Search found 4942 matches

by Punx0r
Feb 04 2020 10:25am
Forum: E-Bike Technical
Topic: How do I step voltage down with low losses, weight and size?
Replies: 43
Views: 2147

Re: How do I step voltage down with low losses, weight and size?

Maybe there's some way to do a simple voltage divider since I run dual controllers into a 6 phase motor that has 2 electrically separate sets of 3 phases. This is seriously ghetto, but if you put a single dioide across the mains (half wave rectification) you will get (110 x 1.414)/2 = 77.8VDC ...bu...
by Punx0r
Feb 04 2020 9:52am
Forum: E-Bike Technical
Topic: Hub motor high frequency noise
Replies: 13
Views: 1317

Re: Hub motor high frequency noise

Tight, well laquered windings will vibrate less. Have a look at this article for a bit on magnetically induced noise: https://eomys.com/e-nvh/notes-on-electromagnetically-excited-noise-and-vibrations/article/magnetic-noise-and-vibrations-in-electrical-machines?lang=en/ Transformers hum or buzz due t...
by Punx0r
Feb 03 2020 3:55am
Forum: Motor Technology
Topic: Hub motors - Why such bad power to weight
Replies: 3
Views: 559

Re: Hub motors - Why such bad power to weight

<t>Because comparitively they are high-torque, low speed machines with a large diameter. Torque production requires active materials (iron, copper) in quantity and the diameter requires significant support structure for not only these active materials but also to carry the weight of the vehicle (bei...
by Punx0r
Jan 31 2020 4:53am
Forum: E-Bike Technical
Topic: Hub motor high frequency noise
Replies: 13
Views: 1317

Re: Hub motor high frequency noise

It's worth trying sticking something to the outside of the covers to see if you can damp it. Maybe any old thing as a test and if it works go for the thick ally you suggest that won't inhibit heat dissipation. Harmonics can be a fickle thing. A certain motor on a certain controller at certain settin...
by Punx0r
Jan 31 2020 4:12am
Forum: Motor Technology
Topic: Same debate again, motor windings!
Replies: 96
Views: 6448

Re: Same debate again, motor windings!

I think of cogging as only a pulling of a magnet away from a tooth not pushing. It is a loss while free coasting and also while powered to a lesser degree with the unpowered teeth i think. If the magnets were always only pulling then the motor would spin indefinitely on its own ;) If you turn the m...
by Punx0r
Jan 30 2020 2:03pm
Forum: Motor Technology
Topic: Same debate again, motor windings!
Replies: 96
Views: 6448

Re: Same debate again, motor windings!

Justin knows a lot about motors and puts a lot of time and effort into researching and writing about them, so if there's anything he says that contradicts what I've said then definitely go with what he says :wink: I always think what the average lay ebike user calls cogging is really the drag of the...
by Punx0r
Jan 30 2020 4:25am
Forum: Motor Technology
Topic: Same debate again, motor windings!
Replies: 96
Views: 6448

Re: Same debate again, motor windings!

No doubt the low iron losses also contribute to low drag when coasting too. they're one and the same :P STOP ATTACKING ME!!! I DEMAND RESPECT AND ADORATION!!! Ahem. Sorry. I meant: you are of course correct :) There was some good discussion on cogging recently: the net force averages out to zero (a...
by Punx0r
Jan 29 2020 10:55am
Forum: General Discussion
Topic: What's with this censoring nonsense happening on the forum?
Replies: 151
Views: 14775

Re: What's with this censoring nonsense happening on the forum?

Anyone else notice the parallels between ElectricTim's portrayal of ET and a certain Biblical martyr? :lol:
timidtim wrote:
Jan 29 2020 12:54am
I'm not ElectricGod...
attacks he received from John in CR, Madden88 and LARSB.
Interesting that you both misspell the same name in the same unusual way...
by Punx0r
Jan 29 2020 4:01am
Forum: E-Bike Technical
Topic: Hub motor high frequency noise
Replies: 13
Views: 1317

Re: Hub motor high frequency noise

1000W for 30mph/50kmh is about right for a bicycle with an upright rider. Couple that with the fact you've checked all possible hall signal combinations suggests your problem is not a false-positive hall configuration. I can't view the video at the moment so can't comment on the possible source of t...
by Punx0r
Jan 29 2020 3:48am
Forum: Motor Technology
Topic: Same debate again, motor windings!
Replies: 96
Views: 6448

Re: Same debate again, motor windings!

Interesting summary, John. The advantages of low phase-resistance and pole count often seem to be countered by a motor that's very hard on controllers, but with yours being split in to 2 x 3 phases, it neatly side-steps that issue. No doubt the low iron losses also contribute to low drag when coasti...
by Punx0r
Jan 27 2020 4:31am
Forum: Motor Technology
Topic: Same debate again, motor windings!
Replies: 96
Views: 6448

Re: Same debate again, motor windings!

Having a high ratio of end-turn length to active winding between the stator teeth intuitively would seem to favour long stator motors, yet it's interesting to observes that many high-efficiency BLDC motors are slim, panacake style construction. So there's definitely more to it than "do all you can t...
by Punx0r
Jan 25 2020 5:17am
Forum: E-Bike Technical
Topic: Doesn't make sense.. does my battery broken?33mΩ too much ir??
Replies: 23
Views: 1390

Re: Doesn't make sense.. does my battery broken?33mΩ too much ir??

