A dummy's guide to electric motorcycles, part two

Dailies -


dummys_2.jpgIn part one of our dummy’s guide to electric motorcycles we learned about general terminology and motor types. Now, Brett Gober, a self-described “knuckle-dragging redneck” that we discovered leaving suspiciously intelligent comments on HFL, takes us through the difficult stuff: batteries. — Ed. >

Electricity is weird. It isn’t that hard to learn about, but there are some counter intuitive things going on sometimes, and it can definitely be confusing. Hell, the idea of flow from one pole to another in a circuit has two conventions “conventional flow” and “electron flow.” We say that charge is flowing from positive to negative, the actual reality is that positive is ground and the negative pole is the one with the excess electrons; the electrons are flowing from negative to positive. When Ben Franklin was observing his little experiments with electricity, he got the polarity wrong. The wrong polarity stuck, they couldn’t change the convention, and it’s been confusing people for 200 years. That’s how it stands today.

Polarity does not matter. Electricity works exactly the same, backwards or forwards. If you hook up a motor backwards, does it make negative power? No, it makes negative torque, negative revs, the damn thing spins the other way. It is essential to understand that polarity does not matter if you want to even try to understand AC.

Let’s go  back to the old “it’s like voltage is the size of the pipe, and amperage it the flow of water through it” metaphor, which I’ve always disliked because it does not explain  the difference between  hi-voltage/low-amperage and low-voltage/high-amperage very well. Use the pipe metaphor and high-voltage looks like a placid river (big pipe, little flow) and low voltage looks like a fire hose (small pipe, lots of flow). I assure you, a lightning bolt is anything but a placid river. Nikola Tesla kicked Edison’s ass because Edison was fiddling around with 12v Christmas-tree lights while Tesla was lighting off discharges of millions of volts, just to see what happened.

If you want a metaphor that we can all relate to, try this one:
Voltage=engine displacement, amperage=carb size
A 50 volt/300 amp system is a 50cc engine with a huge carburetor, like one off a big-block V8. Hauls butt, but it keeps overheating and you can’t get any more top end out of it. You could put two Holleys (600amps, two motors) on there if you wanted, but gosh, the thing already pulls stumps, what are you looking for?

A 300 volt/50 amp system is a 300cc engine with a teeny-weeny carburetor, the one left over after you decided it was a good idea to put  a 4-barrel Holley on your fiddy. Goes fast, but you really wish it had more punch and it can’t pull fourth and fifth anymore. You could punch it out (600volts), but gosh, it is pretty fast already and maybe if you muck around with gearing it will run right.

That makes things a bit clearer, don’t it? Keep in mind, it is just a metaphor and like all of them, flawed, but it is why I look at the KTM Freeride spec sheet and say “Holy Crap, 300v!”

They bumped-up the displacement and I am sure you guys all know what that means.

The good, the bad, the ugly:
Before I can start digging into batteries there are a couple of basic vehicle dynamics things we should look at. OK, so rather than just looking at motors, lets look at the whole system for a moment. On any EV there are three main components: batteries, controller and motor.

The batts act as the fuel tank and the engine at the same time. They are the source of both the energy (how far you can go) and power (does that thing do wheelies?). The bad news is that batteries don’t store a whole lot of energy, the good news is that they can make pretty good power.

The controller regulates power to the motor. You can simply hook up a motor directly to a battery, but better stand back while you do it because it is going to go “twack!” The controller sorta does what a carb or fuel injection system does on an ICE, but it is a weak analogy. Suffice to say that the name, for once, is an accurate descriptor; controllers give you control, it is directly connected to the throttle/twistgrip.

The motor acts as the transmission; it is the interface between electrical power and mechanical power. Electrical power is not mechanical power (the stuff motorcyclists are interested in) until it is converted to torque and revs. Motors make this conversion quite well, this is why multi-gear transmissions are not a necessity on an EV, a motor is quite capable of making torque in a wide range of revs. You could put a multi-gear transmission on a motor, but it acts more like a hi/low range more than the multi-gear transmissions we are used to in ICE vehicles.

Math, it’s gonna get ugly:
We are going to have to do some math here, but stay with me, I’ll boil it down to something understandable.

Gas and energy:
Gasoline is a great medium of energy storage. One gallon of gas weighs about six pounds and can be calculated as having ~33kwh (kilowatt hours) of energy. This means, if combustion was 100% efficient, one gallon of gas could produce about 44hp for one hour (33kwh/0.746=horsepower hours). Combustion is nowhere near 100 percent efficient; in gas engines you see efficiency ranging from about 12 percent (two-strokes) to 25 percent (a really good 4-stroke). At 25 percent a gallon of gas (6lbs) can make 11hp for one hour, convert it back to kilowatts (11hp-per-hour*0.746=8.25kwh), and there is your energy-density (8.25kw/6lbs). Now toss lbs for kgs (6lbs/2.2=2.7kg). (8.25kwh/2.7kg=3kwh-per-kilogram), and  you have the useful energy content after combustion. Doing the numbers like that is a little wacky, 3kwh/kg is way too high, it would mean that a motorcycle running on flat ground  at 35mph would get 100mpg+, possible, but only for little engines. The reason being that big engines only make good efficiency numbers under high loads. Asking a 50hp engine to only make 3-5hp involves a lot of waste, the efficiency goes back down to ~10 percent  and realistically we need to add the weight of the engine in there somewhere. The real number is somewhere between 1.5kwh/kg and 3kwh/kg. If your eyes are glazing over from all the numbers I am tossing out, don’t worry about it, all I am trying to do is show:

1. It is difficult to figure out exactly the useful energy content of gasoline.

2. It is easy to figure out the energy content of batteries (more on this later).

3. It is difficult to rationally compare energy content of batteries to the energy content of gasoline.
Looking at a battery and asking ‘How many gallons of gas is that?’ requires an answer that will have to make a number of assumptions. You can ballpark it (it seems like ~8-10kwh of batt = 1gallon of gas), but there is so much fudge-factor involved I am loath to trust the numbers.

