Tricumbent-Hybrid

Electric Recumbent Trike - Part 1 ...

Apr 2007

This project is where theworkshop.ca has been unerringly headed for the last 8 or 9 years. Since the original Ebike project that was a dismal failure, through the Ver. 2.oh model and the LEV-1 project of 2006. Once completed, the end result will be an electric drive/human hybrid street legal recumbent trike assembled largely from scrap materials.

I knew this old swing-set would come in handy, so it was dis-assembled and squirreled away for just such a project as this.

(Note this image is from the summer of 2006, just to clarify so as not to give the impression that Global warming has advanced to the point that trees are in full foliage in March in Canada)

This bike is a testament to the fact that I'm a patient man, as it was retrieved from a dumpster in Minden Ontario in 2005.

What made it so appealing was that "Old-School" 3-Speed rear wheel.

After a bit of searching on the web I found that this bike is a tru-blu Raleigh 3-speed made in the Nottingham England Factory.

Apparently they command a reasonable-buck on Ebay.

Essentially all I wanted from the bike was the Sturmey Archer internally geared hub.

This hub is an AW series with a gearing of 0.75:1, 1:1 and 1.33:1 ratios.

The idea of using an internally geared hub is to leverage the electric motor's drive capabilities for both improved hill climbing as well as a higher top end speed on flats.

The shifter, like most of the parts that I'm recovering is in need of some extensive refurbishment.

Mechanisms need cleaning, oiling and cables will likely need replacing.

When I grabbed this frame last year I thought that it's somewhat unorthodox geometry would make for a sturdier rear-end than I would be able fabricate.

The frame has had all of it's inferior spot-welds re-enforced with generous beads from the MIG.

Given that this will be my ride for the summer of 2007, it will likely start off as 36V drive, but with an end goal of running 48V after all basic testing is completed.

The sturdiness of the framing is a requirement of the 3 to 4 batteries and payload that the trike will have to haul.

These two matching frames will be called upon to yield their steering heads for the front kingpins of the trike.

Yet another dumpster special, though it took a minor amount of "social engineering" to get the dump-meister to part with the chair as she wanted to be sure that it was going to be used by a deserving recipient.

Social-engineering? What the fuck, I out-right lied about poor little Timmy and how this chair might make his last few months more bearable...

Come-on, who could be more deserving than theworkshop.ca??? 

The parts started to come together as pictured to the right, while I would walk around it thinking, and drinking, and smoking, and thinking some more.

As much as I wanted to start into the steering assembly I had a sinking feeling that it would only lead toward disaster.

The positioning of the front wheels could only be determined once the seat was fixed into place.

Although I had a basic seat frame that I made earlier in the spring as a practice project (to develop some skills with the new MIG welder), it just didn't feel like the right step to be pursuing at this stage either.

For that matter the seat didn't really appeal to me that much.

Even with the cushions installed...

So I left it for a day or two knowing that this project could be driven off into the ditch quite easily by not thinking through the sequence of assembly.

The most logical steps were to work from the rear wheel forward to the motor, then to the seat, and lastly to the front-end. 

Electric Drive Train - Test Bed

I think that either the weather got cool & rainy or it was snowing, but I decided to turn my attention toward the E-Drive hardware.

To the right is a basic "Test-Bed" that I assembled to determine a) if the 24V motor would work @ 36V, and b) what would it's no-load RPM be at the output shaft.

I can appreciate the seasoned EV fabricator's mental retorts that "of course it will work, don't be so fucking stupid..."

But it is a reasonable question, if you've never tried it before, so the question has to be answered now before any further fabrication is done on the Trike chassis, as Battery mounting and placement are sure to arise any day now.

The basic measures of "does it work?" will be the presence of ANY heat generated by the motor in a no-load condition, as well as simply listening for how the motor sounds... This is certainly a subjective criteria, but on a daily basis we (the energy pigs of the world) all hear so many motors that power our daily conveniences that if you're even marginally inclined to mechanical pursuit's you should be able to identify the sound of a motor that is running too fast.

Let's start with the batteries.

Although I only have 2 (two) of the holy Odyssey PC625's I added a 41Ahr Gell cell that still holds a reasonable charge.

Each battery is fully charged and measured prior to starting the hook-up... The cells are wired in series to achieve 36V.

In actual fact the voltage is closer to 40V than it is 36, as the batteries are all sitting at 13.x V when charged.

