Sensei - Electric Ninja 250

[billmi]

I've still got a lot of things I want to do on it, but the Ninja 250 I've converted to electric power is up, running, stable and street legal. I've geared to a top speed of 55mph for in-town commute riding, and am seeing energy consumption that calculates out to 30 mile range on a charge without killing the batteries (80% discharge).







http://www.youtube.com/watch?v=Be2gsItziXI

[rockNroll]

Looks like a fun project How many volts?

[Nemesis]

Wow!

Good stuff! Love the tank cap light....like Ironman's chest thingy. Awesome.

[billmi]

Originally Posted by rockNroll

Looks like a fun project How many volts?

82 when fresh off the charger (which is in the hollowed out tank - the arc reactor lights up to show the charging status). It's powered by 24 Ah lithium iron phosphate batteries that are 3.3 volts nominal each.

[rockNroll]

Oh, cool! So this thing runs along and then just stops, rather than slowing as the batteries drain? Low voltage cutoff?

[Ninja Assassin]

You're obviously too smart for me to discuss things with...

[bdavison]

Im curious.
Are you running a brushless motor? If brushless, how big is the ESC? Is the throttle a pot installed in the handlebars? How many amps is it pulling through the ESC at full throttle, and how are you managing the heat dissipation from the FET's? A watercooled FET stack would be sweet.

How about some tech specs on what equipment you used. Im not really interested in building a electric bike, but I am curious as to what equipment you are using.

[spooph]

Originally Posted by bdavison

How about some tech specs on what equipment you used. Im not really interested in building a electric bike, but I am curious as to what equipment you are using.

I would like to build an electric bike, so I too am interested in what you're using... That looks like a massive Agni motor, no?

[Alex]

Very cool!

["A"]

FTW

[Momaru]

That looks like some fine work there, most impressed.

+1 to the list of persons interested in some tech specs, for curiosity's sake.

[ricochet08]

Love it! Gas tank reminds me of Iron Man!

[Yasko]

[billmi]

Here are the main components in the conversion:

Motor: Motoenergy/Mars ME0709, often referred to as an “Etek-RT” since it was designed as a higher torque replacement for the discontinued Briggs & Stratton Etek motor. It’s a permanent magnet motor rated for operation at 24-72 volts, delivering 8 HP continuous and 19 peak. It’s not as efficient as an Agni 95, but about 1/3 the price.

Controller – Kelly KD724001 – 72V output, 400 amps max, with variable regen. I have programmed it to limit battery draw to 200 amps. Presently I have regen turned off, but plan to implement it with a knob on the fairing to set the regen strength, and a relay to activate it when I hit the rear brake, so that regen kicks in before I’ve pressed the pedal down far enough to squeeze the brake pads. I don’t hold great hope for much range extension, since far more stopping force is available from the front wheel and motorcycles are light (less inertia to recover energy from). Regen has a reputation for not being that much of a serious performance boost (besides a selling feature) in light cars, and less in motorcycles. Running a controller rated for double the amperage I’m pulling into it has resulted in no noticeable heat generation (it’s mounted directly on steel sub-frame so what heat it is generating gets carried away).

The controller includes a pack level low-voltage cut-off feature, but I have it set only as a back up in case the BMS fails, since it does not provide cell level protection.

Throttle – Magura twist-grip 5 KOhm variable resistor throttle assembly (just slips on the bar in place of the stock throttle assembly.

Display – Cycle Analyst tracks speed/distance, battery voltage, amp draw from the battery pack and rider as well as diagnostic data (speed, odometer, efficiency, amp hours drawn from battery since last charge, etc.)

Batteries – 24 Calb 40Ah Lithium Iron Phosphate cells. 3.3V nominal. These cells are rated for peak discharge of 12C (480 amps) for .5 milliseconds, and continuous (30 seconds on, 30 seconds rest) discharge at 4C (160 amps). When I check my logs, I see 200 amp peak draw from the battery pack, but I never see it on the display, which means it’s only happening less than 0.4 seconds in duration (the refresh rate I’ve set on the display). I have yet to see anything higher than 120 amps pulled while accelerating and I draw a steady 30 amps (0.75C) at 30 mph.

BMS – I use a MiniBMS battery manager. Each cell has a circuit board that is tied to a managing board in the dash.

Lithium batteries are are damaged by over-charging, over-discharging or drawing power out or putting it in too fast (amperage – the C rates). Each cell’s MiniBMS board protects from over-discharging by creating a low-voltage cut-off alert if its cell’s voltage drops low enough to indicate it’s in danger of over-discharging. If there is an LVC alert, the BMS main board buzzes and lights a light in the dash (what used to be the oil warning light), it also reduces the throttle leaving enough power to pull off the road, but not enough to keep slamming the batteries. If I did not have cell-level low voltage protection, and for some reason one cell had a lower charge than the rest, it would be possible for the pack voltage to look OK, while that one cell ran down to the point it was damaged, shortening its life, or worse completely empty putting a reverse charge on it and destroying it completely.

