To build, buy, or move on?

[Coloradogoose]

I've been doing research for a while now and I'm hoping for a little advice because my head is spinning. I would like to use an electric motorcycle for commuting however I have a pretty long commute that requires highway speeds for a few miles. I've looked at the options to buy a bike, but they seem to get pretty expensive once they have enough speed and range to meet what I need. I have a rolling chassis for a scrambler that I could build into an electric motorcycle, but I'm not sure if that is the better route. I'll lay out what I need below, as well as some info about the current chassis that I have, and then finally the questions that I am hoping for some guidance on.

What I need from a bike:

I am in a very rural area so I need a minimum 60 mile range with about 10 of that at 60-65 mph and the rest at 30-45 mph. (I can't avoid 5 miles of highway each way. After that I can take backroads). No charging options at work either.

Able to cruise at 60-65 mph for 5 miles at a time

More concerned about top speed up to 65 mph than I am about acceleration

Comfortable for a 1/2 hour commute each way


What I'm starting with:
I have a rolling chassis with 18" wheel/tires installed. It's from an old small-displacement dual-sport and I've done a fair bit of work to get it where it is. All it needs is something to make it go. Everything else is there already. The motor that I pulled from it is trash and it was not a stressed member of the frame. I was planning to drop in a more modern ICE motor but would love to explore electric. Because the wheels are built already I would prefer not to cut spokes and re-lace the rear wheel with a hub motor, but if that's the best way to go, I'll do that. The swingarm is 200mm spacing, so a QS hub should bolt right up.

I have a fair bit of knowledge, skill, and access to tools to customize things. I have a 3D printer, mig welder, small 3-axis CNC mill/router that can do aluminum as well as CAD skills, plasma cutter, and a manual mill that can easily handle steel. I've not built any sort of electric transportation before so I'm planning to build an e-bike this winter as a way to learn a little more about things. I will probably build my own spot welder for making batteries and unless there is an off-the-shelf battery that I can afford I will plan to build my own for the motorcycle.

My questions:
Do I gain little to nothing if I do this myself over something that's already made? I've looked up a lot of e-motos and seriously wonder about options like the Super Soco TC Max, or other bikes that I haven't stumbled on. Any other suggestions for pre-built bikes? I'm not attached to building this myself. I always have enough projects going that I can focus the energy elsewhere if there isn't a really compelling reason to build it myself.

Which brings me to... Is this even worth doing? I have pretty lofty needs compared to city commuter bikes. Am I going to end up spending $10K to get something worth riding?

If folks think I should go the build route... what suggestions for motor and battery specs should I aim for? I can read all day about the motors but I'm hoping for some input from people with real-world experience with this stuff. Mid-mount vs. Hub? Battery requirements? Controller suggestions? Charger suggestions?

I appreciate the time that anyone takes to respond!

 

[amberwolf]

Based on various posts found by google on Wh/mile for motorcycle highway speeds, it looks like anything from 80-100wh/mile+ depending on aero of the bike and wind/road conditions and terrain.

So you'd need around 800Wh - 1kWh just for the 10 miles of highway, plus whatever you'd need for the rest of the journey.

What speeds are you looking at for the other 50 miles?

How many complete stops and starts, and how much sloped terrain, winds, etc?

Depending on those, you might take anywhere from 50wh/mile (potentially less but probably not) to even higher than highway speeds need.

Assuming 50wh/mile, that's 50 x 50 for 2500Wh, 2.5kWh. Plus 1kWh for the other 10 miles, is at least 3.5kWh battery.

Assuming the same as highway speeds (unlikely) then that's 100 x 50, or 5000Wh, so 6kWh battery.

I'd also recommend adding at least 25% capacity for degradation as the system ages, and/or detours or poor weather/etc conditions that worsen performance, so that would be 1.25 x 3500 = 5.25kWh up to 7.5kWh batery size.

That's a fairly large pack. I've got about 2kWh+ of EIG cells on the trike, over 35lbs and size a small stack of hardback books, so you'd be looking at potentially around three times that size and weight.

Building a battery isn't too big a deal if you have experience and/or are willing to read a lot about others' experiences good and bad, and find out what worked and what didn't over time under the same conditions you have. But you might look into used EV pouch cells (leaf, EIG, etc) because their QC level is likely to be higher, and performance over time will probably be better, than 18650/etc types. Might be more of a containment/arrangment challenge, depending on the space available in the frame and the size of pack needed.

Charging there's a lot of options...but if you want something you can build into the bike without worrying about weather or vibration, get something potted. I use the Meanwell LED PSUs, HLG-600H-54A, and they've survived submersion in flashflood waters more than once, and constant shaking around on the roads around here (though that could be a lot worse, it's not smooth riding for much of my short commute). MSJFoto1956 recently got a charger on his bike that's also designed to stay on there, don't recall the brand but it's in his build thread.

