Bike Week

Bike Week was great. I took off a few days from work and spent them working strictly on the bike.

We definitely made great progress:

• new front "dash" created from scratch
• LED headlight is mounted
• LED turn signals are mounted
• gauge cluster is mounted
• battery cables created / used
• Kelly controller programmed
• throttle connected for the first time

The bike hasn't rolled under its own power just yet. Several questions and uncertainties were brought to light regarding exactly how to wire the controller, so we concentrated on other things and made the best use of our time. The following issues or questions came up:

• wiring my controller specifically
• pre-charge resistors
• contactor coil diodes
• contactor behavior / operation
• battery installation / maintenance
• charging standards / connectivity
• throttle resistance readings
• language barrier surrounding Kelly controllers

These still remain to be tackled:

• Tank component mounting
• Turn signal lighting
• All wiring
• Testing / tweaking
• Insurance
• Registration
• Inspection

I'll try and cover some of these as individual posts in the near future to organize what we have now learned first-hand, and that of others. It was fun investing time into this and figuring out how to overcome some pretty tricky design challenges. I'm really looking forward to finalizing in great detail my understanding of all the components and how they work - That and taking a spin around the block on my own, custom electric motorcycle.

-Colby

Quick Update

I've got a new picture of the bike.

As you can see, the seat has been shortened, the fuel tank is back (innards reworked), the chain mounted, and the electronic throttle is attached.

I love the way this looks, to be honest. It's extremely close to what I envisioned almost two years ago.

Nothing has been wired up just yet, but that should change in about one week's time. I've taken a few days off from work in order to concentrate on the bike with my dad. The next primary objective is to get it running under it's own power. The secondary objective is to get it as close to inspection-ready as possible.

In preparation, I did a bit more research on inspection requirements and ordered a Truck-lite 7" round LED headlight. As far as I know, this is the only DOT approved LED headlight on the market. It's pretty important to me that at least this be completely legal. It was expensive, but I think it will be worth it. I also think it'll look just fine on the front of the bike, but we'll find that out soon enough. The turn signals and license plate bracket are another issue. I'm not sure I'll be able to get parts delivered on time, but we can work on mounting points even without the exact components present. The license plate also needs a light and a place for an inspection sticker, come to think of it.

I'll be thrilled to get the thing rolling on its own and wired up a bit. We'll worry about the specifics of insurance and registration when we get there.

-Colby

Wiry Information

I've been doing a fair amount of research on wiring in the past week. It's not a simple task, figuring out what will work safely and reliably. Even now I am not absolutely confident in my decision, but at least I feel like I know what to try and what not to try.

Note: What I discuss here applies to DC and may only partially apply to AC systems.

What I found out:

I went looking for a chart saying voltage X with a maximum amperage Y requires wire Z. That doesn't really exist - mainly, because every situation is unique. There are several charts that do give you a sense of the tolerances, but please use that information carefully. A minimal list of factors that affect the accuracy of any figures you may find are as follows:

• AC vs. DC
• length of the wire
• Amps / circular mils
• Insulation rating
• The immediate environment of the wire
• Acceptable voltage drop
• Voltage rating of the wire

My questions from my last post were in regard to the chart at http://www.powerstream.com/Wire_Size.htm I was asking two main questions about main drive system wiring.

The wiring can vary on either side of the controller. Because the motor controller is just a power-converter, it takes in just as much power as it puts out. The key is that it does its input and its output over different, and varying lengths of time. The battery-side of the controller will not be handling large amperages (maybe 70 amps max for me) while the motor-side could see much higher current (limited to no more than 300 amps for 1 minute by my motor). This is most obvious at peak numbers of course, but still applicable at the continuous ratings for my components. The point is: Yes, different kinds of wire could be used to handle the different kinds of power on either side of the controller. Each wire or set of wires could be size appropriately to its own set of influencing factors. You don't have to though. You could use one size as long as it is rated for the most strenuous parts of the system. It means carrying around a little bit more weight and maybe spending a few cents more for both the wire and hardware to couple it to the battery pack, but that's about all it impacts.