Gas and power:
Gasoline has excellent  power density. If you are willing to toss efficiency out the window, the limits on how much gas you can pour into an engine are, to make a huge understatement, high (think jet turbines, fuel is used at a rate of pounds-per-second). T
he limit is the size of the combustion chamber, pour more fuel into a small engine, it does not make any more power, just blows fuel out the exhaust (running rich). Something like the BMW S1000RR is making impressive power density (good power-to-weight), but it’s only impressive because it’s a one-liter engine, if it was two liters, meh. We look at power density in gas bikes as an overall spec, power-to-weight, of the whole motorcycle. I am only putting this in because, with batteries, we look at the power density of JUST the batts sometimes and it’s difficult to compare that with gas. At least until the whole bike is built, then power-to-weight is something we can compare directly. Enough, lets look at batts.  

Batteries and energy, this is depressing:
Batteries use a couple of specs to describe energy and power. All are rated by amp-hours; how many amps the cell can deliver for one hour. If you have a 10ah battery in front of you and you put a load on it, it will crank out 10amps for one hour. The cell also has a voltage rating, it is a range of voltage, but cells are called out at a nominal voltage, which makes life easier. So, lets call our 10ah battery a 12v nominal. We can multiply voltage by amperage and figure out that the battery has 120 watt hours (it will make 120watts for one hour, 0.12kilowatt hours) of stored energy, divide kWh by mass (in this example, let’s say 1kg or 2.2lbs) and you come up with 120 w-per-kg (a far cry from 3kWh-per-kg), a measurement of stored energy by weight. It will make 120 watts for one hour. It will also make 240 watts for half an hour if the power rating is good enough. Keep going down that road and you can also see the battery make 7200 watts for one second before it is dead. This brings us right to the other spec that we have to know, how much power the battery can make.

Batteries and power, hmm, not so bad:
Batteries are rated a little like motors as far as power goes. There is a continuous rate, and a peak rate. It is called the “C” rating. A 1C continuous rating a battery can, in fact, discharge its amp-hour rating in one hour without bursting into flames. Using our 12v/10ah batt from above, a 1C continuous rating  means that it discharges completely in one hour without heat problems. If the battery is a 2C rating, that means it can discharge its amp-hour rating twice as fast (twice the power!), in our example you can pull 20 amps out (2C times 10ah), but since there isn’t any more energy available, you will only see that 20 amps for half an hour.

That takes care of continuous power, but what about peak? Most batteries can momentarily deliver power at a much greater rate than their continuous rate. It is rated the same way, by a multiple of its amp-hour rating, C. The company manufacturing the battery will say “1C continuous rate, with a 10C peak of 60 seconds,” the time stipulation is what keeps the battery from overheating. The more powerful batteries will actually specify a number of peaks, with different time stipulations on each: “1C continuous, 10C for 60sec, 30C for 30sec, 50C for 1sec.” With our 12v/10ah/1kg batt, a “50C 1sec” rating would allow a burst of 500a. 12v*500a=6kw, 6kw/0.746=8 horsepower, which is damn good for something that weighs 2.2lbs (1kg)! Power-to-weight is something batteries can do, but, as a disclaimer, very few batteries have a 50C discharge rate and a battery that runs flat in 1.1 seconds isn’t all that useful.

Power-density(specific power) is measured in watts-per-kilogram (w/kg), our example cell would be 120w/kg at its continuous rate(1C), 6000w/kg at that crazy one second rate(50C).

What a motorhead looks for is the 3-5 second peak power, that is the number that tells us if the battery can boogie. I’ll go into why that’s the number we care about right after a little more about batts.

Chemistry, or why we shoulda stayed in school:
Batteries are using chemistry to fiddle around with electricity. It would be much easier if there was just a magic box that we stuffed electrons into, after all the little guys are nearly massless objects, but no, the only way, for right now, to store electrons is through torturous chemical backflips and trickery. The various industries that use batteries are creating the kind of demand that has battery companies fighting tooth-and-nail to come up with better stuff, the innovation over the last ten years has been astounding. I am not going to give a complete run-down on every battery chemistry out there, there is so much variation in construction techniques and manufacturers that it wouldn’t be helpful. I can do a general overview.

Lead-acid, the good old days:
The only good thing about lead-acid batteries is their power-density. The energy density is piss-poor. A good lead-acid batt can easily deliver current at a 50C rate. The energy content is somewhere around 20-30w/kg, which is terrible. They make good ICE starter batteries, the newer absorbed glass matt cells are much better than wet cell batts. If you still have a wet cell in your gas bike, do yourself a favor and drop a sealed AGM in it, they last a lot longer and have better cranking amps.

Don’t build electric motorcycles with lead-acid cells, please!

Nickel-cadmium/nickel-metal-hydride, baby-steps:
Hmm, a little better than lead-acid. Fair power-density, you can see 10-20C rates, not as good as lead, but still pretty good. Better energy density than lead, 30-80w/kg. Huge problems with memory  and heat. Very careful battery management systems required, and even then cell cycle life (the number of charge/disgarges a cell is good for) isn’t all that good. Remember all those ni-cad packs in battery powered drills? They work OK, but nothing great. Fairly cheap, despite being made of nickel.

