Micro-house ebike build

Hi everyone, this is my first post to the forum!
I'm interested in off-grid living, and the idea of a CHEAP way to live as much as possible without fossil fuels. It seems to me that among the key factors is minimising needs, and reducing weight. Cars and vans are so heavy, making solar expensive or impossible. Almost all the power seems to go to just moving the vehicle! I hope to solve this issue.

I've seen some great bike trailers using Correx. The drawback with this is that the results often seem poorly insulated - only slightly beter than a tent in that respect. So I've been considering Correx lined with expanded polystyrene. For the curved part I'm thinking of making something that would grow when you are not travelling - this means the curved surface needs to change shape to extend, taking on less of a curve. I'm worried that expanded polystyrene would break. So I am considering expanded polyethylene for the curved part.

I've struggled finding cheap sources of these materials here in the UK (when not buying packs of 50). Can anyone recommend good sources? That's:

• Correx - or another brand if the properties (weight+strength+non-toxicity) are the same

• Expanded polystyrene

• Expanded polyethylene

Advice on other good materials and sources for:

• Reflective insulation layer - maybe there are large sticky sheets?

• Tape or other system to make waterproof and flexible joins between Correx panels, that will hopefully not need repairing often!

Mattress
This rig is to sleep 2 people. I'm considering expanded polyethylene foam. It seems to be non-toxic (unlike many other mattress foams - it's used in baby mattresses for example). And I could cut it such that it could re-form into a 2 person 'sofa' during the day.
If the mattress were 2mx1.3m, then at 10cm thick (too thin?) it would be 7.8kg. But the sources I have found, that's already around £200, which is a lot for just plain foam!

Anyone have better ideas for light mattresses for skinny light people? Light is a high requirement but this is not just for the occasional weekend trip, so doesn't want to be noisy and doesn't want to loose its form after a few weeks.

Even with foam I might have to use a lightweight 'topper' between mattress and sheet, so you're not sweating up against the foam.

Motor
The trailer may weigh around 40kg excluding wheels, solar panels, battery. I am wondering if the 250W limit here in the UK for the motor, would be enough to pull this. No racing involved, just needs to be easy enough to ride for a couple of hours when moving from place to place - the journeys could be done in stages, no rush. Do you think 250 is ok? And, is 250W only the bike limit, or are we allowed to add more power to the trailer?

I also understand that some 250W motors can give a lot more power, and the 250W limit may only apply to 'continuous use' - so I am interested in the possibilities of a 250W rated motor rigged to crank out a lot more when going uphill (increase voltage?) - and tips on that.

On that topic of exceeding the UK 250W limit, would it be advisable to get a 250W rated motor that can be legally 250-exceeded going up hills, or is it possible to use a 1000W motor, but limit it to '250W continuous' via settings or extra hardware, while still being able to access more power to get up hills, and still be legal?

Also that weight doesn't include solar panels and battery. But they are needed. So advice on those would be great! Since it's not just a bike but also a house (albeit a small one!) I am also curious how much solar panels and battery would be advisable. I'm thinking maybe 300W panels?

Which solar panels?


I saw someone else was using Sunbeamsystem panels on their build. They look awesome! They have semi-flexible panels for yachts and foldable ones too. Curiously, the foldable are cheaper and lighter per Watt - surprising. Foldable would make them more multipurpose. Here's the foldable:
https://shop.sunbeamsystem.com/product/tough-124-5-w-fold/
Here's one of their semi-flexible:
https://shop.sunbeamsystem.com/product/tough-111w-black-flush/

Now there are many far cheaper panels around. But it seems to me this company's panels might outlast others by several times over. And they seem to perform well in more variable conditions. But they are very expensive! Does anyone know other panels that do well in terms of weight, performance, and longevity, at a cheaper price?

Battery
I'm wondering if maybe 48V 30Ah battery would be appropriate?
So the battery and solar are more bound by the daily requirements as a house. They'd need to run:

• 15 inch Laptop maybe 6 hours per day

• Charge smart phone

• Tiny fridge if there's one out there!

• LED light in small space, so shouldn't be much

• The bike motor for 2 or 3 hours riding but not really needed every day - can take things slow if it makes things work better

• A bit extra for... whatever - possibly occasional use of a small induction cooker - see below

• Account for some cloudy days - can wait for sunshine for travelling but as a house it needs to be ok for this.

Not sure whether I'll be using it in UK or elsewhere but assume I'm not in the Sahara or Australia regarding solar!

There's someone here on this forum selling batteries (20Ah li-on NMC cells - Eig co20b 20 ah cells boxed and sealed 3.7v screw terminals Energy innovation group high quality li-nmc) - I am wondering if these are a good choice? And how many I'd need? I saw a caravan guy seemed to be doing ok with 120Ah at 12V (equivalent to... 30Ah at 48V?) ... would that seem about right for this?

