E-GO-E-Bike: an E-bike With Easily-Detachable “E," Powered by an EGO Battery

What I wanted:

A little help on the uphill climbs for my brief (3.6 mile round trip) commute to work.

What I needed:

A power solution that could be easily removed on-the-fly from my bike, because there's no secure parking at my office building.

What I didn't want:

Large expense, a noisy motor, an always-electric or high-speed bike.

What I settled upon:

An electric front hub motor kit, tweaked so it can be removed and installed in minutes, and powered by a battery system I already own.

Supplies

Bike:

Almost any bike will work, I happen to have a 7-speed Bianchi Milano Citta, but this will work on my old Diamondback, and probably on whatever you're riding too!

1000W (or 750W) Electric bike hub:

https://www.amazon.com/JauoPay-Electric-Bicycle-Conversion-28mile/dp/B08TMC2F9C, $219 as of this writing. Note: it doesn't come with a battery which is fine, but it also doesn't come with a tube or tire, which is kind of a bummer. And extra-long valves are needed if you want to be able to screw on your valve caps!

EGO battery:

https://egopowerplus.com/power-batteries-chargers/

Using a tried-and-true battery/charger system simplifies everything about an e-bike, and I'm a big fan of the EGO gear. I have a little 2.5 Ah battery for my chainsaw and trimmer, and a big 7.5 Ah one for my lawnmower (which also fits my trimmer and chainsaw), plus a pair of chargers, one faster than the other. These are all quite pricey if you buy them by themselves, so if you don't already have one I'd advise keeping an eye out for sales on bundles, which include a tool plus a battery and charger. I only use this for a short commute that barely drains the power at all, but if I ever feel like going farther, I can easily bring them both along.

Why EGO?

Look around in any discussion of e-bikes, especially in DIY-centric forums, and you'll find a lot of frustration with batteries and how to charge them. It occurred to me that if my EGO gear could be used and if the power ended up being sufficient for my needs, someone else has already done all the math!

I stumbled upon a few e-bikeish discussions about the Ego battery (like this one: https://electricbikereview.com/forums/threads/ego-battery.39836/), and the more I read the less worried I was about a 48V hub controller being able to handle the nominal 56V (but really 50.4V for some damn reason?) battery with no modifications necessary! So I'd be able to ride an electric bike whose battery I'm super familiar with, having moved and trimmed and chainsawed up a whole lot of stuff in my last few years of EGO tool ownership. Plus, hey look: this guy and this guy and this guy all used EGO batteries for their e-bike conversions. We all think it's a swell idea!

Ego Battery adapter:

You can buy these from very smart folks who 3D print them, or maybe even find the files so you can print them yourself. Or look for a broken Ego charger or tool, and harvest the plug-it-in-and-hold-it-there parts. I cobbled mine together using scraps, and while the end product works great (and was damn near free), it took so long to figure out and execute (and mess up and re-execute and fix and tweak), that I nearly ran out of expletives. Be smarter than me; it's a low bar - you can do it!

Double light switch:

One switch is for power, and one to control the speed limiter that's baked in to most e-bike controllers. Any switch that can handle the voltage will work, but I think using a light switch is funnier.

Torque arm:

These are especially recommended for aftermarket hub kits like mine, because the cutouts in the forks of standard bikes (especially ones with aluminum frames) aren't designed to handle the torque that can come from an electric hub, particularly during rapid acceleration.

Spring:

For the battery lock. This was another clunky solution; I'm sure you can come up with a more elegant one.

Thumb screw:

To make the throttle easy to remove without tools.

Gorilla Glue:

For when your gorilla needs repair.

Black Flex Seal spray:

For durability and to hide shoddy workmanship.

Garage Full of Debatably Useful Crap, such as:

Plywood scraps: I used some pretty thin stuff but I think thicker might have been easier, so I'd advise at least 3/4" if you can swing it. And the higher quality you can get, the better.

Flooring samples: Those coaster-sized samples of wood-plank laminate flooring they hand out at big-box hardware stores have a string side and a slightly rubbery side that make them easy to work with. Their thickness varies, but one I had fit the slots in the Ego battery just right, and was what got me started on the (iterative and frustrating) process of making my battery adapter.

Door hinge: salvaged from a standard interior door. The pin is removable, a feature which I defeated (with a wood screw), because spontaneous disassembly is frowned upon.

