How to test how fully is a battery charged?

[ssankurathri]

hi
i have a 9v battery. i would like to test it whether it is fully charged or not...
when i use multimeter, i can see it saying 9v. on the battery the current rating is given as 180mAmph.
what this 180mAamph means? how can i know whether it is generating enough current? i mean is there any way to measure the current?

regards
skr

 

[my_books]

testing battery.....

Use digital auto range Ammeter.

 

[Old Nick]

Re: testing battery.....

hi
i have a 9v battery. i would like to test it whether it is fully charged or not...
when i use multimeter, i can see it saying 9v. on the battery the current rating is given as 180mAmph.
what this 180mAamph means? how can i know whether it is generating enough current? i mean is there any way to measure the current?

regards
skr

You can't measure the charge on a battery directly. Your phone/ipod etc, have systems which measure current-in and current-out thus giving an approximaion of how 'full' the battery is.
180mAmph, will be 180mA-h which is milliampere hours, it is a measure of the batteries charge capacity, 180mAh will supply 180mA for 1 hour.

A battery is a voltage source, and not a current source and V=IR will determine the current (the battery will have an upper limit to what current it can supply though)

 

[nikhilele]

testing battery.....

you connect a 100ohm resistor across your battery..
it will discharge.
and connect current meter in series and connect a voltmeter in parrallel.. initially you will see a 90mA current and 9V...
and as per spec within 2 hours your battery will discharge and voltage will be near 7V..

This is very crude and primitive method...



other wise u have to use constant current sink.. some other similar stuff..

 

[e_eja]

Re: testing battery.....

180mA mean that rate of charge is being discharging for 1 hour by load is 180mA. If you want to discharge exacly the chrge on batery in 1 hour you have to use current sink circuit whitch is independent of the voltage of battery