New to E-motorcycles. I have lots of questions

[manwell14]

Ok. I am interested in trying to build a 2 wheeled recumbent motorcycle that is gas-electric powered. To clarify I want to use something like a smaller 250-500cc MC engine running an optimal RPM to only power a generator that charges a battery. The battery would then be used to power the all electric final drive.

Now to cover some general bases. The bike would be longer to accommodate the engine, the batteries, and the seating position. What I have envisioned would have the motor forward the driver, with the batteries and final drive motor under/behind the seat. It would be equipped with a fairing if not an entire body. Similar to British Monotracer or Lit Motors self stabilizing bike, however it would likely be stabilized by good old leg power. I would like this bike to be able to handle high speeds easily. I live in an area that would require at least comfortable handling at 50-60 MPH

My Logic
It makes sense in my inexperienced mind that you could essentially optimize the energy produced by a small efficient gas engine by storing it in a battery bank, and using it as needed it in an electric final drive. If you were to entirely deplete the battery, then you could theoretically still affectively power the bike from power directly being produced by the engine.

The end result would be a bike that though is heavy, it would require less batteries, waste less gas. have the improved drive characteristics of an electric motor, but still have range and be instantly refillable.

Questions.
1) Is it worth doing generally? Is my logic solid-ish or am I being unrealistic.
2) If I am on solid ground would it be safe to assume, because of the constancy of the generators action, and the variability of the motor on the drive train, would it be reasonable to have a less powerful generator than final drive motor? primarily just for reducing weight.
3) I don't know a great deal about motors. I would like to use a BLDC. I live in a hot environment so I was considering water cooled. Since the bike will be heavy and have gasoline backing it, I would rather go big. I know some of the all electric sport bikes use up to 94ish volt motors, but they are also made of carbon fiber. I've seen everything from 36 to 114 volts. How big is big enough? At what point is there diminishing returns.
4) How will the constant recharging of the batteries affect the total amount of batteries I need.
5) Is it at all recommended to build your own batteries using individual 18650s or is it best to just get something like the Nissan leaf batteries?
6)Assuming that I am on a decent track, recommendations for what components would be nice. Motors, engine, batteries, charging units, controllers, etc.
7) I've read lots of pros and cons on transmissions. I know they are generally not necessary, but I may spend a significant amount of time at higher speeds. I toyed with the idea pulling a transmission from a bike, building another housing for it and trying to basically having a two speed transmission. One for general poupose, and one for long stretches at high speed.
#8) Are there any pre-drawn plans, diagrams, books or references for this kind of thing set up online or purchasable somewhere. I have a hard time searching for it because searching "gas-electric/petrol-electric" pulls up everything but what I'm looking for.

The reason I like this idea, is I feel that doing building it this will give me slightly more design freedom and reliability than just a standard MC build. Being able to kind of bring these elements together allows me to make adjustments more or less where ever I think would be necessary. essentially the entire drive train from beginning to end becomes connected by flexible wires and belts.

I realize I'm being ambitious, but please I welcome all of your knowledge and insight. I am new to this world, and I find it increasingly fascinating. I feel like it will play a big role in the future, and I want to at least have a better understanding than I currently do. I greatly appreciate any information. If I'm way off track please don't hesitate to tell me. I'd rather stop while I'm ahead.

PS as kind of a side note, I would like to do a gas-electric build of some kind. I am a MC fan, and I feel that this would be the "cheapest", most practical, and fit in my garage. However I also like the idea of doing a trike or a small car in a similar manner, so if this in impractical for an MC but not a car let me know.

 

[amberwolf]

What you're after is called a series-hybrid. There have been some of those; I don't recall any MC ones on ES off the top of my head, but you might look around EVAlbum's site to see if any are documented there. Used to be, not sure if they're still around.

There are cars like that; can't recall which ones. Most are parallel hybrid so that both gas and electric can actually drive the wheels.

1) Is it worth doing generally?

That is more up to you; depends on your abilities and budget, and the kind of efficiency you're after. Keep in mind that if you have hills or a lot of stops and starts, a heavier vehicle is less efficient than a light one, and the more of either, or the steeper the former and the quicker the latter have to be, the worse the problem becomes.

2) If I am on solid ground would it be safe to assume, because of the constancy of the generators action, and the variability of the motor on the drive train, would it be reasonable to have a less powerful generator than final drive motor? primarily just for reducing weight.

Not sure what you mean by "solid ground".

If you want it to be more efficient with the gas, you will only run it when the battery drops below a point at which it is worth starting and running the generator for a time.

If you run it all the time, you have more waste heat and more noise all the time, which will all be in front of you.

Personally I'd be using regular actual generator, probably a Honda cuz they seem to be the quietest, rather than building a system for that. Most likely a nice reliable model already exists that will put out the power you need. It would output just the regular wall-outlet-level AC voltage, but then you just use a regular charger for your pack, rather than having to design and build something that regulates the output of the generator into a DC setup that works like the charger would to protect and properly charge the pack with appropriate current limiting/etc.

