Solar camping trailer to recharge ebike while overlanding

To carry my stuff on long journeys I thought of adding a little 2-wheeled trailer to my bike. Say maybe a closed box of 1m wide and 2m long. Above the cargo space a rudimentary sleeping surface (mainly as protection from the elements). On top of the box it could carry about 400Wp of flexible solar panels to feed into the NMC pack. Let's assume the trailer will have a frontal area of 2m² and a fully laden weight of 250kg. 19in moped wheels. A 72V and 40Ah battery pack that receives a full charge every second night in a hotel. Daily distances to be traveled: 100-200km.

Do you think such a setup is feasible for extended travel at 30kph without (much) pedaling in good conditions (occasionally overcast, head wind <2m/s, uphills <10%, ambient temperature below 25°C)?

Can such a heavy weight be handled connected at seat post height? Are brakes on the trailer mandatory on slight downhills (disk braked bike + regen at the rear wheel)?

Is 30kph without suspension but 2.75-19 moped wheels on corrugated (dirt) roads sensible or will the trailer affect the ride too negatively?

Just about the same configuration I have thought would work well. You may only get 200w from the panels on average, because of the orientation. But an additional 1200 wh should take you a bit farther, and camping for a day to charge is always possible. More than 1200wh is definitely possible in summer. Tilt the panels to the sun at dawn, and gather all you can before starting out for the day.

Figure on using 30-50 wh per mile. so the panels would be good for about 50k per day. The battery would take you about another 100k. So over two days,, 200k should be possible.

Definitely possible if you rode slower, it's truly amazing how little power it takes to go 25 kph vs 30 kph.

Do plan to pedal all you can. Steady low effort pedaling will help more than you might think.

To pull a trailer that heavy, I would want a robust hitch. You might look at modifying the bike to have the hitch be part of a very sturdy home made rear rack.

Try to get the weight down lower if you can. And make it shorter so it has less drag. I had dreams of a solar trailer the same size, but only about half a meter tall. A custom made tent covers the bed while sleeping. The top is removable, or at least tilts open, so it can be pointed at the sun in the morning.

Maybe that's what you are looking for.


It is a DIY trailer made of glass fiber, with space for travelling gear and lots of batteries.
Similar to the bushtrekka trailer.
There are hydraulic brakes on it plus a second brake lever on the left side of the bike's handlebar.
For cruising without trailer he simply removes the cabling from the bike.
For climbing hills with this heavy rig he uses an additional small chainwheel bolted on his 750W BBS02. With that IGH hub in the rearwheel he doesn't have to worry about the chainline.
There is a Thule Pack'n Pedal rack on his bike where he places the front end of his folding tent for stability.
The four solar panels with about 32 cells each feed his 48V batteries, approx. 400Wpeak. Of course there is a DC- AC converter onboard to power his laptop etc.




More pics here:

http://www.pedelecforum.de/forum/index.php?threads/mit-solaranh%C3%A4nger-rundtour-durch-spanien.40611/

The post above is well worth reading and leads to some other fascinating links.

Nice rig.

No easy way to do it, that setup pictured above looks about the best one could do with the current state of the art of PV and the consumption of an e bike. Obviously, a lot of weight and "stuff" to pack around, especially in hilly, or God forbid, mountainous terrain. It can be done, for sure, but you better be real dedicated to the concept to put up with the hassle.

My attitude is like it is after decades of off grid use, selling and installing PV of all kinds, I constantly come up against people having a unrealistic viewpoint of what PV can do (it can do anything, sort of....). I really like his little sleeping trailer, pretty cool. The vast majority of the time my ebikes get recharged using my at home grid tied renewable energy system, at home being the point, packing it around involves a LOT of compromises. More power (ha ha) to those who do it though, what we really need is a 10 lb. 300 watt ICE (gasp) generator, 4 stroke, that would use a miniscule amount of fuel and be quiet. From a weight for the amp point of view that would be hard to beat, sad but true. I firmly believe there is a ready market for such a generator, even the smallest Honda 1000 watt'er is too big and heavy. Sorry for the thread drift.

Nice trailer!