Rubber cap: for the handle on the spring-powered battery lock.

PVC pipe scraps: for the aforementioned battery lock.

PC power cable and port, to enable hub detachment. That provides three big wires, but there are five more little ones I connected using one of these.

Old bike tube: for padding and such.

Lots of screws and random hardware.

Tools:

Drill, jigsaw, belt sander, wire cutters/strippers, pliers, screw drivers, hacksaw (or Dremel cutting tool), heat gun, solder gun and solder, a wrench for the hub, and a staple gun.

Step 1: Why Detachable "e?"

I have a short commute to work, and I like to use my bike as much as possible to save gas and get a little exercise. But there are days when various factors conspire against my bike commute, and I decided that this particular power-assist setup might help increase the number of days in the year that I bike instead of drive.

Obstacles to my bike commute:

If I'm out the door just a few minutes later than my ideal time, I find myself pushing harder to get to work, and I show up a bit more overheated than I'd like. On those days it's very easy to listen to the voice in my head that says, "take the car." Power assist means I can let the motors help out on the hills, and will never arrive at the office wishing I had a change of clothes.
If I'm feeling the slightest bit under par (fighting a cold, recovering from the previous night's battle with ninjas) a bike ride amplifies that situation, and a little boost is welcome.

Security concerns:

I ride a weird-looking bike on purpose: if you steal a weird-looking bike, it's harder to get someone to buy it from you (so you can spend the money on Sour Patch Kids and whatnot). I'm overly attached to my current bike and while it doesn't look as weird as my previous one, it does have a freaking bucket on the back of it, which I hope is a little bit of theft deterrent.

There's no truly secure bike parking near my office building, so I'm relying on good locks. I initially didn't want want a hub-replacement conversion kit at all because they come with a flashing neon "steal me!" sign, but I got impatient and wanted a new toy so I compromised by making it all easy to remove, which takes something like four minutes. It will take much less if/when I decide to make it possible to leave the hub itself locked to the frame and just remove the rest.

Off-the-Shelf:

The most elegant easily-detachable solutions out there are the "Rubbee" and the BikeEasy "Clip Bike," both friction-drive devices that you can easily attach and detach. The Rubbee pushes you by turning your back wheel, and the Clip pulls you along by your front. The only disadvantages I can see are their cost and probable reduced efficiency in the rain (though as a strictly fair-weather bicyclist that's not an issue for me). A Rubbee wouldn't work for me because of my silly cargo bucket, but I'd still love to get a Clip at some point, they really are quite cool!

Several years ago I tried to make an easily-removable friction drive using drills, and I did get to the point where I damn near crashed into the fence in my backyard during a test run. I never quite nailed down all the engineering there, but the concept of that old "drill" rig and the solution in this instructable is identical to what Clip Bike says on their website:

"We know that e-bikes are expensive and they get stolen a lot! What if you could simply detach the 'e' from your bike to carry it inside?"

Compromise:

Of course this is less than ideal; if I had a secure place to park an e-bike, I'd be able to leave it assembled during my work day. But in the meantime, this solution will cost you less than $250 if you're like me and you already have an EGO battery or two (for your lawnmower/trimmer/chainsaw/etc), a Garage Full of Debatably Useful Crap, and a nearby hardware store.

For this e-bike, I'm only truly removing all the '"e" if I pull the wheel off too. That's a bit cumbersome (and why I still want a Clip), so for the next phase I plan to make it easy to separate the controller/battery box from the wheel. That way I can decide whether to remove it all or leave just the hub, which might be okay now and then.

Step 2: Disclaimer; Hub Kit Removablification

Disclaimer

This project should be avoided if possible. I avoided it myself for damn near ten years! There are a few built-in risks that go away if you don't have to remove the "e" from your e-bike, chiefly the fact that when you have to take the wheel off and on a lot, there's a chance you'll get sloppy one day and not seat the wheel perfectly, which can be dangerous. I believe I'm mitigating that risk by taking extra care each time on the install, but it's of course better to "set it and forget it." If you have any way to make secure parking happen, or to make room to park your commuter bike inside during the day, then all of this foolishness goes away and you have a much more reliable solution. And you shouldn't stray too far from manufacturer's recommendations unless you're quite comfortable with a whole bunch of little compromises and the mitigating the inherent safety risks.