As an aside, For those of you that send emails asking "Hey Frank, what can I do support theworkshop.ca???" Send me brand new Odyssey PC625 batteries... These are today's technology in energy storage, available, on the market... 

Or if you are an advanced battery technology company looking for a showcase for your product(s) Consider theworkshop.ca your site of choice. 

The batteries are connected to a Yi-Yun CT-660B9 36V/40Amp Controller.

This unit is the spare for the LEV-1 utility trike that is a materials carrier between the pattern shop and the foundry.

How can you justify trying to build a controller that has a Lock, brake, charger and Fet-based Throttle control integrated into it when you can buy it assembled and weather-proofed for $25 USD?

How?!?

The ultimate source I've found is www.tncsctooters.com located in Tennessee in the USA.

I'm not affiliated with TNCScooters, but have found them to be helpful, well stocked and willing to ship to Canada. Although they are servicing the Electric & Gas Scooter markets, the availability of such a broad range of after-market stock as they sell is really what will spur the Light Electric market as more and more folks simply start to build their own wheels rather than wait for a manufacturer to meet the demand.

A FET-based twist grip is wired to the controller to drive the motor at full speed.

I think that these are on special for $7.00 USD this month (April 2007) @ TNC.

(Alternatively, if you don't want to send PC625 batteries to theworkshop.ca, you could forward money to tncscooters as a credit toward the next purchase by theworkshop.ca, don't worry it won't languish on their books for long, as my list of wants exceeds my means...)

The Controller is wired to this Fortress Scientific "Wheel chair motor".

This unit is one of a pair that ran a standard powered wheel chair (courtesy of Ralph M. circa 2003).

The physical motor (less the gear reduction drive & output shaft) measures 3 1/2" in diameter and 8 1/2" in length.

The armature resistance (measured through the brushes) averages 2.0 ohms, with minor points of measurement at 1.6 ohms over the rotation of the armature through a complete 360 degrees.

I could just dis-assemble the motor and measure a single set of coils across the armature, but the reality is that the brushes are seeing a range of resistances as the armature is in motion, and I want to calculate the potential Current draw in a stalled condition as a "worst case scenerio".

24V divided by 2.0 ohms = 12 Amps average current 

24V times 12 Amps =  288Watts (Theoretical Average Power)

and

24V divided by 1.6 ohms = 15Amps max current 

24V times 15 Amps = 360 Watts (Theoretical Peak Power)

Obviously I'm using the terms "Peak & Average" out of context, but the point of the simple maths above is to illustrate the there is range of 288 to 360watts that the motor will consume.

For a 36V system...

36V divided by 2.0 ohms = 18 Amps average current 

36V times 18 Amps =  648 Watts (Theoretical Average Power)

and

36V divided by 1.6 ohms = 22.5Amps max current 

36V times 22.5 Amps = 810 Watts (Theoretical Peak Power)

By increasing the voltage by 50% to 36V the power consumption of the motor increases in a linear fashion to 648 to 810 Watts.

Unfortunately it's not quite as simple as the above, as the motor is designed to meet or exceed the previous 24V system architecture, but what are it's upper limits before the armature begins to stop converting electrical power into mechanical power and start releasing the surplus as excessive heat?

The CT660B9 controller is rated to a max of 40Amps @36V and that will act as a benchmark of the motor's capabilities.

If the motor & Controller survive a series of "Full-Load" tests the controller will be upgraded to a 48V 50Amp Controller.

The highest potential for an "Over-Current" situation that would damage either the controller or the motor would be a "Locked Rotor/Armature" condition. I know this for a fact, after having smoked 2 motors and 3 controllers on the original Ebike project.

One possible option to avoid this scenario would be to apply a simple sensor to the rear wheel that would activate a low-current relay that closes the "Lock" feature on the controller after the wheel is actually in motion (say even as slow as 0.5 Mph).

The other option that I hope to implement is a reasonable amount of calculation toward the actual motor gearing to the rear wheel, such that the trike has a reasonable chance of starting from a standing start in 1st gear, and yet still has enough range in it's available power to either climb hills and maintain a top speed of 32Km/h to adhere to the definition of an Electric Assist Bicycle within the Ontario Highway traffic act.

Misc Test Fixtures

The measurements of the battery voltages and armature resistance are done using commonly available DVM (Digital Multi-Meters).