Mariisa Muller rode across the USA in 80 days last year towing a solar panel.
http://www.pbs.org/newshour/bb/woman-completes-solar-powered-bike-ride-across-us/

yes, the thread is a very good read indeed.

the more i research, the more crazy people i find.. so no doubt that a one-wheel trailer to carry some baggage + 200Wp panel can be advantageous for extended travel. my hope was to add a permanent sleeping space to it. so it will be a squarishc box of 2.5m² frontal area (huge).

thought about the ICE generator as well.. it would make too much sense and be too easy.

i lack of any simple idea to tilt the solar panels or the whole roof (if extendable)..!?

joe81 said:

...
Do you think such a setup is feasible for extended travel at 30kph without (much) pedaling in good conditions (occasionally overcast, head wind <2m/s, uphills <10%, ambient temperature below 25°C)?

Click to expand...

maybe... depends on too many factors to give a solid 'yes/no'

joe81 said:

Can such a heavy weight be handled connected at seat post height?

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again, depends on the bike. I wouldn't trust a lightweight bike for this scheme but I've successfully used heavy trailers with heavy steel bikes connected at the seat post.

joe81 said:

Are brakes on the trailer mandatory on slight downhills (disk braked bike + regen at the rear wheel)?

Click to expand...

over 4% slope I found mechanical brakes prone to overheating and failure. My 'final solution' was using regen on the trailer itself (both wheels) in addition to the (trike) brakes. Motor brakes make excellent drag brakes and are easily modulated and far more adaptable over a mechanical brake setup (done both) and the pain of connecting a cable-pull vs. an electrical connection is significant. Electrical connection is the clear winner.

joe81 said:

Is 30kph without suspension but 2.75-19 moped wheels on corrugated (dirt) roads sensible or will the trailer affect the ride too negatively?

Click to expand...

You know what? the answer is another 'maybe' LOL.

my questions was more about the high leverage point when using the seat post connection. when braking it will tend to lift the rear wheel and downhill + cornering is expect the tendency to move the rear wheel of the bike around. ..highly instable driving situation.. but i have no practical experience if that is only an issue in extreme situations or disturbing throughout the whole ride.

That guys trailer and tent is very close to what I had in mind. I was just thinking a longer trailer to support a comfy bed. And the top of it tiltable, or even removable to set up to catch the morning sun best. The idea is to not start riding till close to noon. Then get only about 60k down the road, which is possible, even easy, on 1000 wh. So no particular need to make it to a plug any day.

Yeah, what he said. A 300w generator that is a quiet 4 stroke is what I really want. I'd settle for 20 pounds weight even. Quiet enough, you could run it all night.

I keep thinking about a trike like Amberwolfs. A six foot long box on the back 16" tall. Mid drive, but a back up front hub motor. At night, set up the box like a covered wagon, with bent pvc pipe for the hoops.

I could compromise, and make the thing a trailer, in that case, I'd still connect like a bob trailer does, at the rear axle on both sides.

ddk said:

joe81 said:

Are brakes on the trailer mandatory on slight downhills (disk braked bike + regen at the rear wheel)?

Click to expand...

over 4% slope I found mechanical brakes prone to overheating and failure. My 'final solution' was using regen on the trailer itself (both wheels) in addition to the (trike) brakes. Motor brakes make excellent drag brakes and are easily modulated and far more adaptable over a mechanical brake setup (done both) and the pain of connecting a cable-pull vs. an electrical connection is significant. Electrical connection is the clear winner.

Click to expand...

[/quote]

so you are using the two wheels of the trailer for regen and propulsion of the whole rig too?

i've just been to the local tricycle dealers and checked out some frames..
thought of cutting a second hand one behind the battery box and attaching a trailer hitch there.
unfortunately they are mostly 48V and i already have battery and rear wheel kit for 72V on the bike..
anyway leaf springs and parking brake are a nice to have.

Easy as pie to attach a trailer hitch to trikes. Most delta trikes use the same steel rear axle assembly. Weld a plate to that, and you can do a simple pin hitch, or a car type ball hitch.

I use a 1-7/8" ball hitch on my CrazyBike2 cargo bike and SB Cruiser cargo trike, and have two trailers built for various uses that have matching tongues. I could also pull regular automotive trailers, though I don't know how big I could go with that before I'd be unable to start moving it from a stop under load.

You can look at the links in my signature for my trailers and bike/trike.