As for what gauge to use, now that's kind of tough to answer. As you may know, I'm basing most of my bike on Lennon Rodger's eMoto. Naturally, I looked at his page and found that he used 4 gauge (AWG) welding cable. When I looked up the specs for 4 gauge wire on the PowerStream chart, I was confused. Firstly, there were multiple amperage ratings, but reading a bit helped. The left amperage column is called "maximum amps for chassis wiring" and the preceding paragraph explains that it is A) a conservative rating and B) for wiring in air, not bundled with other wires. Meanwhile, the "maximum amps for power transmission" column is based on the700 circular mils per amp rule.

What the heck is the 700 circular mils per amp rule?

Let me try to build up to it...

Mils does not mean millimeters. Mils means thousandths of an inch (.001 inches). Circular mils can be abbreviated CM and is used as a unit for measuring circular area, but there's a twist in the definition:

• Circular mils refers to a circular area in terms of the square having sides with length equal to the diameter of said circle.

I suppose a picture would help a lot right about now:

Source RF Cafe

So basically, it's a very rough expression of the area of a circle. We now know that the area of a circle expressed in circular mils is not the exact area of that circle at all. It's an approximation that avoids reference to Pi. And just for the sake of confusion, (somehow) MCM means thousands of circular mils. That is, an area of 400 MCM = 400,000 CM.

Applying our new understanding:

The rule is talking about how much surface area is present for current to flow through. Obviously, since we're talking about circular surface areas, it is in reference to the cross-sectional area of the wires. You may find information about surface areas in regard to a wire with AC, but be careful, as that may be in reference to the longitudinal or "skin" surface area, instead of the "face" or "end" surface area of the wire which I've been describing here.

The 700 circular mils per amp rule, therefore, means that 700 CM of cross-sectional area are being taken into consideration for each amp in the wire. In other words, each amp of load adds roughly .0007 square inches to the cross-section of the wire.

Take a specific example:

PowerStream shows 1 AWG wire as being capable of carrying almost 120 amps according to 700 CM per amp rule. It shows 1 gauge as being .2893 inches in diameter. Since 1 CM is .001 inches, we can divide .2893 by .001, indicating 1 gauge wire is 289.3 mils in diameter. Using our picture and definition, we can put that in terms of CM simply by squaring it. Thus, 289.3 mils * 289.3 mils = 83694.49 squared-mils or CM. Now, we check to see how many amps we can put through a wire with that kind of cross-section by dividing it by 700 CM. 83694.49 CM / 700 CM per amp = 119.56 amps. Cool beans.

Cross-referencing our earlier statement, if each of the 120 amps adds .0007 square-inches (according to the 700 CM rule) to the wire, then the wire's cross-section has an area of .084 square-inches. The chart stated the diameter of 1 gauge as .2893 inches, so we see that .2893 inches * .2893 inches does in fact give us .08369 square-inches. Double cool. That's all without using Pi, so even though it is nice that it matches, do remember that it's not a precise measurement of the cross-sectional area.

After all that, you should know that 700 CM per amp is a "very, very conservative" rule of thumb. Additionally, the shorter the wire, the less area you have to provide for each amp. For my bike, hopefully I'll be dealing with no more than two-foot lengths of high-power wiring. I've read that with such short distances, a rule more like 200 or 300 CM per amp is acceptable. If that's true, then we can safely use a slightly smaller wire. Given that my motor is rated for a continuous load of 125 amps, if I used the 250 CM per amp rule, 125 amps * 250 CM / amp = 31250 CM. Since 1 CM = .000001 square inches, that is .03125 square inches. The diameter of a wire with that surface area is then the square-root of .03125 square-inches, which is .17677 inches. Referencing the PowerStream chart once again, that does fall pretty close to 5 gauge, which is a reasonably accurate result considering Lennon's choice of 4 gauge.

