Search found 25 matches

by BalorNG
Feb 23 2020 4:26am
Forum: E-Bike Non-hub Motor Drives
Topic: My RC Mid Drive with Single Stage Reduction
Replies: 351
Views: 44591

Re: My RC Mid Drive with Single Stage Reduction

How much real no-load draw does it have? I've tested this one with a wattmeter: https://aliexpress.com/item/4000119983883.html And got 1.5A, which is reasonable. Btw, it leaks a lot of magnetic field outside. Hi Balor I managed to measure the no load current of this chinese 6384. At 14.5v supply i ...
by BalorNG
Dec 26 2019 4:19pm
Forum: E-Bike Non-hub Motor Drives
Topic: My RC Mid Drive with Single Stage Reduction
Replies: 351
Views: 44591

Re: My RC Mid Drive with Single Stage Reduction

fixvid wrote:
Dec 07 2019 5:43am
BalorNG wrote:
Dec 06 2019 4:33am
please test no-load current using a wattmeter, I'm interested whether I 'overpaid' 50$
I will put at least a clamp meter on the wires and check for current.
Hey, so, did you test it? My Flipsky motor came with defect halls... got a bit of a compensation, but still bit disappointed.
by BalorNG
Dec 23 2019 11:41am
Forum: E-Bike Non-hub Motor Drives
Topic: 250W RC belt drive - how to pick voltage/gearing for best efficiency
Replies: 18
Views: 2141

Re: 250W RC belt drive - how to pick voltage/gearing for best efficiency

https://i.imgur.com/zvzewkJl.jpg After playing about with reduction, it seems I can use this motor with pretty damn good efficiency (85% after all the reductions!) at 150 watts if I use *less* reduction and run it at about half of duty cycle. That's a 115 kv copter motor rated for 3kw at 12s. 18 po...
by BalorNG
Dec 06 2019 4:33am
Forum: E-Bike Non-hub Motor Drives
Topic: My RC Mid Drive with Single Stage Reduction
Replies: 351
Views: 44591

Re: My RC Mid Drive with Single Stage Reduction

Don't trust the VESC, it also 'told' me something like 6 watts, while my wattmeter showed ~35. I've used 25v, btw, but as I understand, it will draw same amps at FULL speed no-load on any voltage, because no-load speed losses (hysteresis and eddy currents) are linear with speed, and more volts - mor...
by BalorNG
Dec 05 2019 9:31am
Forum: E-Bike Non-hub Motor Drives
Topic: My RC Mid Drive with Single Stage Reduction
Replies: 351
Views: 44591

Re: My RC Mid Drive with Single Stage Reduction

How much real no-load draw does it have?
I've tested this one with a wattmeter:
https://aliexpress.com/item/4000119983883.html

And got 1.5A, which is reasonable.
Btw, it leaks a lot of magnetic field outside.
by BalorNG
Dec 05 2019 7:51am
Forum: Battery Technology
Topic: Series connecting dissimilar battery packs.
Replies: 11
Views: 1242

Re: Series connecting dissimilar battery packs.

Actually, I have no idea :(. Maybe, some sort of relay arduino-controlled relay that automatically bypasses the battery once it detects shutdown? Talking of extra points of failure though... This could not be fast enough to prevent FET failure if the FETs aren't capable of simply handling it on the...
by BalorNG
Dec 04 2019 7:23am
Forum: Battery Technology
Topic: Series connecting dissimilar battery packs.
Replies: 11
Views: 1242

Re: Series connecting dissimilar battery packs.

amberwolf wrote:
Dec 03 2019 9:27pm
BalorNG wrote:
Dec 03 2019 4:53pm
Will some sort of shunt help?
What specifically do you mean?
Actually, I have no idea :(. Maybe, some sort of relay arduino-controlled relay that automatically bypasses the battery once it detects shutdown? Talking of extra points of failure though...
by BalorNG
Dec 03 2019 6:27pm
Forum: E-Bike Non-hub Motor Drives
Topic: My RC Mid Drive with Single Stage Reduction
Replies: 351
Views: 44591

Re: My RC Mid Drive with Single Stage Reduction

I think that goes outside of the scope of lightweight pedal assist.
Note it has nearly 2A of no load current, for instance.
by BalorNG
Dec 03 2019 4:53pm
Forum: Battery Technology
Topic: Series connecting dissimilar battery packs.
Replies: 11
Views: 1242

Re: Series connecting dissimilar battery packs.