I'm also wondering about voltage. It seems 48V is appropriate for the e-bike motors, but 12V for 'house' stuff. Is that right? So would I need extra stuff to handle 48V to 12V conversion? Or is it possible to create a switch system for the battery bank, switching parallel/series set up from 'bike mode' to 'house mode'? Would that make things lighter/cheaper?

Tips on <light+good+cheap as possible for light and good> for what controller and whatever else I'd need for this system, would be awesome.

Extra power

If I chose a motor with regenerative breaks, can you lift the back wheel off the ground and then pedal with the regenerative breaks engaged, to generate electricity for the battery? If so, is this efficient enough to bother? Could that help cut down on larger panel costs?

I also have a nice LED light system that you pull to power ('Nowlight'), though not sure if the weight would help or hinder the overall efficiency - maybe better to leave it and just run lights off batteries?

Breaks
Talking of breaks - is there a certain weight of a trailer above which we should best be putting breaks on the trailer which the bike breaks can activate? (This is irrelevant if motor is on the trailer wheel, but not if the motor is absent or on the bike).

And is there a total weight above which we should be using disk brakes?

Eating
Cooling
Anyone got tips on an ultra-light refrigerator? The ones made for caravans that I've seen look too heavy. Or anyone have tips on how to make one? Shell doesn't need to be strong, and willing to use plenty of expanded polystyrene to insulate. Just need a light and efficient cooling system! Hard to live off grid without a fridge.

Heating[
I have two thoughts:

Induction cooker - Anyone know a really light one? Again the caravan type ones look unnecessarily heavy. I'm also worried how much extra this will add to solar and battery needs. But one does need to eat.

I'm considering designing a micro-rocket-stove. So wood could be used on site, instead of electric. This depends on how thick the steel walls need to be to be ok with the heat. But if it seems doable, I could also make a special radiator connected for heat also. Space is very small and hopefully well insulated, so this should work for cooking using basically small pieces of branches etc., keeping it small. Anyone ever tried something like this?

Travel
It would be nice to be able to take it abroad. Anyone know anything about costs for shipping such a vehicle (imagine the size of a typical correx bike trailer - around 2m long, 85cm wide, 135cm high) to e.g. Europe/Japan/New Zealand? Also is the battery an issue? I heard they may be prohibited to travel with? Also I say ship because presumably it's way cheaper than flying with but if anyone has experience taking a bike trailer or bike rig abroad I'd love to hear about it, especially costs.

I was even wondering if it would be possible to take the battery and motor in ones flight check in luggage and make the trailer anew at the destination, to save huge transport costs...? Not sure if batteries (at this scale) in even checkin luggage is allowed....

I've asked a lot of questions! Sorry for that. I've made many things but never something quite like this, so advice is really appreciated! I think the world needs more micro-houses!

Hmm, where to start. Fantasies are so great, but they are dreams. Reality is a bit uglier in many cases.

On the plus side, you are young and presumably pretty strong. But it just seems like an awful lot to carry around, on 250w. When I did a little bit of bike touring, I needed more like 2000w to get up the hills in the rocky mountains with all my camping gear. I was having to also carry a lot of water, so the load was heavy. That was with a hub motor, so what you need is a mid drive motor. They come in 350w, 750w, and even 1000w. But in a mid drive, 350w will do a LOT. Overload a hub motor, and it melts down in less than an hour on a big mountain. But a mid drive can gear down, and crawl up it with a cool motor.

I'm not up on all the EU ebike laws, but I believe most of it has a class of e bike that can have more watts. England may be, as always, a bit odd. Look closer at laws, and get the max wattage mid drive you can. Then stick a 250w sticker on it for the odd places.

Pare down what you plan to carry. Eliminate refrigerators for example. Lots of fresh food around in most of the world, buy it, consume it, buy more tomorrow. Keep a stash of freeze dried foods as well. Propane cartridge backpackers stove to heat the food. Wife to heat the cocoon at night. Overkill the sleeping bag with goose down. You will learn to sleep in freezing weather fine. Wear more clothes if its cold, fleece is great stuff.

Don't get hung up on solar charging everything. Might be best to just find plugs to charge the bike batteries. Carry enough light, flexy panel to charge your laptop and run some minimal 12v stuff on a lithium battery. Mostly I just mean lights. A very small 12v lithium battery may be something you can fly with. Pedaling to charge the bike battery is possible. It only takes 100 miles of stationary pedaling to charge the bike enough to go 10 miles. Seriously, that sounds like a joke, but its almost that badly inefficient. Yes, people charge phones, and small batteries for led lighting in the third world all the time. They are charging a 100 watt hour battery, in an hour or so of pedaling. Your battery for a big tour will be 1000 to 1500 watt hours. Like I said, possible, but stupid to pedal up that kind of power. For solar, you can carry more panel and extend your range. Carrying 200w worth of flex panel is not that bad. But it won't turn your bike into a perpetual motion machine. But it can help lengthen range, and be worth it. its just too hard though, to carry 4, or 600 w of panel. just too big. But two 100w 18v panels is about 2' wide, and 6' long. The roof of your trailer will work for it fine. Don't buy those expensive panels, if for no other reason than eventually somebody steals them. Get cheaper semi flexy panels and consider them expendable. In the USA, about a buck a watt.