Voltage drop:

The voltage drop along a wire depends on the resistance between the source and the load. All wire resists charge flow and this resistance reduces the amount of voltage being provided further down the circuit. It comes down to how electrons flow through the wire really, so considering water flowing through pipes can help here. The longer the wire, the more electrons there are in the way causing increased resistance. However, the wider the wire, the more electrons are available to carry the current and therefore decreased resistance. Furthermore, all materials have their own unique makeup so the exact resistivity and operating temperature of the conductor in use will definitely have an impact.

These factors are represented by the relationship R = p L / A, where R is the resistance of the wire in ohms, p (rho) is the specific electrical resistance of the conductor in ohm-meters, L is the length of the wire in meters, and A is the cross section area of the wire in square meters. Keep in mind that voltage is actually a potential difference, so L is usually twice the one-way distance between source and load so as to incorporate the losses to and from the load. Also note that temperature will affect the electrical resistivity of the metal.

The amount of voltage drop obeys V = I R, where R is the resistance of the wire in ohms, I is the load current in amps and V is the resulting voltage drop in volts. Based on that relationship, we know how voltage drop will fluctuate, given the details of the circuit. As an example, when the current flowing into or out of the controller varies, we know the voltage drop will vary. Similarly, as the wire heats and cools, it's resistivity will change, resulting in slight variances in voltage drop.

Having a larger amount of supply voltage doesn't change the resistance of the wire, nor the current drawn and therefore does not affect voltage drop. What a larger supply voltage does affect is the percent voltage drop, because it is a ratio of voltage available to the load versus source voltage. That is, if 72 Volts is supplied, and the wire causes a drop of 1 volt, then the ratio is 1/72 which is .01388. In terms of voltage loss, that's 1.38 % which, according to my reading, would usually be very acceptable.

Most of what I found on voltage drop spoke about limiting the percent voltage drop to an acceptable level. The idea is that the load device should be provided an acceptable voltage after the drop caused by the wires. Outside of that acceptable input-voltage range, you're probably sacrificing device life or efficiency or both.

Insulation:

Insulation protects a wire, but can only stand so much heat. If more heat is being generated than the insulation handle, then obviously, it will fail (melt). Apparently, most battery cable has PVC insulation. Most welding cable has rubber insulation and may handle 600 volts. Then there's locomotive-grade DLO cable which may handle 2000 volts. I looked up a few specs for battery cable available at a local auto-parts store only to find that the insulation was rated for a maximum of 60 volts. I know 72 isn't too much of a stretch, but as usual, I'd rather be safe than sorry. I'll probably go with a welding cable instead of at least 4 gauge.

Ideally, wires would be rated for some overall power, instead of just a maximum current. However, as we've seen there are a lot of factors which make that kind of rating difficult to determine. In the end, I'll probably go with two sizes of cable, for the two sides of the controller. Something like 4 or 5 gauge welding cable on the battery-side, and 3 or 4 gauge welding cable on the motor-side of the controller.

References used:

Formulas, charts, notes, and facts:

http://www.rowand.net/shop/tech/wirecapacitychart.htm

http://www.windsun.com/Hardware/Wire.htm

Good coverage of a lot of wiring knowledge:

http://www.epanorama.net/documents/wiring/wire_resistance.html

Voltage drop

http://en.wikipedia.org/wiki/Voltage_drop

http://en.wikipedia.org/wiki/Electrical_resistance

Wire insulation types and ratings:

http://www.kayjayco.com/wiretables.htm

http://www.wesbellwireandcable.com/PowerCable.html (awesome, detailed info for each cable type)

Discussion of calculation of heat generated by wire resistance:

http://www.newton.dep.anl.gov/askasci/phy00/phy00032.htm

Interactive calculators:

http://circuitcalculator.com/wordpress/2007/09/20/wire-parameter-calculator/

http://beta.circuitwizard.bluesea.com/#

http://www.powerstream.com/Wire_Size.htm (Voltage-drop)

Practically exhaustive chart of gauge specifications:

http://amasci.com/tesla/wire1.html

http://www.interfacebus.com/Copper_Wire_AWG_SIze.html

Car-audio speaker and amplifier wiring information:

http://www.the12volt.com/info/recwirsz.asp

http://www.bcae1.com/wire.htm

Other news:

Hooper Imports served me well. I got my parts and they look great. I'll have to report back one more time when I get a chance to actually put them on the bike. The point is they sent exactly what I ordered, and they did so quickly, with no fuss and no issues.

