A portable gasoline generator for long range

[thunderstorm80]

Hi,
For short rides without pedaling, or long ones where you do most of the pedal work at slow speeds - the current Lithium batteries are enough.
But for very long ranges, or if you want to be able to cover a huge distance as a commuting route and do it fast (like 40-50kph), batteries are not enough anymore at the current technology. (the E-bike would have to get dangerously heavy)
I see a lot of portable generators for camping, but they are too powerful (2000W) and VERY HEAVY to be mounted on an E-bike.
Do you know of a small generator (that can produce about 700W) so that it won't be so heavy?

Or,
I know piston engines have a low power/weight ratio at those power magnitudes, but what about Wankel rotary motors?
I know Wankel didn't replaced the piston engine in our cars because it's not very good for engine-braking, but for the purpose I talk about where you need a constant torque and power - it could be very light and brilliant solution. (a fast revolving motor would need to output less torque and so it would be smaller - just like how Geared motors are smaller)

The last option I thought is about RC internal combustion motors for airplanes. Those spin at very high RPM's and so they can be small and elegant for the task. Do you know of a turn-key generator based on RC motor ?

Getting 220V 50Hz generator would be preferred, but DC voltages in the order of 80V as output should be fine too.

[dogman dan]

Pretty much limited to the 2 stroke 800w generators like harbor freights tailgator. Loud, stinky, and still fairly heavy, about 30 pounds. 30 pounds of battery will take you a LONG way, but it is small enough to drag along in a trailer if you are going where there are no plugs at all. Good little generator though, for a couple 250w chargers on a couple batteries, at a car camp.

I would LOVE a very small 300w generator. 300w on the flat, will get a 400 pound load down the road at about 15 mph. You, the bike, the generator, your camping gear.

In a way, the best approach for a gas assist remains a china girl gas kit, or homemade whizzer style rig from a weed whacker motor, combined with a front electric hub. Wont effectively charge your battery, but it will get you to the next plug when it runs out.


There are threads here, for very small home made generators. not sure where, happy hunting.

[neptronix]

Yeah. I understand this issue.
I looked into this and couldn't find squat. You will not find a small generator that is light.

The best thing i found was a 35cc honda 4 stroke at 7.6lbs.
https://engines.honda.com/models/model-detail/mini-4

Okay, it makes 1kW at 7,000 RPM. Obviously you don't want to hear a motor running at 7,000 RPM while riding, and it would be bad for reliability to run it at it's maximum power continuously anyway. But if you run it at 4,000 RPM you are getting around 600W.
Add a small RC motor and RC controller and mounting hardware for the generator part, and you are up to about 9lbs; just barely on the edge of rear rack mountable, and only outputs half the electricity you need at 50kmh.


You'll be hard pressed to find a small wankel. They exist but good luck buying a single unit. And they eat fuel like mad.
https://www.aieuk.com/brouchures-files/ ... r-2015.pdf


Other ideas..

Wait a bit for the 280whrs/kg NMC 811 batteries to come out.
Per my calculations, you should be able to jam 2.7kw-hrs into a triangle pack with those.
This would give you a 48v 56.25AH pack, good for 2.25 hours at a solid 50kmh.

A bicycle/motorcycle scooter is also a wildly non-aerodynamic vehicle.
Craig vetter has shown the world that a motorcycle's fuel economy can be quadrupled-octupled.
http://craigvetter.com/pages/470MPG/470MPG%20Main.html

Some less drastic modifications could yield 4.5 hours of operating time out of the theoretical 2.7kw-hr battery.

A feet forward half-upright bike like a RANS would be a good start for building an uber-aerodynamic ride.
A 2 wheeled recumbent would be even better. Properly kitted, we could be looking at 6 hours of time or more at 50kmh.
Which is longer than i'd like to ride a bicycle for.

[billvon]

Do you know of a small generator (that can produce about 700W) so that it won't be so heavy?

For that you don't want a generator. You want a direct drive gas engine, geared for cruising speed (i.e. 25mph.) If you have a DD hub motor you already have a generator.

You might consider a pusher trailer with a gas engine. It gets the weight, the stink, the vibration and the noise farther from you.

[spinningmagnets]

I'm not suggesting that a push trailer is the solution for this project, but they do exist:

viewtopic.php?f=3&t=9855

[thunderstorm80]

Do you know of a small generator (that can produce about 700W) so that it won't be so heavy?

For that you don't want a generator. You want a direct drive gas engine, geared for cruising speed (i.e. 25mph.) If you have a DD hub motor you already have a generator.

You might consider a pusher trailer with a gas engine. It gets the weight, the stink, the vibration and the noise farther from you.

