Need Help! On Charging time?

[jtivat]

I have some Yaesu radios that had Ni-Cd batteries that where 1100mAh. I then had them rebuilt as Ni-MH at 2400 mAh. The charger for them is rated at 15VDC 200 mA. My question is how long should it take for them to charge?

 

[jtivat]

Anyone? I have had them on the charger for about 10 hours and don't know if they are done.

 

[CNC Dan]

2400mAh / 200mAh = 12hrs.

However you should measure the current (mA) actualy going into the battery as it may be far less than what he charger is rated for.

It will probably start off taking nearly the max available from the charger, then taper off as the voltage of the battery rises and opposes the charger voltage.

 

[jtivat]

Thanks Dan, would it work to leave it on longer? I have no way to check the draw as the radio sits in a base charger covering the leads.

 

[T-Rex]

Shamelessly ripped from:
battery charge

To calculate charge time for your battery, use the following equations:

Slow charger: (Cell capacity in mAh / Charging rate in mA) x 1.4 = Time in hours

Fast charger: (Cell capacity in mAh / Cahrging rate in mA) x 1.5 = Time in hours

For example if you have a 1700mAh battery and a charger charging at 700mA, you will need to charge the battery for approximately 3 1/2 hours.

 

[bmsmith]

At a charge rate of 200mA, I doubt leaving the charger on for some extra time would even hurt the cells. 200mA is less than a C/10 charge rate and most NiCds can handle that rate for long periods of time without trouble.

The formulas T-Rex posted are a good estimate. With your 2400 cells at 200mA, figure 17 hours. I'd charge for 20 hours and be done with guessing.

 

[jtivat]

Thanks for the help.

 

[whiskypapa3]

Since you don't know how far down they are charge them until they start to feel warm. The charge characteristics show a sharp temperarute increase as 90-95% is reached and with 200ma they will get just over body temp. 200ma is in the trickle charge range so it will be hard to over charge them. Full charge from stone dead will take 18 hrs. When in doubt, hang them on the charger overnight after each use. Eventually they will get fully charged. Remember they loose about 1% per day. so give them an all nighter every two-three weeks.