Using RC motors on E-bikes [Archive]

[safe]

Actually in my simulation program I added the ability to use as many RC motors as you want. Yes it could "in theory" work, but someone else had pointed out to me the fact that if it's overly complicated to get just ONE RC motor spinning in the right direction imagine trying to get multiple motors synchronized with each other.

If you put just two RC motors together you are looking at 5000 watts of power... (and maybe even more than that)

This guy is determined to make us all look like wimps!

http://endless-sphere.com/forums/viewtopic.php?f=28&t=8347

(I'm trying to stay near the legal 750 watt range)

 

[erth64net]

(I'm trying to stay near the legal 750 watt range)

If you're referring to a US/federal-level legal limit on homebuilt eBikes, there exists no known federal law, statute, or ruling applying to homebuilt electric bicycles (including motor size):
http://en.wikipedia.org/wiki/Electric_bicycle_laws#United_States

 

[safe]

There are state and local laws and there is the Federal Law for people that want to be able to sell a product legally. It was tucked into the "product safety" category because they knew that a manufacturer would never risk selling something that would allow a lawsuit against them.

Hit them in the pocketbook. :wink:

----------------------------------

The "bottom line" is that as "outlaws" we are free to fiddle around with whatever we want. Unless a policeman decides to bother with us we are usually okay.

But try to sell something illegal... then you hit the wall.

So realistically if you want anything you are working on to have a possible future to it then you need to think along the lines of a 750 watt limit.

Highly powered ebikes will never be sold legally... it's always going to be an "outlaw" machine.

(but being an "outlaw" is cool as long as you don't get caught )

 

[dontsendbubbamail]

I have two of the cheap RC motors and have experienced both bearing and heating problems. The bearing problem was easily and cheaply fixed with some better bearing from VXB.com. I think the over heating is due to overly optimistically ratings by the vendor and cheap construction. If I run the motors at the advertised max voltage rating, they run hot. Running them at 12 V below the max rating produces workable temperatures. I have not tried an expensive motor, but from the threads I have read, I get the impression that the temperatures I am getting are still above what others are experiencing with the expensive motors.

One of my motors is the 130Kv, 130A, 48V HXT 80-100-B. I done some testing of this motor at 36 volts and have pulled a max of 74 amps going up a short steep hill at 25 mph and was running about 30 mph on the level. It is good that I did not draw more amps, because I have the CC HV85 controller. I don't believe you can put 130 A through this motor, but 80 amps will be no problem. Next summer I hope to get the CC HV 110 and see how much current it can take without over heating. Even being limited to 2880 W is still a lot of power for the $150 price tag.

The questions left for me are durability and efficiency. Durability of the cheap motors will be answered for me next summer with I can put some miles on the motor. As for efficiency, just how many more miles will I get with a more efficient motor? My goal is to get 25 miles between charges. For some reason reading threads on efficiency just bores me to tears. My best bet my be to throw batteries at the problem.

Bubba

P.S. Let me know if anyone has a extra CC HV 110 for sale.

 

[safe]

For some reason reading threads on efficiency just bores me to tears. My best bet my be to throw batteries at the problem.

It's human nature to seek the easier solution. More power, more batteries... more... more... we all tend to follow the solution that does not involve pain.

I'm hoping that with the new social trends in America that efficiency and being frugal (efficiency with money) will become exciting to more people. It's something I've always loved to do. My family is said to have a "cheap gene". :lol:

-----------------------------

It's interesting what you are saying about overheating. Basically you seem to be confirming what I've been suspecting with cheaper RC motors that they will work, but you need to run them at about half of their peak power to make them last. So a 2880 Watt motor running at 1000 watts is going to last while if you ran it at it's peak it would not.

You are also running the motor with an unlimited current (or the current is limited by ESC heating) so with a true battery limited current limiting scheme the heat problems and torque would be less.

 

[erth64net]

There are state and local laws and there is the Federal Law for people that want to be able to sell a product legally. It was tucked into the "product safety" category because they knew that a manufacturer would never risk selling something that would allow a lawsuit against them.