You won't be shipping the bikes batteries to NZ, or flying with em, unless its lead. Lead sucks indeed, but you could consider it as a contingency for when you must ship the rig. Meaning buy some lead when there, then leave it when you move on. Otherwise, plan on just staying on one continent as long as possible. Then you get to travel with your lithium.

Galifer said:

I've asked a lot of questions! Sorry for that.

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That's OK, but they need to be answerable questions, and it's up to you to get them there.

Is there enough juice in a 30Ah battery to do all the stuff you want to do? Well, you need to add up those demands in terms of watts. 30 Amp-hours x 48 Volts gives you 1440 Watt hours. We can't tell you how much you need. (Note that any appliance that doesn't run on 48V power is going to cost extra - voltage conversion isn't free. The battery isn't necessarily going to provide the advertised capacity. People here can provide a lot of information on details like that.)

Is 250W enough to move your load? Well, you need to add up your load - not just the trailer weight, the whole lashup including anyone who's coming along and all the groceries and stuff - and decide about speeds and uphill grades. At very slow speeds, at least it isn't substantially about wind resistance, that makes it easier.

One thing I can say, is that as much as I like regenerative braking, it doesn't add up to a whole lot. You could get 10% back, 15% would be incredibly excellent. Electric is mainly about short trips, with recharge from the power grid in between. Don't know about solar panels.

Might be some useful ideas here: https://rvlifestyle.com/tiny-homes-meets-micro-camping

dogman dan said:

I'm not up on all the EU ebike laws, but I believe most of it has a class of e bike that can have more watts. England may be, as always, a bit odd. Look closer at laws, and get the max wattage mid drive you can. Then stick a 250w sticker on it for the odd places.

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Hi Dan,
Yes I looked into the laws and 250 is max. Otherwise you need a license, insurance, MOT (vehicle check) - lots of money and hassle.
The fact that we are allowed to exceed 250W 'sometimes' sounds promising, though I still don't fully understand that in practice. It's 250W 'maximum continuous rated power' - how we can legally use that to up the power for hills without it being classed as 'off-road' rating, I am unsure. But from a hotrod forum I know many 250W motors can actually give way more output.

Eliminate refrigerators for example. Lots of fresh food around in most of the world, buy it, consume it, buy more tomorrow. Keep a stash of freeze dried foods as well. Propane cartridge backpackers stove to heat the food. Wife to heat the cocoon at night. Overkill the sleeping bag with goose down. You will learn to sleep in freezing weather fine. Wear more clothes if its cold, fleece is great stuff.

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Yeah I might be willing to go without a fridge, but this is more of a house that can move, rather than a bike that can 'camp'. Though perhaps it's possible to make a highly insulated low power light fridge? Also regarding propane, yeah maybe.... though cooking with wood would be great, would usually be in the countryside and it's a way of using what's there already, fuel you don't need to carry with you! Plus better for the environment.

Pedaling to charge the bike battery is possible. It only takes 100 miles of stationary pedaling to charge the bike enough to go 10 miles. Seriously, that sounds like a joke, but its almost that badly inefficient.

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Thanks for the info. Good for emergencies then.

Carrying 200w worth of flex panel is not that bad. But it won't turn your bike into a perpetual motion machine. But it can help lengthen range, and be worth it.

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The house criteria is more important than the bike really. So it means traveling slow is no problem. Maybe once a week, going a few hours. For example could travel for 2 or 3 hours in a day, make camp, same again until need or want to rest up for however long. Maybe similar to old style travelling with horses.

Don't buy those expensive panels, if for no other reason than eventually somebody steals them. Get cheaper semi flexy panels and consider them expendable. In the USA, about a buck a watt.

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Yeah stealing is a scary danger. But longer lasting is desirable, not just because of reliability but also because of the environment. Doesn't have to be as good as those amazing ones I linked to, but something better than the ones I've seen on youtube failing after a year or two! Any tips on brands?

You won't be shipping the bikes batteries to NZ, or flying with em, unless its lead.

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Oh that's a shame. Is that for all (/most) international flights? Any difference if sent by sea? Otherwise I guess it means can take everything except batteries. Buy them there I guess.

donn said:

Is there enough juice in a 30Ah battery to do all the stuff you want to do? Well, you need to add up those demands in terms of watts. 30 Amp-hours x 48 Volts gives you 1440 Watt hours. We can't tell you how much you need.