Back on Track

The Spring semester is over. It went well. Now where was I?

Oh right - So here's the deal:

• I'm about ready to wrap this project up.
• It's summer time and I don't have school to worry about.
• The bike is more or less mechanically, ready.
• The really detailed work is what remains.

...So I do believe there's plenty left to learn.

The foam gas-tank replacement didn't pan out. Although aesthetics wasn't a huge concern, using that shell and arriving at something functional and appealing just felt afar off. We turned back to the original tank and my Dad did some intricate metal-work in order to have something compact, workable, and down-right nice looking in minimal time. This is the space that will contain the chargers, DC converter, motor controller, main contactor and a fuse or breaker.

So, now that serious electrical wiring needs to be done, I have several questions concerning the new electrical system being installed on the bike:

What gauge wire should I use for my bike?

Lennon used #4 welding wire, which should be the same as size 4 AWG. But how come all the charts I find out there for AWG show very conservative numbers? For example, this site shows #4 wire being capable of only 135 or 60 amps, depending on use (what's the difference between chassis wiring and power transmission, anyway?). A good point my Dad brought up was that there's only so much surface area at our disposal on the controller terminals and that will absolutely place an upper limit on the size of wire we can expect to need.

Will the battery side of the controller need a different gauge than the motor side?

I haven't posted yet about how my motor controller works, but I some-what understand the principle at work, and that the battery side won't (or shouldn't) see more than maybe 140 Amps, while the motor side could see 300+ Amps. I know selecting too large a gauge is not a serious problem, so I guess I'm asking whether or not there's a reason (and what that reason is) to use separate gauges for each side of the controller.

Can my proposed charging system be implemented?

This is not a question of how well will it balance the batteries, but rather, can it work at all. The chargers have been tested and seem to work fine. We just aren't perfectly clear about whether or not we can leave them connected when the bike is being driven, or if we should add a component or place an existing component such that some charging circuit is broken in order to operate the vehicle. I expect it depends on the exact method in which the chargers are wired to the batteries as well as how the chargers are wired internally, so we're just still researching and figuring this out.

Here's what remains to be done:

• Sort out a wiring diagram for our specific bike.
• Research, select and install electric drive system wiring
• Adjust and install drive chain
• Test throttle switch
• Program controller
• First test of electric drive system
• Break-in the motor
• Install PakTrakr
• Re-cloth modified seat
• Remove and/or treat rust
• Finish and paint component shelves.
• Final paint and assembly

Oh, I did want to mention how I found a supplier of certain Lifan parts. Lifan being Chinese makes it kind of a big deal to have a good supplier of parts here in the US. I ordered parts from Hooper Imports. They're in Redmond, Washington and seem to be very genuine and rather-closely tied to both Lifan and American Lifan out of Dallas, Tx. Trust me, I would have ordered parts from American Lifan, considering their convenient location, but their online parts-store has been "coming soon" for quite some time now. I suppose I could have called, but I didn't have part numbers to reference. I feel good about my order to Hooper Imports, and I look forward to verifying I ordered and received the correct items.

I wish I had an image or two to show the state of the bike, but I'll be sure to snap a few in the coming weeks. I may take a few days off work to help get as much of this done as possible. Maybe by the end of June, we'll have something ridable and almost licensable.

