Search found 230 matches

by thepronghorn
Mar 29 2020 12:31am
Forum: Motor Technology
Topic: 6.5" hub motor advice
Replies: 6
Views: 145

Re: 6.5" hub motor advice

I'd say just use your original motor until it fries. Maybe try statorade to help cool it down between climbs. If you can open the motor up and install a temp sensor, that would also help you roll back the power if it starts overheating.
by thepronghorn
Mar 24 2020 2:33am
Forum: Motor Technology
Topic: 4x4 RC lawnmover - please help for components
Replies: 8
Views: 346

Re: 4x4 RC lawnmover - please help for components

That looks pretty fun. A bit dangerous if there is actually a blade spinning under there and you are driving like that guy in the video... You need 4x reversing esc's capable of around 20A or more. One for each motor. It would be cheaper if you went with just two motors and 2x esc's. Two motors woul...
by thepronghorn
Mar 02 2020 7:50pm
Forum: Motor Technology
Topic: What's so bad about low impedence?
Replies: 30
Views: 1101

Re: What's so bad about low impedence?

what i said in a broader sense to include more than transistors. It all goes back to supply voltage. The power you can get out of a load is given by its resistance (at DC) or its impedance (at AC.) At 32 ohms you can get 4.5 watts out of a 12 volt supply. At 4 ohms you can get 36 watts. So often ca...
by thepronghorn
Feb 25 2020 2:37pm
Forum: General Discussion
Topic: Using BadBoy charger for 30S battery
Replies: 21
Views: 995

Re: Using BadBoy charger for 30S battery

If you don't understand how a badboy charger works, you shouldn't be using one. I'll give you both a hint - you don't.

Without anything to limit current, you will blow your fuse immediately. The peaks of the AC waveform will put 1000s of amps into your battery.
by thepronghorn
Feb 18 2020 3:50pm
Forum: Motor Technology
Topic: Cheap FOCer 2 (Open-source, Low-cost, VESC 6 based ESC) (Prototyped. Materials have arrived for a test batch)
Replies: 45
Views: 5536

Re: Cheap FOCer 2 (Open-source, Low-cost, VESC 6 based ESC) (Prototyped. Materials have arrived for a test batch)

shaman wrote:
Feb 11 2020 11:02pm
SRFirefox wrote:
Feb 11 2020 6:52pm
You could dunk your motor in a tub of water to keep the heat down for the 50A test.
I don't know man. How do I know everything is waterproof up in that motor?
Check phase resistance and insulation resistance. Submerge motor. Repeat measurements.
by thepronghorn
Feb 07 2020 4:46am
Forum: General Discussion
Topic: Forum spell checker???
Replies: 8
Views: 709

Re: Forum spell checker???

markz wrote:
Feb 06 2020 2:13am
so is it the browser or the phpBB forum that underlines, in red, with a squiggly line like in this post, phpBB
it's your browser, right click on the word with the squiggly line, and you will see your browser's spell checking options
by thepronghorn
Feb 04 2020 2:14am
Forum: Motor Technology
Topic: Same debate again, motor windings!
Replies: 96
Views: 5418

Re: Same debate again, motor windings!

https://www.electric-skateboard.builders/t/freewheel-spinning-on-a-mellow-drive/14497 Cogging torque is a "sine save function (repels and attracts equally)" - Mellow boards themselves Just picture a single magnet spinning past some stator teeth. When it is aligned with a tooth, forces are balanced. ...
by thepronghorn
Feb 03 2020 6:53pm
Forum: E-Bike Technical
Topic: How do I step voltage down with low losses, weight and size?
Replies: 43
Views: 1652

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

You need to worry about the peak of the AC waveform, 110*sqrt(2)=156V, being under your battery voltage, so you need a bit more voltage step down than you think. I also doubt the controller will be very happy with pure rectified AC as its voltage source, so you will need to add some capacitance on t...
by thepronghorn
Feb 03 2020 3:52pm
Forum: E-Bike Technical
Topic: Ebikes are they AC, DC or?
Replies: 56
Views: 2231

Re: Ebikes are they AC, DC or?