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Hi Don,
Yes, well I saw a guy break down his usage in a van - 2 computers and a fridge and a few odd extras but no TV etc. He used 120Ah 12V which is same Wh as 30Ah 48V from what I understand. My uncertainty is around fridge and induction cooker - haven't found a light enough solution yet so can't calculate them if I would go with those options.

(Note that any appliance that doesn't run on 48V power is going to cost extra - voltage conversion isn't free. The battery isn't necessarily going to provide the advertised capacity. People here can provide a lot of information on details like that.)

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Yeah this is why I was wondering about being able to switch between 2 configurations of the battery. If I have to make the battery anyway, is that a good idea to make it switchable like that, changing parallel/series connections to have 48V and 12V settings?

Is 250W enough to move your load? Well, you need to add up your load - not just the trailer weight, the whole lashup including anyone who's coming along and all the groceries and stuff - and decide about speeds and uphill grades. At very slow speeds, at least it isn't substantially about wind resistance, that makes it easier.

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Trailer plus me will probably be 110kg. That doesn't include battery, bike, solar panels, and my 'luggage'. And the other person can cycle their own bike! So they're not included.
Speed - UK is max 15mph (25km/h) anyway with motor-assist. That's fine as top speed! As for inclines - well even tiny speeds for hilly areas would be ok I guess. So long as I can move from A to B in normal (i.e. not Holland!) countryside. Kind of like it might be with a one horse horse-and-cart. That can get real slow up hills! But get there in the end.

One thing I can say, is that as much as I like regenerative braking, it doesn't add up to a whole lot. You could get 10% back, 15% would be incredibly excellent. Electric is mainly about short trips, with recharge from the power grid in between. Don't know about solar panels.

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If you think about it, solar is great for off grid living. And if needs are minimal, don't need much electricity to live. In this case travelling is still about 'short trips'. Like a solar van-home but light enough to replace the petrol engine with human+solar power.

Regarding regenerative breaks - I would consider going geared motors instead if this makes a big difference in being able to get up hills. I understand they're better for that. Though... would it be doable to set up my system with a direct drive 250W set to be optimised for low speeds? If I don't need to exceed 15mph (25k/h - which anyway UK and EU rules have motor cut out above that), maybe direct drive optimised for slow speed could be as good as mid-drive up hills? Is that wise?

Might be some useful ideas here: https://rvlifestyle.com/tiny-homes-meets-micro-camping

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Ah yeah I have watched several of his videos and been inspired by him. Basically that but more insulation and folds out to provide more space. A home where only one person can sleep can be a lonely home!

Galifer said:

Regarding regenerative breaks - I would consider going geared motors instead if this makes a big difference in being able to get up hills. I understand they're better for that. Though... would it be doable to set up my system with a direct drive 250W set to be optimised for low speeds? If I don't need to exceed 15mph (25k/h - which anyway UK and EU rules have motor cut out above that), maybe direct drive optimised for slow speed could be as good as mid-drive up hills? Is that wise?

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Sure. What you really need here is a smaller diameter wheel. A geared motor does just the same thing. With more moving parts and worse heat retention, but with a wider practical range of reduction. Common bicycle rims go down to 20 inches, so we're just talking 20/26, but that's enough to make a big difference.

* 250 watt motors: it is my understanding that there are motors officially rated at 250 watts to please the EU that have a "surge" rating of of 500 watts or more. Look for one of those. Geared hub motors have much more torque, especially in that power range, but they will overheat on long uphills, so your route elevation changes are important. Gearless Direct Drive motors are quiet and longer-lived, but can be pretty gutless, especially in that power range.

* Fridge: there are thermistor powered mini, mini fridges that are light and keep food cold, but they also use a fair amount of power. Of course, so does a standard mini fridge!

I would choose xps or phenolic foam over expanded polystyrene as they are better insulation. xps is waterproof. Both are available is single sheets from a builders merchants, often with reflective mirroring on both sides. someone probably sells a flexible sheet for the the curve.

You might want to speak to these guys about the motor https://www.cyclesmaximus.com/ I think they make a street legal motor than can do 1000 watts at 5 mph up a hill whist still going 15mph tops and is legal and '250' watt.

If you've not already seen it you might find this video useful

https://www.youtube.com/watch?v=15HHLY4BfA4

Again, the ONLY motor that makes any sense for your weight and low wattage, will be a mid drive. 250w into a hub motor, with a weight of 400 pounds, and a grade of 8%, will result in about 5 mph travel or less. This is an rpm that with typical motors will result in about 20% efficiency. Ever put your hand on a 200w halogen light bulb? Thats how much heat is being made in that hub motor.

A mid drive motor can gear down, since it drives your bike chain. With a big rear gear, your 250w motor can spin at an efficient rpm, while the overloaded bike crawls up the hill at 3 mph.

In any case,, since you want to conserve power, why would you choose a system that wastes most of it on any steep hill?

