Search found 13820 matches

by liveforphysics
Dec 17, 2017 3:46 am
Forum: E-Bike Technical
Topic: Specific heat absorption capacity of disc brakes
Replies: 47
Views: 850

Re: Specific heat absorption capacity of disc brakes

Road bike brakes don't clear the mud off the tires to keep pedaling in my cyclocross raceing. Disc's give a consistent function and feel no matter how muddy the rims and tires are by the end of the race. I also tend to get a good deal of wheel deformation run out by the end of a hard ride or race th...
by liveforphysics
Dec 15, 2017 11:50 pm
Forum: E-Bike Technical
Topic: Specific heat absorption capacity of disc brakes
Replies: 47
Views: 850

Re: Specific heat absorption capacity of disc brakes

You ultimately win at brakes through whatever mechanism enables the highest rates of energy transfer. This is why racecar brake rotors float on the disc mounting hat, and just operate glowing red visibly while braking. Brakes on F1 cars use carbon-ceramic rotor materials to glow at 1200degC to trans...
by liveforphysics
Dec 13, 2017 6:19 pm
Forum: General Discussion
Topic: ? Gross Brake = 3000w Brushless Hub motor
Replies: 20
Views: 199

Re: ? Gross Brake = 3000w Brushless Hub motor

Yep, likely not peaking 3hp shaft power from 3kW input.

Trying to dyno something for repeatable single digit percentage accuracy is also impractical, as even during the pull as the system warms its changing efficiency, and realistic batteries sag unlike a dyno power supply.
by liveforphysics
Dec 13, 2017 6:14 pm
Forum: Motor Technology
Topic: Last night I had a compact SynSR outrunner nightmare...(open source project)
Replies: 8
Views: 263

Re: Last night I had a compact SynSR outrunner nightmare...

You can see that between those FETs, the 150v part has substantially improved power switching per device than the 200vdc part right? Or you look at it like units of controller heating per amount of drive power, and you find staying lower voltage improves every performance metric. The power bussing m...
by liveforphysics
Dec 13, 2017 3:13 am
Forum: E-Vehicles General Discussion
Topic: Wind and Solar vs Coal, Gasoline, Nuclear
Replies: 1126
Views: 19797

Re: Wind and Solar vs Coal, Gasoline, Nuclear

It's a small-scale pack for grid.

How awesome someone is taking a step towards an energy supply that doesn't ensure extermination of our species by continued use.
by liveforphysics
Dec 13, 2017 3:06 am
Forum: E-Bike Non-hub Motor Drives
Topic: Sur-Ron - New Mid drive Bike from China
Replies: 186
Views: 10871

Re: Sur-Ron - New Mid drive Bike from China

I had some friends who used that motor spinning props, and the efficiency was sad and heating was sad, but it did work for while. They went to a Joby motor and it ended up having half the losses. With motors its tough to know if it's the motor that sucks or the motor/controller combo that sucks, so ...
by liveforphysics
Dec 13, 2017 3:01 am
Forum: Motor Technology
Topic: Last night I had a compact SynSR outrunner nightmare...(open source project)
Replies: 8
Views: 263

Re: Last night I had a compact SynSR outrunner nightmare...

Drop the voltage from 150 if you want to have good power density in the controller.

SR is the future! Nice short flux path rotor!

Magnets won't be a part of mature EVs.
by liveforphysics
Dec 11, 2017 12:48 pm
Forum: General Discussion
Topic: Dirt bike fork on an ebike?
Replies: 14
Views: 229

Re: Dirt bike fork on an ebike?

I had to cut the head tube off the frame and lathe up a new one and weld it on each time I changed front ends.
by liveforphysics
Dec 10, 2017 8:58 pm
Forum: General Discussion
Topic: Dirt bike fork on an ebike?
Replies: 14
Views: 229

Re: Dirt bike fork on an ebike?

If you're used to the feel of the flex in bicycle suspension and wheels, and it's not breaking on you then you're good. I broke even a fox36 fork, and melted down and wadded up the biggest downhill bike brake rotors before finishing races. Most ebike applications have lower component stress levels w...
by liveforphysics
Dec 10, 2017 7:59 pm
Forum: General Discussion
Topic: Dirt bike fork on an ebike?
Replies: 14
Views: 229

Re: Dirt bike fork on an ebike?

I ran a dirtbike front end (forks, wheel, brakes) and a superbike front end (forks wheel and huge dual disc brakes), and both felt great to me. If your riding style involves a lot of hopping you might not like it over bicycle parts, but they feel great and even a single dirtbike brake is better than...
by liveforphysics
Dec 09, 2017 8:09 pm
Forum: Battery Technology
Topic: Super capacitors to save battery life?
Replies: 44
Views: 853

Re: Super capacitors to save battery life?

Maybe I'm not understanding correctly, but if you had a pair of 15Ah packs and you only connected one at to your bike when discharging, just connecting both of them in parallel to be a 30Ah pack would be the greatest return on useful cycle life and cost nothing.
by liveforphysics
Dec 09, 2017 2:37 am
Forum: Motor Technology
Topic: Game Changer Page 3 with video of 1700amps!!!!
Replies: 84
Views: 9478

Re: Game Changer Page 3 with video of 1700amps!!!!

i am talking about using proper milspec connectors rated for the task, not stuff to fix dodgy undersized connectors. Milspec often just means it uses 1950s threaded cannon plugs that suck for cost or to package the space necessary to install. The some of the worst connectors I've seen were aircraft...
by liveforphysics
Dec 07, 2017 12:19 am
Forum: Battery Technology
Topic: Super capacitors to save battery life?
Replies: 44
Views: 853

Re: Super capacitors to save battery life?