Don’t build motorcycles with ni-cads/nimh, maybe 5-6 years ago, but not now. 

Lithium-ion/lithium-polymer, the good stuff, for now:
This is what all the ‘modern’ electrics are using. Within this basic category are about 20-30 or more variations.

They all share similar specs, poor to damn-good power density, 2C-50C rates. All have good energy density, ranging 100w/kg to 180w/kg. Between four and ten times better than lead-acid. Common chemistries are: lithium manganese oxide, lithium cobalt oxide, lithium iron phosphate, lithium vanadium and lithium titanite. Tackling the pros and cons of every single li-ion chemistry is like drinking from a fire hose. Generally, the ones with good power-density have lower energy-density and the ones with really good energy-density have crappy power-density. There isn’t a single chemistry with both, yet. They are all much better than anything else. The biggest concern for vehicle application right now is safety. The power dense cells, the ones we want, have an unfortunate tendency to occasionally burst into flames. Think Dell laptops. Most of the innovation in the last five years has been towards making it safe to look away after you plug a cell in to charge. It is sorta OK to build motorcycles out of them, but you better have your battery management down-pat or the cells will fail.

Better chemistry for better riding:
If you believe the press releases, there is a nano-turbo-transhypertitanate battery right around the corner. Truth is that energy storage is just plain difficult. Optimistically, we could see battery energy-density double in the next ten years. It is definitely not going to happen any faster than that and, pessimistically, it could take 50 years. The power density is already good, not great, but not the huge technical challenge that increasing the energy-density presents.

Back to Power, WTF is happening when you pull the trigger?
So knowing a bit more about batteries and
motors, lets take another look at one of these bikes. We will pick on the KTM, they are big boys and can take the abuse. Spec on the battery they use is 300v, 2.5kwh. Continuous power on the motor is 8kw, peak is 22kw. Those are nearly all the numbers you need to know to figure out quite a bit about what the bike can do. Hmm, need top speed, 42mph. I’d like to know how quickly it gets from 0-42mph, for argument’s sake lets say it’s three seconds.

Remember when I said we want to know what the 3-5 second power rate is on a battery? Mostly it is so that we know that the batts will be powerful enough to force the motor to get with it. We only care about the three second rate because the bike only goes 42mph, thats all the time it takes to accelerate to that speed. A lot of folks look at specs like this and assume that 22kw (peak power)/2.5kwh (energy-capacity) = 8.8 minutes run time. That would be true, but only if you were accelerating at full load the whole 8.8 minutes. 8.8 min*60=528 seconds. 528 sec/3sec=176 full power launches. That is enough to go do some backyard racing. It ain’t enough to go run a 50-mile loop in the woods with your 4-stroke buddies. 20 mile loop? Probably, it depends on the elevation change. 100-mile poker runs are out of the question.

42mph is slow. Can they gear it taller? Yeah, but remember that whole continuous power thing? When you gear-up a bike you increase the amount of power it can use, going faster uses energy at a faster rate. 30mph is the point at which aerodynamic losses start kicking in, at 60mph you use four to five times the power that you do at 30mph. It runs down quick and, realistically, it can’t pull that much more gearing. To go faster you need to make the bike more powerful.

The higher voltage is better, but it has a restriction plate on the “carb.” Its 22,000w/300v=73amps. Pathetic, I can make 73amps with my little finger. Double that amperage, you can pull all the gearing you want.

Weights and Measures:
To conclude, sorry about all of the KW=HP=MPH=KPH=WH=KWH=mumble-mumble.
I am American, and as such I think in mph, mpg, and all the rest of the horrid imperial measurement system.

I run a CNC, so I end up switching from fractions to decimal-inches to metric all the time. The most confusing part about most of this is the number of standards there are, and having to switch back and forth all the time. If you followed all the number crunching, well done, give yourself a pat on the back.

If you would like to learn more about electricity theory in general, go pick up a copy of this book. I don’t think there are any other electricity manuals endorsed by Dave Barry.

– Brett Gober

  • http://electrovelocity.com/ Ben @ EV

    Thanks Brett, I’ve bookmarked this as I think I’m going to need to read it 5 times before I really get a grasp on it.

  • Sean Smith

    I just read this whole dealio while listening to Technologic by Daft Punk.

    Good stuff.

    So, since batteries basically suck ass, is there any other way to get electricity on a motorcycle? We’ve got an ‘engine’ and a ‘trans’ in the form of a battery and motor, but it seems that all the juice we’ve got to run off of is what’s already in the float bowl.

    Is there any way to add a gas tank?

    • steve781

      You can cram a lot of electrons into a capacitor, and you can get them out in a real hurry as well. Unfortunately the easy with which electrons leave a capacitor is also their biggest problem. You don’t want to be around one, or sitting on a bike carrying a big capacitor when something goes wrong.

  • Brett Vegas

    Good, You guys are asking the right questions now. Heh, You could pull power off them overhead lines, like them trains do. Pretty sure there is plenty of juice up there.

    You could do a little screaming engine, and a little screaming batt, and big honking motor.

    Why would ya wants to build one O’them?
    Might not get good mileage, if you are some kinda eco-freek, you would be bummed out. I don’t care about mileage.


    Sorry for speaking pure redneck, but it is the only way to pound this shit through thick skulls.

  • Brett Vegas

    You want to see a trans-hyperdyn-nano-tech battery that makes a gas engine look stupid?