Motors need AC to spin. Even brushed motors take DC in, but they use their brushes and commutator to convert the DC into AC before it goes to the windings. Switching DC turns it into AC. Just because it's not 60Hz doesn't mean it's not AC. BLDC motors take an AC input of varying frequency and amplit...
by thepronghorn
Jan 30 2020 2:41am
Forum: E-Bike Build Threads / Photos & Video
Topic: Radwagon 72v GMAC Phaserunner Build
Replies: 70
Views: 6010

Re: Radwagon 72v GMAC Phaserunner Build

Correction, my 20 amps max regen is just under a 4C rate. My Panasonic Sanyo GA cells have a charge constant of 1.675 amps. Thus a 3p battery configuration gives a 1C rate of just over 5 amps (5.025 to be exact). So 20 amp charge rate is 3.98C for my battery. To be clear, I am not a battery expert....
by thepronghorn
Jan 28 2020 1:31am
Forum: Stand-up E-scooters and E-skateboards
Topic: Big wheel vs Small wheel scooters - saftey
Replies: 4
Views: 1215

Re: Big wheel vs Small wheel scooters - saftey

Thanks for the reply!! So this is interesting... I figured the kick/dogscooter would be much safer than the 8" ones, and I also figured it was about the same or possibly even a bit safer than a e-bike? Now, I have no idea if this is remotely true, so can you help me understand the technical reasons...
by thepronghorn
Jan 27 2020 3:36pm
Forum: Motor Technology
Topic: Same debate again, motor windings!
Replies: 96
Views: 5418

Re: Same debate again, motor windings!

I still don’t understand how transitions, the magnet wire connecting wound teeth, transits, will have more losses if a high kv and fewest turns. As you show it with parallel strands with your graph if you added resistance of the wire it will decrease in proportion to the more strands in parallel. A...
by thepronghorn
Jan 24 2020 8:30pm
Forum: Motor Technology
Topic: Revolt RV-series motor review and comparisons
Replies: 286
Views: 34890

Re: Revolt RV-series motor review and comparisons

...iron losses as proportional to the square of rpm... That part is a new one for me. I always thought iron losses increase in amostly linear. Below is a quick graph I did using Miles' Motor Comparison Spreadsheet with a HubMonster hubmotor as the motor, for which the input numbers I provided to Mi...
by thepronghorn
Jan 24 2020 5:46pm
Forum: Motor Technology
Topic: Revolt RV-series motor review and comparisons
Replies: 286
Views: 34890

Re: Revolt RV-series motor review and comparisons

When people (including me) have said that peak efficiency is when copper and iron losses are matched, we are basing it on approximating iron losses as proportional to the square of rpm just as copper losses are proportional to the square of torque. This does ignore hysteresis losses which are direct...
by thepronghorn
Jan 23 2020 5:46pm
Forum: Stand-up E-scooters and E-skateboards
Topic: Big wheel vs Small wheel scooters - saftey
Replies: 4
Views: 1215

Re: Big wheel vs Small wheel scooters - saftey

For me, once you move above the convenient size and weight of the 8" scooters, you're probably best off just going to a normal bicycle with 26"+ wheels. I feel like the middle ground dogscooter is kind of the worst of both worlds - not very portable and not as safe as a normal bike. I guess the only...
by thepronghorn
Jan 08 2020 3:36pm
Forum: Motor Technology
Topic: Why more KV = more power, the Maximum Power Transfer Theorem
Replies: 51
Views: 3795

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

I don’t agree, can prove it too :D https://endless-sphere.com/forums/viewtopic.php?f=30&t=102934#p1505953 In theory all is equal but in real life it has limitations. -Controller cannot be matched (within reason) to ALL possible kV and winding. It can get too big, too expensive or too complex to mat...
by thepronghorn
Jan 08 2020 3:05pm
Forum: Motor Technology
Topic: Why more KV = more power, the Maximum Power Transfer Theorem
Replies: 51
Views: 3795

