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by liveforphysics
Mar 22 2019 1:47am
Forum: Motor Technology
Topic: Revolt RV-series motor review and comparisons
Replies: 163
Views: 7022

Re: Revolt RV-series motor review and comparisons

Shock loads from impacts, even potholes hit by the tamest of riders put so much higher loads on the powertrain than propulsion torque loads, you don't design a powertrain around the torque loads at all, but the shock loads.
by liveforphysics
Mar 21 2019 4:52pm
Forum: Motor Technology
Topic: Revolt RV-series motor review and comparisons
Replies: 163
Views: 7022

Re: Revolt RV-series motor review and comparisons

As already mentiond, it is the Loctite 648 which should be used for that. The feather key should be up to the task for what the motor is capeable to deliver to the shaft, but i agree that it is a little bit undersized. btw: it is the torque which will shear off the key and not the power! :wink: You...
by liveforphysics
Mar 21 2019 4:25pm
Forum: E-Bike General Discussion
Topic: MiniDyno motor test bench..scaleable 0-50kW
Replies: 9
Views: 510

Re: MiniDyno motor test bench..scaleable 0-50kW

I'm excited to see it running and the learning that comes out of it!

I like that you could make that style of dyno configured towards testing small motors or large motors just by bolting more flywheel plates on or removing them.
by liveforphysics
Mar 21 2019 3:41pm
Forum: Battery Technology
Topic: New weldless battery system crowdfunfing project
Replies: 59
Views: 1599

Re: New weldless battery system crowdfunfing project

The clamping force needs to not be via a low-area "point", but spread over a flat contact area in order to lower the pressure psi. Better electrically too, more surface area for lower resistance higher conductivity. There are conductive epoxies as well, the physical cell-holding force does not need...
by liveforphysics
Mar 21 2019 1:21pm
Forum: Items Wanted
Topic: Looking for a hub motor expert in california
Replies: 6
Views: 156

Re: Looking for a hub motor expert in california

I'm intimately and passionately involved with hotroding and high performance hubmotor development. Also an hour drive (in good traffic) from San Diego.
The only downside is my consulting company is slammed with excessive work, but something could work out for the right project.
by liveforphysics
Mar 21 2019 1:06am
Forum: E-Vehicles General Discussion
Topic: Motor kv and efficiency
Replies: 5
Views: 127

Re: Motor kv and efficiency

Identical power to make your amp turns in a 1t or a 100t.

This is because the current path gets shorter and fatter as turns decrease or longer and thinner as turns increase, this change perfectly balances the I^2*R losses.
by liveforphysics
Mar 20 2019 11:56pm
Forum: E-Vehicles General Discussion
Topic: Motor kv and efficiency
Replies: 5
Views: 127

Re: Motor kv and efficiency

The motor only feels the magnetic field in the slot with respect to making torque. The magnetic field is exactly proportional to amp*turns. It doesn't matter how you get the amp turns.
by liveforphysics
Mar 20 2019 2:15pm
Forum: E-Bike General Discussion
Topic: MiniDyno motor test bench..scaleable 0-50kW
Replies: 9
Views: 510

Re: MiniDyno motor test bench..scaleable 0-50kW

I would use brake drums from semi-trucks. They spin nicely and when they're worn-out you can get them for scrap iron prices.
by liveforphysics
Mar 20 2019 2:12pm
Forum: E-Vehicles General Discussion
Topic: Motor kv and efficiency
Replies: 5
Views: 127

Re: Motor kv and efficiency

Iron losses quickly exceed copper losses if you just keep spinning faster. Consider the slot area from a cross sectional perspective like you sliced through all the end-turns to just see the copper fill in the slot. Not imagine you can power those little pieces of wire in the slot by directly touchi...
by liveforphysics
Mar 20 2019 12:57pm
Forum: Battery Technology
Topic: 26s BMS for 600A max?
Replies: 10
Views: 176

Re: 26s BMS for 600A max?

What controller would 26s make sense for? If you're already eating the penalty of 150V mosfets, you want to run 28s. Hi I didn't find any topic with similar information, so I hope you could help me. I'm working on a 26s50p battery pack for an electric motorcycle. I need a BMS capable of dealing with...
by liveforphysics
Mar 19 2019 1:38pm
Forum: E-Bike General Discussion
Topic: Disadvantages of higher Battery Voltage
Replies: 47
Views: 1952

Re: Disadvantages of higher Battery Voltage

If i was building an EV to take on top fuel dragster records, I would run 20s. If I was building a solar car for maximum efficiency, I would run ~10-20s. If I was building an ebike to run at say <5kW, I would run ~10s-20s depending on controller/motor pairing. Once you master high current interconne...
by liveforphysics
Mar 18 2019 8:59pm
Forum: E-Bike Non-hub Motor Drives
Topic: Sur-Ron - New Mid drive Bike
Replies: 3229
Views: 206175

Re: Sur-Ron - New Mid drive Bike

The 8000 will still give you a big torque advantage at low motor speeds even if they have the same ultimate battery limited peak HP. Since torque/thrust is what the user feels, the 8000 feels that much more nuts than the 4000 up until you're reaching the battery power limits. That said, a 4000 is st...
by liveforphysics
Mar 18 2019 4:08pm
Forum: E-Bike Build Threads / Photos & Video
Topic: Insanity V3
Replies: 51
Views: 2713

Re: Insanity V3

If you're trusting the heat-shrink to be an insulator between the can walls of different series groups, you will find a little vibration quickly chafes through until it shorts out. The heatshrink is a material which also creeps as well as having poor abrasion resistance.
by liveforphysics
Mar 18 2019 3:35pm
Forum: General Discussion
Topic: using voltage sag as indication of bad battery
Replies: 11
Views: 173

Re: using voltage sag as indication of bad battery

Every BMS I've worked with in the last 8 years tracks both the state of health in capacity as well as the state of health in impedance.

