# Portable generator for an electric bicycle



## tm33 (Jun 10, 2020)

Hello,

I'm looking for the lightest and most quite generator possible to be either put on the back of an electric mountain bike or hauled behind on a trailer. I only need about 200 watts of power, but it needs to be able to withstand constant shaking and vibrations from trail riding. Are there any propane or gas powered generators out there that could fit the bill? My budget is about $500, but flexible.


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## iowagold (Jan 22, 2020)

your first questions need to be.
where do you need power?
what are you needing to power as in voltage and current.

you mention an electric bike.
make and model would be nice.

what can you carry for fuel?
weight on the fuel can be an issue.

when do you need to recharge? day, night?
what is your recharge rate or how long to full charge? and the voltage?
how long will the battery last in work hours.

one thing to keep in mind..
any time you change voltage.you loose energy... most of the time is is at least 30% as loss.

does the bike have a removable battery pack?
or can you add more batteries?
if so look in to solar.
and if you can do direct from the panels to the battery charger...
the better the charge.


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## tm33 (Jun 10, 2020)

iowagold said:


> your first questions need to be.
> where do you need power?
> what are you needing to power as in voltage and current.
> 
> ...


I'm building a custom bike, but the concept is the same for all makes and models - a generator that charges the 48 volt battery, and (optionally) powers the 48 volt motor through the controller. The 750 watt, 48 volt motor would need 15.6 amps. I'm not looking to go fast, I'm looking to go far while maintaining close to the top speed. Fuel can be stored under the down tube of the bike, and if weight is really an issue, everything can just go on a cargo trailer. The charger is actually 300 watts and 5 amps (not 200 watts as I mentioned in my original post). Battery would probably be around 14 AH. No doubt there will be a lot of lost power, but a generator will still be a much cheaper option to adding more batteries, and the only option for camping or traveling where there is no electricity. Solar isn't an option as I only ride in the evening/morning/nighttime or in cloudy weather.

To sum it all up, the primary goal is the lightest / quiet generator that can withstand constant, violent shaking while charging the battery on the go. Secondary goal is a more powerful one that can also power the motor (noise level is of top concern so I may have to forgo this option).


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## iowagold (Jan 22, 2020)

tft solar canopy on the trailer, solar fabric on your bike suit.
solar canopy on your tent.

what cell tech are you planning on? current tech or new tech?
some of the emerging stuff for 2025 looks ok.
they are still testing.

weight up and down hills in a trailer is a problem..
regen braking on the trailer helps... at least on the down..
but blue tooth is still sketchy in reliability for power management speed. 
hard wire for testing, but in the long run you will want some sort of secure wireless com.

doing a multi planetary system that can be locked electrical for final drive ratio of zero
would give you the under ratio for going up to keep the current down..
and then the speed / time for hill climb is low too.

for the ultimate future tech
hydrogen, then use water as fuel.
so far in year 2020 the power required is still high unless you find a viable fuel cell catalyst for almost direct separation.
go closed system...
but the good news is you could drink the water!!
and we live on a water planet.

maybe constant work out generator on the pedals...
charge the battery's from that.. kinda like a dyno setup..
good luck on the project!


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## RedOctobyr (Aug 8, 2018)

The Honda EU1000i is high quality, quiet, and light weight (30 lbs) inverter generator, putting out 900W continuous. 

But banging around on trails? Generators are really not designed with that sort of thing in mind. So broadly speaking, I'd feel better with a high-quality unit (Honda, Yamaha) than some of the ~$300 versions with similar output. 

For any unit, you'd do well to cushion the generator as much as possible, to reduce the impacts it feels.


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## jasonjax (Mar 15, 2020)

I'd invest in a higher AH battery and just charge as a separate process removed from the bike.


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## jkingrph (Sep 18, 2017)

I don't know how shaking would affect a generator. I agree about the small Honda, relatively lightweight and quiet. I don't think I would consider propane, you really get into a lot more weight for the fuel carried, plus gasoline is easier to locate in a lot of remote areas. I did have I think a 2 gal fiberglass/polymer propane tank, but they were recalled and discontinued for safety issues and the same amount of gasoline in a small can was several pounds lighter. 

I absolutly know nothing about solar, but i expect the area of panels required would be relatively large, even for a towed trailer, plus I would think your efficiency would drop because of shade in a lot of trail areas, you need direct sunlight for best solar performance.


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## RedOctobyr (Aug 8, 2018)

Since camping was referenced, as well as not having access to power, I'm thinking this is for _long_ distances. Like charging daily, and riding for a week at a time. Something where just larger batteries won't do it, because they still won't be nearly enough range. 

OP, I'm not personally aware of smaller inverter generators. They may exist, but around 1000W is the smallest I can think of. Inverters will be lighter, quieter, and better on gas than conventional generators, so I think they would be a better fit.


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## tm33 (Jun 10, 2020)

jasonjax said:


> I'd invest in a higher AH battery and just charge as a separate process removed from the bike.


That's always an option, but it would mean 600 watts of energy is wasted (if it's not powering the motor)


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## tm33 (Jun 10, 2020)

Thank you for your responses. Honda EU1000i sounds like a great option with only 50 db of noise. I'm going to look for a used one.

I was under the impression that there were 500 watt generators out there, but now I realize those were probably solar.


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## RedOctobyr (Aug 8, 2018)

Well you learn something new every day, I found a 500W inverter generator: 
500Wi | Powerhouse Generators
https://www.walmart.com/ip/Powerhouse-Powerhouse-500-Watt-Gasoline-Inverter-Generator/24403900

But with very little of a track record (in sharp contrast to the Hondas), I would be very leery of relying on something like that. Saving 8 lbs is great, but if you end up with a 21lb paperweight, that's not very useful.


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## tm33 (Jun 10, 2020)

Not very concerned about long term reliability, but it is twice as loud for only 25% less weight. Although it may be just light enough to carry on the back of the bike instead of a trailer.


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## iowagold (Jan 22, 2020)

the honda eu1000i is a way better gen set.
you are better off with a new unit..
run a magnetic dip stick for sure..
and you can convert them to tri fuel.
click here for the honda generator forum


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## Robh (Aug 19, 2019)

If you're that concerned about a generator being bounced around, I don't think anything with gasoline is a good idea.
Check out this one: https://www.amazon.com/Baja-900-Watt-Propane-Inverter-Generator/dp/B083VS1N2M

You didn't say how long it needs to run, so would one of those lithium battery "generators" be sufficient, like a Jackery?


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## Robh (Aug 19, 2019)

tm33 said:


> Hello,
> 
> I'm looking for the lightest and most quite generator possible to be either put on the back of an electric mountain bike or hauled behind on a trailer. I only need about 200 watts of power, but it needs to be able to withstand constant shaking and vibrations from trail riding. Are there any propane or gas powered generators out there that could fit the bill? My budget is about $500, but flexible.


Everyone has their reasons, but if yours is environmental, know that any generator puts out a TON of CO2 that would eliminate any 'savings' you get from an electric bike. Would it be better to simply buy a gas motorcycle or moped? I'm not sure of the use case, so throwing that out there.


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## Old man here (Nov 5, 2020)

I don't think the OP is around anymore. It's been 8 months since he last posted.


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