Hi All,
I hope I am not going to get lynched for starting a new thread but I wanted to present my first attempt at a 3 stage battery charger. The input is 12V DC at 300mA. I am charging 8 x 1.2V Nimh
The curcuit uses two op amps, an LM35DZ along with some resistors and a couple of NPN transistors.
Here is stage one - the temperature is only 15degC, the voltage of the batteries measures 7.7 volts ( undercharged ) so it is getting near the full amount of amps. The 9V battery symbol is put there just to represent some kind of load that the 8 batteries would represent - V2 is meant to be the measurement of the current voltage of the 8 batts.
**broken link removed**
Stage Two - Batteries are now showing 10.45V which is 1.3V per battery - at this point the compator causes the flow through Q2 to be reduced and now the batteries ( which are 2000maH ) to charge at rate of 150mAh ish
**broken link removed**
Stage Three - the batteries temperature hits over 35degC and that causes Q1 to turn off too further reducing the current to a trickle.
**broken link removed**
Any comments, improvements or suggestion are welcome.
Peter
I hope I am not going to get lynched for starting a new thread but I wanted to present my first attempt at a 3 stage battery charger. The input is 12V DC at 300mA. I am charging 8 x 1.2V Nimh
The curcuit uses two op amps, an LM35DZ along with some resistors and a couple of NPN transistors.
Here is stage one - the temperature is only 15degC, the voltage of the batteries measures 7.7 volts ( undercharged ) so it is getting near the full amount of amps. The 9V battery symbol is put there just to represent some kind of load that the 8 batteries would represent - V2 is meant to be the measurement of the current voltage of the 8 batts.
**broken link removed**
Stage Two - Batteries are now showing 10.45V which is 1.3V per battery - at this point the compator causes the flow through Q2 to be reduced and now the batteries ( which are 2000maH ) to charge at rate of 150mAh ish
**broken link removed**
Stage Three - the batteries temperature hits over 35degC and that causes Q1 to turn off too further reducing the current to a trickle.
**broken link removed**
Any comments, improvements or suggestion are welcome.
Peter
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