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> Motorcycle Electric Conversion
AwesomeMatt
Posted: May 05, 2018 04:36 am
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Dealing with my current bottleneck, The Controller.

I have 4 golf kart/forklift controllers.

1 - The original toaster-sized SCR controller. Found some old documents that show specs, it's only rated for 36v and 150amps. 5000 watts. Good enough for moped speeds, but not enough for highway. And it's switching speed is around 10hz. But it appears to at least work.

2 - Clark EV-T5 controller. Not sure if it works. 24v, 75 amps. 1800 watts. Yuck.

3 - Curtis 1204 controller. 36v, 275 amps. 10,000 watts. Probably enough to hit highway speeds. So I open it up because it's marked "Low power, needs repair", and I find this:

user posted image

All the mosfet screws and plates are rusted. All the connections are crusty and white. It's dozens of connections to check, and I'm not hopeful. Googling the fet numbers gets nothing.

4 - Curtis 25864. No specs anywhere. Faint whisper that it's really a Curtis 1206. Found a pinout, nice and easy. Came out of a golf cart. It's spec'd for 36v and 275 amps, but looking up the fets, there's 9 of them, 60v 60amps. So, 32,000 watt. If I'm allowed to push the fets anywhere near their margins.

So I go about trying to test the 1206.

user posted image

Very simple, only 3 big lugs and 5 pins.

Bat+
Bat-
Motor-

And then 5 pins, only 4 of which are used.

1-2 are a 5k pot for speed control.
3 is for reverse (so ignore)
4 is to activate it/keyswitch/etc (presumably tie to positive).

However, without hooking anything else up, when I put voltage across the battery leads, and measure M- and B+... I get full voltage.

... before I short 4 to positive, and before I add a pot.

Which leads me to believe... Fets and blown short, no?

...

I also bought 3 different throttles. First actual mistake, I presumed they would be 0-5k. They're hall effect throttles instead, you feed them 5v you get back 0.8v-3.8v. So, none of them will work with my controller unless I want to spend $58 on http://www.evwest.com/catalog/product_info...products_id=294 <-- A converter thing. Which I obviously do not. So, back to the pot box I guess.

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AwesomeMatt
Posted: May 16, 2018 08:40 pm
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Controller Success!!

user posted image

I basically sat with my thumb up my butt for 3 weeks, figuring the controller was broken because it showed full voltage on the motor output without the keyswitch or the throttle even connected, indicating blown mosfets. And then I was bummed about my throttles all being the wrong type and not being able to use them to test either.

So today I decided to actually just hook a motor up to it and a pot (had a 50,000 ohm rather than a 5,000 ohm, but, no matter).

Well lookie that that. As soon as there's really any load at all on the output, there's no voltage there, so, must have some high impedance path through the controller.

I used an 1800w treadmill motor (easier to carry onto my office desk), threw on the pot, shorted pin 4 to positive, and... nadda.

About to give up and then I tested the pot and even after checking it thrice, discovered I'd wired it backwards (so I was adjusting between 45k and 50k, rather than 0k-5k, and just never bothered to twist it all the way around to the far side).

And the damned thing spins. And it changes how fast it spins when I twist the pot.

A few interesting tidbits:

1 - The max supply voltage is 46.6v. Above that it shuts down. Since it was designed for a 36v kart, and 36v batteries are at absolute most 45v when boiling their electrodes, that's sensible. But it means if I want to use a higher voltage than that I'll have to reverse engineer it to find how it determines that.

2 - The min supply voltage is 28.4v. Below that it shuts down. Again since it was designed for a 36v kart, when your lead acids are less than 9.5 volts on a 12v battery they're plenty dead (heck they're dead by the time they actually get to 12v). Shouldn't be a problem for me, an 11series lithium pack is well dead below 33v (3v/cell) anyway. 28.4v is 2.58v per cell. That's already into damaging territory, but my low voltage cutoff is human-decision-based anyway, so I'm fine making the choice whether I want to stop or continue driving. I don't need it idiotproofed except perhaps to actual idiot level (I leave the lights on, ideally it won't murder my batteries).

3 - High resistance is low speed. The documentation didn't actually say which, controller might be built either way.

4 - Below some resistance, the motor cuts out. So it goes faster, faster, faster, dead, if you bring the resistance too low. I'll need to have my stop switch sometime before this, as, you'd come to a complete stop while at wide open throttle, ease off a bit and then backflip as it slams max power again.

....

Decision Time:

Do I design the pack for 46.2v and start soldering cells, or, wait for a better controller?

It will be a huge pain in the ass to change my mind later, it involves desoldering every single cell, and likely rebuilding the entire battery compartment since it has to be built around the frame.

On one hand, this isn't the voltage I want to run at. It might not even hit highway speeds and there's no way to find out until I try. That would be a huge disappointment.

On the other hand, I'm getting pretty tired of seeing other riders on the road enjoying their summer, while I have a pile of parts. And I don't have another controller to use anyway.

Maybe I'll split my battery pack into two full sets of 11series so I can rewire them for double-voltage later. If I upgrade the controller down the road, I can design it for whatever voltage and, 46x2=92v is an okay target.

Controller claims 275 amps, 46v = 12,650 watts = 17hp when completely topped up. Should be enough for highway speed if the motor will be spinning fast enough with that load. No way to tell. Not sure if the controller has overcurrent protection either, so maybe I can manually demand 500 amps and as long as it doesn't overheat it'll be fine.

