Fastest E Bike Build (UK)

BenRobins3

1 µW
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Jan 3, 2023
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To cut a long story as short as possible, I want to build the fastest E-bike on a dirt bike frame on UK roads, (I will be registering the bike, running with an adequate license, doing a V5S, and insuring the bike).

I have decided on building a bike on a dirt bike frame with dirt bike styling and this won’t change, I am currently looking at a QS 273 50H motor as the 70H won’t fit into a dirt bike drop out. I have decided to run a 96V system with a FarDriver 96530 controller, and will be building a custom battery with ePLB CO20 cells. Ideally I will run 4 packs of 14 of these 3.6V cells, with 2 48v packs in series, then running this in parallel with 2 more 48v packs to have a 96v pack with twice the capacity of a 1p 96v pack. So essentially a 28s 2p pack. I’ll also be running a DC-DC 96v to 12v inverter to power things like horn, lights, indicators, and a separate high power USB port.

Essentially what I’m asking is how good will this setup be in practise, and where could I improve. After a lot of research this is currently the best I can come up with, but I am open to suggestions, as this is sort of a “money is no object” sort of build. The one thing I am sticking to is running on a dirt bike frame with chunky tyres, which I know will hurt my speed, but I purely like the look of it.

Thanks 👍🏼
 
Wow :shock: Fastest E bike
Thinking Death Bike and QS 273
Reality is your building an E motorcycle per your statement
by BenRobins3 » Jan 03 2023 11:18am
I have decided on building a bike on a dirt bike frame with dirt bike styling and this won’t change
Nothing wrong with that. Maybe one of the mods can move the thread to ELECTRIC SCOOTERS / MOTORCYCLES.
You will get better help there.
 
Yeah I think you’re right, the only reason I have posted it to this thread as because the parts I’m talking about, (bar the controller) seem to be more prevalent in the e-bike community more so than the e motorcycle community. In theory yes it will be an e motorcycle.

It may seem like a silly question but I’m completely new to this website and don’t actually know how to copy a post into another thread.

Also as a side note, the so called “death bike” as you put it is a crude version of what I’m looking to build, I have some fabrication experience and so I am hoping to make this look more “finished product” rather than prototype.

Cheers buddy 👍🏼
 
BenRobins3 said:
It may seem like a silly question but I’m completely new to this website and don’t actually know how to copy a post into another thread.
Here is how I do. Open another window. Find post I want to copy. Click on the " Reply with quote button. Copy all the text you see. Paste it here.
marty said:
Leaf Blower
rocket_bike600.jpg
Rocket Bike
Well looks like the Rocket Bike picture disappeared. Not a problem. Still got picture in my computer. Attach, upload, here it is:
rocket_bike600.jpg
 
by BenRobins3 » Jan 03 2023 12:29pm

Yeah I think you’re right, the only reason I have posted it to this thread as because the parts I’m talking about, (bar the controller) seem to be more prevalent in the e-bike community more so than the e motorcycle community. In theory yes it will be an e motorcycle.

It may seem like a silly question but I’m completely new to this website and don’t actually know how to copy a post into another thread.

Also as a side note, the so called “death bike” as you put it is a crude version of what I’m looking to build, I have some fabrication experience and so I am hoping to make this look more “finished product” rather than prototype.

Cheers buddy
Think the death bike was more of what could be done on a bike frame. More for racing than for riding around on, not that LFP did not ride it around.
There is a thread for the controller. Nanjing far driver controllers

Glad you are using a strong frame and look forward to the build.
 
Think the death bike was more of what could be done on a bike frame. More for racing than for riding around on, not that LFP did not ride it around.
There is a thread for the controller. Nanjing far driver controllers

Glad you are using a strong frame and look forward to the build.
[/quote]

After yet more research I’ve decided on a 108v system, with a FarDriver ND108850, which itself comes with complications with discharge rates and my biggest problem now, a BMS for a battery of this size with these sorts of current flow. I’ll still be going with a 3.5t QS273 50H, with the same CO20B cells making up the pack… just need to find a BMS that can handle 850A at 120v for 15 seconds and sustain 500A at 108v constantly… this is proving to be a rabbit hole of options 😬
 
Re: finding a BMS that will pass 850 amps:

I’m out of my depth here, but I believe most super-high-draw vehicles manage their batteries by having a remote BMS that can sense and balance, but modulates a contactor for circuit (dis)connection. The contactor is designed to handle the amps (if properly spec’ed), as opposed to asking the BMS to electrically disconnect the circuit.

Additionally, BMS’s can fail shut, allowing current to flow with no protection. Contactors, on the other hand, need power to close the circuit and are more likely to fail into an open (disconnected) circuit.

Something to consider — keep the updates coming!
 
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