Hit them in the pocketbook. :wink:

----------------------------------

The "bottom line" is that as "outlaws" we are free to fiddle around with whatever we want. Unless a policeman decides to bother with us we are usually okay.

But try to sell something illegal... then you hit the wall.

"safe", within the context of US Federal laws, there's nothing illegal about what us hobbyist are doing, we just cant sell it to others (ie: the average non-mechanical person, who most likely wouldn't realize, nor truly respect, the amount of power more than ~1HP means on a very lightweight vehicle).

So realistically if you want anything you are working on to have a possible future to it then you need to think along the lines of a 750 watt limit.

Highly powered ebikes will never be sold legally... it's always going to be an "outlaw" machine.

(but being an "outlaw" is cool as long as you don't get caught )

Again, we're not "outlaws", and we're doing nothing illegal within the eyes of the US Federal system (as long as we dont try to sell it). Now, state and other more local laws & statues...that's where things get interesting.

 

[safe]

Cheap RC Motor + Cheap Battery?

http://www.all-battery.com/37volt-3200mah20cli-polycell.aspx

These are $22.62.

They can pull:

"15C continuous discharge rate of 64 amps with 80 amp bursts"

...so if you bought 6 of them you would have:

3.7 * 6 = 22.2 volts

$22.62 * 6 = $135.72

80g * 6 = 480g = 1 lb

(plus you need chargers, balancers, etc)

-----------------------------

Now this isn't going to give many miles in a ride, but for experimentation or record setting speed attempts you could at least get into this stuff without needing a mortgage.

 

[safe]

Again, we're not "outlaws", and we're doing nothing illegal within the eyes of the US Federal system (as long as we dont try to sell it). Now, state and other more local laws & statues...that's where things get interesting.

We're in a "gray area". People that ride vehicles that exceed their local laws are... "outlaws" because they are doing things that are technically illegal. As long as you are never caught you don't feel like an "outlaw"... but you still might be. I'm NOT an "outlaw" because Missouri is so lax with it's laws that I fit into the "Missouri Moped Law" that allows up to 50cc mopeds. (but my situation is unique... few states are so generous)

The Federal Law was actually created as a "gift" to the manufacturers because before the laws someone could be sued if someone took their product and got hurt using it. Now that the Federal Law protects the manufacturer from lawsuits (since a legal ebike is technically viewed as a simple bicycle) it would be insane for anyone to sell anything that didn't comply.

You can sell anything over the internet... but just don't try to sell it through an actual "bricks and mortor" store because there is a higher level of scrutiny there.

High powered ebikes are like selling crack to tech addicts. :lol:

 

[safe]

Again... Why Not?

http://cgi.ebay.com/1-LiPo-11-1V-4000mAh-20C-Battery-Pack_W0QQitemZ260314460982QQihZ016QQcategoryZ2563QQtcZphotoQQcmdZViewItemQQ_trksidZp1742.m153.l1262

$65.48

Continuous Discharge Rate: 20C / 80A
Burst Discharge Rate: 20 C / 100A

---------------------------

This is even easier because they are already made into packs.

For someone that might have a "range pack" (weight being not an issue) that would be low cost NiCads or something, you could also have the "sprint pack" which would give you a few miles of fun, but that's about it. The price and C rate would make sense here.

Can these be used in series?

You could power an RC motor with two of these.

1.4 lbs.

 

[johnrobholmes]

I picked up 8 of these 3s packs for a 12s2p setup- 195 watt/hours that gets me 12 miles at 20mph. 3 pounds, very closely matched cells, 220a burst and 110a continuous capable.

http://holmeshobbies.com/product.php?productid=234&cat=0&page=1

The tenergy packs have very high variation between cells, fyi

 

[safe]

$49.95 - 11.1v - 2.2Ah = $22.70 per Ah @ 11.1v

verses

$65.48 - 11.1v - 4.0Ah = $16.37 per Ah @ 11.1v

...$22.70 / $16.37 = 1.39 --> so that's 40% more expensive.

Maybe. :?

Can the improvement in quality really justify a 40% higher price?