    Here you go:

    Don’t need to carry gasoline with one of those, makes a rednecks mouth water just thinking about it.

    The eggheads are still trying to get it to work.

  • Jay Allen

    This post absoulutely rocks! Thanks for the big brained yet down to earth info. I spend my weekdays around 5 – 600 HP VFDs and start to forget all that’s going on; It’s good to hear the theory from time to time.

    Jay Allen
    SW MO

  • Brett Vegas


    We are speaking about theoretical physics.
    I am pointing out the similarity between ‘electron-theory’ and ‘combustion-theory’
    I am not a theoretical physicist.
    I am a quantum mechanic.
    I am the guy that the physicist goes to, when he has a theory and he wants to ‘try it out’.
    I say ‘hmm, dunno, could be a left-hand thread, or a right-hand thread, I gots to put a wrench on it to be sure’

    Heh, you guys want to see the damn-est big motor you ever seen?

    It is two motors, a little one and a big one, they are going to fire it up, then stall it, just to see what happens. Because thats what we do.


  • Brett Vegas

    If volts*coulombs/time=power
    And bore*stroke/time=power

    Which one is bore and which one is stroke?
    Dunno, have to put a wrench on it.

  • Richard Gray

    As I pointed out in an comment to part one of your article you have the analogy wrong. Voltage is analogous to pressure and current to flow rate. This analogy is not merely a verbal metaphor but extends to the complete mathematical analysis of both situations (e.g. the equations for Ohms law also hold true for gas flow through pipes).


  • Brett Vegas


    Good, cool.
    But I am not sure which is which on volts and coulombs. I mean, you HAVE to take time out of the equation to get a good look at displacement.

    I mean, I know that volts=displacement/amps=carb size is a bad analogy. It is wrong.

    I guess I am tring to figure out which is which volts and coulombs. I got volt meter, I can measure it without time. Can’t measure colombs, got no colomb-meter. WTF a colomb.
    Does it matter which is which?

    Thanks Richard, a very very good question/correction.


  • Richard Gray

    Turn the multimeter to the current setting. An Amp is a Coulomb per second (i.e. a flow rate).


  • Brett Vegas


    Uh, yea I did screw up the pressure/flow rate thing. It is the volts/coulombs that is totaly wacking my brain.

    Sorry about that! Crap! I make mess of it sometimes, tring to equate combustion to electrons is mmm, tricky.

    I’ll bone up on coulombs, but I have never seen a good definition.


  • Brett Vegas


    So Amps is volts with time? Naw that can’t bee, its da couloms. Theres an ampmeter, but I want to measure culombs.
    ‘Cause it don’t matter which is which? Nwa, its…
    Realy whish the eggheads would give me a culomb meter so I could figure out how to tune these stupid motors. Fucking things just don’t run right.

    Can’t make any power outta dem.

    I mean, I gotta know wich is which, fucking volts or culombs to get the damn thing to make any power.
    O well, maybee I’ll just go for a ride.

    Perfect Richard, well done.


  • Brett Vegas


    We are going to have to update a few things?


    Hey richard what do you think, is that a hard question to ask?

    Bouncing things around here folks feel free to jump in, ’cause I dunno, I gots to put a wrench on it.

    And much thanks to wes, stefano, and richard.


  • http://www.emotorules.com Harry Mallin

    I’m going to name my first-born “Brett Vegas.” My question relates to the “wires overhead” comment. If you knew that a lightning bolt was going to strike a certain point at a certain time, could you rig a sort of “hook and wire” set-up to power your bike? And how many jigawatts would that likely produce?

  • Brett Vegas


    No. The voltage is realy,realy,realy dangerous.
    Trains are on rails, or floating on magnetic fields, you can pick up power by induction off the rails, but it has to be very controlled in order to not be dangerous. Personal vehicles have rubber tires, running off the over head lines would be damn hard to pull off, theirs no ground. Hard to explain. You need to know a little more theory, and it is a hairball.

    Don’t worry guys,

    3.controllers:how the hell do those things work?
    4. Why the eggheads have it wrong, and rednecks know what they are talking about.

    Sigh, I am pretty good at theory, but my typing rate is abysmal, And if I shut off spellcheck, you don’t even want to know how fucking dyslexic I am. Takes me awhile to get stuff out of my head,
    but the theory is clear as glass. Also I am fucking around on the internet at work, and there is a hungry CNC to feed.

    Fuck, I would love to chat with Ken ahmdall(sp?)
    Mans book is brilliant, and inspired alot of my thinking.

    This is fun.

    Brett Vegas Gober.

  • Mike

    Brett: first, many thanks for another great down-and-dirty article on this tech.

    I think you’re getting a bit tangled up with Richard on the units front. As he notes, you can draw close parallels between water flow and electron flow, but you will find that you run into problems with peoples’ understanding of the way water flow works too; particularly the role of pressure.

    Using the water analogy, a coulomb is a unit of volume, e.g. a gallon (damn you and your imperial units). Thus, amperage (flow rate) is volume per unit time (e.g. gallons per second, coulombs per second).

    Power is an instantaneous measurement, it has no time component. The simplest expression for power input to a circuit is just V*I.

    Energy has the time component (how much power for how long, or the ‘area under the curve’). One expression for energy input to a circuit is V*I*t.

    Going back to coulombs, or charge; that’s I*t, or Q, so you can see people talking about V*Q as another way of describing energy input. This is particularly relevant to electric vehicles because as a consumer you want to know how much energy is left in your battery, and the way that this is typically done is with a coulomb counter.

