LiPoly powered 18HP Twin Motor Brushless MONSTER build!

Patrick, whom I've known and befriended as "Methods" on a few forums over the last 8 years, has managed to convince me that an E-bike can be exciting and fun. I'm not 100% convinced , but I can see a lot of advantages of a fun play-toy being classified as a bicycle, so I'm going to give it a shot. I also have loved watching the LiPo battery and brushless DC motor technology really blossom over the last 5 years.

These are a couple of my two-wheeled buddies that I've become accustom to riding:

GSXR1000 over-bored to 1080cc, high compression pistons and cams. ~340lbs, with 190bhp on tap.


KTM 300MXC with 380cc built engine swap. Roughly 70bhp and 225lbs.

I have 2 other bikes as well, but they are lesser machines, yet still very fun.


So, I think you can get the idea that I've got some pretty high performance standards for something to be an exciting toy. I've got a game plan and some giant brushless DC motors that I think are going to help reach my goals

You can see the pair of hobbycity 7000w motors are taken apart. This is to swap out the cheapy bearings, and swap in the class 7 bearings I ordered today. They were $55/bearing for the class 7 precision bearings! Each motor uses 3. The mounting plate will be fitted with a support for a much larger diameter class 5 bearing, which should carry most all of the drive loading on the shaft.

The drive system will be #35 roller chain and it will feature a 96T sprocket custom adapted to the freewheel of the hub taking the place of the largest 3 sprockets. I sourced the parts from a karting supply wholesaler I used to do business with years ago. The sprockets on each motor will be 10T, and the second motor will also function to help as a chain guide to ensure accuracy of the chain climbing the big sprocket under the massive off-road abuse I plan to put it through.

The bikes pedal chain will have some hooks/tabs to hold it off the rear sprocket gang during motorized operation.

The motors will be mounted to the upper bar of the rear swing arm by fabricating an aluminum TIG welded mounting structure to tie into various points on the upper swing-arm, and offer a large plate to bolt the faces of the motors against. This plate will have thermal compound between the motors and it's surface, and I may also thermal epoxy various other heat sinks onto the plate as needed.

For controllers, I have a 200AMP 72v kelly, and I have a 4x 100amp RC brushless controllers as well. I have a hall-effect throttle and various servo-testers and things available for throttle signals depending on what I plan to use.

One of my biggest concerns is tearing the spokes out of the rim, and/or shearing the dogs of the freewheel. Does anyone have any idea of how much abuse a heavy gage Sun Rhyno-lite downhill wheel can handle before the spokes pull out? If the spokes do tear out, I'm going to TIG weld 6 radial support arms directly to the rim for attachment of the ring gear in a hub independent fashion.

Best Wishes,
-Luke

LOL, in the battery picture, you can see the stickers I had made for the bike. They proudly say "348w max power". :lol:

Hopefully that should help me to be counted as an E-bike and not a motorcycle if I'm caught in a pinch with law enforcement.

The Federal Law for bike builders is 750 watts of power to retain the ebike definition. Once you go over 750 watts you are riding a motorcycle. You can't sell a bike above 750 watts without running the risk of lawsuits.

That said...

Everyone is cheating and going with more power in the aftermarket area and if it looks light weight enough the police will not harass you.

Do you know how you plan to mount everything?

Have you read Recumpences threads about his RC motor geardown product? He's building them and selling them online...

Thank you for the advice. I looked up my local city laws, and they say >350w or able to exceed 25mph changes it from an E-bike to an electric motorcycle. This is why I had the 348w stickers made

I'm certainly not planning to be selling anything, just a toy for personal use

750 watts is the Federal Law... it applies to all 50 states.

However, the Federal Law allows for the states (and cities) to override it and insert their own. Most states are more or less in compliance, but a few go so far as to pretty much ban ebikes.

My state is really loose and allows up to three horsepower.

It might depend on how they enforce the laws.

Someone in florida (who posted here) had a terrible time because the police there were really strict about ebikes.

If a policeman sees you don't impress him with a wheelie. :lol:

safe said:

If a policeman sees you don't impress him with a wheelie. :lol:

Click to expand...

Story of my life. I've got an on-board cam vid of that GSXR holding a wheelie to 142mph, setting it down and ripping to 187mph. Im thinking this should be a bit more tame of an animal to control

liveforphysics said:

Story of my life. I've got an on-board cam vid of that GSXR holding a wheelie to 142mph, setting it down and ripping to 187mph. Im thinking this should be a bit more tame of an animal to control

Click to expand...