If you don't need to keep it on the bike there's a lot more options, but it limits your use of the bike more, as you can't just plug in wherever you happen to be (assuming there's a plug) if you wanted to do much more than your usual commute.



Performance varies a lot depending on the system and conditions it's used under--hubmotors will probably take more power to do the same thing as a middrive for startups from a stop, for instance, under otherwise identical conditions, but they're easier to maintain (and to build if you're DIY). If you don't have lots of starts and stops, the hubmotor will likely be a better choice. Otherwise, a chain or belt drive might be.

On my heavy SB Cruiser trike, I don't go fast but I have to accelerate from a stop many times a ride, so it's power usage is pretty high, using dual hubmotors. It would be lower with a properly geared middrive, or one I could shift gears on specifically for startups vs cruising speed.



For specific controller/motor recommendations, I'd look around at the other build threads for MCs that do what you need to do, and see how what they got performed over time. Some controllers are just too complicated / expensive to setup unless you get them pre-setup with the motor from the manufacturer or seller, like Sevcon, etc. Some have unpredictable quality levels (Kelly, Sabvoton). I haven't used anything with higher power levels, above a few kW, and nothing beyond "generic" stuff, so I can only recommend whatever others have had success with, and avoiding those with posted problems in similar builds.

 

[Coloradogoose]

Thanks for the response!
To fill in some of the other info... My commute is about 25 miles each way. The non-highway portion is backroads, some dirt, and can go from 30-45 mph most of the way. I will only have about 7-8 starts from stop on the whole route. I'd like to budget for the extra 10 miles so I can run an errand or two when I'm in town. The ride to town drops a little over 1,000 feet of vert so I could coast a little on the way in, but would lose any gains on the way home. Other than a steady drop, there aren't any crazy ups and downs on the route.

I like the idea of a mid-mount motor since it wouldn't require me rebuilding the rear wheel and I would be able to play with gearing a little more to get the best balance of speed/acceleration, so I will probably go that way since it doesn't sound like a massive benefit to go with a hub motor.

The info you provided on battery capacity is very helpful. I have quite a bit of space for the battery and I'm not worried about making it easy to remove. I'll know more about if I would like to build or buy a pack once I've attacked the ebike I plan to build this winter, but I anticipate building the battery myself so I can make it the right shape for my bike.
It sounds like controller, charger, etc will be second to figuring out the battery as well as what motor I plan to use.

Any thoughts on the best bet for a mid-mount motor?

Thanks again!

 

[amberwolf]

The two "best" DIY ones I've seen (based on others' experiences so far) have been the QS midmounts and the Zero FX motors, both of them designed for these types of installs. At one time there was a thread (by Methods? cant' remember) about a controller/motor package for those Zero motors; I think Calfee Design is still doing those? There's a QSmotor thread in the sale section with info on various motors they have, and discussion about them, as well as at least one or two QS midmotor threads, and some project threads using these. (sorry I don't have links, but they should be easy enough to find).

There's also the Mars / Etek BLDC motors; pretty common in such conversions. Can't recall the sites that sell these combos, but also should be easy to find.

There's a site called EVAlbum that contains pages for basic info on various types of DIY builds / conversions, some of which have links to their build pages. Those may have more research info on specific conversion setups, especially that use the same basic frame/etc you have, if that matters.



You do need to know what controller/motor you're going to use, to build the battery for it, but that's mostly so you know what kind of current you'll be drawing, and what voltage you'll need, so the battery is built to be easily capable of that without stressing it even as it ages.

And just keep in mind that the battery info I gave before is just rough estimates based on stuff found in "random" posts around a google search, so you'll want to do more detailed research on power usage per mile under your conditions before you commit to that.

As long as you know what it has to do, you can build the battery first, but you don't wnat to build it and then later find out you need a bigger / better one to drive the system the way you need to use it.

 

[c70r]

Amberwolf has spoken a fair bit regarding the motor and has given good advice so I'm just going to chip in regarding the battery.

A cost/time/complexity effective solution is the use of Nissan Leaf modules, especially if you can get your hands on some Gen 4s (2018 model).
Long story short each "module" weighs 8.7Kg and are 14.4V 112Ah each (4s2p 3.65V 56Ah).
5 of these modules gets you 20s 112Ah, 6 = 24s 112Ah and 7 = 28s 112Ah.
I stated the above (20s, 24s & 28s) as they are commonly used depending on the motor/controller.
Just for ease of explanation, say you go for 5 of these modules, 20s and 112Ah gets you 8kWh. The going rate depending on location/country is about $300-$400 per module, that's a total cost of $1500-$2000 which is really really good if you have the space.
For numbers sake 60Wh/mi is a good middle ground for some calculations. 8000Wh / 80Wh/mi gets you a theoretical 100miles.