    You ducked the chemistry issues, so I’m mostly going to duck the fact that battery capacity is often better measured in terms of charge than it is energy. It is worth noting that not all of the lithium chemistries have the thermal runaway issues that plague lithium/cobalt cells (“venting with flames” as it’s called), but of course those are the ones with the best charge density… the universe sucks sometimes.

    (Confusing the issue also is that “power” means different things in different contexts; it’s also used to describe the output from the motor. I prefer to look at torque, though, since that directly translates to acceleration. Power output is, after all, just torque * speed.)

    I would definitely avoid trying to get into comparing electrical and ICE power system units, as they are massively different (and people have weird ideas about how aspects of ICE systems affect their performance that are better not dragging into the picture).

  • Brett Vegas


    Very well written, good questions.
    v*I=power, but I=amps, and amps=coulombs/time.
    You can’t go thinking power has no time component, it has to, or it ain’t power, that was my mistake last article. Energy has no time component, it is just sitting there, getting no ‘work’ done. you measure energy by power/time, how much ‘work-per-hour’, fucking weird, I might have that wrong… hmm.

    Very easy to get tangled in metaphor.
    We need to tune up the Mighty morphing metaphor, it aint right.

    Try this:
    coulombs(fucking volts, call it coulombs for now, the eggheads have it wrong)=bore
    toss time in there, somewhere=power.
    That is still fucked up, not sure where, I’ll grind it.

    That, my friends will blow anybody head apart, don’t think about it too much. It is ok to only have an ampmeter and a voltmeater in the toolbox, we don’t need a coulomb-meater.

    volts=charge without time.
    amps=charge with time.

    You can chase definition around and around, sooner or later you MUST define terms.
    Think of an amp as a volt you pretty much HAVE to measure with time. The Coulomb is the kinda volt you CAN measure with time, can’t measure the volt/time.
    Heisenberg’s uncertainty princeable, you can tell where they are, or how fast they be going, but not both at the same time.

    The eggheads don’t know if it is a left-hand thread or a right hand thread, I dunno either, I check polarity by hooking that bitch up, and seeing if it flings me backward at 40MPH.
    polarity, It does not matter.

    They describe lightening bolts by stroke and bore(sorta), The damn things sure look like a fucking pistons to me.

    They go bore,bore,bore,bore,stroke,bore,stroke, ana bore, stroke-stroke,bore,bore,bore,bore,
    bore,stroke,bore,bore,stroke,Clap, and a grumble. The clap and a grumble is the sound of the hammer hitting the anvil, every time it does a stroke it reverses polarity. The sound is the least powerful part, by alot of orders of magnitude(or thereabouts). Baddass displacement, real long stroke, and damn big bore, runs for bit, and all the gas is gone. The cloud is the gas tank. It does not take very long. Very high power density.

    Pretty damn elegant if you ask me.

    Kennith! Where are you Kennith!

    This is a good ol’ time,


  • Brett Vegas

    To state it a bit more elegantly,


    You look at a batt by looking at voltage, to see if it’s charged, you also need to put a load on it(time) to see if it can deliver. It can ‘look’ charged if it is plumb wore out, voltage recovers.
    You gotta put a load on it(see amps being drawn,do work), to really know if there is anything in there.

    That make any more sense?


    • Mike


      Sorry I couldn’t keep up the conversation, the man demands his share.

      You said:

      > power=charge*(charge/time)

      That’s a big “no”, because what you just wrote is “power equals charge squared divided by time”.

      Also, before that you wrote:

      > You can’t go thinking power has no time component,
      > it has to, or it ain’t power, that was my mistake last article.
      > Energy has no time component, it is just sitting there, getting
      > no ‘work’ done. you measure energy by power/time, how
      > much ‘work-per-hour’, fucking weird, I might have that
      > wrong… hmm.

      You right that you have it backwards here too, though perhaps I should be clearer about what “time component” means.

      Here is power: V * I

      Here is energy: V * I * t

      ‘t’ is the “time component”.

      Another way of thinking about it that might help is that power is a “right now” thing, like speed. Perhaps the confusion comes because many instantaneous measurements are expressed as “quantity per unit time” (like speed in miles per hour).

      Units are a bitch. All I can offer is that at some point it all falls into place, and (particularly if you can make yourself embrace the SI units) suddenly everything seems much simpler.

      For anyone still following – CW’s comment has most of the nitty gritty in one place. Brett’s done a great job of tying everything into the electric moto story, with one basic hole – he still hasn’t told me which one I ought to be buying. Dammit.

  • Brett Vegas


    to put it in pure gasser terms,

    That bmw1000rr is 1000v*200a=200kw
    The little electric is 50v*400a=20kw
    The electric pulls like a chevy 327 small block.
    I liked the table cloth trick they did, if the little electric had a touch more voltage(say~100,bore it out-40kw) I am pretty sure I could do the same trick, same table.
    I shure like stacking holley 4-barrels, I got ‘better’ carberation than the best beemer can make.
    More power-density/displacement, mmm good.


  • Brett Vegas


    I am guessing I am taking the uncomfortable stance

    that a coulomb is a joule per volt
    and vice versa
    Heck toss definition of a joule in there(1j=1w/s)
    and 1volt=1coulomb
    Why does a volt have two names?
    This stuff would be alot easier to understand if we called power=volts*amps, and amps=volts per second.

    Tricky. and I am probably doing something wrong.

    Thats why I keep mixing up ‘pressure’ and ‘flow rate’. we keep getting told volts are different than amps.

    I wonder if ‘pressure’, and ‘flow rate’ switch back and forth? It would be very difficult to measure. Or you could measure it in Hz?