It's not "my method" - it's Georg Ohm's method. I've repeatedly stated you must account for SoC and temperature, so your argument above is moot. Please post details of the method YOU use to determine a more accurate measurement of DC IR. The one that doesn't use Ohm's Law. Because you haven't sugges...
by Punx0r
Jan 24 2020 4:50am
Forum: E-Bike Technical
Topic: Doesn't make sense.. does my battery broken?33mΩ too much ir??
Replies: 23
Views: 1390

Re: Doesn't make sense.. does my battery broken?33mΩ too much ir??

I left this thread alone hoping it would just quietly go away, but since you're bring it back up: "The two-tier DC load method offers an alternative method by applying two sequential discharge loads of different currents and time duration. The battery first discharges at a low current for 10 seconds...
by Punx0r
Jan 23 2020 3:25am
Forum: Battery Technology
Topic: Help me build a quality, datalogging, charging/discharge bank @ home, DIY.
Replies: 56
Views: 3348

Re: Help me build a quality, datalogging, charging/discharge bank @ home, DIY.

They are expensive but so is a five grand bench PSU and the OP says he's got money to spend. The crestchic units are widely used in private industry, not just government projects. There may be cheaper alternative manufacturers.
by Punx0r
Jan 22 2020 3:44am
Forum: E-Vehicles General Discussion
Topic: Wind and Solar vs Coal, Gasoline, Nuclear
Replies: 6287
Views: 346473

Re: Wind and Solar vs Coal, Gasoline, Nuclear

Pls quote the part of the article that says AGW is/will accelerate plate tectonics. kthxbye
by Punx0r
Jan 21 2020 10:06am
Forum: Battery Technology
Topic: Practical advice on achieving the 10min full charge LTO(Titanate) cells are meant to deliver
Replies: 65
Views: 4366

Re: Practical advice on achieving the 10min full charge LTO(Titanate) cells are meant to deliver

Ride a folding bike long distance? Nope! ... and Street AC/DC recharging in 40mins ... As to 25kg+ battery it's not a deal breaker on its own ... 25kg (by the time it's built into a sturdy pack you're looking at ~30kg) on a bike frame is a lot. Before commiting to something like that I really would...
by Punx0r
Jan 21 2020 9:59am
Forum: Battery Technology
Topic: Practical advice on achieving the 10min full charge LTO(Titanate) cells are meant to deliver
Replies: 65
Views: 4366

Re: Practical advice on achieving the 10min full charge LTO(Titanate) cells are meant to deliver

10min charge (6C) can be achieved on LiCO cells - just look at the RC world. Not very safely at dozens of kW Nor conducive to cell longevity You don't have to buy RC cells - they're just the cheapest and most readily available. TBH the price of 6C-capable cells is not the most serious drawback in t...
by Punx0r
Jan 21 2020 3:41am
Forum: Battery Technology
Topic: Practical advice on achieving the 10min full charge LTO(Titanate) cells are meant to deliver
Replies: 65
Views: 4366

Re: Practical advice on achieving the 10min full charge LTO(Titanate) cells are meant to deliver

Ride a folding bike with a 25kg+ battery? Nope!
Ride a folding bike long distance? Nope!

10min charge (6C) can be achieved on LiCO cells - just look at the RC world.
by Punx0r
Jan 21 2020 3:30am
Forum: E-Vehicles General Discussion
Topic: Wind and Solar vs Coal, Gasoline, Nuclear
Replies: 6287
Views: 346473

Re: Wind and Solar vs Coal, Gasoline, Nuclear

No, that article absolutely does not support the argument presented by ZeroEM.
by Punx0r
Jan 17 2020 3:38am
Forum: E-Vehicles General Discussion
Topic: Wind and Solar vs Coal, Gasoline, Nuclear
Replies: 6287
Views: 346473

Re: Wind and Solar vs Coal, Gasoline, Nuclear

The Australian government unfortunately appears to be in the pocket of it's coal industry. Renewable energy and EV use are way below average for OECD countries.
by Punx0r
Jan 15 2020 6:41am
Forum: Motor Technology
Topic: ESC, 14S 300A $700, waterproofed
Replies: 1
Views: 747

Re: ESC, 14S 300A $700, waterproofed

Would love to see one torture tested on a dyno 8)
by Punx0r
Jan 14 2020 10:31am
Forum: E-Vehicles General Discussion
Topic: Wind and Solar vs Coal, Gasoline, Nuclear
Replies: 6287
Views: 346473

Re: Wind and Solar vs Coal, Gasoline, Nuclear

One thing that would help, regardless of any prediliction for climate change denialism, is to stop cutting down the forests that transport water from the coast inland.
by Punx0r
Jan 14 2020 5:42am
Forum: Motor Technology
Topic: Why more KV = more power, the Maximum Power Transfer Theorem
Replies: 51
Views: 4268

Re: Why more KV = more power, the Maximum Power Transfer Theorem

This is true. I think a lot of information out there is more relevant/true to battery-fed DC brushed motors with simple switched control.
by Punx0r
Jan 14 2020 4:16am
Forum: E-Vehicles General Discussion
Topic: Can EVs survive without subsidies ?
Replies: 100
Views: 9262

Re: Can EVs survive without subsidies ?

Hillhater wrote:
Jan 13 2020 6:00am
True, but you still have to lubricate the cylinder walls somehow.
Most of those large marine “diesels” run on fuel that is closer to sump oil than it is diesel :shock:
Yes, you do it the conventional way: from below the piston and use oil control rings.

Yep, bunker fuel