Greetings, care to help design a build?

Hello people. I've been interested in EV's for some time, and I've got a classic car that I've wanted to turn into an EV for a decade or so. However, before I spend the money on that I'd like to get my feet wet with an old motorcycle I've got first.

When it comes to motorcycles, I'm more of a cruiser guy. I've seen a few off road and sport bikes, but I'd love to get on an electric cruiser. To that end, I've got a 1979 Honda Goldwing Gl1000. This was part of what were known as the naked goldwings because it was before they came with all the saddlebags and fairings. I think this bike would be perfect as an EV as well because the traditional motorcycle "gas tank" on this bike is actually a storage area made of 3 different compartments. This would be perfect for protecting controllers and electronics. The bike its self is shaft driven. This brings me to the first of a few possibilities. Would there be an affordable motor that could direct drive the shaft its-self? One that would be able to handle a gear reduction ratio of 3:1 and provide enough rpm's to get up to 80mph (130kph) for sustained distances?

Goals:
100 mile freeway range
80 mph drive speed
Would be great if it could charge at a lvl 2 charger

Build thoughts:
The curb weight for this motorcycle is about 600lbs before rider. This isn't a light weight peppy bike. But it also doesn't need to be super torqued on the low end. The motor will likely need to be liquid cooled to maintain speeds like that.

Motor and Controllers:
My first thought would be maybe a club cart motor and controller for this. They usually run at a 12:1 gear reduction but I need much more research and any additional thoughts or ideas would be super appreciated. I had considered the 14kwh Qsmotor hub motor, but it's about $2500 before tariffs kick in and I'd like to keep this first build more budget friendly as I have another project after it.

Batteries:
I know that lithium ion cells are the most energy dense at the moment, but I'm put off by the cost and the low number of cycles available per cell. I'm leaning towards lifepo4 packs for this. I know they take up almost twice the space for the energy density, but they cycle so many more times, and frankly the more stable chemistry is less off-putting as well. This bike has TONS of space for batteries and I can add saddlebags as well to get any thing extra that may be needed.


Me: I'm a "mature" full time college student and father of a 4 year old. So this build is going to be done slowly over time, but I'd like to at least plan out the build so I can keep my eyes open for deals and bargains that would advance it as time goes by.

The problem is essentially that in order to drive that much weight (even after removal of the ICE components) that fast and far, you'd need more batteries than can fit on the bike - especially the lower density LifePo4 cells. One way around it that has been suggested for other similar builds is to add a sidecar to carry the extra batteries, or even the whole pack...

Scizmz said:

However, before I spend the money on that I'd like to get my feet wet with an old motorcycle I've got first.

Click to expand...

FWIW, because of battery capacity vs places to put them, motorcycles can be harder than cars to convert.

Would there be an affordable motor that could direct drive the shaft its-self? One that would be able to handle a gear reduction ratio of 3:1 and provide enough rpm's to get up to 80mph (130kph) for sustained distances?

Click to expand...

That depends on the voltage you use it at. The higher the voltage, the higher the RPM for the same motor.

For power levels sufficient to do it sustained, you'd need to determine how much power it will actually take to reach that speed, under the worst conditions you'll encounter (uphill a x% slope into a headwind of xMPH), then find a motor that can do that.

For the shaft drive, you just have to make a coupler that will connect the output of the motor to the input of the shaft. As long as you're using a motor that spins it's axle, then that's relatively easy. If you use a motor that mounts by it's axle and spins it's case, it's more difficult but not impossible. You can probably use the original coupler for the ICE as a base part to modify into the motor coupler.

Goals:
100 mile freeway range
80 mph drive speed

Click to expand...

At a guess, it's going to be 200-300Wh/mile for 80MPH on a typical unfaired motorcycle. (my SB Cruiser trike is very unaero, and only goes 20MPH, but it still takes 60Wh/mile to move it around!). Let's just call it 300wh/mile for your worst case scenario.

So, 100 miles x 300 wh/mile = 30kWh capacity battery pack to go 100 miles at 80MPH. If you don't need 80MPH for the entire distance, then the pack size is smaller, but if you need 80MPH for any significant portion of your range, it's going to take power to do it, and capacity to provide that.

Let's say you use a "72v" battery pack (you may want to use higher voltage, but this is the lowest you'd probably start with). 30000 / 72 = 416Ah.

That's a VERY large battery pack. I don't think it will fit in the frame even if you used the entire space, removing everything there, and having a hubmotor in the wheel instead of a motor in the frame. It will also likely weigh nearly what the bike does. (I have a "52v" 40Ah pack made from cells out of an old Zero motorcycle, and it is almost 40lbs, so only about 5/7 of what a 72v 40Ah pack would weigh. It is over a foot long, a bit less than a foot tall, and a handspan wide. The proposed pack will be more than ten times that size.