  • Brett Vegas


    I think I see the failure to communicate.

    You think of voltage as a ‘push’
    I am thinking of voltage as a ‘pull’


    That is a hard one to ‘get’.
    I never thought of voltage as a ‘push’



  • CW


    Excellent article. Thinking of voltage as “pushing” will most likely make it easier to understand. I’ll try to take a stab at it:

    A Coulomb is defined as the charge of 6.241 × 1018 electrons.

    An Amp is 1 coulomb/second, so think of current as a rate of charge or electron flow through a circuit

    A Voltage is the amount of potential or “electromotive force” “pushing” on electrons in the circuit.

    So given Ohm’s law, V=I*R, if you raise the voltage, the current increases proportionally for a constant resistance; that is, if you “push” the electrons harder (raise the voltage), the flow rate of charge/electrons will increase to maintain equality.

    Now regarding energy and power:

    Energy is measured by Joules which is 1 Coulomb * 1 Volt. In other words, a joule is the energy created by moving 1 coulomb of charge (electrons) with a “force” of 1 volt. You can increase the energy of a battery by increasing the voltage (i.e. force pushing on the charge) or increase the amount of charge (i.e. amount of coulombs or Ah). There is no time unit here

    Power is measured in Watts which is = 1 Amp* 1 V = 1 Coulomb * 1 Volt / second = 1 Joule/second. In other words, the power created by moving 1 coulomb of charge (electons) in 1 second with a “force” of 1 volt. Since power is the rate that energy or work is performed, you can increase the power of a battery by increasing voltage (i.e. the force pushing on the charge) or the flow rate of charge (current).

    Hopefully this makes sense and doesn’t muddle things up any more.

  • http://bubblevisor.blogspot.com/ lenny

    after reading the post i started reading the comments..

    sf is now

  • Brett Vegas


    Heck we can’t muddle it up any more than it already is, won’t know until ya put a wrench on it.

    I sorta think thats why they are build those big supercolliders, is to try to decide if it is a ‘push’, or a ‘pull’. Or just to see THAT much energy happen.

    In practice it does not matter. In theory I think it matters to know if the damn electrons are running away from something, or bookin’ home to get a beer/hang out with a chick.

    If it is a ‘pull’, it makes more sense to me.

    I think of voltage as a cable. with various amounts of ‘tension’ on it. low voltage sags, high voltage is ‘tight’.
    Conventional thinks of voltage as a liquid, with various amounts of pressure. What the hell is a liquid under low pressure? I’d say my fluid dynamics is rusty, if there was anything there to rust.

    The fucking confusing part is we are both right, in practice. I am not sure what current theory states. I’ll go look it up.

    I’ll try to grasp voltage as a push, but it does not match my observations. Could be seeing it wrong. dunno.

    Nice find on a hard number for coulombs, what the hell is that? Is that a constant multiplied by the number of frigging electrons? Wicked cool, no idea what that means. So 6353.338?

    The weird thing is you can make one volt with one joule-per-coulomb, or make one coulomb with one joule-per-volt.
    The joule is a unit of ‘energy’. It is the only part of that daisy-chain that has a time factor.
    From that I would deduce that deciding if it is a ‘push’, or a ‘pull’ is pretty much up to the operator.

    When I look at lightening that sure looks like low-frequency high-voltage AC. There is nobody modulating the frequency. Ground is ‘pulling’, the cloud is -, mother earth is +. (conventional notation). Electron flow is changing, it bounces up and down, ‘current’ is always flowing to ground, it never goes the wrong way.
    The electrons are ‘confused’ by the current, they go the wrong way(back up to the frigging cloud). Current drops off, the electrons say ‘Oh THAT way is ground?’ and go to ground. It switches polarity several times.


  • Sean Smith

    After reading the comments, I now know what it’s like for non-motorhead people to talk to me.

    It feels like this is the signal that electrics are here to stay. It’s like someone took a conversation between me and my boss talking rod-ratio, and piston acceleration and replaced all the tech stuff with shit you’d here in the pits at the tatooine pod racer GP.

  • CW

    I see how you can think of it pulling. Either way of looking at it is valid, but when using “flow” analogies I think it easier to think of it as “push”.

    Don’t think of voltage as the actual “liquid”, voltage would just be the pressure pushing (or pulling) on a the “liquid”. The “liquid” would be coulombs of charge or electrons, and the flow rate of the electrons would be current.

    The formatting on my last post was messed up: Coulombs are defined by a constant number of electrons – 6.241×10^18. which is the quotient of Avagadro’s constant (remember the mole guy from chemistry class?) and Faraday’s constant.

  • Eddie Smith

    Awesome. Does this mean I can finally walk into the KTM dealership and ask them to install a new powerband without being a noob?

    No more need for mechanical engineers in powertrain; I made a “C” in circuit theory. Guess I better get good at chassis design.

  • Brett Vegas

    I’m Up,

    How you boys doing?

    Don’t stay with it too long, we are lifting heavy shit here. I HAD to go home and drink a 6-pack, sleep on it. If I had a chick she woulda been disappointed last night.


    Shit man, electronics IS mechanical engineering, it is just that they are following a real weird rulebook. I can’t do a circuit board, but I can tell the EE what I want. Uh, yeah, we have to tell KTM to get with it. I’m not totaly sure what I want, mmm, hell start with 150v/200a/AC/275-325lbs. Be like my POS DR-z, sorta. That is something I would like to pull the trigger on. Pretty much why i am here, fix the damn tuning.


