chicksdigmiatas

iTrader: (11)

I am totally going green. Whaling seems fun.

Joe Perez

iTrader: (8)

Like I said, I tried doing the trip on a borrowed bike (a fairly nice one) a couple of years ago and just couldn't make it work. For the time being, this is the only way.

Oh, and remember the thread "A few words on cheese"? I suck at lifestyle modification. This, however, is something that I think can work.


Green... I never thought I'd say the word. Am I turning into a California hippy? I sure hope not.


And how much torque are you applying to the rear dropouts from the axle when you're pedaling at full tilt, in such a way as to break them or change their shape from a U to a V?

(answer: Zero. Unlike what a 500 watt 3-phase motor whose armature is the axle will be doing.)

kotomile

iTrader: (24)

Very cool project, Joe, even if it's not quite the technological tour-de-force we we thinking of.

When I was in Monterey I gave riding a bike to and from class a shot. It's 8.33 miles each way (actual bike miles, from my trip computer) and the "to" portion was mostly uphill, especially once on the Presidio.

I tried to bike there and back every day, and that lasted about 3 days. With unit PT and everything it just wasn't going to happen that way.

Luckily, the Army started providing us with bus passes, so I could take the bus in the morning (the uphill journey) with the bike secured to the front of the bus. Then I'd ride home in the afternoons. This also handled the sweatiness at work situation nicely.

Bike as daily thread:
https://www.miataturbo.net/insert-bs-here-4/my-new-daily-huge-gas-saver-39608/

gearhead_318

iTrader: (1)

This may be something to model the electric bike project after:
http://www.msnbc.msn.com/id/29259226...-electric-hog/

rmcelwee

iTrader: (1)

Funny that you brought up me/Beast. Ever since I got into the Geo Metro thing I've been trying to come up with a lightweight project using the G10 (Suzuki 3 cylinder). I've been stuck in the mud with the V8 Miata and don't see me finishing (or even continuing) for quite a while. There's a guy on m.net who swapped one (G10) into an M1 but for fun but I've been dreaming of some kind of tube chassis. There is a guy on my Metro forum that built a tube go cart with the G10 but I have no idea what it weighs.

Maybe this is what you need to build <G>:

sixshooter

iTrader: (12)

Do want.

rmcelwee

iTrader: (1)

While trying to find some info on that locost I found this. Color me impressed!



hand made frame, model A cowl and doors, model A rear doors blended to 20's turtle deck. stock 1.8l with zoomies, stock EFI and ECU, runs like a top all day. Grill is two fender trim pieces from a 50's 60's something. Right now its the stock rims with radials, I have some 14x4 steel rims but they also have radials and look like go cart tires. maybe some bias ply tires, or im thinking of painting the stock 5 spokes with red oxide primer.

icantthink4155

iTrader: (12)

And we've all agreed that it has to sound like complete ***.

rmcelwee

iTrader: (1)

I wouldn't want to be walking beside it...

Joe Perez

iTrader: (8)

It's alive.

I only realized after the fact that I happened to choose Independence Day to declare my (admittedly partial) independence from gasoline. Kind of interesting, I suppose. Although I don't believe that Great Britain is a petroleum-exporting nation.

The goodies arrived last week:



This is a really clever design, I must admit. And I'm furious that I didn't think of it myself. All the time I'd been dreaming about doing this, my sketches had involved various permutations of either friction-drive (shaft against tire) using an RC airplane motor, or some kind of geared motor coupled to the chain.

Well, wouldn't you know that the Chinese came up with the rather elegant solution- just put the motor inside the wheel!

So that's basically what we've got here. A giganic, brushless 3-phase permanent magnet DC motor, where the outer shell of the motor forms the wheel hub (to which the spokes are attached), and the armature of the motor is the axle. Apparently these things are popular as hell over in China, but they've just started making their was into the US rather recently and in small numbers.