I know my DD hub motor is also a generator. The TC4080 retrieves back kinetic energy on demand very well.
I had this crazy idea, which is of course not practical - that if I could ask any random car driver to attach a rope and drag me along a section at 40kph, I could reg'en substantial amount of power...
If there was a way to "harness" some of the excessive power all those 4 wheels around us has, but so far only their wind-drag is an (almost) practical one. (like drafting behind a truck)

My so far working practical solution, which works well at the moment, is using 4 Satiator-chargers as one big brick.
I can rapidly charge at any place with electricity at 360*4=1440W of power. (But only because my battery can accept that fast charge rate without being deteriorated)

[billvon]

My so far working practical solution, which works well at the moment, is using 4 Satiator-chargers as one big brick.
I can rapidly charge at any place with electricity at 360*4=1440W of power. (But only because my battery can accept that fast charge rate without being deteriorated)

That is great - but Satiators are pretty heavy per watt, which can further reduce your range. A hacked fan-cooled Meanwell supply might get you more power per watt, and a longer range (and/or higher speeds.)

[thunderstorm80]

I'm not suggesting that a push trailer is the solution for this project, but they do exist:

viewtopic.php?f=3&t=9855

A hub-motor like this will have a hard time pushing a fully loaded touring bike on it's own due to lack of traction, but if it's an additional motor to the main (and bigger) one in the frame, this is a very good idea which can also share some of the torque load.

[thunderstorm80]

My so far working practical solution, which works well at the moment, is using 4 Satiator-chargers as one big brick.
I can rapidly charge at any place with electricity at 360*4=1440W of power. (But only because my battery can accept that fast charge rate without being deteriorated)

That is great - but Satiators are pretty heavy per watt, which can further reduce your range. A hacked fan-cooled Meanwell supply might get you more power per watt, and a longer range (and/or higher speeds.)

But those are fan-less sealed chargers, and for that I believe they have an excellent power/weight density. (but correct me if I am wrong here)
A fan-less device is much more reliable on a long distance touring trip. (being rain-proof and dust proof is one of them, fan failure is a second reason)
Could you show me an example to one of the chargers you talk about?

[billvon]

But those are fan-less sealed chargers, and for that I believe they have an excellent power/weight density. (but correct me if I am wrong here)

Agreed. They are great chargers, and the sealed case is an advantage if you are going to be all-weather touring. Forced air cooling power supplies can use lighter heatsinks (since they don't need to rely on convection to cool themselves) but obviously are not a good choice if you are going to be charging in poor weather.

The ideal would probably be a homebrew or repackaged charger heat-sunk to the frame of the bike - thus eliminating the requirement for separate heatsink altogether. But that's a lot of work.

[X2flier]

I believe that the best machine has no moving parts. Windows and transformers are good examples of doing a job without moving parts.

I would take a slight turn from the original direction here, and suggest a small fuel cell could be running at full power while traveling, with good efficiency and little (if any) noise. The fuel cell would only be running as the batteries become depleted, and it would quit when the batteries are fully charged, or when the bike is within battery range of the destination or maybe a food/ water/ charging break.

The fuel cell could run on bottled Natural Gas, or maybe propane or hydrogen. The "bottles" would probably resemble those used in home-style propane torches (10" ~254mm) long cylinders, 3" ~76mm in diameter). You could carry a few for longer trips, or maybe buy or refill them from (pardon the pun) "gas" stations along the way.

On a side note, in 1970 there was a guy in Denver running his regular ICE car (converted for using hydrogen fuel) entirely with hydrogen that he cracked at home from a standard homestead windmill (Denver Post). Once you spend maybe a few thousand dollars on the equipment, you may never need to buy fuel again. Windmills (or solar cells, no moving parts) and electrolyzers are far more efficient now than in 1970.

[thunderstorm80]

I believe that the best machine has no moving parts. Windows and transformers are good examples of doing a job without moving parts.

I would take a slight turn from the original direction here, and suggest a small fuel cell could be running at full power while traveling, with good efficiency and little (if any) noise. The fuel cell would only be running as the batteries become depleted, and it would quit when the batteries are fully charged, or when the bike is within battery range of the destination or maybe a food/ water/ charging break.

The fuel cell could run on bottled Natural Gas, or maybe propane or hydrogen. The "bottles" would probably resemble those used in home-style propane torches (10" ~254mm) long cylinders, 3" ~76mm in diameter). You could carry a few for longer trips, or maybe buy or refill them from (pardon the pun) "gas" stations along the way.

On a side note, in 1970 there was a guy in Denver running his regular ICE car (converted for using hydrogen fuel) entirely with hydrogen that he cracked at home from a standard homestead windmill (Denver Post). Once you spend maybe a few thousand dollars on the equipment, you may never need to buy fuel again. Windmills (or solar cells, no moving parts) and electrolyzers are far more efficient now than in 1970.