That would also let you use the same charger to just plug into the wall wherever you go to recharge, saving gas (probalby a fair bit of it). Otherwise you need either a second charger or a second stage to the existing one.

3) I don't know a great deal about motors. I would like to use a BLDC. I live in a hot environment so I was considering water cooled. Since the bike will be heavy and have gasoline backing it, I would rather go big. I know some of the all electric sport bikes use up to 94ish volt motors, but they are also made of carbon fiber. I've seen everything from 36 to 114 volts. How big is big enough? At what point is there diminishing returns.

Depends on what you're after. Higher voltage has advantages in smaller wires, lower currents (for the same power), but the higher you go the more physically dangerous it is to handle/service, and the more expensive some of the parts become to deal with the voltage.

Lower voltage has the advantage of being pretty common, and relatively safer than the higher voltages, but larger wires to carry the higher currents, as well as sometimes bigger components for the same reason.

Higher voltage is easier to use for speed (makes a given motor spin faster than lower voltage would), but you can make up for that in ohter ways (gearing, motor winding, etc).

You'll probably want to look around at the various threads in the Motor Technology subforum's sticky index thread, and the various builds in this MC subforum (like JonesCG's race bike stuff), to see what others are doing and why; it'll help you figure out what you might want to do.

4) How will the constant recharging of the batteries affect the total amount of batteries I need.

The less charge you use from them, the less capacity they have to have. But if you are using them to actually support the power the motor needs, they have to be able to supply that power.

If you have a generator system capable of running the motor by itself, then even that doesn't matter much, and you can simply size the pack for however long you would want it to run without the generator.

5) Is it at all recommended to build your own batteries using individual 18650s or is it best to just get something like the Nissan leaf batteries?

Depends on the work you want to do. Read around the many 18650 build / troubleshooting / sale threads and you'll see a lot of info on decisions, problems, solutions, whys and why nots, and hows. There is no one right way, but a lot of little good advices.

It's possible to build an 18650 pack for "free", but it's a lot of work and might have to be larger than other methods because the cells would be used, or the wrong kinds, or both. There's threads about that, too.

Just looking for 18650 in the thread title will help find most of the ones you want. Laptop might find others.

6)Assuming that I am on a decent track, recommendations for what components would be nice. Motors, engine, batteries, charging units, controllers, etc.

Can't really help with that without knowing vehicle and rider weights, terrain, weather (wind/etc), accleration desired, and so on. I think first you'll want to read up on the general idea of the electric motorcycle / vehicle, and the types of stuff you are wanting to do in building it, to decide if you do indeed want to do it that way. It's kind of a lot of reading/research, but knowing more will definitely help you out more by letting you ask questions you may not even have thought of yet.

Then you will probably also have a better idea of what power requirements are going to be, and then see how big and heavy stuff will have to be to do what you want, and thus a better idea of size, weight, etc.

#8) Are there any pre-drawn plans, diagrams, books or references for this kind of thing set up online or purchasable somewhere.

I don't think anything like plans exist. The best you could do is read up on build threads for other people's vehicles that are similar to what you want, and then copy the bits you like out of each one.

Not that I've ever done that.

There's also the ES wiki, the forums here, EVAlbum, DIY Electric Car forums, sites like Ebikes.ca with simulators and other tech info (which even though it's about ebikes, just scale it up for your purposes).

The reason I like this idea, is I feel that doing building it this will give me slightly more design freedom and reliability than just a standard MC build.

Well, reliability would be "higher" with a parallel hybrid than a series (because then either drivetrain could run the wheel(s) even with total failure of the other, but efficiency is probably higher with the series.

Design freedom...well, you can pretty much design anything almost any way you want regardless of what others have done. Depends on your abilities and budget, etc. more than anything else. And imagination. You can even put the gas engine in the wheel if you like (it's been done long ago in at least a couple ways; see the Horses of Iron thread by Lock/LockH).

I realize I'm being ambitious,

Nothing wrong with ambition. As long as you're willing to learn as you go for things you don't yet know, and do a lot of research on what has already been done that you want to do, and why they did it a certain way or didn't do it another way...or just do stuff and then learn from the mistakes you'll make.

You should see my stuff--I limit my ambition only to my budget (zero) and my resources (whatever I can scrounge), and my abilities of the moment (which I often overreach, and discover I didnt' know as much as I thought I did...but sometimes I get lucky and it works and I learn something new. )

 

[SlowCo]

What is the longest distance you need to cover in what terrain (steep hills) and in what temperature? Maybe you'll be better of building an all electric recumbent and use the budget, space and weight needed for the gasoline generator instead for batteries?

 

[manwell14]

Sorry it took so long to respond. I got busy.

Series Hybrid! Thank you so much. I've keep thinking I'm crazy, but now that I know what it's actually called I can actually do research and not just blindly fumble in the dark.

Lots of good information. I greatly appreciate it. Not sure why I didn't include basic rider info.

