Simple controllerless e-bike build

neptronix

neptronix

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Hey there.

I'm interested in rolling my own simple setup. I've been searching a lot on this site.

I have a hybrid style bike with an aluminum frame. I figure this is the least desirable bike... But i do not want a lot of power. Just 200-300 watts to assist up some hills.
Not interested in regen, cruise control, or anything fancy.

I am wondering if i can run batteries direct to a hub motor without a controller. I am thinking of using two 18v batteries, with one switch per battery to activate it, so that there are two speeds, 18v and 36v.

I'd like to use DeWalt batteries. I assume the BMS on those prevents them from going under the charge level that lithium batteries like.

Is this feasable?

Thank you.
-David
 
Hi,

well, it is and it isn't.


if you have a brushed motor you could do this. But the brushed motors aren't that great, they create a lot of heat, and the brushes wear out, etc... you're better off getting a brushless kit with a controller and a throttle, it's not much more wiring then the configuration you're thinking of.

Why do you want to avoid the controller?
 
To be completely honest, i've been searching around the forums and it seems like programming/selecting a controller is no easy task.
There is not much information, but a lot of jargon. I wish there was some kind of FAQ, because this stuff is intimidating.

Since my electronics knowledge is pretty limited, I'd do the typical thing and buy a bionx kit, but it sounds like they are not too reliable.
All other kits seem kind of flimsy so i would rather roll my own.

Hence, i was thinking.. two speed dewalt lithium setup for momentary hill assist w/a brushed motor rather than a sophisticated setup, as a starter project.
Or maybe even 3-4 DeWalt cordless drills in some kind of bizarre chain driven driveshaft.
 
Are you wanting to do it because of stealth or just a better more reliable setup? The crystalytes are good products I think. I've been using my crystalyte 5303 and controller for a year now and it's awesome. Not flimsy. I've had no problems.

The nine continents are pretty good too and I think the infineon controllers are pretty good. I got my hub motor made at ebikes.ca . From what I can tell, it's pretty rugged and tough. I've fallen off numerous sidewalks and I hit a huge pothole one day and I've never broken a spoke. If you are going to buy a crystalyte controller, buy the analog type, not the digital ones.

The magic pie goldemotor kits have the controllers inside the hub. They only go about 18 mph but if you want that kind of setup, might be something to think about. Also the E+ or Eplusplus.com hub kits also have the electronics and batteries both inside the hub motors. They are expensive, though.
 
Go get a 409 and do it if you really really don't want a controller. It should work fine. I've never heard of brush wear being an issue. And even if they do wear out after two thousand miles, you just replace them. No biggie.

Like it was said the brushed hubs are more inefficient. With the heat that brings this point could be an issue. With no current limiting of a controller you might have to limit assist to only certain conditions. For example mebbe like.. only above 5mph while pedaling and only above 10mph while not pedaling. Which even if that is the case isn't a big deal.

Probably easier to just go with a controller though, brushed or otherwise. There is no programming necessary with either brushed or brushless controllers. Only the RC drive guys need that. And even that is changing now.

What size wheel are you going to use? Running a clyte dc 700c on 33v dewalt thru the ebikes sim it looks like even as high as 7.5mph the motor is trying to draw over 1250W, which means like 40+ amps there. At 25% efficiency that is a lot of heat! Whether or not it will work and live is going to depend on how you use the button. Well maybe there are better brushed hubs out there for big diameter wheels..
 
I just want a reliable, low power, low complexity setup. Something that is not intrusive, for sure.
Just a throttle and small motor, because the majority of the time i will be pedaling for exercise.

If that's possible with a controller, cool. But a lot of the controllers i see have connectors for all sorts of stuff & sensors..
With them being from China and limited information being available, that's one reason why i'm hesitant.

Brushed motors needing work at 2000 miles sounds like a pain in the butt. I didn't know they were that bad. But if they work with a straight battery connection for short periods of time, that may work for me.
The crystalite and magic pie look like far more than what i need, but the magic pie is interesting.

Where can i find more information on the magic pie setup?
 
Oh, and i have a 700c rim. It's a fairly light hybrid bike.

Just found out that aluminum forks are bad. I wanted to put this motor on the front... am i going to need to switch out my fork ?
 
I don't blame you for just wanting a motor and battery. I wanted the same thing and I hope done day they can make the controller a lot smaller because out of everything, the controller is the thing that really bothers me about electric bikes. I don't mind throwing a battery in a backpack or even having it on the back but the damn controller is kind of a pain.

Here is the magic pie. Might want to read some reviews on it. One man's trash is another's treasure though. I think the only complains were that it went kind of slow. Lots of speed demons on this forum, though.

http://goldenmotor.com/

click on "ebike DIY" button on the left to see the magic pie.
 
Why doesn't someone make a controller that you can slide down into the seat tube or up in the seat tube of your bike?
 
Hybrid's are not too bad for conversions, the aluminum fork is a bit of a bother. If you can find a steel fork, it might be worth it to switch it. With aluminum only perfection will do. You would definitely need a torque arm.

I think you'll end up with a brushless in the end, but yeah for now sure, go for a brushed with a couple of switches. It can be done. Wilderness energy brushed are pretty cheap.
 
I gave the wrong website for E+ e-bikes. Here is the hub motor kit that has the controller and batteries in the hub. Makes it so you don't need even a rack on your bike.

http://epluselectricbike.com/shop/products/E_Flex_Kit_750_Watt_Electric_Bike_Conversion_Kit-39-4.html
 
If you go brushed hub adding a controller is another $15 plus shipping for a low power one. Two wires in from the battery, two out to the motor, and you have three wires for the throttle. Seven wires, thats all my bike uses. To turn it off I unplug the battery. Pretty simple.