The MiniBMS also protects against overcharging. The pack of batteries is charged as a whole, so just like with discharging (if I had 24 individual chargers this would be a non-issue) if one cell is not perfectly matched to the pack, it could be full before the others, and end up over-charged while the rest are still being charged. Each cell is monitored, and as it nears being full, a resistor shunts part of the charge across the cell, so it charges slower while the rest of the cells catch up. When any one cell gets full, the MiniBMS shuts off the charger. The shunting balances the pack, so that eventually each cell will be charged to the same level, finishing their charge at the same time.

Since the maximum lifespan can be achieved from the batteries discharging them 80% or less on each charge cycle, it’s important to track their charge level. Lead acid batteries drop in voltage steadily while they are used, so it’s easy to know how full they are by their voltage. Lithiums don’t behave the same way. LiFePO4 batteries drop slightly in the first 5% of use, then hold nearly steady (very minor drop) on out to about 80% discharge, then their voltage starts dropping, gentle at first, then like a cliff. Voltage is not a reliable way to track charge level, so I use the amp-hour count of the cycle analyst to see how much power I’ve drawn from them since charging.

[oroboros]

wish I was a genius... or, are I?

[slolane]

SWEET!!!

Well done

[JeffM]

Agreed, very well done.

Costs?

Jeff

[the big mike]

Very cool, what does it sound like if you drive it?

[spooph]

what's the torque on the Mars, and how does that compare to the Agni?

Am I right in assuming Agni is top-shelf, or is something I don't know.... It seemed like most teams were running Agni at the TTGPX..

[Scott1620]

Awesome

How much did those components cost minus the bike? Also where do you buy these components?

I have dabbled in electronics/lithium polymer batteries in my R/C electric airplanes, so I know of pretty much all those components (just smaller versions).

[Green Streak]

That is so cool! But how much does it weigh with all those batteries, etc.??

[bob706]

Very cool

[billmi]

Thanks for all the positive response.

JeffM, I haven’t kept an exact tally. It’s been pretty transparent, because I’ve done it a chunk at a time as I went and have funded almost all of it by selling old stuff out of the garage and attic on ebay and craigslist as I’ve gone (including the original carbs, engine, etc.). All told, I think it’s getting close to $4K.

Thebigmike – follow the link to the YouTube clip in the first post.

Spooh – I don’t know the torque stats offhand, but I’m pretty sure dyno curves are available for both on their respective manufacturer’s sites. Agnis are a good choice for racing because they are lighter in weight. For top shelf though, I think there will be more people running AC motors as time goes by. Chip Yates is running an AC behemoth in his bike that just set the 190mph top speed record for electric motorcycles. If/when you start looking at doing a project seriously, hop over to elmoto.net - there's a lot of info and discussion there as most of the folks have done or are doing builds.

Scott1620 – Parts were sourced from all over, some manufacturer direct, but most from dealers in the US.

GreenStreak – I haven’t weighed it, but it’s about the same. There are 80 pounds of batteries and the motor is 28 pounds – but I have lost the weight of an engine, transmission, cooling system, carbs, lead acid battery, etc.

[spooph]

Fantastic! Thanks for the info!

[CZroe]

I've seen electric Ninjettes before but yours looks much better. I love it!

[wayanlam]

that does look really good!

just needs a little custom faring done, to extended down and around the battery and you would barely notice the bike has been gutted and refitted with an electric motor.

a lot of research and knowledge to put this together so well. fine job indeed

[CThunder-blue]

Amazing! I love the Iron Man charge indicator.

[Tony B]

Yep dead cool, love it !
Around 25 years ago I drove an electric van whilst working for the Post office. I delivered parcels on the outskirts of town. It looked like a standard CF Bedford, but had a leccie motor and 1 and 1/2 tons of batteries under the cargo floor. It had a good range of 25 to 50 miles, entirely dependant on how fast you drove! If you just tootled gently around the side streets, 50 miles was easy, but if you floored it on the main road, you could almost watch the charge needle drop. I scared the life out of a sports car driver one day, we were on a twisty downwards hill, and I saw him look in his rearview mirror, and floor it, I guess he thought he would leave the rattly old PO van behind. But as well as the great acceleration the van had, with the batteries under the floor, it hugged the road like a Fi car, (oops, sorry, indycar to you guys ), the sports car driver couldn't believe his eyes at the bottom of the hill, when he saw me almost in his boot, (TRUNK!), I saw him look back up to his mirror, and he nearly drove off the road in shock
Sorry, didn't mean to hijack, great bike, I guess battery technology is the main bugbear with electric vehicles at the moment ?