More tame in raw performance terms, but hopefully you'll be pleasantly surprised how the fun factor is greater in some ways. For me down here in Costa Rica, it's the complete lack of rules that apply to me on my ebike, so literally any route that doesn't present a physical barrier to my progress is my road.

I can't wait to see your progress.

John

Welcome to the forum!As a fellow GSXR man(07-750)I think you will like the fact that you can ride your ebike anywhere and can be alot fun like the gas versions -just different.Look forward to seeing you build finished.

Thank you all for the warm welcome guys!

I'm thinking this bike will be a lot of fun. I hope to have things finished up in 2 weeks, but depending on what snags I hit, it could be longer. I tackle projects pretty quickly though

Best Wishes,
-Luke

4s2p 22.2v?

Nope

20s and 3p with 4900mAh cells. Rated for 15C continous or 25c burst. (I tested and they did 20C continous and held the voltage the whole time).

14.7Ahrs.

1087 watt hours.

Charged voltage of 84v.
Nominal voltage of 74v.

Peak current of 367 Amps.

Continous current of 220Amps.

Pack can peak about 29,000w, and continously sustain 16,300w.

LiPoly is not a saftey battery, but I'm not building this toy for being safe with

If I use the Kelly controller, I will stick the motor legs in series, and ensure they are mechanically locked in time with eachother.

If I use the RC brushless controllers, I will have to change the pack around, as each RC controller can only handle 12s max.


I also still need to find a clever solution for cell ballance and rapid chargeing.

Ah, I was thinking you would leave the 22v packs intact for 88.8v 9.8ah. Theres so many great affordable chargers out there that will just work out the box for those packs.

I have a whole collection of LiPoly chargers, including the largest hyperion made, but it will only charge a max of 12s.

I would like to have a charge solution that enables me to plug in a single connector, and charge from a lightweight very high power unit. I would like the ballancing to happen internally in the battery, and be constantly functioning.

I've been tossing the idea around of building a single stage high speed switching power supply with PWM and a cap bank for output current regulation and voltage cap. For saftey I would set it up to only charge the cells to 4v to give a little headway for errors. I think i could build a crude charger in the 1kw range that was around 3lbs or so, but it wouldn't be a very safe way to do it, and i would love to find a better option, but I want to keep it light and portable.

Best Wishes,
-Luke

Hi Liveforphysics,

awesome base to start with, i really like the specialised bikes and a freind has the fsr, really nice.
this should be an awesome build, best of luck with it and keep those pics coming!!!
Methods is right with the thrill of a fast ebike, sure it wont be as quick as the gixxer or ktm but when did you last ride those through your local park and greenland?
rock on, like the others im sure you'll have a blast with your ebike.

Cheers,

D

Thank you! I'm also happy with my choice in bicycle. I bought it used, just for this project. It has scratches most everywhere, and you can tell it's had a pretty rough life. Fortunately, I couldn't find any cracks in the frame, and all the suspension pivots are free of slop. I think once I'm finished, a good sanding and some paint should leave things looking nice.

You're absolutely right about the advantages of the E-bike. The GSXR1000 would get some pretty dirty looks racing along a bike path, or the KTM tearing through a park trail. The E-bike should be quiet and bicycle-ish enough that it should hopefully be able to avoid bringing much trouble onto itself.

liveforphysics said:

You're absolutely right about the advantages of the E-bike. The GSXR1000 would get some pretty dirty looks racing along a bike path, or the KTM tearing through a park trail. The E-bike should be quiet and bicycle-ish enough that it should hopefully be able to avoid bringing much trouble onto itself.

Click to expand...

There is exactly the reason for everything i've done in the last 2 years - you'd get pinched on a motorbike in the forest where i live in 5 mins flat whereas i've never had an issue of any kind on the Kona and i have to say electric trail riding baby, it rocks 8) now get that FSR up and running!!!

Cheers,

D

oh man.. that looks sweeeet !!!! 8)

Given you can stay upright on that GX and KTM and are alive to type this thread, you pass the 2 wheel capable test

You are pretty much skipping my last 4 years of tinkering and getting right into the good stuff from the start.. pls keep the pics comming this is great !'

Welcome to ES btw !

Hi Y,

dooood, it looks like a new breed of bike is arriving in earnest on ES.
Have to say though Y, we all give a nod to the norco :wink: i reckon you should rc it up and go back to 24's join us brother!!!! lol

Cheers

D

Heh.. already on it.. i'm calling matt tonight for details of my rig.. :wink: .. it will have the biggest motor Dave makes or a pletty if needed..