---------------------------

I was also thinking that you could use these as a sort of "reserve tank" in combination with your main heavy and bulky pack. The idea would be to run the main pack down to it's end, then unplug and switch to this lightweight pack. I could mount this under the seat on my #003 project. For speed runs I could remove the main pack and just use the reserve. That way I'm less likely to get stuck 10 miles from home with a bike without power. (it would allow me to ride with less concern about running the main battery empty) With NiCads as my main (cheap) battery they don't care if they are run down to empty.

The prices continue to be improving.

 

[johnrobholmes]

Can the improvement in quality really justify a 40% higher price?

vs tenergy - Hell yeah it does. You are lucky if 10% of tenergy cells aren't crap out of the box.

If you want value, look at these packs http://www.hobbycity.com/hobbycity/store/uh_viewItem.asp?idProduct=7639&Product_Name=ZIPPY_5000mAh_6S1P_15C_
I haven't used them myself, and I know the construction normally needs a once over, but it would be a great pack to try for value.

.69 per watt/hour or $7.7 per amp hour at 11.1v if you prefer.

 

[safe]

Hell yeah it does. You are lucky if 10% of tenergy cells aren't crap out of the box.

I've used Tenergy NiCads all summer long and so far not a single flaw. Hmmm.... your claim sounds exaggerated.

But this does look good.

Capacity: 5000mAh
Voltage: 6S1P / 6 Cell / 22.2v
Discharge: 15C Constant / 25C Burst

$76.85

For a "reserve pack" or a "speed run" testing pack this could work well... (excellent price)

It would take about 6 to equal my NiCads so:

$76.85 * 6 = $461.10... still not that bad.

 

[johnrobholmes]

Tenergy nicads are not Tenergy lipo. I have used them, and they are overpriced crappy cells with horrible quality control. If you want to save a buck, do it right and at least pay less.

 

[safe]

Tenergy nicads are not Tenergy lipo. I have used them, and they are overpriced crappy cells with horrible quality control. If you want to save a buck, do it right and at least pay less.

The product you pointed to looks very impressive. A great value. It's even better in price than the Tenergy.

Once I get the Project #003 running then I've got a nice mountain bike with good components that I want to convert to an electric road racer. On that bike I would go with the RC motor and some pack like this.

Great to see all these low prices... finally...

 

[johnrobholmes]

Yep, those zippy's are next on my list if I need more batteries.

 

[MitchJi]

Hi,

http://endless-sphere.com/forums/viewtopic.php?f=14&t=8369&p=126746#p126733

Who is the best supplier of Lipoly batteries for ebike power range of 48 volts?

Zippy.
They have at least 10 different sub brands....

 

[MitchJi]

Hi,

For me one of the big advantages of using RC Motors is the opportunity to get much better quality components at an affordable price. The quality of Hackers, Pletti etc. isn't available at any price in normal ebike components.

The typical ebike quality is pretty poor (to be generous). For example:
http://www.ebikes.ca/troubleshooting.shtml

9. Ball Bearings Shot
The Crystalyte motors use sealed ball bearings which should provide a good many years of maintenance free service. But because both the Crystalyte axles and bearing housings appear to be hand machined, the tolerances aren't always tight enough and the ball bearing gets crushed a bit when pressed into place. A damaged ball bearing has a noticable grinding feeling as the wheel is rotated, and it can cause enough additional drag that the no-load current of the motor is abnormally high, upwards of 2-3 amps. It is often necessary to replace not just the ball bearing, but the side cover as well, since that is frequently the origin of the problem.

I ruled out a Pletti due to price but with good Hackers and Astroflight motors available for under $300 I think its a reasonable decision to pay a little more for better quality.

If you want to save on the Controller (compared to Castle HV). A friend, who is very particular about component quality, has used Astroflight Controllers on quite a few Ebikes....

Astro controllers are all brushed, except the tiny ones

Oops!

Thanks John!

Mitch

 

[johnrobholmes]

Astro controllers are all brushed, except the tiny ones

 

[Miles]

This topic has now been "archived"

The discussion on regen. has been split-off to its own topic: http://www.endless-sphere.com/forums/viewtopic.php?f=28&t=8486