Carrying pressurized hydrogen could have -a bit- more reliability issues than the rotating fans of a fanned-charger.
About methane or propane that might work - although you can't get them as easily as petrol or 220V outlet in a gas-station, but it should be available and still contain WAY more Whr/Kg than our Lithiums.
The fuel cell idea is very interesting. Could you link me to a certain key-product which can be bought?
I don't want to rely on something I've built by myself with no experience in the topic, while on a big touring trip.

[X2flier]

The fuel cell idea is very interesting. Could you link me to a certain key-product which can be bought?I don't want to rely on something I've built by myself with no experience in the topic, while on a big touring trip.

Thunderstorm,

I don't have a good source yet, but I am looking. Hopefully, somebody here can chime in.

Once I build a good ebike, then I will know what I need for power out to run the bike, and (slowly) charge batteries with the excess. I plan to add the fuel cell last, obviously.

[neptronix]

All the fuel cells i've seen at ebike sizes are wildly expensive and large.

Hydrogen is just a lossy and more expensive way to burn natural gas, unless you can find a holy grail fuel cell that exceeds 60% efficiency. You might as well just run an ICE off a natural gas tank if you wanna be greener.

Although the noise, yeah..

[Grantmac]

An electromagnetic clamp to limpet onto semi trucks.

[wturber]

This has come up before and this type is the lowest weight currently made generator that anybody has come up with.
https://www.amazon.com/d/Outdoor-Genera ... +generator

There is a small 300 watt unit was made many years ago (I think in the 50s/60s?) and is sometimes sold as an antique.
You might try to add your own motor and make something like this work.
https://www.amazon.com/Bicycle-Generato ... B001WB3TZ4

I like the fuel cell idea if you can find one.

[neptronix]

Geez, 19 pounds and then you've gotta waste some gasoline converting 120v AC to ??? DC..
Sad that that's as small/light as it gets.

[wturber]

Geez, 19 pounds and then you've gotta waste some gasoline converting 120v AC to ??? DC..
Sad that that's as small/light as it gets.

Kinda makes you wonder if there is a niche market for small DC generator. I guess the big issue is the motor that drives it.

Here's that older generator I mentioned. Kinda noisy and obnoxious ... but small.

[amberwolf]

There've been threads about using a tiny RC gas engine to drive an RC electric motor to make a generator. They're probably somewhere in this list:

search.php?keywords=generator*&terms=al ... mit=Search

(liek this one viewtopic.php?f=3&t=18800&hilit=generator* )

There's also a number of range extender threads with helpful info:

search.php?keywords=range+extend*&terms ... mit=Search

[wturber]

Here's another candidate. But still 20 lbs.

https://www.powerhouse-products.com/pow ... uct/500wi/

[Chalo]

Seems to me that there is a very limited range of usefulness for a stinking gas generator in this application. If you spend either the same number kilograms or the same number of dollars on more battery (and you are realistic about the number of dollars you'll spend fueling and maintaining the thing), you can buy a whole lot of trouble-free range and not have to tolerate the accompanying fumes and noise of a motor.

In the other hand, if you're using the generator so you can wander off the grid and away from opportunities to recharge, then you'd probably be much better off with a gas fueled bike that is built for the job and has an overall better engine.

[X2flier]

There've been threads about using a tiny RC gas engine to drive an RC electric motor to make a generator.

"A tiny RC gas engine" these days is usually a converted weedwhacker engine. For the price, you spend half (or less) for a complete weedwhacker than what the equivalent "RC aircraft" engine would cost at a hobby shop. Then you throw away everything except the engine/ gas tank/ exhaust system.

The conversion needed from weedwhacker to aircraft use is fairly cheap and well-documented on the RC forums. YouTube has examples of weedwhacker engines running bicycles with just a propeller pushing air, but they are too noisy (and dangerous) to be tolerated by the public. They do have enough power, though.

[amberwolf]

Yes, that is discussed in the link I'd provided in my previous post (and probably in others in the search list also posted).

[neptronix]

In the other hand, if you're using the generator so you can wander off the grid and away from opportunities to recharge, then you'd probably be much better off with a gas fueled bike that is built for the job and has an overall better engine.

Totally.
Build it like a chevy volt and start with the ~8lb honda engine. It's a 4 stroke, so it will at least make efficient use of the fuel and pollute less.
Pair with a small DD hub for regen and additional power when you need the boost to climb a hill or whatevs.

But we're trying to get away from stinkers here. I'd personally use slower speeds and aerodynamics to stretch out batteries rather than this route.

[flat tire]

This is the most poorly thought out idea I have ever heard. You are describing a shitty gas powered bike with unnecessary electrical bits. Just make a regular gas powered bike, or get a motorcycle: motorized bicycles are the wrong tool for long cross country trips anyhow.

If you're committed to electric try a big battery. By the time you're installing a genset and fuel you can probably fit 2 or 3 kwh which will see you thru to a full day of riding at bicycle speeds with pedaling.