If you make fairings (especially Vetter style) you could cut that power consumption quite a lot, and get by with a much smaller battery pack, and cut the motor size, for the same speed and range. You might be able to get as good as 1/3 of the capacity needed for the same speed and range with a Vetter fairing. One page with some Vetter info: https://en.wikipedia.org/wiki/Craig_Vetter_Fuel_Economy_Challenge


If it helps, these may give you more insight into the power requirements (wh/mile) for the speed you want:
https://www.google.com/search?q=wh/mile+for+80+mph+motorcycle

https://www.google.com/search?q=wh%2Fmile+for+80mph+vetter+motorcycle




Something else to think about is C-rate. Each battery (cell type) has a specific max and sustained spec for how much current it can provide, usually expressed as a multiple of it's capacity or C-rate. A 1C battery, that's 10Ah, can only supply 10A. A 10C 10Ah battery can supply 100A. Most common batteries are around 2C discharge rate (and around 0.5C charge rate, sometimes less). Unfortunately many sellers exaggerate their batteries' abilities, so take them with a grain of salt....

If you used a 400Ah battery, rated for 2C, it would be capable of 800A constant current. If it's a 72v pack, that's 72v * 800A = 57600Watts, so it could easily handle quite a lot of power output.

If you had exactly the same battery but only half the capacity, it would also have half the current delivery ability, which means it would still be capable of a lot of power, 28800W.

Either one would likely run your bike wiht no problems.

The smaller the battery pack, though, the smaller it's abilities, *or* the higher-C-rate cells you must use, to get the same power capability out.

Would be great if it could charge at a lvl 2 charger

Click to expand...

That's solely dependent on the charger you use, and the electronics (if any) that you make to connect it to the supply.

Whether it will be able to charge the batteries quickly or not depends on the battery cell specifications. Every cell brand and model is different, and each has compromises of some qualities to get the others, so some can charge fast, some can discharge fast, and some have high capacity. And there's every combination between.

The motor will likely need to be liquid cooled to maintain speeds like that.

Click to expand...

Probably not. Plenty of motors can handle that power--they jsut have to be large enough.

I'd guesstimate you'd need 10-15kw minimum to sustain 80MPH; there's online calculators to help you figure that out. Most likely someone has published a CdA figure for the bike you have, which you can then use to help calculate power usage based on wind resistance at speed.


BTW, one possible source of parts that might be cheap is to buy someone else's conversion that they've given up on. There's a lot of them out there. (dunno how many are actually for sale at any given moment....)

Just for grins, here is the grin tech simulator using a hubmotor (that coudln't actually do what you want, but I've pushed it with a custom setting to "change" it's winding to let it do ti for the simulation):

https://www.ebikes.ca/tools/simulator.html?motor=MX4503_SA&mass=363&hp=0&axis=mph&batt=cust_72_0.001_400&autothrot=false&cont=cust_1000_7000_0.000001_V&kv=25

I doubt the CdA (aero) setting is right, so it probably takes more power than it says in the simulation. If you have the CdA for your bike you can plug it in and play with stuff to see what it really would take to do what you're after.
Some of the numbers it gives, for a full-throttle speed of 82MPH, using a 400Ah battery pack. I deleted out stuff that isn't relevant/etc.

Mtr Power 19091W
Load 19174W
Mtr Amps 457.3A
Batt Power 23663W
Batt Amps 330.2A
Batt Volts 71.7V
Consumption 288.6 Wh/mi
Range 99 mi

amberwolf said:

At a guess, it's going to be 200-300Wh/mile for 80MPH on a typical unfaired motorcycle. (my SB Cruiser trike is very unaero, and only goes 20MPH, but it still takes 60Wh/mile to move it around!).

Click to expand...

80mph takes 16x the power of 20mph. So assuming the same Cd, duty cycle, and time at speed for the 80mph motorcycle, that's roughly 1kWh/mi.

That's a chump's game.

First off, thanks for taking the time to reply. I appreciate any feedback.

FWIW, because of battery capacity vs places to put them, motorcycles can be harder than cars to convert.

Click to expand...

I'm aware of this, but I feel like many people here are underestimating the amount of space a bike like this has. This is no milk jug sized battery like came off of an Alta bike. The existing engine is 30" wide. With that gone, it opens up a ton of real-estate for batteries.

You can probably use the original coupler for the ICE as a base part to modify into the motor coupler.