That said, this rig works quite well for me and I hope it inspires other folks with restrictions similar to mine, but of course: you should never go faster than you're willing to crash, you should always wear a helmet, and you should always ride defensively as possible, because cars (especially here in the USA) are programmed to kill you.

Onward!

Battery

I'm sure you'd still be able to power your hub with a different kind of tool battery if you've already invested in a different electric tool platform like Greenworks or Stihl or whatever, but I haven't looked in to that, so you should.

It is of course a calculated risk to use tool batteries; you're always going to be safer with a battery that is guaranteed to work with your system. Also tool batteries generally have much lower capacity than "real" e-bike batteries, so range is going to automatically be lower. For example the highest capacity battery EGO makes is 10Ah, and that's pretty much the low end of where e-bike batteries start, and they go way up from there.

Hub kit:

Here's the front-wheel electric hub I ended up with (my awesome kids teamed up to buy this for me for Christmas 2022, which is a pretty good argument for having kids):

https://www.amazon.com/JauoPay-Electric-Bicycle-Conversion-28mile/dp/B08TMC2F9C

Below is some text in all its almost-correctly-translated glory ("If you chasing a higher speed," LOL) from that Amazon listing (for if and when that link disappears):

"About this item

[HIGH SPEED] - 48V 1000W Powerful brushless gearless front hub motor can be reach up to 28mile/h (45km/h) speed, and restricted to 750W and 24mile/h speed by default as a road-legal pedal bike conversion kit.Aluminium Alloy rim with spokes. Dropout: Front 100mm/Rear 135mm.

[Dual Mode Controller] - Motor works under Hall effect and non-Hall effect, extend life for electric bicycle.( If the components break down, controller will switch into non-hall effect mode, the motor will still be working.)

[RIDE EASILY] - 8 point high effective Pedal Assist System (PAS) can activate the hub motor with the pedal driving, allows you to combine electric power and your own effort with a nice and easy riding way.

[Durable Construction] - Double Wall Aluminum Alloy Frame provide high durability as a bicycle wheel, 12 G × 2.6 mm High Carbon Steel Spoke provides nice stability for the rides, the magnificent construction can support a heavy weight up to 220 Lbs.

[ALL Necessary Components Included] - 1000W Hub Motor Wheel, intelligent controller, twist throttle, brake levers, 8 point pedal assist system, cable ties and user manual. (Battery and tire are not included.)

Key Features:

1. 48 V 1000 W super power Brushless Gearless Hub Motor

2. Restricted to 750 W and 24 mph by default as a road-legal kit.

3. Aluminum Alloy Double Wall Rim, with 12 G × 2.6 mm Carbon Steel Spoke.

4. Rare-earth metal magnet are used in the motor to efficiently produce large power.

5. Brake Levers cut off the power supply to the motor safely.

6. 8 Point Crank speed sensor for pedal assist, can allow you to works with all pedals, including Speedplay and Eggbeaters.

7. Dual Mode Controller, Motor works under Hall effect and non-Hall effect, extend life for electric bicycle. (If the components break down, controller will switch into non-hall effect mode, the motor will still be working.)

The 1000 W system requires a 48 Volt battery with a nominal capacity not less than 11.6 AH or 52 Volt battery with a nominal capacity not less than 13 AH (If you chasing a higher speed)"

"What to leave in, what to leave out"

Because I wanted to minimize fussing with wires when installing and uninstalling, I made the following adjustments:

Throttle:

The mounting bolt required an Allen wrench, so I swapped it out for a thumbscrew that can be tightened and loosened by hand. Because my bike is a seven-speed with a shifter that gobbles up extra space on the right handlebar grip, the throttle was a little awkward when mounted there, so I moved it to the left handlebar. The little display is upside down and using my left hand for the vroom-vroom took some getting used to, but it fits there well and works great.

Brakes:

I skipped these. The hub kit comes with two of them, but all they appear to do is cut power to the hub. I can already do that instantly using the throttle, and for the lower speeds I'm sticking with, the standard brakes on my bike work just fine.