I think i'm going to leave the Norco alone and just build another rig..

Changing out the bearings is a good idea, but that may not be the only problem you have with these motors. I can't tell which model of HXTs these are, but in general, I wouldn't try and get these close to what they say is their max rpm, as they will run very hot, especially uder the kinds of loads you will see in a high-end ebike application. If you are using this model, the max voltage you can feed it is 48V. If you tried to feed 74V into this motor, new bearings or not, it is going to fry. You can't just put these motors in series, like with brushed motors, and you can't use a single controller with two brushless motors. Aslo, as far as I know, the Kelly brushless controllers require hall sensors, which no RC motor uses.

You could mechanically have these in series, but I think you need to use separate RC controllers, and limit the packs to a 12s configuration. With the same 60 4900Ah cells, you could do a 12s5p configuration. That would simplify the charging process for sure. How many cells are in each of these Rhino packs, 3s? 6s?

If you want a single connection charging solution, you can do that with a 12-channel BMS board and a 50V CC/CV supply/charger. The "DIY" BMS board we are doing (see here for the board...) normally is setup for use with LiFePO4 cells, which have lower voltages, but with changing one part and one resistor per channel, you can also use it with LiPo cells. Check with Patrick on this, as I think he is the one who "pioneered" this idea.

Another option would be to us a single Hyperion charger that can balance charge up to 12s. What I would do is make a special harness that connects all the balancing plugs for the paralleled packs together. This way the cells are paralleled first, and then in series so the can be thought of as 12 big cells.

-- Gary

Ypedal said:

Heh.. already on it.. i'm calling matt tonight for details of my rig.. :wink: .. it will have the biggest motor Dave makes or a pletty if needed..

I think i'm going to leave the Norco alone and just build another rig..

Click to expand...

coool 8)
what bike are you looking to advance 50 years as your base Y????

Hi Gary,

sound advice as always.
I know you probably haven't but i can't hold off asking any longer so forgive me but.....
any testing on the hacker yet?
i'm thinking that i may have Matt ship my GB with no motor slots as i'm still undecided on motor but i guess really it's not a problem as i can have the motor holding part of the GB milled here to suit, i'd rather have Matt do it obviously but i need the GB here so i can measure up really.
Sorry if you haven't had chance to test anything yet but i'm itching to get to testing myself, im sure you know this feeling

Cheers,

D

deecanio said:

Hi Gary,

sound advice as always.
I know you probably haven't but i can't hold off asking any longer so forgive me but.....
any testing on the hacker yet?
i'm thinking that i may have Matt ship my GB with no motor slots as i'm still undecided on motor but i guess really it's not a problem as i can have the motor holding part of the GB milled here to suit, i'd rather have Matt do it obviously but i need the GB here so i can measure up really.
Sorry if you haven't had chance to test anything yet but i'm itching to get to testing myself, im sure you know this feeling

Cheers,

D

Click to expand...

I'm sorry, but I haven't had the time yet. I got sidetracked making a 16s5p a123 pack for this bike. Tha is just about complete, so I hope to get to the Hacker test this weekend.

I have another option I'm looking at as well. I had a long talk with Bob, at AstroFlight, about using his 32 series motors on ebikes. Apparently more than a few people have been ordering some for this purpose. The long and short of it is that I'm going to try a 3210. He's making up a 10-turn model for me, which has a kV of 135 and an 8mm output shaft. I'm going to marry this up with the first one of Matt's drives that I'm getting.

Although the 3210 shows that it is out-of-stock on their website, Bob says they are building 5-6 a day, mainly for their industrial and military customers. He also told me they now also have a new 3215, in addition to the 3210 and the monster 3220. I want to try the 3210 first, to get a good performance baseline, but I definitely want to test a 3215 as well, so that is next.

-- Gary

ok, thanks for the update Gary.
I guess really it'll come down to whatever i choose with all given info - i'll leave the motor until the very last piece of the jigsaw then which will hopefully give me more options to choose from, and just have Matt ship the drive without mounting slots, as i said no biggy i can have my own milled and each time i look at the forum a different motor is touted anyway.
I'll have a look at those Astro motors in the meantime, kv sounds good for all of them.
ooops, should stop jacking livefophysics thread can you let me know once the throttle boards are available too? thanks.

Cheers,

D