    Yeah, I know, it is fucked up.
    It is pull. Always. I have put a wrench on it several times. Got a breaker-bar. Slipped a 6-foot pipe over the handle of the braker-bar. slipped a 12-foot pipe over the six-foot pipe.
    The theads were not right-hand. The threads are left-hand. Voltage always pulls, checked it several times. That is pretty much the issue at hand. Not totaly sure, but, shit, you want me to slip a fucking 24-foot pipe over the damn 12-footer? Damn thing is a left-ty/tighty all day long, and if it wasn’t tight before shure as hell is after me checking it like that.

    Huh, no shit. I would need some scoolin to ‘get’ what that number means.{6.241*10 to the 18th power}? If there is a hard number on it i can crunch it, might take me awhile. Know a bit about farady, never even heard of avagadro. I liked chem, but slept through most of it. Know what a mole is, but damn rusty. Good number to keep tabs on, have to get help from some eggheads.

    Sean, yeah, fun huh?
    read Feynman, total redneck physics to the Max. ‘seven easy pieces’ has some funny shit in it.

    We be having a good ol time.
    Crap, I hope Richard isn’t all butt-hurt over this shit. Richard, I need you around, I don’t know a bunch of rules. Got it?
    I won’t stomp on you, but DNFWM. We are all here to have fun. K?


  • Brett Vegas

    Here check this one out:

    Mighty Morphing Metaphore II:

    You ever build wheels? Built a couple, like umm I dunno, 500-1000? Wheels are bitchin’. MTB wheels are super-bitchin, right? All you red-neck MTBers raise your hands, yup, wheels are cool.

    So, wheels are a round thing under tension.
    A good wheel is a round thing under more tension.
    A good hand-built MTB wheel lasts 3-5 years.
    A loose-built MTB wheel(stock, machine-built) lasts 1-3 years.
    The key to building good hand-built MTB wheels is getting the tension even, both in ‘trueness’ and in ’roundness’(any MTB mechanics know exactly what I am talking about here, but motorcycleist might not)

    How many spokes does a wheel have?
    Well, 72,48,36,32,28,24,18,umm some of the roadies go lower than that, but that is about all the spoke patterns I have messed around with.

    There are several lacing patterns. Three-cross and radial are the most common. There are wacky crows-foot patterns, 4-cross, 2-cross, 1-cross, whatever, don’t matter, just as long as you know that there are alot of ways of skinning that cat.

    Electricity is damn wheel, the load is on the axle, as the wheel rotates the spokes ‘load’ and ‘unload’. I can’t visualize electricity, but I can visualize a wheel.

    If you build a wheel with too much tension, you either round off the flats on the nipples with the spoke wrench, or one of the spokes breaks.
    Because the spoke isn’t very thick, 1.6mm-2mm.
    You have to have a ‘feel’ for the torque, in order to build a wheel that is true and round.
    The only way to learn it is to build alot of wheels, I didn’t get any good at it untill I built 20-30.

    Fun huh?

    Fire off any questions. I dunno if I am going to light up the HAAS today, might go fire up the K100 an take the day off, I think I deserve it.


  • Brett Vegas

    You boys ever heard:

    “Well shit, looks like you are trying to push up a wet rope to me”

    Pure unadulterated redneck perspective of electricity.


  • Richard Gray

    I’m still here and not at all butt-hurt. Looking forward to your next post.


  • Brett Vegas

    Crap, I forgot to add to the MMMII,
    It is better to look at it like a batt is a wheel, to simplify things. The fully ‘tensioned’ wheel is a charged batt, a detensiond wheel is ‘discharged’.
    Load is amps, tension is volts.

    We MUST use amps and volts, or everybody gets confused. Thats the rules. No more fucking around.
    Cops are good, they keep you from crossing the double-yellow line.

    ‘don’t cross the streams!’
    ‘well, OK, cross the streams, but I’m not sure what will happen…’

    Hope that helps. Be easier to do this if I could edit posts. Could wiki this shit, but wicki is a load of garbage and good. And HFL, I like wes.




  • Brett Vegas

    Hi, Richard.

    Good, Good.

    What are your thoughts on MMMII?

    Am I getting somewhere?



  • Brett Vegas

    Hi, Mike.

    Sorry, had to take some time off.

    Ok, now get ready for some deap-troated guffaws.

    Gadzooks!(monikel falls out of left-eye),(shines spats) Are those coo-coo-clock builders making
    Why That is ingenious!
    A penny-farthing!
    What will they think of next!
    They are just on the verge of Juiles Vern!
    (polishs spats,straitens vest, puts on top-hat)

    Wheres the cranks? Or do you just ride that thing downhills? Kick with your feet?

    I have to say I wouldn’t have gotten where am with out help from ely schless. He is the dumb red neck that told me watts gots no time component. I gots about a million shares of toilet paper(EM-electricmoto), I thinks elys got 15mil. He would probly pool and split 50/50 with me. Thats cool.
    I don’t know who has the rest, never met any of them. Let them get fucking stinking rich for all I care.
    top-hat,vest,spats, tailcoat and all. Don’t care.

    Mike, we can go into that other stuff later. I’m gonna chill out. Sorry about that. I’ll clue ya though,ac=pullpull. but you know that, so chill.

    Did you guys see the piece of shit who ever is running EM built? The took an old can-o-snails and stuffs a 50cc in it, kept the 21in/18in wheels. I hate cannondales, the headtubes bust off all the time, and they ride harsh. I like steel bicycles.
    What a heavy turd. Dumbshits.

    Thanks guys, I’m going out for a smoke.


