Research "MPPT" = Max Power Point TrackingI have used a small joule thief with old solar cell. Its current increased from 0.15 mA to more than 20 mA. But I can only add them in parallel, and the voltage and the current increases. Do you have an idea to add them in series ?
Thank you.Research "MPPT" = Max Power Point Tracking
MPPT is a circuit that extracts Maximum Watts from the Solar Cells.
Watts = Volts x Amps
You need to maximize Watts, not just volts individually, and not just amps individually.
The Joule Thieve may, or may not, be operating the Solar Cells at Max Power Point.
There are many combinations of Volts and Amps , where the Watts is below Max Power.
Thank you. I try to design my own charger.This is an example MPPT device. It comes setup for LiPo, check the datasheet for the charge controller chip, maybe it can be configured for NiMH?
https://www.kr4.us/sparkfun-sunny-buddy-mppt-solar-charger.html
Side note; if you have the option of switching to lithium batteries, you may find greater efficiency (less power lost to heat during charging, lower self discharge rate).
No it is not. That would violate the laws of physics.A solar Cell is 1,5 V with 16.50 mA
With a joule thief 2.3 V with 24.18 mA
Why not ? I just send you the pictures.No it is not. That would violate the laws of physics.
Bob
Ok. I see. Maybe it is increasing the efficiency of the solar cell. You know a joule thief is working like a buck booster.Because no circuit can put out more power than it takes in.
1.5V at 16.5 mA = 24.75 mW
2.3V at 23.16 mA = 53.3 mW
Bob
Yes. Multiple solar cells with a joule thief on each, and I want to add them in series.I am not entirely sure what you are asking. Are you trying to charge multiple cells in series, or do you have multiple solar cells you want to place in series.
Your solar cell will take 133 hours to charge 1 AA 2000 mAh. Charging two would take twice that.
Bob
Thank you. I have added also the circuit diagram. As below.The pictures are nice but meaningless unless we know how everything is connected. Assuming 3.88 V is from 2 cells in series OC, open circuit, then under load V might be about 2.9 V , ready to charge 2 batteries in series.
Disconnect charging when battery V = 3 V, about 2 weeks later ? Might be best to add a blocking diode between solar & batteries if leaving connections over night.
by Duane Benson
by Jake Hertz
by Duane Benson
by Jake Hertz