Click to expand...

Exactly what I was thinking. It may make it more difficult to set up the drive-train as I no longer have a sprocket that I can change the size of to work with, however I was also considering possibly hooking up a cvt clutch from a scooter to a motor in order to get a proper torque curve/gear ratio to work with this bike if needed. I wouldn't need quite as much voltage, and I could parallel the batteries instead of running them in series for the additional ah needed for distance.

At a guess, it's going to be 200-300Wh/mile for 80MPH on a typical unfaired motorcycle. (my SB Cruiser trike is very unaero, and only goes 20MPH, but it still takes 60Wh/mile to move it around!). Let's just call it 300wh/mile for your worst case scenario.

Click to expand...

I will be building fairings for the bike to help with wind resistance. It's messy work, but anybody that rides knows that above 45mph you start hitting decent resistance, and I do want to minimize that as much as I can. If not for the power requirements, than for myself personally.

Let's say you use a "72v" battery pack (you may want to use higher voltage, but this is the lowest you'd probably start with). 30000 / 72 = 416Ah.

That's a VERY large battery pack. I don't think it will fit in the frame even if you used the entire space.

Click to expand...

So, I started with my estimates based on the provided schematics of a123's lifepo4 72v 200ah size dimensions. I've got room for a 200ah pack where the motor is now fairly easily, and I can easily fit 2 100 ah packs where saddle bags would go if needed. The big downer there is cost, but again this is just the early part of the design stage.

The motor will likely need to be liquid cooled to maintain speeds like that.

Click to expand...

Probably not. Plenty of motors can handle that power--they jsut have to be large enough.

Click to expand...

Interesting, it was my understanding that heat at higher rpms tends to be an issue with motors for extended periods of time.

BTW, one possible source of parts that might be cheap is to buy someone else's conversion that they've given up on. There's a lot of them out there. (dunno how many are actually for sale at any given moment....)

Click to expand...

Solid idea, i'll keep an eye out for something. Thanks again!

Scizmz said:

I'm aware of this, but I feel like many people here are underestimating the amount of space a bike like this has. This is no milk jug sized battery like came off of an Alta bike. The existing engine is 30" wide. With that gone, it opens up a ton of real-estate for batteries.

Click to expand...

Oh, I know--I had a friend that had multiple Goldwings (though after the fairings / etc came standard), and Kawasaki Voyagers too, that we worked on together now and then. They're pretty big bikes.

But the battery space has to be in the right shape if using prismatic or pouch cells, and I'm not sure if it is, unless you make something other than the usual "big brick" out of the pack. (which complicates a number of things, including keeping proper pressure on teh cell surfaces).

I wouldn't need quite as much voltage, and I could parallel the batteries instead of running them in series for the additional ah needed for distance.

Click to expand...

You want them in series, that doesnt' affect your range.

Ah doesnt' determine range, if you look at my primitive math in the first reply, you'll see Wh does. (V x Ah).

It's messy work, but anybody that rides knows that above 45mph you start hitting decent resistance,

Click to expand...

15-20MPH is actually where it starts to get serious for aerodynamics reasons. You yourself may not notice it, but the power source does.

Interesting, it was my understanding that heat at higher rpms tends to be an issue with motors for extended periods of time.

Click to expand...

It's not the RPMs for a motor (vs an ICE) that create the heat, its' the load vs the motor's designed ability to shed the heat.

Every motor is different. Explore the http://ebikes.ca/simulator after reading the whole page to learn more about it.

i talked to a bike owner a while back as he had seen they made a hydrogen version of a suzuki brugman and he wanted one but the specs were "lackluster" to say the least.
i explained him the math that replacing the entire hydrogen system and filling every inch of that space with a lithium battery would yield far better results and give better range then the hydrogen version could.
in the end i made him a battery that was custom fit for a frame of a brugman after making "slight" mods to the frame to make it more space efficient. the battery was made into 3 sections put in series (180v fully charged) and took up every inch of room under the plastic.
in the end he had a bike that could do 120 miles at 65mph and could outrun a ferrari off the line. but it took quite a bit of effort and money to get it approved by the goverment, wich in the end was the biggest issue in my country.

converting a petrol to a electric motorbike is not -that- difficult, getting it legal is the biggest problem.

ps: dont even consider lifepo4 for a choice, high capacity 18650 is your only choice if you want to do it. maximizing battery density and stability (so no pouches!) is key in making a form factor battery that fits the bikes cowling and does not explode.

flippy said:

high capacity 18650 is your only choice if you want to do it. maximizing battery density and stability (so no pouches!) is key in making a form factor battery that fits the bikes cowling and does not explode.