-Colby

Road-Legal Lighting

As I got to thinking about which type of lights I would like to use and how, I started wondering what was legal and what wasn't. I went searching for the Texas Transportation Code and I found this website: http://law.justia.com/index.html

Just click the link to your state, your state's "codes" and then the "transportation" section.

It was helpful to read about the specific light intensities, heights and colors that are legal in my state.

Keep a couple things in mind though:

• I'm not 100% sure these all apply to motorcycles, but I'll post more as I find out.
• Legislation can change so remember that anything you find online could be outdated.

-Colby

Yes, I'm still here.

Sorry I'm just now getting around to updating. It pains me to have waited so long. A fair amount of progress has been made, but at the same time, several more large hurdles remain.

Cut to the Chase:
So here’s what we’ve got at this point. The bike’s frame is just about ready, as most of the alterations that remain are minor and aesthetic. The only big modification that is not complete is the gas tank area. The power train parts are ready. The battery trays are done and the motor mount as well.

The drive system is right at 99% done. As far as I know, we have everything, and we just haven’t hooked it all up yet. We went with a chain and sprocket system, mainly for how easily it can be tweaked. Additionally, the swing-arm won’t have to be removed to replace the chain as it would for a belt, plus the parts were readily available. We found a new rear sprocket locally somehow and dad came up with a creative way to mount it. Seeing as how the old rear sprocket had the exact bolt pattern for the hub and how the new rear sprocket had an extremely open center area, we just combined them. I am only slightly concerned about the strength and balance of the weld, but those can be slowly tested or measured and corrected as needed. For clarity, we’re using the old rear sprocket only for mounting the new one – there will be no shifting of gears or de-railing of the chain between gears, as the two sprockets are in the exact same three-dimensional plane on the axle.

Once a Fuel Tank:
As an experiment really, we covered the gas tank in plastic-wrap and then aluminum foil and covered it in Great Stuff – an expanding spray-on foam. This resulted in a form which matches the tank overall. Dad shaved / ground / sanded down the outside to give it a good external shape and we played around with ideas about mounting it, covering it in fiber-glass, and how much space it gave us to work with (a ton, internally). Here's what that looked like:

On a separate afternoon however, we got to looking at the original gas tank, how symmetrical it was, and its fair condition. An hour or so later, we’d cut the bottom off of it and had just a top shell like so many others modders have done. I wasn’t sure about if it would really work out or not, but as of this moment, it has more potential (in our minds) than the foam shell. It is of course very symmetric (which is pretty important to me) and without a bottom contoured around the backbone of the bike, the internal space should be ample.

Right now, the plan is something like this: Ease of access is important since several core components are going to be housed within the tank. We might try hinging the tank at the seat and simply providing a sturdy metal plate beneath the backbone to which the tank can be secured and potentially air-sealed. Within the tank, we’ll keep it simple I bet and use simple flat plate to which we can mount the battery chargers, main contactor, main breaker and d.c./d.c. converter. Whatever gauges, LEDs, and other indicators end up being used can either be wired up to a dash area or back-mounted and exposed directly through the tank itself.

Stay in the Light:
The headlight is a stubborn problem for me. I want it to be reliable, safe, unique, legal and as efficient as possible. Those are competing interests, it seems. I don’t know a ton about the various lighting technologies (LED, Halogen, and HID) but I want to keep the front of the bike distinctive, clean, and functional. Wikipedia yields the following:

• Halogens are prevalent and inexpensive, but require high power on average.
• HIDs are the brightest, somewhat efficient, have good longevity, but are expensive.
• LEDs are bright, very efficient, have superior longevity, but can be the most expensive.

My brother had this idea: It could be advantageous to have multiple technologies on the bike for different purposes. Yes, an all LED bike would be cool, but if it's not practical (not to mention legal), then it's just not. Anyway, a running-lamp could probably be LED and homemade without any legal or safety issues. Meanwhile, the actual headlight for actually lighting the road could be a halogen module that's DOT approved. I don't see myself riding much at night, but I guess it is bound to happen eventually, and I don't want to be pulled over for having too bright or dim a headlight, so I might just go this route. From what I've seen, it wouldn't be too difficult to build my own LED module. Keep in mind that the laws where you live might also have a lot to with what you feel comfortable doing.