Pedal assist system (PAS):

Based on the review below, I skipped this too. I know that there are adjustable systems out there, but the PAS on this "bargain" setup is apparently permanently turned up to 11; according to the review below it jumps up to full speed right away! That seems a bit unsafe and frankly presumptuous, doesn't it? I found that the throttle provides very smooth acceleration; plenty of "just barely" before it's cranked all the way up. I never "floor it" right off the block, in fact I'm only using it when I'm going uphill and am already moving forward. I do pedal a bit while I'm using the throttle, both because it feels weird not to and because it allows a smoother transition away from power (once I've made it up the hill), but I decided that actual PAS on this system would make it feel less responsive and harder to control.

PAS Review: "The PAS is not adjustable so when you start to pedal, it seems to want to go to near full throttle, too fast for what I want. When using the twist throttle (which is quite smooth and comfortable), if I start to pedal, it immediately wants to go up to 25+ mph, too fast. If I disable PAS, it works fine as a motorcycle with pedals. It's very strong, excellent on hills and quite easy to get accustomed to, but I built it for my wife who is not interested in winning acceleration races, so I guess I'll just disable PAS altogether."

-from https://www.amazon.com/gp/customer-reviews/R2WPHVKI6L00XE/ref=cm_cr_dp_d_rvw_ttl?ie=UTF8&ASIN=B08TMC2F9C

Step 3: Proof of Concept

For the version-1 proof of concept, I cobbled together a connection to the battery using two household extension cords with their male ends zip-tied side by side, so they plug in to all four parallel slots in the Ego battery. It worked okay, but looked janky and produced a single, tiny spark when connected; perfectly predictable, but janky nonetheless. For that reason I’ll skip the how-to details on it, and encourage anyone inclined toward something like this rig to move on to the 3D-printed version you can get online, or something like the improvisational monstrosity I fashioned for version 2.

Mounting:

I removed the rings from a 9"x12" three-ring binder and zip-tied a section of pipe insulation into the space where the rings were, which sat on the frame. To the top, I added a rectangle of thick plexiglass I had on hand that the battery could slide onto. A small ball-and-loop bungee cord latched the two front panels together at their corner in front of the diagonal ("down tube") of the bike frame to keep the binder attached.

Controller:

I zipped the controller and all the wiring into the shell of an old day planner (or possibly a CD holder? I honestly don’t remember), then zip-tied that inside the binder so it sat inside the frame, below the top tube.

Wires:

By eliminating the pedal assist and brakes, the only three wires (or wire clusters) that needed to come out of the zipped bag were the ones for the throttle, the battery, and the hub.

Straps:

I added a compression strap to secure the battery, and the shoulder strap from an old laptop bag to make it easier to carry when disconnected.

Torque arm:

I landed on a torque arm solution that still allows easy removal of the wheel, which transfers the force to a point higher up the fork so it's not wiggling the cutout loose. I made mine by modifying a piece from an old set of training wheels left over from one of my kids' old bikes, but a store-bought, permanently-mounted one would be safer.

I do believe my low-impact behavior while driving this thing reduces the risk: always very gradual acceleration, never from a complete start, but I can see being forced to speed up faster than I'd like off the block sometimes (due to the fact that all cars are trying to murder me), so I'm glad to have a torque arm.

Version 1 report:

Pros:

As a proof-of-concept this worked great, and only looked a little wonky.
I really like how the Ego battery looks like it was made by Stark Industries, and placing it where a gas tank would go on a motorcycle makes my inner bratty little kid happy.
I like that the controller doesn’t add much thickness because it sits between the tubes of the frame, and I saw no reason to stray too far from this layout for version 2.
I tested the speed using a phone app (which seemed accurate enough based on testing in a car), and the result was: 14 MPH on flat or very slight uphill inclines, about 8 MPH up steep hills. That's a bit less than what the hub kit promised, but it’s plenty for me, and so much fun!
There's no real speed benefit going downhill with the speed limiter wire engaged. The claim is 28 mph when that's disengaged, but I won't normally need that kind of speed. That said, I decided to wire it up so I have a cool "turbo boost" button or something, because of course I did.

Cons:

I didn’t like the how long it took to install and remove, mainly because of all the fussing with straps and the bungee.
I didn’t like the sparky battery connection.
I found that leaving the battery connected throughout the day drained it even with the power turned off at the throttle, so that means I had to unplug and re-plug more than I'd like (see above, re: "janky"). I decided that a switch that interrupts the actual power wire between the battery and the controller might fix that.
The binder (predictably) flexed a bit so the battery tended to sag a little to one side, and at 9"x12" the dimensions turned out to be a bit bigger than needed.
This solution of course required removing the whole hub with a wrench and bringing it into my fourth-floor office each day. That's not the end of the world: high-end bike owners do that all the time, right? But this thing is pretty heavy and a bit awkward to carry, especially when it's tethered to the controller/battery rig. For that reason I decided that I'd try to make the hub easy to disconnect from the rig as possible, so I'll have the option of leaving it D-locked to the frame.

