Re: LEAD ACID BATTERY


budgie wrote:

On 1 Apr 2006 04:10:42 -0800, "RHRRC" <h.lewis@xxxxxxxxxxxxxxx> wrote:


budgie wrote:
On 31 Mar 2006 13:26:58 -0800, "RHRRC" <h.lewis@xxxxxxxxxxxxxxx> wrote:

(snip good stuff

'C' is merely a short-hand way to refer to the capacity of a battery at
its declared (20hr) discharge rate.

Sorry, couldn't let that one go through to the keeper.

'C' refers to the capacity of the battery at the rate that (superficially) is
the one-hour rate.

i.e. the 13Ah battery's 'C' is 13A.

<snipped>

Sorry to say you are in error.

The nominal 'C-rate' of a 13Ah battery is 13amps.

As previously stated 'C' is a capacity - not a current - that is why C
is used rather than A or I!


FFS what extreme pedantry. "C" vs "C-rate" indeed. Just ahve a quick look at
the usage of 'C' in describing charge rates. You'll be scratching to find many
references to 'C-rate'.

And your line: " 'C' is merely a short-hand way to refer to the capacity of a
battery at its declared (20hr) discharge rate." was so wonderfully precise?


You obviously do not understand that, for example the origional posters
13Ah Pb-acid battery, when discharged at 13amps will not last for 1
hour.
When discharged at any rate other than C/20 it will not provide 13Ah!

Since a batteries available capacity is a function of its discharge
rate some form of standardisation is required to be able to readily
quantify different batteries.

IEC, EN, JA, etc,etc, have standardised a methodolgy which, for
rechargeable lead acid batteries, is the quantity 'C' defined as the
available Ah obtained when the battery is discharged at a rate that
causes the battery to reach the given (end) terminal voltage in 20 hrs

This seems to work for most which is perhaps why its is a worldwide
standard and is adopted by *every* significant battery manufacturer.

For interest the rate for NiCd is C/5.

If you have another methodology that you think is advantageousnby all
means advocate its use please do not use the symbol 'C' as this is
already used by the battery fraternity.

How do you intend to measure battery capacity?





Review your other line: "The nominal 'C-rate' of a 13Ah battery is 13amps."

Try reading the two in conjunction.

.

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