bhartshorn
1 mW
Hello everyone, just a noobie EV enthusiast here. I've wanted to build an ebike/escooter for many years but haven't had the time or means.
Anyway, I picked up this "GT Asteroid" electric scooter a while back with the intention of overhauling it with LiPo, brushless outrunner, real controller etc. It's finally time to get started! I am looking for some advice and guidance as I purchase some first parts. I should state my goals first, I suppose:
So, my plan right now is this:
Motor & Drivechain
In order to get started, I need to get the motor ordered, so I need to decide on a motor KV. I have a basic understanding of KV from building RC planes, but I'm not confident I understand how it applies to torque-y loads. I built a spreadsheet to play with gearing, voltage and KV.
Can someone take a look at my spreadsheet and check if I'm on the right track? It can be downloaded here (LibreOffice Calc format):
https://files.thehartshorns.net/f/a5e73d3821484282bfcd/
So, the existing drivetrain is:
#25 chain, 90 tooth wheel sprocket, 16 tooth motor sprocket
I would like to avoid the trouble of changing to a heavier chain and sprocket standard, but I'm not sure the #25 chain is heavy enough. The nice thing about the #25 chain is that I can very easily (and very cheaply) get different sized motor sprockets and replacement chain. Is this chain basically guaranteed to fail with the amount of power I'm looking at?
Next, motor KV:
With the existing gearing (16/90), 48V, I'm looking at a "max speed" of:
I highly doubt I will get ~41 from the 130KV motor at 48 volts, seems counter-intuitive from what I've seen with other builds. I don't like either of these KV options with the stock gearing, so I'm thinking about these options for gearing:
So, can you all help me choose? From my RC experience, I have the impression that, for a given motor size, you can squeeze more raw power out of a higher-kv motor at the expense of running hotter. I also understand that properly matching voltage and gearing probably has a larger influence.
Motor Controller
The motor controller doesn't seem like an overly hard decision, there just seems to be so many options, and I haven't seen them enumerated anywhere, so I could use some recommendations. From what I've seen regarding this motor, I'm spitballing that this configuration will be around 3-4kW, but my specialty is computers, not electrical design, so correct me if I'm wrong. From what I've seen around here (especially ElectricGod's posts), a decently-built 12FET controller should be sufficient, especially with upgraded mosfets (if needed).
I'm considering between these options:
Are there any others I should consider? I definitely want regen, and open-source/open development/frequent updates is a huge selling point for me. That said, I would like to be able to go a bit cheaper if there's something that offers competitive performance.
Motor Mount
The existing motor mount is awful. Here are a few pictures:
https://files.thehartshorns.net/d/eb5359897d944221b676/
It is sandwiched between two nuts on the wheel axle, and anchored with one bolt to the frame. Should I just use this and deal with the awkwardness, or should I try to replace it? I have access to a TIG/stick welder for a couple more months, so I could weld to the frame, but maybe there's downsides to that that I don't understand?
Anyway, thank for reading down this far. I really appreciate this community, you are a great bunch! (I've been lurking for a couple years; hah) I promise I'll turn this into a build thread when I actually get something done!
Anyway, I picked up this "GT Asteroid" electric scooter a while back with the intention of overhauling it with LiPo, brushless outrunner, real controller etc. It's finally time to get started! I am looking for some advice and guidance as I purchase some first parts. I should state my goals first, I suppose:
- keep close to stock FOR NOW. This means utilize stock wheels, brakes, throttle, battery tray, etc
- reliable (simple, robust drivetrain)
- decent power
- ~20 miles range is sufficient
- I don't mind spending money on good components, but I want to keep the expensive "quality" parts to a minimum and re-use existing or buy budget parts where possible.
So, my plan right now is this:
- replace stock motor with sensored Alien Power C80100
- match the motor with an appropriate motor controller which can grow with the build (higher voltage, higher gearing, etc)
- probably 48V worth of hobbyking RC LiPo packs - I will likely go higher voltage later
- use existing chain & sprocket, changing motor sprocket if needed
- use existing brakes, I realize they suck (rim brake and odd "band" brake)
- use existing thumb throttle - I can hack together a microcontroller to translate if needed
Motor & Drivechain
In order to get started, I need to get the motor ordered, so I need to decide on a motor KV. I have a basic understanding of KV from building RC planes, but I'm not confident I understand how it applies to torque-y loads. I built a spreadsheet to play with gearing, voltage and KV.
Can someone take a look at my spreadsheet and check if I'm on the right track? It can be downloaded here (LibreOffice Calc format):
https://files.thehartshorns.net/f/a5e73d3821484282bfcd/
So, the existing drivetrain is:
#25 chain, 90 tooth wheel sprocket, 16 tooth motor sprocket
I would like to avoid the trouble of changing to a heavier chain and sprocket standard, but I'm not sure the #25 chain is heavy enough. The nice thing about the #25 chain is that I can very easily (and very cheaply) get different sized motor sprockets and replacement chain. Is this chain basically guaranteed to fail with the amount of power I'm looking at?
Next, motor KV:
With the existing gearing (16/90), 48V, I'm looking at a "max speed" of:
- ~25mph for 80KV
- ~41mph for 130KV
I highly doubt I will get ~41 from the 130KV motor at 48 volts, seems counter-intuitive from what I've seen with other builds. I don't like either of these KV options with the stock gearing, so I'm thinking about these options for gearing:
- (18/90) with 80KV for "max speed" ~28MPH
- (14/90) with 130KV for "max speed" ~36MPH
So, can you all help me choose? From my RC experience, I have the impression that, for a given motor size, you can squeeze more raw power out of a higher-kv motor at the expense of running hotter. I also understand that properly matching voltage and gearing probably has a larger influence.
Motor Controller
The motor controller doesn't seem like an overly hard decision, there just seems to be so many options, and I haven't seen them enumerated anywhere, so I could use some recommendations. From what I've seen regarding this motor, I'm spitballing that this configuration will be around 3-4kW, but my specialty is computers, not electrical design, so correct me if I'm wrong. From what I've seen around here (especially ElectricGod's posts), a decently-built 12FET controller should be sufficient, especially with upgraded mosfets (if needed).
I'm considering between these options:
- Nucular controller - https://endless-sphere.com/forums/viewtopic.php?f=31&t=75494
- Power Velocity - http://powervelocity.com/ (Would the 4kW model be sufficient?)
Are there any others I should consider? I definitely want regen, and open-source/open development/frequent updates is a huge selling point for me. That said, I would like to be able to go a bit cheaper if there's something that offers competitive performance.
Motor Mount
The existing motor mount is awful. Here are a few pictures:
https://files.thehartshorns.net/d/eb5359897d944221b676/
It is sandwiched between two nuts on the wheel axle, and anchored with one bolt to the frame. Should I just use this and deal with the awkwardness, or should I try to replace it? I have access to a TIG/stick welder for a couple more months, so I could weld to the frame, but maybe there's downsides to that that I don't understand?
Anyway, thank for reading down this far. I really appreciate this community, you are a great bunch! (I've been lurking for a couple years; hah) I promise I'll turn this into a build thread when I actually get something done!