Latest project - transcon bike

JackFlorey

100 kW
Joined
Feb 19, 2020
Messages
1,573
Location
San Diego
The almost-complete vehicle:20210907_141457.jpg

The view from behind:20210907_141510.jpg

Trailer has two charge controllers, an 18ah battery, three 100 watt panels and space for stuff. I get about 130 watts in full sun.

The bike is a heavily modified RadCity. Controller was replaced with a Phaserunner/Cycle Analyst combo, hub has a temperature sensor and Statorade added, and there's an extra chainring up front.
 
wow looks like the right climate?

If you were **only** using solar, what would be the ratio of X days charging (stopped, optimal panel tilting) to Y hours travel (most efficient speed, on the flat with a tailwind)
 
Yes, looks like a very cool bike to ride.
Probably could load it up with a ton cargo, trailer looks very stout :thumb:
 
john61ct said:
If you were **only** using solar, what would be the ratio of X days charging (stopped, optimal panel tilting) to Y hours travel (most efficient speed, on the flat with a tailwind)
Unknown; not enough testing yet.

However, at an average of 16mph I can get 12.5wh/mi out of the bike alone, or about a ~200 watt average draw. I am getting ~120 watts from the trailer now in full sun. So the most efficient use of the bike would probably be to drop the speed until I am using 120 watts and then just ride all day. If you estimate about 13 mph for that, then an average "sun only" day would be about 80 miles. (Around here you can get about 6 hours of equivalent direct sun a day this time of year.)

But for any long trip it's a safe bet you'll be able to charge at some point along the way. So solar becomes a range extender more than a sole source of energy.
 
by JackFlorey » Sep 08 2021 10:21am

john61ct wrote: ↑Sep 08 2021 1:15am
If you were **only** using solar, what would be the ratio of X days charging (stopped, optimal panel tilting) to Y hours travel (most efficient speed, on the flat with a tailwind)
Unknown; not enough testing yet.

However, at an average of 16mph I can get 12.5wh/mi out of the bike alone, or about a ~200 watt average draw. I am getting ~120 watts from the trailer now in full sun. So the most efficient use of the bike would probably be to drop the speed until I am using 120 watts and then just ride all day. If you estimate about 13 mph for that, then an average "sun only" day would be about 80 miles. (Around here you can get about 6 hours of equivalent direct sun a day this time of year.)

But for any long trip it's a safe bet you'll be able to charge at some point along the way. So solar becomes a range extender more than a sole source of energy.

Glad you have a firm grasp on energy usage. Enjoying the project, keep it up.

Everyone wants to go fast and use little energy. I like to go far and watching my usage is a habit now. Not that I don't have fun. The wind is the biggest watt sucker. All the little things matter and add up the watts. There are some real road warriors here on ES, find there threads and read up them.
 
Today's test ride:

Start 11am
Stop 2:30pm

Round trip, lots of stops, ~400 foot elevation change repeated several times during the trip

Distance 14.5 miles
AH used 5.6 (@52 volts)
AH generated 4.4

Cruise power ~250 watts
Peak power 1000 watts
 
Today's ride:

48 volt 32ah (in theory) battery, 1000 watt motor
Trailer loaded with fake load (24 lbs of water)

101 miles
4000 foot elevation gain (google said about 6000 feet climbing total)
Left at 8am, returned at 6pm, ~2 hours of stops so 8 hours of riding total

45.7ah consumption on Cycle Analyst

20ah opportunity charging
7.5ah solar

Got home pretty low but with about 10% range remaining (per the Cycle Analyst estimator)

Problem - even with Statorade the motor temps were regularly getting over 90C. I set the temp limit to 90C-100C so it never got above about 96C but 1) that's really hot and 2) that means the output was throttling back to 400 watts or so, not enough to haul the bike up the steeper hills. I assisted as much as I could, but since it was over 100F during the middle of the ride, I was overheating as well.

This showcases the benefits of mid-drive for loaded touring. At 10mph the motor was current limiting a lot, which means that the windings are seeing the maximum possible current (limited to 35 amps by the phaserunner.) Even that is a lot for those 12-14ga wires in the Z910 connectors. And if I increase that limit, it will just overheat sooner. With a mid-drive you just downshift, the motor runs that much faster and doesn't have an issue with winding current.
 
NICE! I was looking into that at one time, and made a coffin shaped trailer that could be a bed, plus carry 100w on the top. But in 48v, only 25 watts. I figured Id pedal up 50w, pull 25w out of the panels, and then the pull on the battery would be only about 125w for 15 mph. So say 800 usable wh in a 1000wh battery, Id get at least 6 hours of ride time before the battery was dead. By then hopefully in a place I could charge overnight.

Never got the project finished, the tow bike and all my batteries went up in the fire.