[Snake]

Cool project.

[setasai]

Little late but totally amazing. I love it. It'd be perfect for the small commutes. Now if only we had a real IronMan Core to power it, we'd be golden!

[CZroe]

Originally Posted by Tony B

Yep dead cool, love it !
Around 25 years ago I drove an electric van whilst working for the Post office. I delivered parcels on the outskirts of town. It looked like a standard CF Bedford, but had a leccie motor and 1 and 1/2 tons of batteries under the cargo floor. It had a good range of 25 to 50 miles, entirely dependant on how fast you drove! If you just tootled gently around the side streets, 50 miles was easy, but if you floored it on the main road, you could almost watch the charge needle drop. I scared the life out of a sports car driver one day, we were on a twisty downwards hill, and I saw him look in his rearview mirror, and floor it, I guess he thought he would leave the rattly old PO van behind. But as well as the great acceleration the van had, with the batteries under the floor, it hugged the road like a Fi car, (oops, sorry, indycar to you guys ), the sports car driver couldn't believe his eyes at the bottom of the hill, when he saw me almost in his boot, (TRUNK!), I saw him look back up to his mirror, and he nearly drove off the road in shock
Sorry, didn't mean to hijack, great bike, I guess battery technology is the main bugbear with electric vehicles at the moment ?

I'm surprised he didn't blow his bonnet (HOOD!).

[Tony B]

Originally Posted by CZroe

I'm surprised he didn't blow his bonnet (HOOD!).

[shawn57187]

Just curious, but why couldn't the battery be relocated within the old fuel tank? That way you could put on the fairings and it would look more or less stock.

[Tony B]

Take a look at a tank when it's off the bike, it isn't very deep, as it has the tunnel for the frame. A tank can be any shape to suit a bike, but the battery is very large and square, you can't change that.
Also, the battery is waaay heavier than the tank.
Only way to hide a battery's bulk would be to have lots of separate cells dotted around the bike, though I don't know if that's feasible.

[sendler]

Very nice, top shelf electric build. The idea of an electric conversion is what has recently prompted me to start riding again after 20 years off of the bike (my kids are grown now). I bought an 09 Ninja to ride for the summer, if it ever quits raining, to make sure I like riding to work well enough to justify taking the plunge to build an electric. Electric conversions are not cheap. Electric Motorsports is a good, one stop shop for electric conversions and the low total weight of a stripped motorcycle makes usable performance possible that no car conversion can come close to.
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http://www.electricmotorsport.com/st...otorcycles.php
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I drive an 01 Honda Insight which gets 62mpg average year round and 66 mpg in good summer weather so the Ninja may not beat the car at the fuel pump but it will be good experience to evaluate the feasability of a 40 mile commute in Syracuse weather. I bought used with 700 miles so I can always get my money back if I wanted to sell. I don't think that will happen though as the bike is a dream to ride. Amazingly stable and solid on it's line at freeway speeds.
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The weight of your batteries is on par with the best but the size looks a little large? I am guessing that I will barely squeak by with 72v/60Ah to get me to work where I can plug in to top off for the trip home. 50% larger than your pack is really getting big and heavy (and expensive) at 108 pounds. Where to fit them all? I will be very interested to see your real world power consumption once you start riding your electric bike regularly.
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My car is the best thing on the road and costs me $5.50 a day round trip. If you milk a stock Ninja, you can match that. The Honda CBR250R is only slightly better at 71 mpg. When gas goes to $8/gal in a few years the cost will be double . The electirc bike should be about $1.50 or a little less. 8 KWhrs round trip?
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I am very interested to hear about your general riding impressions. 0-60 time? Is that a 3700 rpm motor? What final gearing ratio did you use? How much power does it actually use round trip. What is the best electric forum that you could post on? Thanks for letting us in on this great project. Plug in electric bikes and scooters can truely help save some fossil fuel for my future grandkids if we can lead by example for the large emerging nations.

[IndyTwoFiddy]

Looks awesome...

[Reddoak]

That's pretty cool! Any chance I could come out that way some time and see it in person?

[sendler]

Any data on the actual power consumption per trip yet?

[Pyro]

Assuming you get about 4kW/h out of a litre of petrol, you should get similar figures

24x40Ahx3.3V ~= 3168 Wh. so it's even less than a litre of petrol but you don't lose power when idling, for what it's worth.

Your power usage should be similar to petrol otherwise.

[sendler]

We won't have to guess what the power usage will be when he tells us what his data logging power meter says.