How to charge 24V Ni Cd battery?

[p.gholap93]

I have NiCd battery pack of 20 cells. Battery specifications are as follows-
Voltege-24V
Current-5AHr
Each cell is of 1.2V and 5AHr.What charging voltage and charging current should I set on power supply for charging the battery?

 

[3v0]

I charge using a current limited PSU. At C/10 we can charge the battery continuously without harm. With my PSU I would set the voltage up above (1.4*number_of_cells), short the output, then turn the current up to 500mA and connect the battery.

The battery is charged when the voltage of the battery stops increasing or even goes down. Measure this with the PSU off.

If this is an old battery the cells may be of uneven quality and charging it will be difficult.

 

[p.gholap93]

With my PSU I would set the voltage up above (1.4*number_of_cells), short the output, then turn the current up to 500mA and connect the battery.

My battery is quite new. I follow the same method while charging any battery on power supply. In your case,charging voltage for the battery is 28V (1.4*20). So you charge 24V NiCd battery at power supply voltage of 28V. Is it not going to damage the battery or cause any harm to it?

 

[alec_t]

Is it not going to damage the battery or cause any harm to it?

Using that voltage you need to limit the current to 500mA.

 

[p.gholap93]

Using that voltage you need to limit the current to 500mA.

I charged the battery with 28V voltage and current of 500mA. Now, how do I come to know that the battery is charged to its full capacity? And once it is charged fully, what will be its voltage? Will it be 24V or 28V?

 

[Nigel Goodwin]

Once it's fully charged then the voltage will fall slightly, that's what you need to monitor for to tell if it's fully charged. Another option is the battery temperature, they will get hotter once fully charged.