Was easy to incorporate the hitch ball on mine cuz they're custom built, but you could do it with a regular bike if you built a frame that clamps onto the chainstays and sticks out past the rear wheel, mounting the ball just behind the rear tire. Unfortunately with a regular bike this would put a lot of weight behind the axle and make it difficult to handle, so you'd need to put weight up on the front of the bike to compensate for that. And a front hubmotor may not have enough traction to help you get started under various loading conditions. A rear hubmotor will fix that, but doesnt' add weight to the front.

A long bike helps a lot with the front weight thing.



I highly recommend that you make the trailer itself as low-slung as you can--see my MkIV flatbed trailer for one possible way to do this while still using large-diameter wheels that solve a few problems:
--you can use the same wheels on bike and trailer, so you only have to carry one size of spare stuff for them.
--larger diameter wheels roll more easily over stuff, making a better ride even without suspension, and cause less problems getting a load over rough roads or terrain, get stuck in potholes less than small wheels, etc.
(I forget what else I was going to say here )

Making the trailer wider helps with load stability but it also causes problems of fitting between bollards on trails, or riding on sidewalks, etc., if you are ever needing to use it in those situations. So I have two trailers; one of them (MkIII) uses smaller wheels cuz I built it before I thought of the other method, but it is narrower so it fits where bike-sized stuff is meant to go. Someday I'll rebuild it to use bigger wheels, but I don't use it much compared to the wide low MkIV, so not a lot of motivation to do it.



I've also used a hitch made from handlebar stems and headtubes/bearings/etc, and a front fork/steerer attached to the rear dropouts (see DayGlo Avenger), but it was a bit complicated and all depends on the strength of the connecting bolt between the stems; could certainly be improved, and I found it easier to just use the ball hitches.

Totally agree with your ideas amberwolf. Unfortunately, I have some constraints of what I can achieve here starting from central China. Ideally I thought of using the exact same 19" moped wheels all around the bike. Now I think a little suspension for the trailer (so that the camper box doesn't fall apart on these bad roads) is mandatory. I cannot build a suspended chassis from scratch. So going with a tricycle frame is the best option I see right now. Yes, it has small wheels and will be high against the wind...

Dedicated bicycle hitches are only for 45kg trailer weight in Europe. That seems a little flimsy. I think I'll go for an automotive hitch attached to the (aluminum ) seat post.


Any ideas for DIY
- Building a clamp for the seat post with even spreading of the clamping force?
- How to mitigate the bending load where the seat post and frame meet? I thought of stiffening it from the inside... ...somehow...?
- I like the idea of tilt-able solar panels (I guess 1000's of kilometers of my trip will be east to west). How to combine this smartly with an expandable roof? Are there commercial camper roofs that can be lifted only on one side (while traveling at bicycle speeds)?

On point about late in the day and early in the AM charging: no matter how precisely an array is aimed directly at the sun, during those times the array will produce a lot less power then mid day aimed at the sun. I have a Wattsun tracker for a 1940 watt array, it is 2 axis, it tilts up and down and also east/west. It (used to, the gears developed too much play and then stripped, I didn't spend the money to rebuild it as more PV in a fixed array is now cheaper and way simpler) aims dead nuts at the sun all day. Looking at the grid tie inverter display, it was easy to see this lesser output during these times. Tracker manufacturers and sellers will not point this out, they'd like you to think that you'll get full output, ain't so. Much more atmosphere for the sun to shine through at those low angles. Just something to consider when considering a tilting trailer for use late and early. I wish I could remember the percent difference exactly , but it was about 15 to 25 % less, enough to matter anyway if one was really crunching the numbers for an anticipated output.

Mariisa's ride across the US was very impressive, but I'd like to see a graph showing what her small solar array contributed in total, versus her own physical output, plus, I'm sure, her night time charging off the grid. The fact that she crossed the country with two modules on a trailer, doesn't mean she crossed the country using solar power. For sure it helped, but a minor factor, maybe 10 or 15% at best? The first time a cyclist makes the trip without pedaling and without grid charging while parked will be a whole different deal, and it won't be done with 200 watts or so of PV.

joe81 said:

my questions was more about the high leverage point when using the seat post connection. when braking it will tend to lift the rear wheel and downhill + cornering is expect the tendency to move the rear wheel of the bike around. ..highly instable driving situation.. but i have no practical experience if that is only an issue in extreme situations or disturbing throughout the whole ride.