Step 4: The "Real Thing"

For a minute I planned to ditch the layout of this design in favor of a wider, side-mounted solution, but I realized that would have cause me to lose the coolness factor (and balance) of the battery location, so I decided to work with the original design and just upgrade all the bits.

I doodled until I landed on ways to address all of the issues that I flushed out in the proof-of-concept phase.

Features

Ego battery mount with electrical connection, mimicking the slide-on connections on EGO chargers and tools. I cobbled mine together using scraps, but there are a few folks out there selling 3d-printed versions, and that's highly recommended if you've got a few bucks to toss their way. I added a spring-loaded locking mechanism, designed like the closure on a "cat carrier."
A plywood "box" (is it a box if there's only 3 sides? I'm hereby saying "yes," and will be calling it that) with one hinged side that can be easily latched over the top tube, with cutouts fitted to the tube and padded with rubber (from an old innertube), fastened from below to the down tube of the bike frame.
The controller box is stuck to the non-hinged side of the box, with all the wires tucked out of the way.
To prevent battery drainage, a switch* interrupts the connection between the battery and the controller.
The speed limiter wire is connected to a switch*, which I will refer to as the "TurboBoost™," and will make a rocket-blasting-off noise to myself (and whomever else is within earshot) when I flip it.

*At first wanted to use standard single light switches for both of these, because they're super cheap and also it would be kind of funny, but I eventually settled on a double light switch, which was less cheap and still kind of funny. That said, most any switch or push button or toggle or knob that can handle the voltage could be used here.

Step 5: Ego Battery Connector

Ego Adapter:

For their electrical contact points, EGO batteries have slots on their underside with clearly-marked positive and negatives, plus slots marked "D" (for "Data") and "T" (used by the chargers; "Thermistor" maybe?). Metal blades on the chargers and tools fit into those slots, and are pinched snugly by the copper bits inside. All I needed for this rig was the positive and negative, and I wanted nice big blades similar to the ones used by EGO.

Buy, don't build:

I suggest buying a 3D-printed adapter, or finding a broken EGO tool or charger that you can scavenge. Or if you're really good at making stuff, you can engineer yourself an awesome adapter. Or if you're a hack like me, you can make something like I did:

I bought a 1/2" copper pipe connector with what I thought were sufficiently-thick walls, cut it lengthwise with a Dremel, and hammered the pieces flat to make the blades.

EGO tools and chargers have sturdy plastic tabs which fit into slots that run along each side of their batteries. I had a little square vinyl flooring sample that was just the right thickness (I'd been using it for a coaster, so I'll call it that from now on, okay?), and it fit perfectly in those slots. I took a notch out of each corner to allow the coaster to slide flush with the slots in the battery, marked where the positive and negative slots hit, and cut two slots in the coaster (using a Dremel's cutting wheel) for the blades, so they lined up with those positive and negative battery slots. I notched a piece of scrap wood to fit the copper blades, then screwed the wood to the coaster. I slid the blades through the slots in the coaster, and screwed them to the wood.

After that I just kept adding bits and pieces until my adapter fit the battery. I also added some mass so I had plenty of surface that I could send screws through for mounting to the top of the box. I've spared you the details because A. I'm sure you'll buy your adapter instead of building one, because you look pretty smart, and B. if you're improvising your adapter you won't have the same scraps as me, so your version will end up much different. Feel free to look at the photos though, so you can feel my pain.

I drilled a small hole in each blade and soldered a wire to it, then drilled holes through the bottom of the adapter and box so the power wires could make it to the controller. Those wires are the only ones that really need to pass the top tube of the bike, everything else can be routed out from below, to the throttle or hub.

Spring Lock:

EGO batteries have a notch near their power slot which locks into spring-loaded tabs in the tools and chargers.

