S3: maxV & minV - General Discussion and Assistance - CHDK Forum

S3: maxV & minV

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S3: maxV & minV
« on: 15 / February / 2009, 12:17:45 »
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I have 2 sets of 4xNi-MH 2600mA (min. 2400mA) 1.2V rechargeable battery for my S3.

How to calculate the maxV that is supposed to be delivered by these batteries?

And what's the minV required by S3?

thanks.

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Offline wontolla

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Re: S3: maxV & minV
« Reply #1 on: 15 / February / 2009, 13:46:17 »
You have to calculate those values for a particular set of batteries:

First, go to CHDK menu ->OSD Parameters -> Battery and select "Show Battery volts".

Use your camera until the batteries run out of power (somewhere around when the Canon red battery icon appears). Look at the voltage in your screen and that's the minV.

Fully recharge your batteries and insert them in the camera. Write down the voltage as it is the maxV.

CHDK takes those two values to calculate the percentage and to display the battery icon.

Re: S3: maxV & minV
« Reply #2 on: 15 / February / 2009, 22:59:28 »
You have to calculate those values for a particular set of batteries:

First, go to CHDK menu ->OSD Parameters -> Battery and select "Show Battery volts".

Use your camera until the batteries run out of power (somewhere around when the Canon red battery icon appears). Look at the voltage in your screen and that's the minV.

Fully recharge your batteries and insert them in the camera. Write down the voltage as it is the maxV.

CHDK takes those two values to calculate the percentage and to display the battery icon.

thanks wontolla, and that's what stated in the wiki.
But I was hoping to find out if the batteries are really what they claim to be, min 2400mA!

I also have some 2500, 1800, 1300mA batteries...

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Offline fudgey

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Re: S3: maxV & minV
« Reply #3 on: 16 / February / 2009, 13:34:14 »
But I was hoping to find out if the batteries are really what they claim to be, min 2400mA!

I also have some 2500, 1800, 1300mA batteries...

Umm... so you want to measure the capacity of the batteries, i.e. how much energy they have in them after recharging? Voltage has nothing to do with it, you need to discharge the batteries in a controlled measurement for that. The camera could be used for that of course, by using a suitable script.


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Offline wontolla

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Re: S3: maxV & minV
« Reply #4 on: 16 / February / 2009, 17:57:54 »
Those figures are mA/h (miliAmpere per hour) which is independent from voltage. It means how much current the batteries are capable to deliver in one hour.

You would need an amperimeter and connect it to the camera or one of those expensive battery chargers.

Quote
The camera could be used for that of course, by using a suitable script.
Didn't know it was possible but sounds interesting!

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Offline fudgey

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Re: S3: maxV & minV
« Reply #5 on: 16 / February / 2009, 18:36:43 »
Those figures are mA/h (miliAmpere per hour) which is independent from voltage. It means how much current the batteries are capable to deliver in one hour.

The nominal capacity is published in mA*h, not mA/h. Also, it doesn't tell how much current the cell can deliver in an hour. The unit itself tells how many hours you can draw one milliampere from it before it's all drained. But the nominal capacity is not actually measured at 1 mA discharge current nor 2300 mA (and that 2300 mAh reading is not accurate at either current), it's measured at something a lot higher, typically 0,2C (5 hour discharge) i.e. at 460 mA for a 2300 mAh NiMH cell. At high currents, perceived capacity is significantly reduced.

This mAh reading is just a rough approximation of energy stored in the battery. Energy is most definitely dependent on voltage, and a current*time value doesn't take it into account at all, which is why mAh values are only good for comparing batteries of the same technology (roughly sharing a voltage discharge curve shape at a given temperature and age) or when using low-tech devices with linear power supplies (unlike our cameras).

The accurate way of comparing battery capacities for use in a specific camera is to test it in that camera using a well defined procedure in controlled climate. Such a test spec exists, and actually a thread on these forums exists as well...

Re: S3: maxV & minV
« Reply #6 on: 17 / February / 2009, 01:46:50 »
thanks guys, appreciate for all the replies.

especially to fudgey, for his technical information  :)
« Last Edit: 17 / February / 2009, 02:32:51 by totalz »

 

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