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Back in the 80's I developed a seatpost-connected trailer for dragging my kids around. It handled way better than other trailers/connections I'd used previously.

But this trailer development was in Lincoln, NE USA where the landscape is very flat and the roads, while not completely paved, are pretty good to excellent.

joe81 said:

ddk said:

joe81 said:

Are brakes on the trailer mandatory on slight downhills (disk braked bike + regen at the rear wheel)?

Click to expand...

over 4% slope I found mechanical brakes prone to overheating and failure. My 'final solution' was using regen on the trailer itself (both wheels) in addition to the (trike) brakes. Motor brakes make excellent drag brakes and are easily modulated and far more adaptable over a mechanical brake setup (done both) and the pain of connecting a cable-pull vs. an electrical connection is significant. Electrical connection is the clear winner.

Click to expand...

Click to expand...

joe81 said:

so you are using the two wheels of the trailer for regen and propulsion of the whole rig too?

Click to expand...

Funny you ask. Other users on this board attempted to convince me I'd need the motors to help operate/push my setup, but I'd already developed an e-trike capable of transporting the whole mess (mass) for my specific situation. Yet operated legally in my jurisdiction.

And...

It's all about the specifics; specifics base the engineering involved to meet minimum needs for maximum requirements. (hence the term, YMMV, is always invoked)

With solar panels, unpredictable in operation, along with other battery-charge sources, the basic issues involve 'power harvesting', 'battery capacity' etc. (oxymoron warning) and it is always better (at least in my mind) to keep things (especially very complex things) as simple as possible.
-Therefore, no, I did not use the motors for anything other than brakes, using slightly depleted battery packs as a power sink.

Basically I'd already built what you're proposing to do but with my specifics being different than yours
means my trikes' build met my needs and me, not being familiar with exactly what you require can not answer your questions exactly (or even generally).
Also, I have little experience traveling in China (closer to 'none').

joe81 said:

i've just been to the local tricycle dealers and checked out some frames..
thought of cutting a second hand one behind the battery box and attaching a trailer hitch there.
unfortunately they are mostly 48V and i already have battery and rear wheel kit for 72V on the bike..
anyway leaf springs and parking brake are a nice to have.

Click to expand...

The specific trike I developed is found elsewhere on this forum but spans three threads and many pages, Also for reasons involving redundant, backup and emergency (limp along) systems it was far easier to use 36V motor systems. (all about KISS principles)
Basics:
I built my trike by modifying a semi-standard "granny" delta trike. Amberwoof's trike is somewhat based upon it. It's a:
-semi-recumbent delta trike with 17" high comfortable seat , two motors; a front wheel hub motor and a mid drive through an IGH transmission.
-Simple two-point suspension (front wheel and seat)
-300W solar panels. Two 22V 150W panels that could switch between series or parallel operation.
-One panel installed on the trike. One panel installed on the trailer
-60Ah of battery in three packs packs being switchable between motor systems, charging systems and braking systems. (KISS system- a lot of DPDT 30A switches)
-Parking brakes consisting of two strips of velcro holding the hand brake levers closed (LOL-KISS)

After I'd built and tested this thing for a couple of weeks with many, many road miles, things changed, requiring/forcing me to abandon the project.

Yeah, about the output of the solar. I never meant to imply you can get 100% out of them in the am. This is why I was saying you get perhaps 1000 wh per day, from a 300w panel. Half it's rated output, for 6 hours a day. Any more is great, but don't count on it.

If you can remove the solar trailer cover, or just tilt it, it becomes possible to do better by aiming it better when stopped. Better than tilting the whole trailer, since you can't nap in the bed with it all tilted.

One option worth considering, a shorter in height trailer. The top tilts up, then under it, a second light weight top tilts up. Now you have an A shaped roof on the trailer that needs only a strip to cap the gap at the top to be waterproof.

At night, park with the solar facing east, so you get at least some of that morning PV. Start riding when the sun gets high enough to do ok with the panel flat.

dogman dan said:

The top tilts up, then under it, a second light weight top tilts up. Now you have an A shaped roof on the trailer that needs only a strip to cap the gap at the top to be waterproof.

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If you make that A so the second half is hinged from the first half *at the top* then there's no need to have a separate waterproofing strip to be applied each time it's popped up.