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

john61ct wrote:
Jan 08 2020 1:15pm

....
john61ct, Kv is not going to help your example. We are talking about getting peak power out of motors disregarding heat generation. Changing Kv does not change heat generation for a given torque. I think you know that and were just hoping this thread debunked that. It does not.
by thepronghorn
Jan 08 2020 2:51pm
Forum: Motor Technology
Topic: Why more KV = more power, the Maximum Power Transfer Theorem
Replies: 51
Views: 3795

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

power = torque * rpm torque is proportional to phase current rpm is proportional to bemf thus, power = phase current * bemf Maximum peak power output from a motor is reached at 50% of max speed, 50% of stall torque, 50% efficiency This power usually isn't sustainable or achievable for larger motors ...
by thepronghorn
Jan 04 2020 4:17pm
Forum: Motor Technology
Topic: Why more KV = more power, the Maximum Power Transfer Theorem
Replies: 51
Views: 3795

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

.... Notice how we haven't and will not be able to exceed 1000W of output power from the motor and this peak is at 50% of the unloaded KV and is only 50% efficient. You might notice from the math that if we produce 19.9V BEMF out, the motor is producing 19.9W with 20W input which is 99.5% efficient...
by thepronghorn
Dec 07 2019 3:34am
Forum: E-Bike Non-hub Motor Drives
Topic: My RC Mid Drive with Single Stage Reduction
Replies: 351
Views: 44741

Re: My RC Mid Drive with Single Stage Reduction

.... The only difference is that i use 11t sprocket instead of 10t, but i remember using the same on D5035 and it wasnt even close. I tested it sensorless and with the same phase current of 30A. I would say that in this unfair configuration it's a little bit behind D5035 but very close in terms of ...
by thepronghorn
Dec 06 2019 5:14pm
Forum: E-Bike Non-hub Motor Drives
Topic: Hubs for left side drives?
Replies: 12
Views: 1796

Re: Hubs for left side drives?

Not sure how much money you have, but LMX has a solution.

https://lmxbikes.com/en/spare-parts/94- ... r-hub.html

Image
by thepronghorn
Dec 03 2019 5:27pm
Forum: E-Bike Non-hub Motor Drives
Topic: My RC Mid Drive with Single Stage Reduction
Replies: 351
Views: 44741

Re: My RC Mid Drive with Single Stage Reduction

New toy time: .... This puppy with chinese pedigree is very close in size to the orange D5035 but it's much heavier(~+250g) and at half the price! I wonder if it's more copper in there.. I didn't test it yet cuz i had a hell of a time enlarging the 8mm ID of 11t sprocket to 10mm as this motor's sha...
by thepronghorn
Oct 11 2019 6:42pm
Forum: Motor Technology
Topic: APL's DIY axial-flux motor
Replies: 1017
Views: 86477

Re: APL's DIY axial-flux motor

.... I'm still doing searches on the 1.41T thing, it's difficult to find the right search title. But what I see so far is that indeed, a typical core does approach 1.41T, when the tooth face is closer to 1T. magnetic-flux-density-at-rest-simulation.png Lots to look at yet. Lebowski said 141%T not 1...
by thepronghorn
Jul 29 2019 6:19pm
Forum: Motor Technology
Topic: APL's DIY axial-flux motor
Replies: 1017
Views: 86477

Re: APL's DIY axial-flux motor

flat tire wrote:
Jul 29 2019 1:57pm
APL wrote:
Jul 12 2019 1:49pm
free energy shit
What the hell? The guy that built this beautiful looking motor is one of these people? No wonder he can't get it to work.
Note he said wind to heat generation, so I'm pretty sure he realizes that the energy isn't free free.
by thepronghorn
Jul 29 2019 6:18pm
Forum: Motor Technology
Topic: BESC - beefed up VESC motor controller for high power ebikes
Replies: 142
Views: 23076

Re: BESC - beefed up VESC motor controller for high power ebikes

galp wrote:
Jul 29 2019 10:03am
Part you listed is obsolete. :confused:
The datasheet says obsolete, but it seems to be readily available and active from digikey and mouser, so it's probably fine to use for new designs. With HighHopes and zombiess recommending the chip, I'd say it comes with some pretty strong credentials.