If you have a 1,000F 2.7v cap, and you put 10 in series you have a 100F 27v capacitor.
by liveforphysics
Dec 06, 2017 8:32 pm
Forum: Battery Technology
Topic: Super capacitors to save battery life?
Replies: 44
Views: 853

Re: Super capacitors to save battery life?

When you work the numbers on it, for the same amount of weight, volume and cost you add to the vehicle, more battery vs more capacitor makes for longer life as well as potentially better range for the times you need to use all of it. Awesome trip! I've been thinking about trying to hit the south pol...
by liveforphysics
Dec 05, 2017 10:35 pm
Forum: Motor Technology
Topic: Hi power inverter for Nissan leaf motor. Dyno's 302.3hp p15
Replies: 506
Views: 38793

Re: Hi power inverter for Nissan leaf motor. Dyno's 302.3hp p15

I finally saw your video! Outstanding!
Way to represent EVs!
by liveforphysics
Dec 04, 2017 8:42 pm
Forum: E-Bike General Discussion
Topic: Mobipus FOC sine wave controller
Replies: 11
Views: 542

Re: Mobipus FOC sine wave controller

You can still get more power from a ~20s system. That's an amazing drag time! My ebike runs 11.51 @ 110.5mph in the quarter mile, and if I were going to do a ground up unlimited budget and time build, I would change my bike from 28s to 20s and run a turn less on the motor. I already have a complete ...
by liveforphysics
Dec 03, 2017 6:04 am
Forum: E-Bike Photos & Video
Topic: my workshop burned down and then what happened
Replies: 3
Views: 210

Re: my workshop burned down and then what happened

Condolences. Looks like many creative art bike builds.
by liveforphysics
Dec 03, 2017 6:01 am
Forum: E-Bike General Discussion
Topic: Reliable 4 season car replacement practicalities
Replies: 16
Views: 397

Re: Reliable 4 season car replacement practicalities

Get some adequately powered heated riding gear. I made my own from adding carbon fiber tow (spools are cheap on ebay) and using crimp connectors to join it to copper wire, use silicone rtv to bond it to the inside of your riding gear and run from a 12v DCDC. I've riden in freezing rain over a mounta...
by liveforphysics
Dec 03, 2017 1:15 am
Forum: E-Bike General Discussion
Topic: Reliable 4 season car replacement practicalities
Replies: 16
Views: 397

Re: Reliable 4 season car replacement practicalities

On a fast ebike, 20-30mile trips take about the same time as a car, while being a lot more fun IMHO.
by liveforphysics
Dec 01, 2017 6:27 pm
Forum: E-Vehicles General Discussion
Topic: Madness. Why such slow penetration for hybrid?
Replies: 65
Views: 1251

Re: Madness. Why such slow penetration for hybrid?

Fossil fuels are subsidized annually at a tune of ~$5.3 TRILLION. https://www.scientificamerican.com/article/fossil-fuel-subsidies-cost-5-trillion-annually-and-worsen-pollution/ The sum of all RE subsidies combined through the history of humanity is less than a single year of fossil fuel subsidies. ...
by liveforphysics
Nov 30, 2017 5:21 pm
Forum: E-Vehicles General Discussion
Topic: Wind and Solar vs Coal, Gasoline, Nuclear
Replies: 1126
Views: 19797

Re: Wind and Solar vs Coal, Gasoline, Nuclear

No matter where you live, if the air is poisoned, it's not going to make any difference if you're a billionaire or broke, if interior surfaces of your home are warm or cold, how much snow or sunshine may be around, or how whatever metrics related to 'economy' may be, because you're dying or dead. Su...
by liveforphysics
Nov 29, 2017 6:14 am
Forum: E-Vehicles General Discussion
Topic: Wind and Solar vs Coal, Gasoline, Nuclear
Replies: 1126
Views: 19797

Re: Wind and Solar vs Coal, Gasoline, Nuclear

sendler2112 wrote:
Nov 28, 2017 6:11 pm
billvon wrote:
Nov 28, 2017 11:58 am
I lived in Boston for four years.
You should know better than to say many of the things you have been saying.
Works fine in Minnesota winter to be 1-wheel drive.
by liveforphysics
Nov 29, 2017 3:27 am
Forum: E-Bike General Discussion
Topic: The 10.000W target!
Replies: 62
Views: 2872

Re: The 10.000W target!

I can vouch John's bikes are all 10kW+ and easily do 60mph+ Only the bike I made for my wife has been under 10kW so far, and it's 8kW. One man's rocket is another man's snoozer commuter. That said, use the best suspension, brakes, wheels and tires available if you're going bicycle parts vs scooter w...
by liveforphysics
Nov 28, 2017 5:48 pm
Forum: E-Vehicles General Discussion
Topic: Wind and Solar vs Coal, Gasoline, Nuclear
Replies: 1126
Views: 19797

Re: Wind and Solar vs Coal, Gasoline, Nuclear

Do mind that the other 99% of the country looks more like this: Summer means staying inside in AC for ~3 months. Winter means staying inside in heat for ~3 months and preferably owning an all wheel drive car large enough to handle the impact from all the various idiots from California sliding their...
by liveforphysics
Nov 28, 2017 7:40 am
Forum: E-Vehicles General Discussion
Topic: Madness. Why such slow penetration for hybrid?
Replies: 65
Views: 1251

Re: Madness. Why such slow penetration for hybrid?

Landing at the airport at LAX today, it was a delight to see maybe 1/4 of the taxis and 1/2 of the uber pickup cars were already pure EVs. GM bolt makes a taxi or uber car no gas/hybrid taxi could be competitive with already, and EVs will only get cheaper and better.