Is this better than jump leads ?

Lets put it this way, a cig lighter socket fuse is usually rated at 10 amps and a car uses over 80 when cranking. Does that look like it can supply 80 amps?

OK for trickle charging a battery but I'd not use it for jump starting a car.

OOO I see not enough power. I guess the old fashioned way for me and my oldie cars :) ... well only when I do something silly like leave a light on and come back to a flat battery the next day. I was hoping something like this owuld save me some embarrasement from the neighbours going "oooo look shes done it again third time this month dopey cow"

you still need another car as a power source, you then need to leave the lead connected for at least fifteen minutes to transfer some power, then, hopefully your car will start.

I have used one of these and it is fine as long as you have time. When the battery is flat there is no time, no spare car or nowhere to put the second car close enough.

Still for the price.............

That gadget will work, but you'll have to leave it connected for an hour or more before you can start the disabled car. Trad jump leads will do the job in 5-10 mins.

And decent ones will do the job instantly.

Not on a modern Turbo Diesel, they won't.

I've had a jump pack *and* jump leads connected up and still had to wait around 10 mins to get enough power in the battery to fire it up.

The AA bloke even had to leave his FOAD jump starter hooked up for 5 mins before he could fire it up, too.

Ford Scorpio 24v and FOAD jump leads, will start near enough anything - including a really shady old diesel engined tractor that hadn't been turned over for around 15 years - needed about 2 minutes solid cranking and a burning oily rag shoved into the inlet manifold to finally start the bastard thing, but the Scorp was more than up to providing the power.

Means either the jump leads are of insufficient capacity or the connections poor.

Means he didn't make a decent connection for whatever reason.

It's only really a question of making a good low resistance connection between the batteries so enough current can flow. The actual clip connection can be a problem with some types of battery terminal. And of course the length/cross section of the leads.

80?

You can add a zero to that if it's a large petrol or a mediumish diesel on a cold morning.

Typically 1200- 1600amps for a big diesel at least.

Tim..

Or even removing the earth lead off the battery and connecting the jump lead to that so you're not trying to charge the battery and turn over the car...

Really? How does it do that without melting the cables?

That makesa sod all difference after the first couple of seconds on a car though.

Briefly.

Battery taking about 8amps and starter around 250 amps. Aint gonna make much difference.

Also, is it just me or does anyone else find the term "earth" for the negative system on a car annoying? I know its traditionally called that, but nothing could be further than the truth with those four black insulators on each corner of the car. Ok, so I called it that when I was a youngster in the seventies, but then went into electronics and it always grated on me from then onwards.

In electronics it's still called "ground". Even on mobile phones, etc., which are just as isolated from the physical Earth / ground.

If it is equipment connected to an earth wire which is eventually connected to an earth spike in the ground then that is correct, but that can never be the case with a car mounted on four giant rubber insulators. Its a pedantic point I grant you, but technically, nothing on a car can be considerd at earth potential and as I said, speaking as an electronics engineer, it niggles mean when its called that. No problems, just not technically correct, thats all.

Come on Conor. You are conveniently ignoring the original point. Whether its

250, 400, or 1200 amps is all a matter of the vehicle type, but the premise is sound that the maximum current a battery will draw is miniscule compared to the cranking current.

It isn't be technically correct but even in electronics, e.g., IC pins are still labelled "ground" even if they are not electrically connected to the ground - for example on portable electronic devices!