Next up, start making cardboard battery boxes and seeing how/where I can stuff them into the bike.
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dmg
Posted: May 16, 2018 10:51 pm
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i would go with the split option of 11 series.
17 hp is absolutely not a lot, and you lack a transmission sad.gif

actually if i where doing this i would had left the tranny in place anyways.. not sure what these electric motors rev to, but i hazard it would had been far more sensible option to leave the clutch and trnasmission in and simply replace the crankshaft with a straight shaft and use a small chain drive to get an electric motor to spinn that.. would had saved a lot of thinkering , and you would have better managment on how the power gets delivered..
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AwesomeMatt
Posted: May 17, 2018 12:27 am
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QUOTE
17 hp is absolutely not a lot, and you lack a transmission


17hp is enough to climb a steep hill at highway speed.

It's not a track bike. I'm not 18. If it can quickly accelerate to highway speed and maintain that... that is my requirement for a vehicle.

It doesn't need a transmission for anything other than maybe long hill climbs. It has massive torque available instantly.

QUOTE
actually if i where doing this i would had left the tranny in place anyways.. not sure what these electric motors rev to,


They limited only by resistance. It'll accelerate forever without a load, it never has a speed it's trying to attain.

QUOTE
but i hazard it would had been far more sensible option to leave the clutch and trnasmission in and simply replace the crankshaft with a straight shaft and use a small chain drive to get an electric motor to spinn that.. would had saved a lot of thinkering , and you would have better managment on how the power gets delivered..


1 - I don't need any management on how the power gets delivered. Electric vehicles generally have no gears.

2 - I don't know anything about engines, at all, zilch. It has a combined engine and transmission. I would have had to disassemble the engine, reassemble the transmission, figure out how to plug all the oil ports, make some kind of gasket and housing and mounting system for the motor and a chain system to interface with the crank, keep the clutch lever and shift lever, and in the end had no space or available weight to put any batteries.

That'd be about the worst possible design situation I could be in. It would have saved me from tinkering... two L-brackets to mount the motor, and the spline coupler to the driveshaft which I made in an evening. I don't see that as a good tradeoff.
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dmg
Posted: May 17, 2018 08:43 pm
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well, can't speak for you, i just threw in my 2 cents..
gearbox would allow to pull less current, as the electric motor would need less tourqe for the same power as it could rev higher. but it does not mather now, you got the thing chopped up allready.

even so i would go with the split option of 11, better to have more options/power than needed, than need but not have...
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AwesomeMatt
Posted: May 18, 2018 10:09 am
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Battery Bulk:

My big goal was to get 60 miles (100km) worth of range at highway speeds. I need ~140-200 watt-hours to travel a mile at those speeds.

I have these 4x5 battery holders, an 18650's average voltage through it's discharge curve is ~3.7, maybe 3.75v, cells are roughly 2000mah each (good ones are 2600, I'll stuff in as many of those as possible), so each 4x5 brick of 20 cells is roughly 150 watt-hours and weighs 2 lbs.


Battery Weight:

At a brick a mile, I need to find room to fit 60 of the bricks in the frame (9000 watt-hours). Since I'm doing strings of 11, might as well round it up or down to 55 or 66 bricks. It'll weigh about 120 lbs to do that.

Motor is 92lbs, so motor+battery is 212 lbs, plus the weight of wiring and the battery enclosure.

The original engine according to spec was 181 lbs dry. Plus fluids. Plus exhaust. Plus fuel.

I should weigh the bike now and compare it to the 467lbs it was originally.

In any case, I'm in the right ballpark I'd say.


Battery Sizing Layout:

My first big happy surprise. I had more room in the frame than I thought.

66 bricks is roughly 2 milk crates worth, bulk-wise.

Just looking at the bike, I figured there was no way I'd find room to fit them. I've been putting it off forever, but tonight I dummied up a bunch of empty battery trays and started seeing where they could go.

user posted image


1 - Below radiator, in front of frame: 4x4 bricks, +4 if I remove radiator. 16-20 total.
2 - Below/between frame, below motor (as in pic): 3x4 bricks. If I double-stack (each stack is 2.5" tall), double that. Brake disc is 6" above ground, so I figure I'm okay with that clearance for city riding? 12 or 24 total.
3 - Beside motor: Sloppily, sticking out of frame, 5 first tier, 8 on second tier, 8 more on third tier. 21.
4 - Above Motor Right: 5x2 bricks. Three tiers. The mounting for the motor sticks out 2" so I have to separate right from left. 30 total.
5 - Above Motor Left: 4x2 bricks. Three tiers, but it's getting ugly to not narrow at the top of the frame. 24 total.
6 - Under Tank: 2x2. Not much space, hard to fit, but room for 4 total.
7 - Above Swingarm Triange: 3x2. 3 tiers. Nice and narrowly tucked, won't interfere with my thighs. 18 total.

Grand total: 125-141 bricks.

Jeez, I only needed room for 66.

Heck, I only have enough weight available for 66 (not 250-280 lbs).

I don't even have 141x20 = 2820 cells = 21kwh of cells. That's almost as much as a Nissan Leaf.


This isn't the layout I'll be using, or even the orientation, it was just the easiest way to slab up cell holders and ballpark the spacing available. If I'm over what I need by at least double... I can afford to make some choices based on cosmetics, not "What used to look like a motorbike now with a bunch of bricks".

I can skip the whole row in front of the frame. The 2nd tier below the frame. I can slim a whole row of bricks off of the left and right sides each. Still have room for 66. Easy.

Expecting my hubris to bite me later, but, for now I have some breathing room.
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