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   Tinker ☀️ (tinker@infosec.exchange)'s status on Friday, 03-Apr-2026 23:47:21 JST Tinker ☀️

   So question... I have a fantasy where I buy an old beater gas car and later convert it to an electric vehicle.

   In this fantasy, I also put solar panels on the car to help offset charging.

   I like sun/moon roofs. They make it to where I don't feel so trapped in the car. And getting a sun/moonroof on these old beaters doesnt cost more - just a little harder to find.

   Do I get a sun/moonroof or do I get one completely closed and put a solar panel over it. Does it really matter with that small of a footprint?

   I think I over think my fantasies...

   #ev #cars #diy #solarPunk

   • Embed this notice
     Rich Felker (dalias@hachyderm.io)'s status on Friday, 03-Apr-2026 23:47:20 JST Rich Felker

     in reply to

     • m4iler the Boogeyman :debian: :t_blink:

     @m4iler @tinker I forget the details but my recollection from last time I looked is that there's a process (at least here in Virginia) for registering custom project cars that doesn't have all the requirements of manufactured cars.

     I'm not sure if you'd even have to do that if the vehicle was already registered before the overhaul, though. If you got antique tags it wouldn't need yearly inspections, and you might just get away with having modified it to electric without reporting that. 🙃

   • Embed this notice
     m4iler the Boogeyman :debian: :t_blink: (m4iler@infosec.exchange)'s status on Friday, 03-Apr-2026 23:47:21 JST m4iler the Boogeyman :debian: :t_blink:

     in reply to

     @tinker My thinking is that I have no idea how US law works and if you could even get that thing road-legal.

     But I wish you all the best on your mission! Soon, there will be third-hand Teslas you can salvage for cheap and put the chassis of... well, anything on it!

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     Rich Felker (dalias@hachyderm.io)'s status on Friday, 03-Apr-2026 23:50:45 JST Rich Felker

     in reply to

     • Lily Star

     @starlily @tinker You can use an off-the-shelf boost converter or maybe even just a voltage multiplier circuit (which is easy to DIY).

   • Embed this notice
     Lily Star (starlily@mastodon.social)'s status on Friday, 03-Apr-2026 23:50:46 JST Lily Star

     in reply to

     @tinker I've recently learned that while the panels are DC and the car is DC, you can't directly charge the car with the panels. Mostly because of the voltage difference, but also no one makes any thing to interface them.
     AC charging is a double conversion (inversion?). Practical experiments by a friend have proven the loss is too great without a LOT of panels.

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     Rich Felker (dalias@hachyderm.io)'s status on Friday, 03-Apr-2026 23:52:25 JST Rich Felker

     in reply to

     • Orb 2069

     @Orb2069 @tinker You can do similar with thin film flexible solar attached to the body, but you'd need a lot of aerodynamic and weight mods to the vehicle to be able to get any appreciable distance out of the solar unless you were only driving like once a week or something.

   • Embed this notice
     Orb 2069 (orb2069@mastodon.online)'s status on Friday, 03-Apr-2026 23:52:26 JST Orb 2069

     in reply to

     @tinker

     https://aptera.us/

     .... Almost manages to get useful solar onto a car, but the weight/aero/efficency restrictions of making the cell output meaningful kind of rule out retrofits.

   • Embed this notice
     Rich Felker (dalias@hachyderm.io)'s status on Friday, 03-Apr-2026 23:58:25 JST Rich Felker

     in reply to

     • Anton Piatek

     @sldrant @tinker 100kwh is so excessive for an EV. You can reach highway speeds with around 15 HP (early to mid 20th century cars with 15 HP didn't, but they had zero aerodynamics) and 30 kwh is plenty to go several hours at that draw (and much longer with regen braking, or cruising slower without fighting air resistance).

   • Embed this notice
     Anton Piatek (sldrant@mastodon.social)'s status on Friday, 03-Apr-2026 23:58:26 JST Anton Piatek

     in reply to

     @tinker honestly I have 5kw solar and it makes little difference to the 100kwh battery in the car (more so as I have 15kwh of house batteries that are first in line to charge).
     Unless you're in an extremely sunny part of the world, solar on the car is only good for the radio (and even then, one 400w panel isn't going to give you much range)

   • Embed this notice
     Rich Felker (dalias@hachyderm.io)'s status on Saturday, 04-Apr-2026 00:05:20 JST Rich Felker

     in reply to

     • Anton Piatek

     @sldrant @tinker The capacity is chosen according to the distance you want to be able to travel and the power draw. If you get rid of the ridiculous overpowered motors and heavy mechanical components designed to accept that power from the motors, you don't need nearly as much capacity.