The battery is a real piece of art:



Inside the aluminum tube are several dozen Samsung Li-Mn cylindrical cells (same as what's in the Tesla), plus an integrated Battery Management System up in the top. Total weight is about 9 lbs, which is stunning when you consider that this pack is rated at 36v, 12 Ah. And that's the 1C discharge rating, not the 0.05C rate that SLA batteries are typically rated at. In other words, it'll supply ~430 watts continuously for a full hour without breaking a sweat, and still deliver full rated capacity. (Hooray for technology).



So, construction begins:

Step 1 is the installation of the controller. Ok, technically step 1 was the mounting of the new tires. Just as with cars, all department-store bikes seem to come with shitty all-season tires, and I simply could not abide those. Picked up a set of Michelin Pilot Citys (the RT-615 of the bicycle world) and I am quite embarrassed to admit that I simply could not get the damn things mounted. Unlike most bicycle tires, these suckers have a steel bead like a car tire, and I just didn't have the right tools for the job. (How many of you folks mount your own car tires, eh?) On the plus side, I discovered the first of many cool bikes shops- the Revolution Bike Shop in Encinitas- where I had them mounted for a paltry $14 total. Given the pain involved in getting them on, I splurged on a set of mega-thick tubes and filled them with Slime. Repairing a flat roadside is something I wish to avoid having to do with these. (Still, I'm carrying a CO2 inflator and several spare cartridges.)


Anyway, the controller:



A surprising amount of fabrication was involved getting the damn thing up in there, and it's an astoundingly close fit. Technically, the controller is quite interesting. It acts as a synchronous six-cycle inverter; there are three hall-effect sensors inside the motor, and as the three sets of windings are in a logical Y-configuration, each winding set gets operated in the positive direction for 1/3 of each cycle relative to its previous neighbor and then in the negative direction for 1/3 of each cycle relative to its next neighbor, all the while performing PWM based on the 0-5v input from the throttle. Brushless DC motors are really fascinating things if you're into that sort of technology.


The mounting is finished up, the basket is mounted, and I found a really clever use for the old inner-tube that I pulled out of the front wheel:





A few lights, a mirror, some silicone grease and a bit of sweat later, and here she is standing proudly in the parking lot of the Vista Technology Center, a feat I'd never have accomplished without the assistance of the electric wind:




(Yes, I actually went into the office today. It's far easier to work when there's nobody else around.)

y8s

iTrader: (8)

are you going to cut ***** holes into the motor housing?

curly

iTrader: (25)

Well that was quick. Mind telling us the price of the controller, battery, hub, and any other electrical expenses? Looks like fun, and easy.

Also, what's the final weight?

y8s

iTrader: (8)

i'm going to googleguess here that all-told, it's about 8-900 for the big ticket items exclusive of the bicycle and tires.

gearhead_318

iTrader: (1)

I predict wheelies.

rmcelwee

iTrader: (1)

So when are you building the next three so you can hook them together and have something that resembles a car?

Joe Perez

iTrader: (8)

I'm not sure that I am yet at a power level where *****-holes are a requirement. As it stands, the hub seems to be reasonably sealed against dust and dirt, and that's probably a good thing. It's also running reasonably cool, as measured by the palm of the hand after the ride home. Definitely warm enough to detect, but not hot by any stretch.


Pretty good guess. The complete electronics package of motor (with wheel), controller, battery, charger, throttle, brake levers, and wiring was $796. I've got about $110 worth of lighting on the bike (two 2 watt LED headlights, two very bright LED taillights), another $100 in rubber, a decent mirror, and of course the milk crate on the back and the rack that it's sitting on (probably ~50 for all those.)

So all told, this bike is worth more than my '90 Miata.



I honestly have no idea. I'll have to see if I can manage to balance it on a bathroom scale for long enough to get a stable reading.

It's definitely heavier than stock, but it's not outrageous, especially considering that some folks use lead-acid batteries on these. I can still pick it up pretty easily, and it doesn't feel monstrous on the road. The fact that it uses a permanent-magnet motor means that there is some drag at the motor when pedaling with the throttle off, however it's not particularly horrible, and after all, the primary point of this whole thing is to get some exercise.