My spring-loaded lock (see diagram) was inspired by the latches in a pet carrier (which we use when we want to bring our cat to The Bad Place That Smells Like Fear for vaccinations and whatnot). I'd saved the cut-offs from a piece of cattle fencing (which we'd used to provide habitat for some peas in our garden), and I hacked off a small "T" made of welded metal: rotated sideways, it mimics the pet carrier's latch handle: a vertical rod with a horizontal one sticking out of its middle. I roughed up the top of the rod with a few notches, and then melted a rectangular piece of PVC pipe around it using a heat gun and some pliers, and filed the PVC down a bit. The notches grabbed the soft PVC pretty well, but the fit on between the metal and the PVC ended up still being a little loose, so I added some Gorilla Glue into the gap to stop the wiggle.

The lock is located in one of the two vertical bits of plywood with curves cut out of them to fit the top tube of my bike. The one near the handlebars is shorter because it lives "inside" the box, but the one facing the seat had to be tall enough to stick out of the box to reach the slot in the battery and to accommodate the T-latch.

On the top edge of that piece with the curve, I drilled out a rectangular hole for the PVC tab, which narrows into a small round hole for the bottom rod and its spring. An oval hole in the side facing the seat allows the "handle" to stick out sideways and travel up and down, and I added a little rubber cap to the end of the lever. It looks pretty gross up close but works passably well, so please pretend the photo looks more like the illustration, okay? Thanks.

Step 6: Tube-mounted Box

I'd planned on the box being vaguely 9" wide x 9" tall x 3" deep, so I started by cutting a 9"x3" piece of plywood for the top of the box. I cut out a notch for the spring latch, placed the battery and adapter on the plywood, and figured out where everything would sit. Once that was settled I sent a bunch of screws through until it all felt solid.

The rest of this part went quite quickly compared to the more improvisational previous steps:

I cut out a second plywood arc to match the one with the latch, cut two 9" plywood squares for the sides, and screwed the right-side one to both the arcs and the top of the box.

I added a door hinge to what would be the left side of the box, to allow the whole side to open up and grab the top (horizontal) and bottom (diagonal) tubes of the bike frame. That hinge introduced a small gap at the top, so I cut an equivalent amount off the bottom that 9" square, so the height of both sides were equal.

To anchor the box around the bottom tube, I drilled two oval holes in the front bottom corners of the box sides, to accommodate a 3.5" bolt with big plastic "beads" on it (I can't remember where I got these; maybe salvaged from the unused parts of TV wall-mounted unit?). These have a little leeway to slide up against the bottom tube, and while the plastic seems fine, I hacked a section out of a skinny inner tube that slid over them with a little effort, so it's all nice and rubbery now.

Step 7: Controller, Switches, Cable Management

I did a test fitting to figure out where the controller and switches would go, cut a hole for the switches, and wired up the power and speed limiter. Note: there's a metal tab you have to remove on double-switches like this if you want them to act like discreet, separate circuits (detailed wiring instructions come with these to make it easy). I did that, ran the red positive power wire to one side of one switch, and the positive wire from the battery to the other. The speed limiter is controlled by connecting or disconnecting two tiny blue wires, and those went to both sides of the second switch. TurboBoost™ engaged!!

Note: only after I wired this up did I realize that the "on" position means the speed limiter is on, so the switch has to be in the "off" position to activate TurboBoost™ mode. That makes the TurboBoost™ branding somewhat problematic, so we may have to revisit that with a focus group and perhaps an advisory committee and circle back later. Maybe instead of activating TurboBoost™, I should be deactivating SnailMode™? Input welcome, please schedule a meeting and we'll make sure everybody's on board.

When I screwed it all together I realized my controller was a notch too low, and it butted up against the frame. I was trying to allow as much room as possible above the controller so it was easy to hook to box over the top tube, but I went a notch too far! A 9.5" square side might have dodged this issue. And while I could have fixed this by moving the controller up a tiny bit, the too-thin plywood had splintered a bit during the drilling of the oval holes in the front corner, so I decided that a little fortification was needed. I added a couple steel strips to the box, and that moved the corner anchor out just far enough to fit perfectly.

Step 8: Moving Fast and Breaking Stuff

Apparently I rushed it and missed something:

I got it all wired up and ready to go, slid in the battery, flipped on the power switch, pressed the "ignition" button (yes, I call it that) on the throttle, and the familiar blue power bars lit up on the little screen. That's kind of all that this screen does so I was happy! However...