My basic idea is to essentially use a steel framed salvage bike. Use the front fork and triple tree assembly and the rear swing arm. I'd make use of the existing brakes, suspension, etc. It would be elongated out to make room for the battery bank, electric motor, lower seating position etc. It will have a fairing of some kind. So in order to make it with my skill set and somewhat limited access to tool, I expect total weight of the bike will be about 750 to 900 pounds. I'm about 220 so total weight about 970-1100 pounds give or take. I'm aiming high with the weight, because I don't what to be underpowered. As far as location, I'm in the southern US. Terrain is pretty flat. No mountains. Weather is warm and humid. Wind is usually not an issue. Spend a lot of time praying for a merciful breeze. On battery alone, I would like to be able to handle about 20-30 miles at around 60mph. I would like to be able to exceed speeds of 75mph in short bursts. As far as acceleration I just want to be able to get out in front of traffic when necessary. My driving/riding style is pretty relaxed and actually quite conducive to an EV. With the gas engine on, I would like to be able to maintain 60mph "indefinably". Any thing less that that becomes dangerous on the roads here. I use to own a Honda rebel, so I am speaking from "picking up pieces of my bike off the ground" experience.

I like the idea of getting a generator. My initial thought was to get a cheap salvage MC engine, just because it would be easy, but it would have a lot of unnecessary added weight from the transmission and what not. Buying a new Honda generator would be pricey. Even finding one used would be pretty expensive, but now that you got me thinking about it getting a non-automotive engine might be a good idea. It would reduce the weight. They sell 300+cc engines meant for running equipment, that are more what I'm looking to spend. It could easily be used to power a separate generator. I will say I also like the idea of going high voltage. I'm not scared to work around it, and I have a pretty safe work ethic.

Does any of that seem to too unreasonable? I'm aiming high I know, but I'm trying to be practical for the area I'm in. Once you get hit on a slow bike, you really don't what to every get caught without "get away" speed again.

And again thank y'all for responding. I greatly appreciate it.

 

[amberwolf]

As far as location, I'm in the southern US. Terrain is pretty flat. No mountains. Weather is warm and humid. Wind is usually not an issue. Spend a lot of time praying for a merciful breeze.

Sounds like north Texas (lived there in farm country near Denton as a kid).

On battery alone, I would like to be able to handle about 20-30 miles at around 60mph.

First you have to figure out how many watts it will take you to maintain that speed, which means you have to know approximately how aero your vehicle will be. You can make a guess, using online calculators, for a typical motorcycle.

Or you can look at what others with elecric MCs are actually getting; like this search
https://www.google.com/search?q=watts+at+speed+for+motorcycle&ie=utf-8&oe=utf-8#q=electric+motorcycle+watt+hours
which has a number of examples.

At a guesstimate based on some of what I skimmed, it'll take around 8000w+ to maintain 60MPH, and might average around 150wh/mile.

150wh/mile means that for 30 miles (nonstop) at that usage, you'd need a battery size of at least 4.5kwh, which isn't really all that big. I think I have about that much battery I can use on my SB Cruiser trike, and it's probably about teh size of a big luggable toolbox, and probably weighs a lot less than my smaller St Bernard (Kirin). Mine is made in two packs of a little more than 2kwh, so I can carry it all if I want the range, or leave half at home if I don't need it so it doesnt' actually detract from my efficiency, and leaves the space for other cargo/etc.

Now, if you need to stop and start a lot, you could potentially double that power consumption depending on weight/etc, and how many of those stops you have, etc.

ALso remember that probably around every 10mph additional speed, your power usage will double, IIRC.

I would like to be able to exceed speeds of 75mph in short bursts. As far as acceleration I just want to be able to get out in front of traffic when necessary.

But how *quickly* do you want ot get out in front...if you need to accelerate quickly while almost at your "top speed", you might want a setup that can actually exceed the top speed you would use it at by some significant margin; this allows you to still have a lot of oomph to push faster very quickly.

Look at some of the various discussions (arguments ) about voltage vs current and motor performance, multigear transmissions vs direct drive, etc. They talk about the power curves; basically there is a point in the speed curve where power begins to fall off.

Or you can play with the simulators for motors, like the ebike one at http://ebikes.ca/simulator .
Even though it's not for your vehicle usage, it gets the idea across.

My driving/riding style is pretty relaxed and actually quite conducive to an EV. With the gas engine on, I would like to be able to maintain 60mph "indefinably".

Then you need a generator system that can output continously however much power it actually takes to maintain that speed with that vehicle. Preferably more, so it can also charge the pack while doing that, in case you need it.

I like the idea of getting a generator. My initial thought was to get a cheap salvage MC engine, just because it would be easy, but it would have a lot of unnecessary added weight from the transmission and what not. Buying a new Honda generator would be pricey. Even finding one used would be pretty expensive, but now that you got me thinking about it getting a non-automotive engine might be a good idea. It would reduce the weight. They sell 300+cc engines meant for running equipment, that are more what I'm looking to spend. It could easily be used to power a separate generator.

Just keep in mind that a dedicated generator system will probably already be optimized and will probably be smaller and lighter than one you build yourself, though at the power level you need it will also probably be expensive.