Oh regarding motors, QS provide plug and play setups for both hub motors and their mid-drive motors.
If I remember correctly they were at one point selling a setup which included their 138 70H mid-drive, controller, dash and throttle/handlebar switch combo for around $600.

If you decide to follow through with my post this is what you'd achieve.
- 8kWh battery for $1500-$2000
- Motor/controller setup 15kW peak/5kW continuous for $600 +ship/taxes

Rest of the cost would be things like the making of mounts, battery box, maybe some basic switches/wiring.

 

[Coloradogoose]

This is really helpful so far! I genuinely appreciate the time you guys took to help point me in the right direction on this stuff. I had hit a point of analysis paralysis and was really struggling to make decisions. My hope is to start shifting the direction of the build this winter. I'll pick up the motor and controller first so I know that I'm committed to a specific build before I start working on the battery. The Leaf batteries look promising so I'll probably work in that direction.
Amberwolf, I will do my own calculations on the battery size so I have no one else to blame if it doesn't meet my needs, but the info you gave me will help me to know if I'm in the ballpark once I do my homework.
Hopefully I'll be able to post some build pics soon, even if it's nothing more than the rolling chassis.
I will add to this thread as I go, and continue to check in to see if more folks have suggestions. Thanks!

 

[larsb]

QS3000w mid motor kit with votol em72150 controller would be cheap and meet your goals. I’m doing 50km per day on one since more than a year. The battery pack, as already said, will be the major part of the build.

What’s your budget?

 

[Coloradogoose]

I'm not sure what my budget will be yet. Part of my budget will be determined by what I can get for my CRF250L that I've had for a few years. Once that is sold I'll be able to better determine where to start with budget. I definitely know that I will need to invest real money into the battery to meet the requirements I have. I'm hoping to be able to commit between $2,000 and $2,500 toward the battery. Much less than that and I question if it will have the juice I need. Much more than that and I start to wonder if it will be worth the investment. Of course that can all change in a heartbeat depending on what I get for my CRF, so we will see.

 

[larsb]

seems doable :thumb:
You'd probably end up with a total more to the 2500$ end of it for the pack. Used EV cells would be my first choice if not for one thing: it gets really difficult to fit a pack of that size on your bike when the modules are large and boxy.

i'd do it with 18650 cells. Looking forward to what the build will look like. Good luck!

 

[c70r]

Going to chip in a little towards cost and battery explanation.

For example we'll use the Zero FXS as an example. 6.3kWh nominal battery and they state a range of 100miles for city and 60miles for highway at 55mph. The bike you intend to build will follow a similar aerodynamic so we can use it for some maths. If 6300Wh is getting 60miles at 55mph then the Wh/mi at 55mph is 105Wh/mi.

So in that case if you go for the 5 Leaf modules, that gets you 8300Wh / 105Wh/mi which would give you a range of 79 miles at 55mph which is plenty.

5 of the 2018 Leaf modules is about $1500-$2000.
QS Motor/Controller combo should come to about $800-$900 after the shipping and import fees.
Expect to spend a couple hundred dollars on various miscellaneous items.

Complete build for as low as $2500.

I think the bigger issue is to see whether you can fit so much battery capacity into your bike. I saw that you mentioned that it's a small displacement dual-sport and I don't believe that they tend to have a large space where the engine was.

 

[larsb]

Africa twin or a larger sport bike would be more suitable than a smallish dual sport, some ingenuity will be needed to fit the batteries.

I’ve had three separate packs connected in parallell at the most but i don’t really recommend it if it can be avoided since it drives complexity, wiring and connection issues.

 

[tylerwatts]

Interesting build, like your donor. I did a (dirty) engine swap years ago in a similar bike and simply cut the front frame loops out and bent new ones to match the shape. I would do this here and stack the leaf modules upright (wiring on top) transversely across the frame and make new frame rails to support. Make sure you do this with frame on a bench, no suspension etc on it or standing on its own weight otherwise the frame might distort a bit.
Also, this probably dictates how you then mount your motor as the battery would be in the way. But again, steel swing arm, I would try mount the motor as close to swingarm pivot as possible, on the swingarm even.

Have you seen the new 3000w motor design with mounts for fitting it onto the swingarm bolt? I like that idea and I'd have it move with the swingarm as it isn't a large mass that close to the pivot.

Post some pics so we can see the bike and understand a bit better.

Cheers
Tyler

 

[tylerwatts]

Is this the bike?

Really nice donor choice. I think it might be an aluminium frame though. At least the lower rails look tubular not cast, can still replace them with aluminium tube!

Cheers
Tyler