jump starter battery

[T i m]

No, I agree, but only (IMHO) when you aren't taking into account the 'bigger picture'. Many of these portable batteries are also used for charging portable devices where the battery measurements are in mA because they still are often a fraction of an amp. I would know how many 500 mAh's you could get out of a 10 Ah battery pack but many wouldn't.

Yes, but at least they are still in the same base.

No, I don't think it is, considering the understanding of most buyers. Many wouldn't realise that 10 Ah is bigger than 8000 mAh.

I don't believe cm are std units(?) and with m you are bound to have sub m measurements, even on a building (29.99m etc). So, would 29990 mm be that much more complicated? The sign might be 3000 x 1500 x 100 and therefore also in the same units scale.

Not quite the same but wasn't it 'just' an Imperial V Metric error that caused the loss of the Mars Climate Orbiter?

Cheers, T i m

[T i m]

And me ... in fact I quite enjoyed learning about all the different measurement units and the history behind them (especially the electrical ones like Ohm, Henry, Volt and Kelvin etc).

And so it all made sense. I have been 'lucky' that I been interested in science from an early age and so 'took on' all the information that I could that I came by re 'our world' (and even outside of it). ;-)

I can't remember how many times I've been able to assist, guide or warn people of something, simply because I understood the science (to a basic degree) and the units. Skills (inc rough / mental arithmetic) mostly 'assumed' by the 'old skool' folk but seemingly fairly rare in many younger people today? ;-(

Cheers, T i m

[Bob Eager]

My grandmother was a whiz at mental arithmetic. So was my mother (particularly good at working out racing odds).

I am pretty good too (my teacher always thought I was cheating). And #2 son is the same (and he's 19).

[Dave Plowman (News)]

When I was a kid in the '50s, one 'duty' was to do the shopping at the local Co-op on a Saturday morning. Just the usual stuff a family needed for the weekend - before fridges etc arrived.

And as well as a list, my mother gave me the *exact* money. Of course there was retail price maintenance in those days so all shops charged the same.

[T i m]

Many that I have come across have, just using an old car battery (and not a particularly big one, with a built in handle) and some short (1m) jump leads.

I think a key is that the jump battery has good level of charge in it itself and that, plus the residual charge left in the vehicle battery is enough to get it running.

In fact I don't think that process has ever failed, given that the vehicle was willing to start, given half a chance and that the vehicle battery wasn't quite enough to spin it over (rather than dead flat / faulty etc).

It's certainly never failed to start any of the motorbikes. ;-)

Cheers, T i m

[T i m]

It's funny, I don't think you can ever predict someone's skills in that direction until you play them a 501 (darts). ;-)

I can visualise the position but rarely come up with an accurate answer (especially these days). Like, if we are about to pick up 10 rolls of turf and they are of typical weight then they shouldn't overload my trailer by a reasonable amount (not a guess but a rough_and_ready evaluation).[1] ;-)

An that's the thing, to those of us who can't do (reasonable level) mental arithmetic, it does seem like those who can are cheating (even if we know they aren't). ;-)

Cheers, T i m

[1] 10 x ~20kg in a 275kg (payload) trailer. ;-)

[Dave Plowman (News)]

Yes. If there is some charge left in the battery, the jump start one does a lot less.

[F Murtz]

It seems these things are the go nowadays.