Panels have improved since then, you should be looking at 18v from each panel, at noon anyway. so you have at least 100w of 36 or 42v for 3 to 4 hours at noon. 350-400 wh. Enough to ride a couple hours at a 200w drain.
 
This is pretty cool, dude. I especially appreciate the measurements you made.

You know, this would be real even better in something like a velomobile or perhaps use solar panels as a roof for a semi recumbent, trike, etc.

Do you have issues with cross winds and your solar trailer?
 
neptronix said:
Do you have issues with cross winds and your solar trailer?
Not so far. That's one reason I went with a two wheel trailer - it would take a lot of wind to disturb it. (There is of course more resistance when I am towing it.)
 
How much does your current solar trailer weigh?

I imagine an evolution of this design might look like Paul Elkins' coroplast mobile bicycle camper:

[youtube]ZiejAhol4Ps[/youtube]

Except with solar. And a large multi-kWh pack. Shaped correctly, a larger/taller trailer would be more aerodynamically efficient than what you currently have, while being able to fit more solar panels, and contain enough room to sleep in and carry cooking equipment, eating utensils, tools, spare parts, ect.

If you want to lug that kind of weight around, you definitely need a motor suited to the task. You can't go wrong upgrading to a Leafbike 1500W motor. At your low speeds, I'd recommend a 6T or 11T wind depending on what voltage you want to go with. You won't have anymore issues with overheating.

ZeroEm said:
There are some real road warriors here on ES, find there threads and read up them.

The Humungos rules the wasteland!
 
How is the seat for those 8 hr rides ?
Have you considered a suspension seat post for those rougher roads after a weeks riding ?
After my last multi day riding holiday, i would have gone for a suspension bike + seat post, + fatass seat ! :eek:
 
Don't be put off by the seat - they normally have very comfortable chair-like seats, I've never seen one like that before.
 
Look it has a cup holder. I need on like that but first going to try to modify a tandem for my use.

If he can do a 100 miles a day on the bike he is using now there is no telling how many miles he would get out of a LWB recumbent.
 
Hillhater said:
How is the seat for those 8 hr rides ?
Have you considered a suspension seat post for those rougher roads after a weeks riding ?
After my last multi day riding holiday, i would have gone for a suspension bike + seat post, + fatass seat ! :eek:
Not too bad. Between gel shorts and a reasonable (compromise) gel saddle it was annoying but not painful.

The bike started off with a fat comfy seat and that was actually worse, because it interfered with pedaling and caused a lot of rubbing.
 
ZeroEm said:
Long trips, might think of a Mid Racer.
I've gone through a lot of recumbents commuting to work.

I used a Greenspeed trike for a while. It was great for a lot of reasons, but it was hard to get into and out of, and I can't see much from two feet off the ground (and cars couldn't see me.) After a few close calls I retired it.

I had a Linear recumbent for five years and basically wore it out. The build quality wasn't great to begin with, and once things started wearing enough that (for example) the seat and wheels wouldn't stay in place, I sold it and moved on to a:

Longbikes Slipstream. That was a very nice bike, and much higher quality than the Linear. It was comfortable, visibility was a little better than the Greenspeed, it was stable and could carry a lot of weight. Its big downside is its size. You can't ship it anywhere by any means (other than boxing it and shipping it ground freight) and maneuvering it when not riding it is super painful. To go from work to home with dedicated parking spaces was OK, but trying to go to the store was super painful. The front wheel didn't do curbs so there was a lot of getting off, hauling the thing over the curb, then trying to roll/steer it while hunched over (and often with 30 lbs of groceries in the back.)

Eventually I moved back to the old safety bike design, partly for the visibility, partly for the ease of maneuvering it when not riding it and partly because I got a lot more exercise riding it (could go more places, was way easier to get on for a five minute ride with the kids.)

All that being said the Slipstream would be a pretty good tourer, as long as I was riding on well prepared routes - it doesn't handle rough roads, curbs or narrow roadsides well.
 
ZeroEm said:
If he can do a 100 miles a day on the bike he is using now there is no telling how many miles he would get out of a LWB recumbent.

Even a semi-recumbent would be a great candidate for this project if he insists on the old safety bike architecture.

Further, all of the minor improvements he could make to improve efficiency could add up to something significant, in addition to the major improvements that would be made. Careful selection of all components would be in order. I think it's feasible that he could get 150+ miles per day from solar alone at a cruising speed of over 20 mph with the right design tweaks. The drag of the trailer, the rolling resistance of the chosen tires, the efficiency of the motor, and how many watts of solar panels the trailer can fit will be the most significant aspects regarding ultimate miles/day from solar alone.
 
The Toecutter said:
How much does your current solar trailer weigh?

I imagine an evolution of this design might look like Paul Elkins' coroplast mobile bicycle camper:

[youtube]ZiejAhol4Ps[/youtube]

I frocking love this guy, as well as the youtube channel. Tip of the hat, sir.
 
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