One interesting phenomenon which I noted this morning that I hadn't expected- you know how when we were kids on BMX bikes, you occasionally wanted to stand up and fling the bike sharply left to right (like a NASCAR driver scrubbing the tires) while coasting downhill? When you do that, you can really feel the gyroscopic stabilizing effect of the newly massive rear wheel. It's not really problematic, I just wasn't expecting it.



Well, the system isn't that powerful. Some of these loonies are running 72-96 volt systems, and they can wheelie pretty easily. I tried it this morning, and I was able to wheelie the bike at low speed using a combination of full throttle, furious pedal torque, and pulling back on the bars sharply, but it's not as though it wants to wheelie all by itself. Power delivery is quite smooth.

Some of these hills do make me wish that there was a bit more torque, and understand why some folks are running 48v systems on the street. There's one stretch in particular, towards the end of my ride home, which is about a 15% grade continuously for a little over half a mile. About 3/4 of the way up that one, I started thinking that adding a 12.8v Li-Fe battery in series with the existing pack might not be a bad idea.

Or I could just man up and develop some stamina. I'm gonna shoot for that one.



Hehe.

Believe it or not, I am seriously tinkering with the idea of a battery-powered trike. There are some pretty decent motorcycle-style hub motors available (such as this one), though for the sake of off-the-line acceleration, it might be better to use a seperate motor (examples) and mate it to a Harley-Davidson transmission and swingarm.

Just a dream at the moment. I'd need something in the neighborhood of $7,000 worth of battery right now (be it LiFePO4 or LiMn) to really make it practical, but there are interesting development afoot in battery technology. If any one of the dozen or so miracle-technologies that are supposed to happen over the next couple of years actually do happen, battery cost (and weight) would probably be halved.

rmcelwee

iTrader: (1)

I've been hearing about the new miracle battery (just around the corner) for 10 years. Same thing with the new miracle solar panel.

mgeoffriau

iTrader: (7)

It astounds me that you can build your own electric bike, and yet you (apparently? Did I miss the joke?) believe that you have to balance the bike on your bathroom scale to weigh it.

Step 1: Weigh yourself.
Step 2: Weigh yourself holding the bike.
Step 3. Subtract result of Step 1 from result of Step 2.
Step 4. Profit.

Joe Perez

iTrader: (8)

Well, the difference I see here is that there actually have been several miracle battery breakthroughs over the past two decades, with a steady trend towards continuous, incremental improvement.

Think about the battery in your cell phone or your digital camera. The ones that are smaller than Hustler's dick and can yet play Angry Birds for an entire workday or take four hundred photographs with flash. Those are probably LiPo, which was just a laboratory fantasy in the early 90s, back when lead-acid was king and NiCads offered only marginally higher energy density while practically discharging themselves while just sitting on the shelf.

Then LiCoO2 was introduced, coupling the massive density of LiPo with huge discharge rates and near 100% DoD. LiMn and LiFePO4 came along and sacrificed a bit of energy density in exchange for much lower cost, hugely improved cycle life, low self-discharge, and much improved safety (you can drive a steel rod right through them and they won't explode.)

It would seem that a corollary to Moore's Law exists here, and I don't think it's all that unreasonable to expect that within a few years time we will be seeing energy density improve even further (the nanowire battery guys are already claiming 10x improvement in their functioning prototypes) while the production cost continues to fall (folks at MIT have already engineered a virus which automatically manufactures cobalt oxide anodes and carbon-iron phosphate cathodes).

Battery technology is finally getting to about the same level of technological innovation that semiconductor fab was at in the early 80s. Remember what happened to big, expensive computers?

Joe Perez

iTrader: (8)

Uhm, yeah. That would probably work.

(slaps self on forehead.)

Sometimes the obvious solution eludes the complex mind.