These are my 2 (two) main meters, the one on the left is a Fluke (quality brand meter) that is on a generous loan by "Little-Big Pete" to whom I'm in his debt...

The one on the right is a Chinese piece of shit that chews through batteries and occasionally offers flakey readings that are so outrageous by an order of magnitude that I drop the leads and step back from the circuit I'm measuring incase it really is running at 5,000V...

This is a Starett Mechanical Tach that I use very infrequently, but is worth it's weight in gold on the occasions that I do use it.

The tach literally clicks off the revolutions of the shaft that you are measuring and is timed against a wrist watch for 60 seconds...

I generally perform 3 readings and average if there is a slight variance or throw out a truly whacked measurement.

At 36V I consistently read 110Rpm off the gear reduced output shaft.

This number 110RPM became the focal point from which all gearing calculations were to be made from this point forward.

The rear tire is 21" in diameter and I calculated it's circumference or roll-out, that value was converted to Metric (which could have been done at any time).

Given the 3 speeds of the internally geared hub, I calculated the roll-out for each gear given a single revolution of the hub gear.

The Hub gear and the bottom-bracket drive gear are set in a ration of 2.66:1 as the BB Drv is considerably larger.

This is all happening on a spread sheet, where I calculated for a series of Motor to Hub gear ratios that ranged from 1:1, 2:1 to 2.66:1, translating into Km/h across the gears.

The numerous calculations are also repeated over a range of motor RPMs ranging from 100RPM down to 70RPM... Note that I never calculated for the "No-Load" RPM of 110 that was measured, as I assume that it is an ideal condition that is not likely to ever exist.

There is considerably more on the original spread sheet but the summary above is the range of speeds that I hope to design towards.

Bear in mind that the trike will also have a "Human Power Assist" drive system that should be able to keep the desired speed up as the terrain varies. My greatest concern is to maintain a speed of over 10Km/h on steep hills.

Although not an essential piece of equipment @ $50 Cdn a digital battery charger eliminates a lot of the guess-work when charging different types of batteries, especially Over-charging.

Also. If you don't have a volt-meter (which is an essential piece of equipment) the charger does display the batteries voltage to the tenth of a volt through the charging process.

Mechanical Castings - Motor Mount & Primary E-Drive Gear

This is a foam hub that I assembled to provide a platform for the 2 (two) drive & driven gears to mount on that will be fixed to the motor's output shaft.

Several options were considered for the motor mount, but most required considerable welding to the main boom of the trike and lacked any true degree of flexibility if I decided to change things radically down the road (ie; gearing ratios).

So I opted to create a casting that would support the motor and allow it to be re-positioned along the length of the boom at any location.

I determined the bolt placement by tracing the pattern onto a piece of paper relative to the vertical postion of the motor.

The tracing was scanned and tilted to 12.5 degrees to match the rear-end framing vertical support. A tool path was generated that would layout all my fixtures that would be glued together to form the mount assembly in foam. 

The tool path was run off on the CNC mill and assembled as shown to the right.

The 3 (three) boom clamps are actually split and will bolt together to firmly clamp the mount onto the boom when positioned.

Even if this project were to die on the vine at this point (which it will NOT!) I'm well pleased with how the motor mount turned out.

It's taken years to evolve theworkshop.ca to the point that an idea can be taken from an embryonic state to finished fixture in a period of 2 days if I were only able to keep my focus.

I can appreciate that the  appearance does look 19th century but as the shit hits the fan and the roving masses blink in bewilderment at the lack of reality TV, these castings will do just fine...

The Motor mount works like a charm, and likely is overkill as it's probably the most solid part of the project next to the motor's actual gear-reduction housing that weighs at least 5 lbs on it's own.

The rusty "Driven Gear" mounted on the bottom bracket is only for reference, and proves to me that I'll have to cast a custom gear mount for it as well given that there will be alignment problems with the chain drive from the "Human Drive" if I don't make allowances at this point.

The motor Gear hub cleaned-up nicely on the lathe and has a second gear mounted on it's back that will be driven by the Human drive assembly.

In closing this first installment, the electric drive assembly will be finished and tested against the calculated rear wheel speeds in a no-load condition to test to see if my math holds any majour flaws, as well as to settle the final placement of the motor, batteries and additional frame supports before fabrication the seat assembly.

Human/Hybrid Electric Trike, 2, 3, 4

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