They tend to.

yes


> The idea of plugging a small battery into a a cigar lighter socket is to put
> a sufficient charge into the car battery so it can then turn over the
> engine.  If the car battery is completely naff, then this whole idea fails.

jump leads are somewhat slow at givig enough charge to a flat battery
to get it to start, imagine how long it would take using a bit of
speaker wire!


NT
From: NT on 5 Sep 2009 16:02
On Sep 5, 8:26 pm, Andy Burns <usenet.aug2...(a)adslpipe.co.uk> wrote:
> On 05/09/09 18:29, Peter Parry wrote:
>
> > The car
> > lighter socket is rated at 10A, the starter on a cold day can draw
> > 200A.   If the battery is just a teeny bit flat (it never is) plugging
> > it in and leaving it for an hour might transfer just enough power to
> > give you one brief go at starting but I wouldn't bet on it.
>
> If the gizmo's battery holds enough charge, then 10 amps for 10 minutes
> could charge the car's battery enough to give 200 amps for 30 seconds,
> ok in practice perhaps half of that allowing for efficiency losses, but
> if the car won't start in 15 seconds of turning over you've got more
> problems that a flat battery...


The trouble is you'll never get 10A. When charging, battery terminals
go up in voltage. When discharging, they drop very slightly - in both
cases the exact opposite of what you want to get decent current flow.
Hnece to get anywhere you need extremely thick cable.


NT
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