If you go brushless, well you don't have a say in the matter. You're going to have to use a controller. So either way you go it doesn't really make sense to not use one. It'd be kind of neat if you do it though. Just to be able to say you don't have one. :)

BTW I pulled that 2000 mile figure out of thin air. I have no idea how long the brushes last. The point I failed at making was, in proper use they last a darn long time and cost like $10 to replace. The efficiency/heat is the big draw back to brushed motors, not the brush wear.
 
Yeah, i've been reading very mixed things about the magic pie setup. It sounds kinda funky IMO.
I think i'm going to cross that one off my list unfortunately.

I notice there are a lot of speed demons too :p.. IMHO, over 25mph is kind of scary on a bike so i'm not interested in that too much. I've got a car for that ;)

I doubt we'll ever see a seat tube bike controller. Those things need to dissipate heat somehow. That's why the casing is aluminum and often designed like a heat sink, after all.. and i think that seat tubes come in different sizes, so it's not a one size fits all thing.

On another thread, someone mentioned that washers on an aluminum frame work great if you have low power needs like i do, so i'm not worried about that anymore.

Yeah, honestly i'm getting a little turned off from brushed motors the more i read. The efficiency is what irks me. I'd rather carry a light load of lithium batteries that are easy to remove and recharge with the stock dewalt battery, but with the motor being ~50% efficient, i would need more lithium batteries. Seems kind of worthless and you're right, i'll probably end up getting a brushless in the end.

I wonder if someone makes a simple brushless controller.

The other option i'm thinking about is an Amped Bike kit + dewalts.
*scans phone list for electrical engineers :p*
 
the more I think about it the more I think you definitely want a Brushless Geared motor.

Brusheless for efficiency, geared for the freewheel ability, so if you're mostly pedaling you won't have to deal with the motor drag. Non-geared motors have drag due to the magnets being dragged past the coils while you pedal. this makes them slightly harder to pedal than geared motors, which typically have a clutch. the motor disengages when you let off the throttle.

A Bafang motor is very light, freewheels nicely, efficient and would power you to 15-20 mph no problem. get a kit with a Bafang motor and a controller pre-wired and you should be fine. I got such a kit on sale for $200 laced into a rear 26" wheel. worked fine until I sheared the gears off the motor housing, but I'm 230 LBS and put a LOT of torque on the pedals to do that. it was my own fault.

Russel reviewed a kit like this and I believe he's still using it, now with lithium batteries.

http://endless-sphere.com/forums/viewtopic.php?f=3&t=8001

P.S. My first motor was brushed, the brushes went fast, and I cooked the motor going up a small hill. I'd say less than 1000 Mi on the brushes. and while they are replaceable, I broke 2 bolts uncovering the motor, and stripped a couple other ones. the motor was a Aotema, I do NOT recommend them.
 
I didn't know that geared brushless motors had an internal clutch, that's perfect!!! i don't want any drag after all.
And i can't think of a way to do a chain drive system with a clutch without doing some major fabricating.

I was actually thinking about going with the amped kit ( geared ) because the controllerless system seems to have it's own set of issues..
And suddenly loading all the torque all at once sounds like it would be a bad idea. I have an aluminum frame so i can't be really pushing it.

I'm 230lbs also and will be conquering hills, but looking at your experience and russel's, i think those nylon gears will be an issue for me just the same on the bafang.

I think frankly a lot of this Chinese stuff is not made to haul around our fat American asses... ;)

Pretty convinced that i should just go with an amped kit and then figure out how to get DeWalts to work with them. Probably 2x 36v.
Unless there is something better, but i keep hearing good things about the amped kit.

You guys on this forum have been very helpful, thank you very much!
 
It's a pretty cool forum, isn't it?

So, my bafang blew up on me, but I'm 230 as well. I do have a BMC motor, which is the Bafangs bigger, American made cousin. it's geared, brushless, with a clutch and nylon glass composite gears(strong) and I routinely take it up 25% grades and pull 1200 watts. also, you can add steel gears to either kit if you're worried. I bought a steel gear from Holmes Hobbies for my Bafang.

BTW, a BMC motor weighs less than just about any gearless motor.

-Aaronski
 
Yes indeed. Much better than the car forums i'm on.. :p

BMC looks like another good option, but it's quite a bit more expensive than the ampedbikes kit; $200-$300 more O_O.

Seems like it can handle more power and is built quite tough. i think that would be a good choice if i were overvolting.
But i don't want a lot of power honestly. Anything over 20mph is scary on my hybrid bike, lol..

My girlfriend wants an EV bike though, so maybe i'll just get the ampedbikes kit for now, and if i get addicted to electric power like everyone on here seems to get, i'll do the BMC kit later.
 
looks like a good kit. you should also checkout ebikekit's offer in the for sale section here. they're doing a very similar kit for $200. If I hadn't just bought a house, and have a baby on the way I'd be buying one right now.
 
$200 is nothing. Jesus Christ. Thanks for the tip!!

No mention if it's brushed or brushless. Trying to find that out first.
 
most are brushless these days. The only brushed motors that I know of are the Crystalyte Sparrow and Clyte DC motor.
 
yea. brushless. 99% are brushless these days. except, as was stated, the crystalite sparrow, which goes by many names...
 
neptronix said:
I think frankly a lot of this Chinese stuff is not made to haul around our fat American asses...
Click to expand...

Yes. Many of us need what would be considered a cargo setup in China.
 
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