The link to the electric pedicab, takes you to a mid drive trike, btw. It does not HAVE to drive the bike chain, it could also be a 250w motor driving a separate chain, or belt, on the left side of the bike. The key is low gearing, however its done.

You don't know me, but FYI I used to work for a hub motor bike kit company, deliberately destroying them by overloading them and riding up a mountain in the desert. This data was then used to establish limits on the warranty, particularly total weight. What you would do with a 250w hub motor would last about 20 min.

Not sure how long the cheaper flexy solar panels will last, I'm in year two of using some on my RV. I have 180 watts of panel, and if they face the sun good enough, I can pull about 100w from my house battery with little or no drop in my battery voltage. It keeps the 12v electronic parts of my RV going, the boards in my gas fridge, water heater, and furnace, as well as a small 12v tv. If I turn on the big TV it pulls about 150w, after passing through a 12v DC to 120v AC inverter. So it gradually drops my voltage when I turn on the watt hog 32 inch tv. two of the 200w flexy panels will be very light, and will fit on your rooftop with ease, and power everything you need, like lights, charger for your laptop, etc. Not gonna run a fridge, which is too heavy anyway.

You keep talking about towing a "house" with a bike. Get a grip dude, you are going camping. But you can still camp in style! You can make a nice snug shell with a coroplast or thick tent fabric outer layer, and a foam sheet inner layer that will be light. For your fridge, look into very thick foam shipping boxes for frozen meat. Find somebody who buys frozen steak, and get his box out of the trash, or recycle bin. A yeti cooler would be great, but again with the weight.

You gotta pare down the weight to camping. Or get a house small enough to tow behind a very small car.

donn said:

Sure. What you really need here is a smaller diameter wheel. A geared motor does just the same thing. With more moving parts and worse heat retention, but with a wider practical range of reduction. Common bicycle rims go down to 20 inches, so we're just talking 20/26, but that's enough to make a big difference.

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Cool. It would be easy enough to use 20 inch wheels!

LeftieBiker said:

* Fridge: there are thermistor powered mini, mini fridges that are light and keep food cold, but they also use a fair amount of power.

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I've been looking into it more today. Seems the compressor type are the most efficient, but super expensive for portable ones. I've seen some good offgrid conversions of freezers into 12V fridges. Seems the companies massively under-insulate fridges in general so there's the best saving - add insulation! But those good DIY ways are re-using standard freezers, great for off grid houses but not portable. I think for this current project, putting a polystyrene box in the ground with a wet cloth over it taking advantage of latent heat transfer through evaporation would be the lightest and simplest option for now. In future I'd be interested to research the possibility of using gravity to mechanically drive the compressor motor of a compressor fridge, would seem an appealing avenue. I wonder if anyone has done that? For a permanent house that would be great, just have to list a weight regularly to keep it going. And for a travel version, could just attach whatever weighty object you find on site, to a pulley system. Whether that's doable and whether it would ever be light enough, I have no idea.

LeftieBiker said:

Gearless Direct Drive motors are quiet and longer-lived

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Yes these points are very appealing.

NickF23 said:

I would choose xps or phenolic foam over expanded polystyrene as they are better insulation. xps is waterproof. Both are available is single sheets from a builders merchants, often with reflective mirroring on both sides. someone probably sells a flexible sheet for the the curve.

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I've read up on EPS and XPS and it looks to me that EPS gives better insulation per weight (low density EPS is around 10kg/m3). And weight is quite crucial for me. Also, EPS has the disadvantage of allowing air to move through it, compared to XPS. But this factor should be significantly reduced when used as a composite, having impermeable surface either side (in this case Correx), plus this waterproofs it. If I've understood correctly. Also EPS is cheaper, which is handy.

If you have a good source for these materials in low quantity I'd love a recommendation!
Regarding phenolic foam, had not heard of that. Seems much safer when it comes to fire, which is handy. However it uses pentane as a blowing agent in manufacture, which I wonder could off-gas unhealthily. Also "Phenolic foams come in varying densities in the range of 35 kg/m³ to 200 kg/m³" - not sure which end for appropriate material but even the lowest is 3.5 times more dense than cheap EPS. So might not be best for this application.

dogman dan said:

Again, the ONLY motor that makes any sense for your weight and low wattage, will be a mid drive.
[...]
A mid drive motor can gear down, since it drives your bike chain. With a big rear gear, your 250w motor can spin at an efficient rpm, while the overloaded bike crawls up the hill at 3 mph.

In any case,, since you want to conserve power, why would you choose a system that wastes most of it on any steep hill?

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Very good points Dan, thank you for your kind attention! And I feel very grateful that someone as experienced as you is helping me out - many thanks!