Good idea. This thread has me thinking about building the trailer, minus the solar panels. Got time, got steel, got no money for the panels.

I loved touring on the bike, but just can't handle sleeping so rough. I need to carry a good bed. Busted up old bones just can't do the thin pad on the ground.

I came to the trailer idea from wanting to carry solar + load and then thought to add insulation and have a simple sleeping surface. Different initial requirements - maybe similar result. :wink:

Unfortunately I cannot weld and have no workshop myself. So I need to rely on support from companies..

With the box being 2.1m long and 1m wide I need ground clearance anyway. If I forego the suspension and go for strong moped wheels (with bouncy tires) - what do you think about just welding a 20mm outer diameter steel pipe of 1.3m length to a ladder frame, add some thread to the ends sticking out and use DH front hubs for the wheels?

..like this: http://i945.photobucket.com/albums/ad291/Giraut/Bicycle%20camper%20trailer/bicycle_camper_trailer-bed1.jpg
only elevated sleeping surface over cargo space and wheels sticking out.. :lol:

..so much inspiration.. even my beloved wood stove in a canvass like camper..
http://weburbanist.com/2012/10/15/bike-campers-12-mini-mobile-homes-for-nomadic-cyclists/

I like the idea of solar recharge and tossed around various trailer builds for a recent long tour.
Be great to have a trailer for general duties at home as well.

After the GD ride though, it would be a firm no for most 1st world touring. The 150w panels I used were next to useless given the time needed to recharge (and with in mind the real world charge rate return mentioned above).

Napkin math told me that to be satisfied 6-800w (deployed when stationary) would have been better, more realistic in use, then heavy, and arkward.

The trouble is.. when touring, it may sound easy to get 5/6hrs charge but being able to recharge in an hour or two is more realistic (of weather conditions and the time you wanna be laying around waiting). Anything more than a couple of 00 watts (arguably any at all) deployed is verging on being a road hazard (imo).

I'd give a trailer a go in Australia or other long between drinks tours. Personally i'd avoid anywhere (eg USA) where you could just carry an extra battery. You can find places to recharge during the day if want to still camp out of town. My camping gear is pretty comfortable inflated mattress, tent etc. I even had an electric fence :wink:

3kg of extra battery is a lot easier to carry than 7-10?kg of panels plus the proportion of the weight of trailer / the idea, dedicated to moving the panels around.

Then again;;

i'm afraid i wil carry more than 40kg in lipo + panels additionally with the trailer.

nice coffin.

more inspiration popped up on my facebook.. :?
http://www.goodshomedesign.com/this-man-built-the-worlds-smallest-campervan-with-a-4ft-living-space/

I was just thinking to bolt steel parts to an aluminum ladder for the frame. Since I have those laying around too.

Bolt on axle assembly. and bolt on hitch assembly. A steel tongue can bolt to the ladder rungs. Or to wooden rungs added. Plywood bottom, and the rest of the box made from coroplast and small wood or pvc pipe sticks.

Box will be a meter wide, but no more than 30 cm tall. Just big enough to carry the bed, and some camping gear. Carry a small tent still, so you have a place to change your clothes, or cook when its raining, etc.

Minimal welding really. Tongue is a square steel tube bolted to the ladder, with a hole on the end. Axle can be a simple steel rod, or a pipe with a rod welded to the end of it. No springs for me on the trailer. It could be a commercial set of light trailer springs bought off the rack though. I have thought about making the trailer axle from cheap steel front spring forks, but only because I have a bunch laying around.


Modify this to have a simple pintle hitch to pull it. That will be a bit of welding, but not much.

Reminds of this bike seen in my latest Sportmans Guide mailing:http://www.sportsmansguide.com/product/index/swiss-army-mo-93-military-bicycle-7-speed?a=1847491

I'm entertaining the idea of a single wheel camper trailer. To get load off the bike I would want to place weight behind the wheel too. The only real disadvantage I can think of is some more difficulty moving the trailer when not connected to the bike. Yet I can´t find trailers that have been made like that. Any idea of what I might have missed?

Since it will have considerable weight to accelerate and and brake I thought of adding a second motor to the rig within the trailer's wheel. Regen by switch but how can I tell it to just add say 200W irrespective of speed to whatever the other motor is doing?