     Refusing to trickle charge with low solar output is a consequence of a bad charger, not anything fundamental. If you were doing a custom build intended to use solar, you wouldn't build that flaw into it.

   • Embed this notice
     Anton Piatek (sldrant@mastodon.social)'s status on Saturday, 04-Apr-2026 00:05:21 JST Anton Piatek

     in reply to

     • Rich Felker

     @dalias @tinker 100kwh is the batter capacity though, not the horsepower.
     Most are bigger than that these days.
     My rather old leaf is 24kwh batter and even that I couldn't really charge that much unless we have a perfect day as the car won't charge until you've several kW generation so any cloud means you are generating but can't charge

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     Rich Felker (dalias@hachyderm.io)'s status on Saturday, 04-Apr-2026 00:19:24 JST Rich Felker

     in reply to

     • Anton Piatek

     @sldrant @tinker If you assume 10 kW average net power to run (maybe a little low but I think it's doable) and 500 W of charging, the ratio of charge time to driving time is 20:1. That wouldn't fully meet most people's commuting needs left parked in the sun during work, but if you were going for an extra small battery pack for low weight and higher efficiency, it could make the difference of being able to use a smaller size.

     I think it's probably not worth the trouble of integrating in a vehicle unless you can get the power draw much lower, though.

   • Embed this notice
     Anton Piatek (sldrant@mastodon.social)'s status on Saturday, 04-Apr-2026 00:19:25 JST Anton Piatek

     in reply to

     • Rich Felker

     @dalias @tinker sure but custom charging circuits is a serious business, and also you need enough for the whole pack.
     My leaf is ok as a 2nd car, but 24kwh only gets me 50mi as its aging, and worse in winter. That's only useful as a short daily commuter and could never be our only car.

     I'm not saying it's impossible, as I've never designed a 10x kw charging circuit, but I'd be very sceptical it's worth adding a few 100 w solar for charging a car unless it's a go cart or as a novelty...

   • Embed this notice
     Orb 2069 (orb2069@mastodon.online)'s status on Saturday, 04-Apr-2026 00:20:57 JST Orb 2069

     in reply to

     • Rich Felker

     @dalias

     I worked it out at one point and I think the only way you can get 40mi range out of the Aptera in the Continental US is by parking it in the southern tip of Nevada on a clear day, in the summer, facing North on an incline.

     ... And the only way they get that level of performance is by not technically being a car and not having to meet the safety testing requirements of the NHSTA.

     @tinker

   • Embed this notice
     Rich Felker (dalias@hachyderm.io)'s status on Saturday, 04-Apr-2026 00:20:57 JST Rich Felker

     in reply to

     • Orb 2069

     @Orb2069 @tinker That last line is the reason why, and the reason it sucks. They're wasting a lot of mass on mechanical components and motor strong enough to withstand the torque to do 0-60 in 6 seconds. Make it only do 0-60 in 30+ seconds and you'd have a LOT more range.

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     Rich Felker (dalias@hachyderm.io)'s status on Saturday, 04-Apr-2026 00:25:24 JST Rich Felker

     in reply to

     • Anton Piatek

     @sldrant @tinker With decent aerodynamics, 10 kW can reach and maintain highway speeds, at least if you're not going up mountains (in which case you do like a trucker in the right lane). Something like a century ago, ICE cars did 65+ km/h with 15 HP and ridiculously bad aerodynamics; fixing that would get you the rest.

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     Anton Piatek (sldrant@mastodon.social)'s status on Saturday, 04-Apr-2026 00:25:26 JST Anton Piatek

     in reply to

     • Rich Felker

     @dalias @tinker I guess you run into the issue of building a custom vehicle that lightweight and getting it signed off a road safe. Not sure it's possible at all in the EU as it wouldn't have any safety crash data. No idea what is possible in other countries.
     10kw is going to be pretty slow though and unlikely suitable at motorway speeds, so there's likely a challenge of use case too