My battery is 'flat' ?

[MikeM100]

Anyone have any idea as to how this expression came about ? 'Empty' or 'low' is understandable but why 'flat' ?

[barrymagrec]

I have always assumed it refers to use of a hydrometer to test the specific gravity of a lead acid cell, a low or "flat" reading indicating a discharged cell - I could easily be wrong though.

[Peter.N.]

That sounds about right.

Peter

[dseymo1]

Perhaps by analogy with a flat tyre, car batteries causing perhaps the most obvious trouble when discharged?

[Terry_VK5TM]

Perhaps as in when a person is feeling "flat" - IE lacking in energy?

[Bookman]

Here is another possible answer as derived via the www; it refers:-

"This use of flat for an electric battery was first used in 1951 according to the OED (sense 9c). The others related senses are: 9a) wanting in energy and spirit (1604); 9b) depressed, dull or inactive trade (1831); and 9d) a drink that has lost its flavour or sharpness (1617)."

I particularly like the latter anology

[Jon_G4MDC]

Wasn't the Polaroid land camera first to have a "flat" battery but when fully charged?
I think so but happy to discuss.

[AC/HL]

That's physically flat, the question was about electrically flat.

[Graham G3ZVT]

We say flat beer, flat broke, flat tyre, meaning empty or lifeless.

We also say "flat out", meaning quite the opposite!

[Terry_VK5TM]

Originally Posted by Bookman

"This use of flat for an electric battery was first used in 1951 according to the OED (sense 9c)....

I came across another mention of the above on another forum (didn't save it, will see if I can find it again), that mentions the use of "flat battery" in a car(?) manual from around the mid to late 1940's.

So the term itself doesn't seem to be (relatively) that old.

Found it:-

https://english.stackexchange.com/qu...attery-is-flat and it was 1941 and not a car manual - halfway down the page.

[terrybull]

I think Rambo1152 has it. This is from Google and seems likely to me.

The word “flat” can mean (according to the Google dictionary) “lacking interest or emotion; dull and lifeless.” This definition fits pretty well, in a figurative sense, with a flat battery. ... But an American would be more likely to say they have a “dead battery”

[boxdoctor]

I remember in the 1940s my father referring to warming the failing twin-cell cycle lamp battery off his bike by the fire-side because it was "flat", so the term is not that recent, I think.
(Incidentally, this process would give him one extra trip to and from work before he had to buy a new battery. ) Tony.

[Peter.N.]

I remember doing something similar, it effects partial 'depolarization'.

Peter

[barrymagrec]

Originally Posted by Peter.N.

I remember doing something similar, it effects partial 'depolarization'.

Peter

The storeman at C.A.S.T.E. Bletchley Park used to do that with the pentorch batteries which he would only issue if you gave him the old ones back...

[emeritus]

I remember mum saying that, during the war, they would sometimes put their No.8 torch batteries in a warm oven to get more life out of them: new ones were often in short supply.

[Paul Stenning]

We did that in the 70s as kids, put radio and cassette recorder etc batteries on heaters and radiators to get more life out of them. It got a few more hours use out of them.

[stevehertz]

Originally Posted by terrybull

I think Rambo1152 has it. This is from Google and seems likely to me.

The word “flat” can mean (according to the Google dictionary) “lacking interest or emotion; dull and lifeless.” This definition fits pretty well, in a figurative sense, with a flat battery. ... But an American would be more likely to say they have a “dead battery”

I read a lot of US forums and they frequently talk about "bad" components where we would say "faulty", "duff" or "U/S". It still makes me titter after having seen it hundreds of times. I imagine a capacitor sitting on the naughty step.

But yes, I think if "flat battery" is derived from "dull" or "lifeless", then that's spot on isn't it? I mean, a 'flat battery' is not the same as a 'dead battery', as the former is capable of being re-charged, revived. Whereas a truly dead battery is not. Saying that, people do refer to a dead battery when they mean a flat one. That's just one of those things though.

[Station X]

I don't think anyone would be so pompous to say "Your battery is discharged", "Your battery is flat" is the common expression.

As for a battery being dead, that's not the term I'd use!

[G6Tanuki]

I guess it's all a matter of colloquial usage: my Stateside colleagues would say their car wouldn't start because its battery was "dead", not flat. "A flat" to them is a flat tyre (tire!).

"Discharged" is the expression I'd expect to find used in any more-technical discussions about batteries though: my APC UPS-monitoring software talks about 'charge' 'discharge' etc, and says "the unit will signal via the control-interface and a continuous tone on the audible alarm when the battery is 90% discharged".

[Heatercathodeshort]

To add a touch of humour. The Ever Ready 1289 [One of the oldest types] was always known as the 'flat battery' due to it's shape. J.