So I conclude that even with 20 inch wheels and a direct 250W rated motor that can go, let's say 500W uphill (?) would still not cut it in this situation. Right? And is this taking into account the option of having a motor that is optimised for low speed? I do not fully understand that aspect but have seen some Chinese motor companies seem to offer such options, cannot remember if they were direct drive or not, however.

Now sorry to complicate things but I was thinking that stage 1 would be to just make a trailer. But my more long term aim would be to make the trailer and bike as one unit, saving weight from reducing overall parts/structure. And also allowing both to be 'encased' to reduce drag. Also I'm only around 55kg so I could make it aimed for my own weight, which would also help reduce structure weight.

In that can the 2 wheels of the 'trailer' side would be the back 2 wheels - and then 2 front wheels on the 'bike' part at the front. Now in that situation, this relates to what you said:

The link to the electric pedicab, takes you to a mid drive trike, btw. It does not HAVE to drive the bike chain, it could also be a 250w motor driving a separate chain, or belt, on the left side of the bike. The key is low gearing, however its done.

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I'm not sure if mid-drive and direct drive are only different in position or is we are talking about different motors - I was guessing the latter, since people say direct drive are quieter and longer lasting - but please correct me if I'm wrong. So... would it be wise to use the benefits of a direct drive type motor by not using it to directly drive the wheel, but instead rig the back gears of a salvaged bike and use that to drive the back wheels via a chain? I'm thinking that this could allow gearing (largely from available bike parts) but give the benefits of the quieter and more long lasting direct drive type motor? Potentially also could still employ regenerative breaking, but retain freewheeling on the pedals? either by using 2 chains, one for motor one for pedals (so a few gears for pedals up front and the motor gears at back, could be triggered together by a single gear lever); or putting the freewheeling mechanism on the pedal section instead of the back wheel?

Also thanks to @NickF23 for that link - those trikes look great! And extraordinarily expensive . but good lead for learning about Watts and UK regs! Also thanks for the vid link, yeah I did see that as it happens! Been trying to learn as much as I could before composing my first forum post.

Not sure how long the cheaper flexy solar panels will last, I'm in year two of using some on my RV. I have 180 watts of panel, and if they face the sun good enough, I can pull about 100w from my house battery with little or no drop in my battery voltage. It keeps the 12v electronic parts of my RV going, the boards in my gas fridge, water heater, and furnace, as well as a small 12v tv. If I turn on the big TV it pulls about 150w, after passing through a 12v DC to 120v AC inverter. So it gradually drops my voltage when I turn on the watt hog 32 inch tv. two of the 200w flexy panels will be very light, and will fit on your rooftop with ease, and power everything you need, like lights, charger for your laptop, etc. Not gonna run a fridge, which is too heavy anyway.

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Thanks for this info! Great to hear reports 'from the field'.

You keep talking about towing a "house" with a bike. Get a grip dude, you are going camping.

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:lol: I like your directness I've lived in a cave I called home, which was not too dissimilar dimensions to the build I'm working on! For me what would make it home is that:
- I have space to sleep comfortably with my companion.
- I can work (online/computer) - hence needing solar and batteries.
- I can sit comfortably with one or two friends and play music.
- I can stay warm, and eat, and wash/toilet (the latter are quite simple to sort).

I don't need to stand up. Can do that outside. And you can choose what kind of outside you want!
One of the big space guzzlers in the West is the way of sitting. Needs so much extra space! And therefore also weight. So this is more like an ultra small Japanese style room really. I understand it would not be appealing to most Westerners but I've lived in several caves I couldn't stand up in. Very happy life. Also makes you spend more time outside in the world!

You can make a nice snug shell with a coroplast or thick tent fabric outer layer, and a foam sheet inner layer that will be light.

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Yeah that lies at the heart of my plan. Expandability is something I've planned out also, plans are going well on that! Small travel size is important. I kept the transport-mode width at 85cm so far with UK bike path regs in mind.

For your fridge, look into very thick foam shipping boxes for frozen meat. Find somebody who buys frozen steak, and get his box out of the trash, or recycle bin. A yeti cooler would be great, but again with the weight.

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Thanks, that would be a lot easier than making a box from sheets. Great idea!

You gotta pare down the weight to camping. Or get a house small enough to tow behind a very small car.

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I was thinking that 40kg for the portable room was pretty paired down already! I'm working on a much smaller one for 'camping' also but not sure I can get this kind of space for the 'house' much lighter! Sounds like it might be possible using motor involving gears and exceeding 250 up hills....? Concerning that, if there were a total of 150kg (including bike, person etc.), and with suitable gears involved, what would you say is minimum actual wattage we need for pedal assist at 10% gradient? That's the figure I guess I need when checking the peak output of the 250W rated motors.

Also you mentioned about the heat issue. Will it get hotter simply due to using more wattage? If so, isn't that the same issue for the 500w...1000W etc. motors? Or is it more problem at lower speeds due to less cooling from the passing wind?

