Solar-powered recumbent build

barl

1 µW
Joined
Jul 19, 2022
Messages
3
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This was a bit of a budget build, but with really good results I think. A local metal worker gave me the recumbent in 2014. Apparently an old student of his had welded the seat tubing and built the seat. I believe the frame is factory, but I don't know what company even so if anyone might be able to guess please do. When I got it had been in a pretty bad crash and sat for something like 20 years. I fixed it up and rode it around Philly a bunch. Needed a new rear wheel, parts had to be bent back into place, I used a lathe and a skate wheel to make an idler, brakes and derailleurs had to be rebuilt and/or tuned.

Fast forward to the e-bike part of the build this year. I went low-powered compared to a lot of what I've seen on these forums, one of those 450W/24V kits with a chain and sprocket. I got a 7s4p lithium ion battery which fit perfectly in a bar bag slung behind the seat. Got it running just as a "regular" ebike. Pretty fun little machine.

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Then I used a harbor freight solar panel (100W, 5.5 amps, but shorter than most at 3 feet) with a really cheap charge controller and a DC-DC booster. It worked to charge it but would only get up to 0.6 amps in full sun. I did learn a lot in the process of getting it to work, though.

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While I waited for a boosting charge controller (still cheap, like $25) I mounted the panel on the mousetrap back rack using a combination of a foot wide swath of 3/8 inch plywood and steel conduit tubing that I bent, crimped, and drilled to use as support arms.

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In full sun I get about 3 amps continuously, which is pretty amazing to me, as I had guessed in my calculations that I wouldn't do that well with efficiency (voltage is being boosted from ~24V to 29.5V). So far riding it has been great, in one recent test I went 4 miles and the battery voltage decreased by only 0.1V. I thought it might feel tippy but I barely notice the extra weight while moving (the panel is ~16 lbs.) The only upgrade it needs is a thicker rear wheel/tire with a disc brake mount for the sprocket. I already got the new sprocket that will fit the 6-point mount so someday I'll do that bit, maybe even build the wheel.

Really enjoyed k2orbust's Nazca build https://endless-sphere.com/forums/viewtopic.php?f=6&t=109786 I was just finishing mine when I discovered that thread. Wish I had fork suspension! Maybe we should get all the solar builds linked in a central thread (if that hasn't already been done, a cursory search didn't yield anything.)

Next project will probably be a solar trailer to power a diamond frame ebike.
 
Go team solar recumbent! 🌞🚲 There are a few solar powered e-bike projects groups on Facebook but it's a far flung little community of tinkerers. I've been riding mine to work every day and it charges itself nicely at the bike rack.
 
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Built for the competing in the pedal / electric "production class" at the World Solar Ralley in Akita Japan 1996
The race was a 1k sprint for best time on Saturday which set the starting grid for a 100k endurance the following day.
Most of he rules required the parts used must come from "off the shelf" components with the exception being the motor and controller could be experimental.
A max of 20 AH sealed lead batteries.
Production solar panel restricted to a total size of one square meter of cells not counting any gaps between cells.
A front streamlined fairing was allowed but not a rear fairing was not.
The solar panels ( smaller in size then most other entrants ) were mounted in a way to help reduce the turbulent bubble behind the bike and were approved for competition by the the technical inspector.
Motor used for this build came from a semi truck heater fan 24V with brushes.
Controller came from a small company called NuSun.
 
Welcome! I haven't been brave enough to buy any solar panels yet (for any type of project), but I did get a recumbent a while back!
 
Hey, that's a great little machine! I love that you used the MY1018 brushed motors, though they're inefficient their simplicity for these little builds makes them great.

Think you're just gonna constantly tinker with it? Any next plans?
 
Thanks all! Yes I will continue to improve it, rear wheel is next on the docket. It needs to be thicker and have a disc break mount for a sprocket.

And yeah, I know it's a cheapo motor, I could see upgrading that someday. I wonder if a hub motor would work. I know they're meant to fit between cranks. The front of the bike has a post for the derailleur but the frame is quite thick (maybe 35 mm)(edit, actually 44mm). Anyone seen one fit onto something like that? I could take a closer pic if necessary.
 
Few videos I found interesting on the topic of solar ebikes, maybe you can find some ideas in them:

https://youtu.be/15HHLY4BfA4

https://youtu.be/a-4JPYHcfxQ

https://youtu.be/XIMM25unnU8

I would love to find some time to start my own solar recumbent project.
 
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