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| Home | 1:Parts | 2:Hardware | 3:Software | 4:Data | 5:Wiring | About |
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Here's the story of why I built this project. I want to hear yours! Come join the discord chat forum!
If you'd like a more detailed rundown on how the system technically works check out the new MPPT Algorithm page.
I wanted to charge my eWheel with solar. Yes, adding extra nerd to nerd, but it's going to take some smart shit to fix our planet so settle down and solar-up.
I found a HUGE 2 meter x 1 meter solar panel locally on craigslist from an ex-installer who never used it.. 450W for $50. He was just excited to see it finally get used (he was going to make a table out of it but didn't have any space in his 50sq ft San Fransisco apartment 😅).
The trouble is that this utility-scale super efficient panel is open-circuit 84VDC. Ouch. Zero cheap MPPTs will run a panel of that high a voltage. Turns out lots of people would rather run at higher voltages like 60-80V though, it's way easier to add panels together in series and use the same small-gauge wire.
Turns out my favorite swiss-army-knife for power-conversion, my $22 Drok DKP6012, has a secret uart and can be interfaced-with via serial. And so can my Drok Boost converter! A plan was formed.
I found some excellent used LiFePO4 batteries on craigslist and set-about making my own MPPT to tie it all together, of course using my favorite microcontroller, the venerable ESP32. It'd have the ADC resolution I'd need to accurately read the input voltage, enough uarts to talk to everything, and WiFi so I could interface and exfiltrate the data.
| Tesla p100d | eWheel (my KS18XL) |
|---|---|
| 100kWh | 1.6kWh |
| 315 mi range | "70 mi" range (in real world let's say 55) |
| [math] = 317 Wh / mile | [math] = 29 Wh / mile |
That's 11x, eleven times better efficiency / mile than a (very efficient) state of the art electric car. And electric cars are just as particulate-emissions polluting as gas cars (because heavy, wheel wear, break wear).
If we really want to make a difference let's get people on e-scooters, eBikes, eWheels, and analog-feet– and reserve going fast for electric trains.
ONE used solar panel unceremoniously stuck on my roof charges several kilowatt of power a day, more than completely recharging my ewheel every night and running all my computers all day. You'd need roughly 50, FIFTY of the same 2m^(2) panels to do that for a Tesla. Electric cars, as cool and great as they are, are not scalable.