After a little more jostling, I donned my helmet and got ready to ride but... no power. At first it still lit up but just wouldn't provide any vroom vroom, but then the screen wouldn't even light up.

The Ego battery has a big power button on it that lights up when you press it, so it was easy to see that it wasn't dead.

I assumed some of the wiring had pulled loose so I cranked down on all the crimped connections, then went back and tested again: no power.

Then I went back and did an extra-good job on the soldered connections, and even soldered up some of the crimped ones.

Success! The little screen lit up, and I gave the throttle a very tiny twist and it clearly wanted to go vroom-vroom.

All the direct-connect wires had looked fine, so I assume I just over-stressed one or more of them while I was bundling them up with zip ties. I adjusted the location of the controller and the routing of all the extra wiring, re-zipped them, and dropped it all back on the bike for a test ride.

Step 9: Version 2 Report

Version 2 report

Pros:

This works great! All the fun of version 1, but a vast improvement.
It's much faster to add and remove than it's floppier prototype.
The stability is great, the battery is solid and nothing rattles.
It's super fun to have access to the the speed limiter switch! With SnailMode™ disengaged, I hit 25 mph, which was awesome and also too fast for comfort. It's nice to know I can go a bit faster if I feel like it, even though I'll rarely use it. Again, that's slower than what was promised in the description of the kit, but that's probably explained by the fact that this battery is designed for a friggin' chainsaw!!
There's no beating the Ego battery and charger for ease-of-use and reliability; it really simplifies everything and looks cool and makes me happy. The black box underneath really shows off the Stark aesthetic.

Cons:

I posted a work-in-progress (before the black paint job) to a DIY e-bike group on [monolithic social media entity redacted] and someone commented "What in the methamphetamine is going on here? Jk man cool build!" and I think that pretty much sums it up. In any case, prettification is under way.
While removing the hub and the box doesn't take long, I like the option of leaving the hub now and then, just because it's all a little heavy and awkward to carry. To make that possible, I wired up two plugs to accommodate all 7 wires in the bundle leading from the hub.

Step 10: Class, Range, Aesthetics, Next Steps

Class:

I'm located in California and I wanted to figure out whether I was bending any rules of the road with this rig, so I did a little poking around and I think I figured out what I'm riding, legally speaking.

Here's what the CA DMV says about e-bikes:

Electric Bicycles

An electric bicycle is a bicycle equipped with fully operable pedals and an electric motor of less than 750 watts. Three classes of electric bicycles have been established:

Class 1: A low speed pedal-assisted electric bicycle equipped with a motor which provides assistance only when the rider is pedaling and ceases to provide assistance when a speed of 20 mph is reached.
Class 2: A low speed throttle-assisted electric bicycle equipped with a motor used exclusively to propel the bicycle and NOT capable of providing assistance when a speed of 20 mph is reached.
Class 3: A low speed pedal-assisted electric bicycle equipped with a speedometer, and a motor which provides assistance only when the rider is pedaling and ceases to provide assistance when a speed of 28 mph is reached.The operator of a Class 3 electric bicycle:
Must be 16 years old or older.
Must wear a bicycle safety helmet.
Must not transport passengers.
May ride an electric bicycle in a bicycle lane if authorized by local authority or ordinance.

All electric bicycle classes are exempt from the motor vehicle financial responsibility, DL, and license plate requirements (CVC §24016).

So if I'm reading this right, it's a "Class 2 Electric Bicycle," because...

"An electric bicycle is a bicycle equipped with fully operable pedals..."
It's Class 2 because it will go using just the throttle and without pedaling, and stays at under 20 mph: "Class 2: A low speed throttle-assisted electric bicycle equipped with a motor used exclusively to propel the bicycle and NOT capable of providing assistance when a speed of 20 mph is reached."
It's 750 Watts when the speed limiter is engaged: "An electric bicycle is a bicycle equipped with ... an electric motor of less than 750 watts."

...Also, it's a "Class 3 Electric Bicycle," because

If I were to engage my TurboBoost™ (or more accurately, disengage SnailMode™), it becomes a 1000W Class 3 "motorized bicycle or moped," which is still street-legal if it stays under 30 (which it very much does):

"...a two or three-wheeled device,
capable of no more than 30 miles per hour (mph) on level ground, and
equipped with: Fully operative pedals for human propulsion..."

