68 lines
1.7 KiB
Markdown
68 lines
1.7 KiB
Markdown
E = 1/2 C V^2
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10x 2.7V 500F capacitors
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35 x 60mm
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500F:
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-> E(14V) = 36 kJ
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-> E(10V) = 25 kJ
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-> E(14-10V) = 11 kJ
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16 x 27 mm
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12V x 20A = 240 W
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say a 4 second tug
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that's 1 kJ
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E = 1/2 C (Vf^2 - Vi^2)
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C = 2 E / (Vf^2 - Vi^2) = `2 * 1k / (14^2-10^2)` = 20 F
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So we're talking super-cap range
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A 9ah battery is like $22
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https://www.digikey.com/en/products/detail/abracon-llc/AHCR-S04R0SA227Q/23018981
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$7.20
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220F - max storage is 1.76 kJ
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https://www.digikey.com/en/products/detail/abracon-llc/AHCR-S04R0SA127Q/23018999
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$5.17
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100F - max storage is .80 kJ
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oh but these all have peak currents of like 10A
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and what do you do after dark
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and on and on
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just put a damn battery on it and move on to the next problem
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PWM vs MPPT chargers
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- MPPT are up to 30% more efficient, especially in lower light
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- PWM are simpler
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- Both need a microcontroller I guess
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https://www.instructables.com/DIY-1kW-MPPT-Solar-Charge-Controller/
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https://github.com/opensolarproject/OSPController/wiki
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https://www.arduined.eu/arduino-solar-charge-controller/
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https://hackaday.io/project/159708-arduino-pwm-solar-charge-controller
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http://www.andrewwhyman.com/blog/electronics/arduino-pwm-charge-controller/
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https://web.archive.org/web/20161023034412/http://256.uk/?page_id=23
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![[MPPTschematic.jpg]]
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https://www.solorb.com/elect/solarcirc/scc3/index.html
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how to drive an IRF4905 - should be able to replace BC337 with 2N3904 (but how are those BJTs not a short?)
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https://forum.arduino.cc/t/automotive-pwm-control-of-p-channel-mosfet-irf4905-as-high-side-switch/434372/93
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![[a5f9f8ce1c919c81156c09ffb5a3e5eed443ef58.gif]]
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https://www.instructables.com/ARDUINO-SOLAR-CHARGE-CONTROLLER-Version-20/
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https://github.com/gameinstance/switcharger
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![[getnt29x2jjg7gb9.png]] |