Click to expand...

Lots of EVs use pouch cells-- many more than those that use cylindrical cells. You and I probably agree that RC lithium polymer packs are not a good choice for a practical road vehicle. But I think using a pack that has hundreds or even thousands of individual welds in its construction is an equally bad idea (especially with DIY level quality control). That why most e-car and e-motorcycle manufacturers don't do it.

yes, carmakers (exept tesla, that has like hundreds of thousands of cars driving around the world for years now...) use pouches and they also have litteral hunderds of pounds in structural protection and compression housings with massive bolts to keep the cells from puffing up and exploding. that shit takes up too much space and weight in a (motor)bike.
building a safe housing that an compress the cels enough is simply too heavy, big and form factor limiting that it is not practical in a space and shape limited frame like a motorbike.
18650 cell based battery can be made into quite "organic" shapes, especially when compaired to pouches. a feature that is much more important then whatever advantage pouches appear to have.

flippy said:

yes, carmakers (exept tesla, that has like hundreds of thousands of cars driving around the world for years now...) use pouches and they also have litteral hunderds of pounds in structural protection and compression housings with massive bolts to keep the cells from puffing up and exploding. that shit takes up too much space and weight in a (motor)bike.

Click to expand...

I have a battery pack from a Zero motorcycle that contains 2.4kWh nominal in a package no bigger than a normal car starting battery. It includes a metal case with whatever compression is necessary. I don't know how many of these modules were used in the motorcycle they came from, but it's neither to big nor too heavy for the energy it contains. No 18650 pack I've ever seen would be significantly smaller or lighter for the same energy, and most would be bigger.

the zero packs are not that great dispite the quite apple-like pricing. i have had to repair a lot of them. the casing is WAY not strong enough to prevent cells from puffing up. they keep them in place, they dont provide any meaningful compression force.

That's an ambitious build in my opinion. Probably doable, but not as planned currently.
I think you'll have two main problems:

1) The range: if you really want to get 100 miles out of it, then you'll need a solid battery. You did not say the intended average speed for this range, but this matters quite a lot. It takes some serious power to run at those speeds and that implies a gigantic battery. In this regard, the educated guess of amberwolf seems pretty accurate to me.
So maybe you should clarify what sort of rides you plan to do: running on a freeway most of the time? small roads? are you a lead foot kinda guy?

In any case, I'm pretty sure you can forget LiFePO4 in this kind of application. I'm a huge fan of this chemistry, it has some really nice features (especially numbber of cycles and discharge currents), but it's just too big and too heavy. Your frame is quite big, but as far as I can guess on the pictures, if you fit an inboard motor you could probably put no more than two 72V 40Ah A123 Packs side by side, and I'm not even entirely sure two can fit (to give you an idea so you can make test fits and see for yourself, my pack dimensions are 180 x 250 x 420 mm for a 72V40Ah LiFe A123 battery). So, provided you could fit two of these, that would be around 80km of autonomy if you ride rather agressively. It's not bad, but it's about half of your target. Each of these weight 25 kilos so you can't really add saddlebags or your battery alone would be around 100kg...

I'm pretty sure you'll have to go for Li-ion cells here.
Unless, again, you're not a really agressive rider, in which case you might get away with something like 100Ah, using two big 40Ah packs in the frame and a smaller 20Ah pack wherever it could fit.

2) Your transmission: I might be wrong, but a ratio of 1:3 seems really low to me. Most inboard motors are designed to run at higher speed, with less torque. You should be more afraid of not having enough starting torque to begin with than not reaching a 80mph top speed. With this gear reduction of 1:3, I don't think you could even start moving. Look at all the inboard motor builds, they are all using gigantic sprockets for this reason.

So either you come with some kind of additional gear reduction directly on the motor (like a planetary gearbox), or either you'll have to ditch this transmission and go for a chain. Or use a hub motor, which could also help with your battery space in case you stick with the LiFePO4 plan.
In any case, you'll have to find a solution, this is a big problem to solve, don't expect the motor to be fine out of the box with that kind of gear ratio.

with such big batteries you must use a hub, there simply is no space for a motor.

This is a great discussion. I really appreciate all the information, as it is very apropos for a project that I am considering also.

I've been spending some time of the last six months beginning to learn about an EV motorcycle conversion, at least from a theoretical perspective, but really wasn't finding anything that I would consider a good rolling donor frame.

I ride a 2005 BMW K1200s as my main city and commuter bike since 2011 and had 59K miles on it, when suddenly for some inexplicable reason without any kind of warning, it decided to throw a rod through the lower crank case a couple of weeks ago.