I've not been working with alibaba ebike BMS's though, which are lucky to just balance a pack without killing it themselves.
by liveforphysics
Mar 15 2019 11:46am
Forum: Motor Technology
Topic: Serious FOCer (84V VESC 6 based controller)
Replies: 13
Views: 444

Re: Serious FOCer (84V VESC 6 based controller)

Woot!!! Yes to TO247 based VESC!!!
by liveforphysics
Mar 14 2019 5:53pm
Forum: E-Scooter and Motorcycle General Discussion
Topic: MotoE paddock fire - all bikes destroyed!
Replies: 13
Views: 421

Re: MotoE garage fire

A witness claimed a prototype charger started smoking unexpectedly while the bikes were not charging at that time. Then the charger caught fire and caught the tent on fire and spread to the whole paddock. I wish them all well and I'm so excited to see this electric GP series of racing! Evidently the...
by liveforphysics
Mar 14 2019 5:07pm
Forum: Battery Technology
Topic: capacitor lipo hybrid. did i predict the future again?
Replies: 11
Views: 354

Re: capacitor lipo hybrid. did i predict the future again?

Every lithium battery you've ever used is already intrensically a super capacitor in parallel with an electrochemical cell. Well, it's a capacitor, at least. And I would add that pretty much every battery - every battery that has parallel plates with a small amount of electrolyte between them, whic...
by liveforphysics
Mar 14 2019 3:38pm
Forum: E-Bike Non-hub Motor Drives
Topic: SURRON LB: RESEARCH & DEVELOPEMENT
Replies: 153
Views: 10169

Re: SURRON LB: RESEARCH & DEVELOPEMENT

Nice job sir! That gives a nice boost in range!
by liveforphysics
Mar 14 2019 12:59pm
Forum: E-Bike Non-hub Motor Drives
Topic: SURRON LB: RESEARCH & DEVELOPEMENT
Replies: 153
Views: 10169

Re: SURRON LB: RESEARCH & DEVELOPEMENT

Range isn't something you're going to improve greatly with a cell swap, because range is about energy. You could improve it some (maybe 25-35% with a MJ1 cell or 35E cell, or M50 cell). The cell swap advantages come from the ability to double/triple the power available from a pack at the stock weigh...
by liveforphysics
Mar 13 2019 8:03pm
Forum: General Discussion
Topic: Discharge unbalanced battery
Replies: 7
Views: 184

Re: Discharge unbalanced battery

An incandescent car headlight bulb, or a bunch of car headlight bulbs with both high beam and low beam wired all together in parallel is a crude but functional method.
by liveforphysics
Mar 13 2019 5:45pm
Forum: E-Bike Non-hub Motor Drives
Topic: Sur-Ron - New Mid drive Bike
Replies: 3229
Views: 206175

Re: Sur-Ron - New Mid drive Bike

Beautiful belt drive setup!! Great video showing the sound difference too! Once you go belt it's hard to go back to anything else. I bet all the components combined together in that belt drive conversion kit weigh less than the mass of the chain alone, and have lower losses at all torque levels and ...
by liveforphysics
Mar 11 2019 10:13pm
Forum: E-Scooter and Motorcycle General Discussion
Topic: Alta Motors Redshift
Replies: 115
Views: 5143

Re: Alta Motors Redshift

New guy here... I have come across this site, and recently a buddy from Joby said it is the leader for this stuff. I have two Redshifts, a 2017 MX019 and a 2018 EX006. They so rock. i sold my KTM250MXC, but still have a 2001 TM 250 2T, and an R6, and. TM 530 BlackDream. And an ATK. I am not an addi...
by liveforphysics
Mar 11 2019 6:09pm
Forum: E-Bike Non-hub Motor Drives
Topic: SURRON LB: RESEARCH & DEVELOPEMENT
Replies: 153
Views: 10169

Re: SURRON LB: RESEARCH & DEVELOPEMENT

30Q ages well in high-rate use situations and poorly in low-C rates. 30T is a 2170, but has fantastic power density, and would be the ultimate hotrod/drag pack cell. 40T is also a 2170, and has good power and fair energy density. LG M50 has good power and great energy density. The best cell for you ...
by liveforphysics
Mar 11 2019 2:04pm
Forum: Battery Technology
Topic: What battery to choose after your last one burned your house.
Replies: 43
Views: 1339

Re: What battery to choose after your last one burned your house.

.......and howmany cars that run on liquid dino juice burn down every day for no reason? ..... Sure,.....but again you are avoiding the point...that there is no totally safe, non flamable , 18650 lithium pack . Remember your statement earlier.... 18650 is the only way. a single 18650 hold roughly 1...