Many thanks all of you folk. I'm learning a lot!

NickF23 said:

If you've not already seen it you might find this video useful

https://www.youtube.com/watch?v=15HHLY4BfA4

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I just re-watched a part of this video where he talks about taking batteries on planes. He said something very interesting - the he used small separate batteries, each of which did not exceed the limit for cargo plane rules! That sounds like an awesome idea. Has anyone here anything to say on that topic? Building a battery pack that can decompose into these smaller units for transport?

I looked up the regs and they seem maybe similar internationally. Here's an example from New Zealand:

• Up to 100 Watt hours (Wh) or 2g lithium content

• maximum of 20 spare batteries per person

So that would be 15 modules for a 1.5kWh battery. Sounds promising!
Also could this help solve the voltage issue? Could connect those modules up in 48V scheme for bike power, and 12V for 'camp' mode?

[Edit:] Now I checked the Wh rating of the batteries I'm looking at:
https://endless-sphere.com/forums/viewtopic.php?f=31&t=102908

If my maths is right, they're 74Wh each. So it sounds as simple as just disassembling the battery for international transport. For 1.48kWh that's 20 of those. Sound like a good plan?

Galifer said:

If my maths is right, they're 74Wh each. So it sounds as simple as just disassembling the battery for international transport. For 1.48kWh that's 20 of those. Sound like a good plan?

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Might be a good plan if it doesn't blow your other plan by adding too much extra weight. An easily dissembled/reassembled battery pack probably means added weight in extra wiring, connectors, packaging, etc. And when finally reassembled it likely would not be as compact size-wise. And, the additional expense may blow up your main requirement (second line of your introduction):

Galifer said:

I'm interested in off-grid living, and the idea of a CHEAP way to live...

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99t4 said:

Galifer said:

If my maths is right, they're 74Wh each. So it sounds as simple as just disassembling the battery for international transport. For 1.48kWh that's 20 of those. Sound like a good plan?

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Might be a good plan if it doesn't blow your other plan by adding too much extra weight. An easily dissembled/reassembled battery pack probably means added weight in extra wiring, connectors, packaging, etc. And when finally reassembled it likely would not be as compact size-wise.

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True, though it would be a great advantage to not have to buy a new battery when going to each new country! Plus with tools at home, even making one should work out way cheaper than having to buy one. Abroad without tools I'd be limited to an off-the-shelf option.

And, the additional expense may blow up your main requirement (second line of your introduction):

Galifer said:

I'm interested in off-grid living, and the idea of a CHEAP way to live...

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Still may work out cheaper than buying one big one, it would seem. I'm all for lowering costs but solar and batteries still need to meet certain minimum energy and quality needs. So a certain level of cost is just necessary. And pays back anyway through having no rent costs and hotels, restaurants etc which can be very expensive if you travel for a while. Also hoping that spending properly on these points will give small scale energy independence for this kind of trip for years to come, and be useable later if I need to add more solar and batteries for off grid living with greater needs in future. I'd like to aim for that eventually, which is why longevity of panels was also an issue.

Do you know whether I'd have to make them all independently functional to fly with them? Or maybe able to simply disassemble it into components, taping the connections of each cell (so they can't contact any metal) and wrapping or boxing each individually? That way, could still have a case with all the other components, and just need to slot in the batteries and connect it all up once arriving?

I sure wouldn’t want to disassemble and reassemble a battery with any frequency, especially if my lifestyle depended on the battery working every time. It only takes one “whoopsie” and you need a new cell, a new BMS, new bus bar, new plug, or whatever.

I guess the same sort of caveat applies to a 40kg caravan. I mean, sure, why not? But it won’t be at all fault tolerant. It would be like living in an egg carton.

My thinking is you make the thing as heavy as you have to, and give it as much power as it needs to get around, legal or not. But make sure it’s slow enough that nobody has any reason to suspect it is over the power limit. Use a 250W e-bike, and give the trailer its own motor and battery. If you’re clever, you can fit the tongue with a surge brake and a “surge throttle”.

This does seem like the sort of pipe dream that results from liberal application of an actual pipe.

Galifer said:

Do you know whether I'd have to make them all independently functional to fly with them? Or maybe able to simply disassemble it into components, taping the connections of each cell (so they can't contact any metal) and wrapping or boxing each individually? That way, could still have a case with all the other components, and just need to slot in the batteries and connect it all up once arriving?

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Wouldn't it be better to think realistically about whether you will want to build such a battery pack, and will want to disassemble/pack/reassemble 20 subcomponents before getting too far into the weeds, air travel luggage regulation-wise?

If it were me, I would find an enthusiast in my destination willing to build me an appropriate battery pack and have it ready for me when I arrive.

Put your more powerful electric motors on your house???
Keep your ebike legal and make the house move your bicycle.