So, now I am considering three options:

a) sell it for parts, salvage yard (easiest/cheapest)

b) buy a replacement ICE engine and swap or try to do a rebuild old engine (second cheapest)

c) use this as the rolling donor for an EV conversion (most expensive and time consuming, but interesting and I'd learn a lot)

Before my engine on the old bike blew up, I was actually starting to look at commercial e-motos (Zero, Energica, Lightning), but a version that can handle my daily commute of 45 miles each way with speeds between 0-90+ mph, is going to cost anywhere between $15-20k, which I'm not quite prepared to spend just yet. So, in the interim, I got a replacement 2006 K1200s for $4.5K with about 28k miles on it to handle my daily commute to the new job.

Right now, I'm still in the process of removing the old ICE motor from the bike, and once that's done, I can assess if it might be possible to rebuild (I got a replacement lower crank case for like $75 and a replacement engine block for like in case the old one is not usable for about $125), obviously I also need a new rod and probably the piston head and who knows what other internal parts might be salvageable. I've seen replacement motors available on ebay for between $700-1,400 or so.

I'm not a mechanic and not particularly mechanically inclined, so I'm looking at all of that as huge learning experience.

Or, I could just forget the ICE and try to do an EV conversion, which between a motor, batteries, controller, chargers, DC-DC converters, and misc., could easily be between $5-10k or more, and that's a fairly expensive learning experience with no guarantee at the end that I'd be able to meet the requirements of my daily commute, especially since I might not be able to recharge at work as I'd have to get permission to run an extension cord somehow out to the parking lot (no public chargers close enough to the office to walk).

Like the Goldwing that started this thread, the BMW K1200s is a pretty big and heavy bike, even one all the ICE equipment is removed, but it is fully faired and I love the style, form factor etc. compared to a lot of the commercial e-motos. I also really like the low maintenance of the drive shaft.

It does also seem to have a fair amount of space for the EV components once all of the ICE equipment is removed. For example, once you get rid of the engine, exhaust, radiator, and gas tank,

I did a rough estimate that I could probably fit three Tesla Model S modules either vertically or horizontally.

According to the EV West site, each battery module is
Capacity: 232Ah, 5.3kWh
Height: 3.1 Inches
Width: 11.9 Inches
Length: 26.2 Inches
Weight: 55 Pounds
18650 EV Module - 22.8 Volt, 5.3 kWh
Maximum Discharging Current (10 sec.):750 Amps

So, three modules in series gives me about 16kWh at about 68V, right?

Unfortunately, if I'm looking at a typical Curtis HPEVS AC-20 Brushless AC Motor Kit - which come in 48 Volt 72V, or 96 V

So the voltage is too low for the 72V motor (though pretty close) and too high for the 48V motor. Not sure if I might be able to fit in a fourth module, but that still leaves me at 88V which is to low fir the 96V version and too high for the 72V version.

I'm sure there are lots of other battery/motor options I'll have to do a lot of research, but that was my first try at trying to ball park some specs/components.

Any information, thoughts, ideas, suggestions, recommendations greatly appreciated.

Pardon in advance for my ignorance. I'm new to this and just trying to learn, but feel free to mock, belittle, tease.

cheers,

PKady

I honesty feel that an electric motorcycle is the most demanding design to wrestle with. Ebikes are often happy with 48V and a pack that is less than 1,000-WH. EV cars have a lot of space to work with, compared to a motorcycle. The Tesla packs are so large that even though they provide very high performance, they actually draw low amps per cell, which helps them to get the max life and max range per volume.

Zero uses 28S 102V nominal. They have exceptional performance. A Goldwing is heavier than a Zero, and 72V 20S is a lower voltage than the Zero. You may not be looking for exceptional performance, but the less power you have to work with, the more you may benefit from using two or three gears.

As far as the cells, I would recommend drawing up at least three designs. One of them should ponder using the Chevy Volt cells. They are small pouch cells with a high C-rate.

"Salvaged EV cells index, Leaf, Volt, Tesla, etc"
https://endless-sphere.com/forums/viewtopic.php?f=14&t=89680

Small pouch cells are good because you can tailor the capacity and voltage a bit better than larger capacity cells.
Cylindrical cells have higher Wh/l than pouch cells, but pouch cells have the same or even slightly better Wh/kg.
So on that metric if capacity was the goal, cylindrical cells would be the go, but they are also quite poor on the discharge capability, and they need to be thermally managed or they live a short life. In the end, most electric motorcycles opt for a pouch cell design, and 200 km at highway speeds is still largely out of reach for most bikes.