Here are some links I stumbled across while trying to find either professionally manufactured (and DOT approved) LED headlights or how to make my own.

http://ecomodder.com/forum/showthread.php/led-headlight-6514.html
http://www.hebeiltd.com.cn/?p=zz.led.resistor.calculator
http://ledsupply.com/led-resource.php
http://www.mvlc.info/index.html
http://www.projectresponder.com/pse/d304-Solstice-Solo-10w-LED-Light-Euro.htm
http://www.candlepowerforums.com/vb/showthread.php?t=228933

Still to do:
The tank needs a sturdy hinge and secure point, and a way to seal it off. The seat needs to be trimmed and re-covered, and potentially hinged as well. A shelf needs to be made under the tank and the components fitted and mounted to that shelf. The headlight technology and hardware must be researched and a solution planned. New high-power wiring should be accounted for and purchased. Original wiring harness and connectors should be used where convenient. Any missing or broken parts on the bike need to be ordered.

I'm already working on another post concerning motor controllers - what they do and how. I'm doing my best to get some facts straight and present all the material in a way that is easy to grasp. I'm learning an awful lot, so hopefully it will be of some help to others as well.
-Colby

Important Progress

Seeing as how I've spent 3 or 4 of the last 5 weekends on the bike, I figured I'd provide an update while it was still June. Things are moving along just fine, with a great deal of help from my father and his varied expertise.

What plan:
We've cut, heated, bent, tacked, welded, ground smooth, and stared. I'm really pleased with the way our semi-precise design and ideas are turning out. The bike frame has undergone more modifications than I ever intended, honestly, but it's opened the door to a far better looking and more well-constructed vehicle too. I had a plan, based on my rather time-expensive quarter-scale 2D profile of the bike (in the photo gallery). I'd placed battery cut-outs all around my rendering in order to get an idea of what could fit where. It ended up being useless really. Once we got the frame sitting next to the batteries down in the shop, it was obvious what to do. Thus, we've spent several days measuring parts, thinking about where they can and should go (considering maintenance and factors out of our control), modifying the frame to be what we need, and carefully adding anything we need as we go.

The Result:
Instead of batteries lying in all different directions, being difficult to remove and replace, and perhaps most importantly difficult to wire up, all the batteries sit uniformly in three efficient pairs. They will have space for removal, wiring, and routine inspection. Also, instead of a frame that suggests it can support two people, the frame has been trimmed in the rear. This cuts some weight, shows some individuality, and makes it a bit less misleading at first sight. Sure, we've added far more material up front to support the batteries, but every bit of weight counts. As much as I'd love to share a picture, I'll not be posting any until we reach a certain milestone on the frame. Then, I'll show it off for sure.

Hurdles Remaining:
I have yet to decide on the exact type of drive system. Partly, I'm still unsure whether or not it will work. I haven't seen many belt-driven EVs, but then again, I haven't searched, so I need to figure out what my options are, and make a decision. Going the belt route may have it's issues though. I'll need a way to couple a belt pulley to the wheel, or rather, the existing piece that grabs the wheel. Besides that, there's plenty of wiring to figure out and other parts to order and custom make. We'll get there.

Another Find:
Lastly, I wanted to direct anyone interested in Lifans to http://www.americanlifan.com/lifan3/customer/ which is the forum for American Lifan it appears. It's new to me, so I'm posting it. I'm not exactly an American Lifan buff, so to speak, but it does have very knowledgeable folks behind it providing help to owners of just about anything Lifan has made. I've had a few problems getting my account approved but I'm sure it will be done soon. I'll probably be asking some questions on there before long. Apparently, they get a lot of spam from gmail accounts, so they prevent gmail-based accounts from being created. A bit of a bummer, but oh well.

-Colby