So I'm riding a Class 2, which occasionally might think it's a Class 3.

Range:

I haven't really tested this at all, except to notice that when only using power for going up hills, my small 2.5 Ah EGO battery gets me to work and back with barely any loss of charge.

That said, the math seems pretty straightforward, and based on this page, I'm guessing that my 2.5 Ah battery will take me at least 14 miles, and my 7.5 Ah battery will take me at least 42. That's conservative too, and is based on burning up 10 Watt hours (Wh) per mile. That would vary so much depending on terrain and how much throttle is being used that I wouldn't really bet on any of those numbers, but it's a ballpark figure I can start with.

Next Steps:

Unpluggability update: Done!

A total of eight wires are bundled up in the cable that runs from the hub to the controller; three big ones that do the major stuff and five little ones that are just for the Hall sensors. With it all tethered together the only removal option is to remove both the box and the wheel, but it might be nice sometimes to remove just the the box, and leave the wheel D-locked to the frame. To make that possible, I cut the hub wire (ditching a couple feet of excess wire), soldered a PC power plug to the three big wires from the hub, and wired a port to the box, leaving the small wires disconnected. A little zip-tied strain relief, and the plug works great! I've added an extra D-lock into the mix, so I have one for just the frame to the rack like before, plus another for the hub to the frame to the rack. Way too much work to steal, I hope!

Without the Hall sensor it runs a bit rougher and makes a whirring noise, so I hooked them back up with this cool 5-pin plug.

Aesthetics, additions:

I coated all the visible surfaces with black rubberized spray, for a little added durability and to hide my shame. I did like that look, but then I remembered something I saw at HarborFreight (one of my Happy Places): A 12"x12" self-adhesive rubber mat, for like four bucks! So I picked up a couple and cut them down to fit, with cutouts for the switch plate and hinge. I also screwed a piece to the right side (actually the piece I cut out for the switch plate) to the back that hides the controller. The mats stuck quite well and should be super protective and I think they look really cool, and I am going to put these on everything I own.
There's a little gap between the top tube and the plywood to which the battery is mounted. At first I added a cleat up there to wrap up the extra length of cable running to the hub (there's almost twice the needed length, presumably to allow for behind-the-seat installations), but I removed that when I made the hub unpluggable, so I might be able to use that for storage: a wrench for when I do remove remove the hub, perhaps? Or I could hide a garage door opener in there, and run a pushbutton to the outside!
The carrying strap on the prototype worked well, so I added one to the new rig. There's a good deal of space on top of the box between the battery and the bike stem, so for now I've added a surface-mounted clip there where I can tuck a folded-up shoulder strap. A retractable solution would be more fun, so I'll keep thinking. Idea: these "mouse straps" are around $20!

Other possibilities:

Other bikes: Now that this rig is as removable and versatile as it is, I can try it out on different bikes, or even let friends play with it. Update: I need to extend the front corner if I want to use it on my larger-frame Diamondback mountain bike. To make the dimensions adjustable, I'm replacing the front-corner brackets with a DIY "turnbuckle," made with two eyebolts attached with a coupler nut. I'd use an off-the-shelf turnbuckle instead, but I couldn't find one with the right dimensions to handle the rubberized cross piece that snugs under the downtube.
Motorized beach cart: I've been doing sand sculpture for a while, and my local event requires a bit of a hike through dunes to get out to the beach. Transporting all the shovels and buckets and even plywood forms is always a huge chore, and I've thinking for a long time about how to make that easier. Can I make a beach cart with this rig as its driving wheel? Maybe I can come up with a way to widen the tire for use on sand, possibly a used motorcycle "paddle" or sand tire could be rigged it so it can be strapped to my hub's wheel. The throttle is slow and sensitive enough that I could make it crawl up a hill at walking speed, so do I think this is achievable.
Along those same lines, could I make a $100 garden cart into a $1000 motorized garden cart?

Watch for updates:

Many of my Instructables really end up feeling "done," and while this rig feels like it's in a good state right now, I doubt I'll stop tinkering with it because I'll be riding it a whole lot, and will definitely end up adding features and refinements. So if you folks don't mind, I plan to treat this 'Ible the same way, and will document any new tweak I deem worthy of documentation.

Thanks for looking, and please drive/ride safe!