Sunday, October 30, 2016

Pull-up might improve charging current

I added a pull-up to CH2 of my charger to increase 2SK1290 gate voltage. Because the maximum output voltage might be less than Vcc - 1.5V. The added pull-up occurs input/output inverting, so the OP amplifier had to exchange the input signals.

The new CH2 circuit 173 mA flew compared with CH1 118 mA for the same NiCd6 battery.


The chart shows 950 mAh Eneloop current change dissipated by GE digital camera. E12 was applied for the pulled up CH2. I think that too little charging current does not excite battery.

The pull-up circuit 7.5mA for NiCd6 or 8.3mA for NiCd5 flows. The gate voltage was the same before. CH2 flows much than CH1 nearly 50mA range. OP amplifier LM324 sinks 5mA only at full range.

When batteries are off, The CH1 2SK1290 gate voltage wave distorts a little. While the CH2 one is right sinsoidal. The both of their frequency are 28.3 and 305 kHz.

The pull-up might effect good at low stationary charging stage.

Thursday, October 27, 2016

Cause unknown decreased charging current

I have made a constant current and constant voltage batteries charger. The constant current is 200 mA.
When the deteriorated 1000 mAh Evolta batteries were discharged, they could discharge nearly 800 mA as follows in the next chart.
The actual current has to be scaled down 2/3. I missed the scaling.

I have been charging another deteriorated 1000 mAh NiCd GP batteries. I have found that 2SK1290 gate voltage is 3.16V lower than 3.37V as before. I don't know why the gate voltage has dropped.

Ref.
http://enokie.blog.fc2.com/blog-entry-1454.html