  • Brett Vegas


    Bet there is some MTBers with some o’ those GOLD VEGAS MTB FRAMES. i never made very many. Good bikes. Stout, with geometry for the 4-inch fork.
    lost money on every one, but the first scratch is on me.
    I wonder how much one of them things would go for on e-bay?

    That my friends is is very funny,
    I don’t know about you, but I am laughing my ass off over here.



  • Brett Vegas

    since we are just chilling out,
    sure like to pull the trigger on a 1volt/1000a
    unmodulated ac. clap and grumble.


  • Brett Vegas


    Ok, I think I found it.
    Page ten has a scrawl of the standard.

    4th line Xi-Yij-xj Othc

    Not sure what Othc is.

    Damn thing looks like a switch to me. or a butter-fly valve, like on my 4-barral holley
    Pivots on the Yij, left-hand thread, just like I told ya. Not sure what that thing does, but thats what I’m talking about. Might be a one-way revolving door, dunno. left-hand thread.
    Checked it twice.
    Don’t know where Othc goes when you flip the switch. Right side or left, but that kind of thing does not bother me.

    Heavy. Extreme caution required. Slow. Turn ahead. Construction ahead. Fines double. I am right on your ass on my k100, err 15 car leagues back. The lights ain’t on, but it is a square headlight in your rear-veiw-mirror, just like a caprice or a LTD ford. I don’t look like I am going anywhere in a hurry, just bubba crusing.


  • Brett Vegas

    Who Do I want to work with?

    Well shit. Do you put a clap and a grumble on any thing other than an H-D? I always thought buewll made some nice frames too, if you could deal with the lawn-mower engine. Hate harlys, leak oil all over the place. Dress like pirites.

    Plus, you know, I am American.
    Can’t state in SI alone, must use both.

    That sounds like a good ol time.


  • Brett Vegas

    pretty sure cerns using ‘election flow’ not ‘conventional’.
    But the scrawl says standard, so I would have to put a wrench on it, and try to turn it over.
    They are accelerating protons, that looks like the crank to me…

    ‘What do you pull, load.’


  • Brett Vegas

    to state it more elegantly



  • Brett Vegas



    Not sure about -=.


  • http://www.thisblueheaven.com Mark D.

    Just bought “There are no electrons”. Once I finish it, I’m going to re-read this post/thread, and hopefully understand more than 10% of it.

    Hans Camenzind’s “Much ado about almost nothing” is also a great read. http://www.amazon.com/Much-Ado-About-Almost-Nothing/dp/0615139957/ref=sr_1_2?ie=UTF8&s=books&qid=1271345895&sr=8-2

  • Stefano

    Thanks Brett for this great post.They say you learn something everyday, well this will do for today.

  • brettvegas

    Hi, stefano

    Long time no see. Good to hear from you.
    Thanks for the help, I am still learning.


  • Nick G

    I didn’t read all the comments, but 1 Amp = 1 Coulomb / Sec, and a Coulomb (sp?) = 1 mole of electrons.

  • brettvegas

    To give credit where it is due, for a start,

    Terry Pratchett(sp?), discworld. I filed off the serial numbers of
    ‘whats a quantum mechanic? dunno, spose it’s somebody that fixes the quantums, I guess’ and stole it from him.

    Neil Stevenson, everything he wrote.


    Steven Baxter, everything he writes(though I am still working on his latest)

    too many to list, sitting at the coffee shop, I will work on a full list monday.



  • brettvegas

    Nick G,

    Nice find. I am going to have to look at definitions of mole.

    Sigh, Credits must be acknowledged, just bummed if I have missed an author.

    Here you go:

    David Drake
    David Gemmel
    S.M. Stirling
    William C. Diets
    Dan Simmons
    David Weber
    Frank Herbert
    Robert A. Heinlein
    Keith Laumer
    Brenda Cooper
    Larry Nivin
    Christopher Anvil
    Alastar Reynolds
    Gary Zukav
    Alfred Bester
    Rudy Rucker
    John Varly
    Steve White
    John Ringo
    Lars Walker
    John Dalmas
    Fred Saberhagen
    Elisabeth Moon
    Koushun Takami
    William Gibson
    Simon R Green
    Rodger Zelazny
    Bruce Sterling
    John Steakley
    Poul Anderson
    Jerry Pournelle
    Eric Flint
    Keith Laumer
    Spider Robinson
    Steveb Brust
    Vernor Vinge
    Robert Ludlam
    Leo Frenkowski(sp?)
    Dave Grossman
    Samuel R. Delany
    Gordon Dickson
    Harry Harrison
    Richard A. Lupoff
    Neil Stevenson
    Ursula K. Laguine(sp?)
    Madiline l’engale(sp?)
    Harry Shear(sp?)
    Bill Marr(sp?)
    George Carlin
    Douglas R. Hofstadter(heavy!)
    Keith Giffen
    Robert Loren Fleming

    Woof, thats alot of names!
    I politely recommend not reading all of them at once. I am bummed I cannot remember the names I have forgotten.

  • http://jarvis8massey.bravejournal.com Perfect Puffy Nipples

    Puffies are teh funzorz. I often fantasize about grabbing some perfect puffy nipples and slap’em back and forth. I’m not sure why they turn me on so much, must be something to do with my teenage years and one of the first times I got a woman to let me touch her juggs, they popped out of her top and the nipples were all puffy, I was fascinated and couldnt take my eyes off of them. At the same time i had this rush of adrenaline and pure teenage hormone fire so strong that still to this day, whenever any of those memories are triggered I go instantly hard as a rock.