1.7 KiB
E = 1/2 C V^2
10x 2.7V 500F capacitors 35 x 60mm 500F: -> E(14V) = 36 kJ -> E(10V) = 25 kJ -> E(14-10V) = 11 kJ
16 x 27 mm
12V x 20A = 240 W
say a 4 second tug
that's 1 kJ
E = 1/2 C (Vf^2 - Vi^2)
C = 2 E / (Vf^2 - Vi^2) = 2 * 1k / (14^2-10^2) = 20 F
So we're talking super-cap range
A 9ah battery is like $22
https://www.digikey.com/en/products/detail/abracon-llc/AHCR-S04R0SA227Q/23018981 $7.20 220F - max storage is 1.76 kJ
https://www.digikey.com/en/products/detail/abracon-llc/AHCR-S04R0SA127Q/23018999 $5.17 100F - max storage is .80 kJ
oh but these all have peak currents of like 10A and what do you do after dark and on and on
just put a damn battery on it and move on to the next problem
PWM vs MPPT chargers
- MPPT are up to 30% more efficient, especially in lower light
- PWM are simpler
- Both need a microcontroller I guess
https://www.instructables.com/DIY-1kW-MPPT-Solar-Charge-Controller/
https://github.com/opensolarproject/OSPController/wiki
https://www.arduined.eu/arduino-solar-charge-controller/
https://hackaday.io/project/159708-arduino-pwm-solar-charge-controller
http://www.andrewwhyman.com/blog/electronics/arduino-pwm-charge-controller/
https://web.archive.org/web/20161023034412/http://256.uk/?page_id=23
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https://www.solorb.com/elect/solarcirc/scc3/index.html
how to drive an IRF4905 - should be able to replace BC337 with 2N3904 (but how are those BJTs not a short?)
https://forum.arduino.cc/t/automotive-pwm-control-of-p-channel-mosfet-irf4905-as-high-side-switch/434372/93
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https://www.instructables.com/ARDUINO-SOLAR-CHARGE-CONTROLLER-Version-20/
https://github.com/gameinstance/switcharger
!