That would fly fine in New Mexico. Not so sure in Europe where people actually obey laws. Right now, because of Covid cheap diesel, semi trucks carrying hazardous cargos are going 85 mph on the freeway. No enforcement in NM, also because of covid.

Back to original topic. You can use a direct drive hub motor to haul quite a bit of weight, and yes, 20" wheel would be the way to go since that is how you actually gear down a hub motor, whether direct drive or geared. I built a special bike like that, which was designed to tow a trailer I made that was like a rolling coffin. It was long enough for me to lie down in, with the lid propped up. The lid was just long and wide enough for 4, 12v 50 watt panels which would go directly to charge my 48v batteries. I never completed the project, since that bikes battery burned my garage down. Instead of going camping, I was rebuilding my house. The insurance settlement worked out good, and some left over money bought a van and a 26" trailer to tow behind it. Suddenly a spare house sounded like a great idea. Meanwhile my pension came in, and I could afford it all.

I digress.. The bike.

This bike ran on 1000w, but because of the way electric motors work, it maxed out at about 800w draw when running up an 8% grade loaded to 400 pounds, and stayed cool. ( 300 pounds is the normal limit for 26" wheel with 1000w) 400 pounds is me, the bike, the batteries, the water, the tool kit, the change in my pocket, plus the trailer and its camping gear. It adds up FAST! It could, and did, pull more weight on flatter terrain. It did have a low rpm direct drive motor, like you were saying, optimized for slower travel. This DOES NOT make it pull more weight up a hill!!! But it did enforce a slower top speed at all times, which increased my range. Range was the thing this bike was built for, it had the ability to carry four 1000 watt hour batteries. Cost had me running only half full, with 2000wh in the front trays, and other stuff in the saddle bags. But here is the bottom line,,, on the flat you can tow a 400 pound load at 10 mph with 250 w. But add a hill, or even a mild wind, and now you are running 5 mph, and again, your motor becomes a heater, and melts itself. I melted quite a few motors, one of them in 15 min. that one was running 500w.

But here is the thing that concerns me,, you are talking everything for two. Its going to be more than 400 pounds total, even if you are light. You will want a decent bed, which is going to be a bit heavier than a simple backpacker pad. You are going to want a folding chair, x 2. You will need ALL your clothes, not just what you need for 3 days. This is why you need a mid drive that gears down the motor to the point where its only able to run 3 mph, when in its lower gear, to get 250w to haul a load close to, or over, 400 pounds total. Bear in mind, a good long range battery alone is 30 pounds, (2000 wh) Motor and such adds 15 more, so whack a solid 50 pounds off your total. The trailer should come in at about 50 pounds, minus the solar stuff and its battery.

See how fast this adds up? Sturdy bike with big battery and motor, 100 pounds, trailer with solar, 70 pounds, you are another 120 or so. Now you are down to everything in your house, including water if you need to carry any can't weigh more than 150 pounds. This is real close to a typical long trip backpack load, where your bed is much lighter, and you are not carrying any musical instruments or refrigerators, or ice chests or computers.

This is why I call it camping. But here is an Idea. Two bikes can carry 800 pounds total load. You pull the trailer with the bed, she pulls the trailer with the kitchen. 150 pounds is a real nice kitchen!

On traveling with the batteries. its just flying that limits you. If you take a ferry or train, you may be able to load your e bike just fine. Particularly if your rig makes it hard to notice your batteries.

Shipping batteries by mail or whatever, that has a huge pile of regulations attached that you can never meet. Most batteries ship from china under china rules, and when they hit the dock in the west, the label says, " power supply" or " toys", anything but " gigantic lithium battery"

If you tour the world,,, you are going to wear out your battery by the time you start flying places. Just stay on the larger continents, and cross borders like normal. Buy a new battery when you get to a new continent that requires a shipping, which will be timed to when you need new ones anyway. Bike battery used hard,, two years. Sure, its good for much longer running your laptop, but as a high drain rate battery, two years is typical. Only those who don't use them much get three, and you will be using it every day. Speaking of shipping the whole rig,,, it might be cheaper to ship just the motor and basic gear, and build a new rig when you get to the western continents.

Now I have to eat some of my words. At the second hand store yesterday, I got to look at one of those 12v micro fridges.

This was a coleman, 40 quart cooler. I was quite surprised at the weight of it, not really much more than a similar high quality cooler that size, such as a Yeti. Very thick walls on it.

The power it draws would use up 100% of what a 100w panel puts out, when not perfectly angled to the sun. ( 50 watts or so) So it would be light enough, and could be powered about 6 hours a day in sunny weather. This won't be enough cooling to carry around raw meat, but could keep a few eggs, and some lunch meat or cheese cool enough. Not sure about your diet, but you can do things like powdered or canned milk, canned meat or fish, when you can't buy fresh food daily.

So a small electric fridge is possible, particularly if used mostly to keep food bought in the morning cool till its eaten at night.