I want to build a velomobile for long trips. Currently, I have 7s 80Ah 'main' battery and after a bit of a fiasco with a 200kv motor I'm contemplating a 130kv motor - but to reach desired RPM more voltage will be required. I contemplate getting an extra 3s ~90Ah auxiliary battery. Each will have it...
by BalorNG
Dec 02 2019 7:04pm
Forum: Battery Technology
Topic: Series connecting dissimilar battery packs.
Replies: 11
Views: 1242

Series connecting dissimilar battery packs.

I want to build a velomobile for long trips. Currently, I have 7s 80Ah 'main' battery and after a bit of a fiasco with a 200kv motor I'm contemplating a 130kv motor - but to reach desired RPM more voltage will be required. I contemplate getting an extra 3s ~90Ah auxiliary battery. Each will have it'...
by BalorNG
Nov 28 2019 2:46pm
Forum: E-Bike General Discussion
Topic: Tesla S3X power consumption versus high power electric bike (estimates)... WTF
Replies: 27
Views: 2395

Re: Tesla S3X power consumption versus high power electric bike (estimates)... WTF

Yup, aerodynamics is a force NOT to be underestimated. With good rolling resistance tires (forget moto tires!) RR can be significantly reduced, too. I am designing a e-velomobile with CdA of about 0.07 - so 2kwh battery should last me about 500 km with average speed of about 50kmh, and that is a rel...
by BalorNG
Nov 28 2019 12:52pm
Forum: E-Bike Non-hub Motor Drives
Topic: 250W RC belt drive - how to pick voltage/gearing for best efficiency
Replies: 18
Views: 2141

Re: 250W RC belt drive - how to pick voltage/gearing for best efficiency

Well, that's reasonable... though you can 3d print a 'belt chainring' too, which will be easily removable. Btw, I've actually used PLA+ to 3d print a 10T cog, put on 180w (actually more like 150w, as it turns out) motor AFTER 10x reduction gearbox , and it held up just fine. If you don't want a midd...
by BalorNG
Nov 28 2019 2:07am
Forum: E-Bike Non-hub Motor Drives
Topic: 250W RC belt drive - how to pick voltage/gearing for best efficiency
Replies: 18
Views: 2141

Re: 250W RC belt drive - how to pick voltage/gearing for best efficiency

By using a small light weight 2kW peak power RC motor rated for a 12S battery at just 4S Yup, like I said in the post above, undervolting the motor shifts it's efficiency band towards the wattage range (and RPMs) OP is striving for. And yes, I did read entire thread, it was very educational (and OP...
by BalorNG
Nov 28 2019 12:19am
Forum: E-Bike Non-hub Motor Drives
Topic: 250W RC belt drive - how to pick voltage/gearing for best efficiency
Replies: 18
Views: 2141

Re: 250W RC belt drive - how to pick voltage/gearing for best efficiency

As I understand it, resistive losses are I^2R, so doubling current quadruples resistive loss. Indeed, resistive (copper) losses are not unlike aerodynamic losses - they start off small, but ramp up quickly. Iron losses is not unlike rolling resistance - they rise linearly with speed (also producing...
by BalorNG
Nov 27 2019 4:13pm
Forum: E-Bike Non-hub Motor Drives
Topic: 250W RC belt drive - how to pick voltage/gearing for best efficiency
Replies: 18
Views: 2141

Re: 250W RC belt drive - how to pick voltage/gearing for best efficiency

They use a potentially 2kW motor with a 1:10 gearing on the crank. That means that it can only deliver roughly 200W continuous an around 400W peak power. It means nothing of the sort. Watts is torque times RPM. Reduction decreases RPM while increasing torque. Provided you have enough volts and ampe...
by BalorNG
Nov 26 2019 3:33pm
Forum: E-Bike Non-hub Motor Drives
Topic: 250W RC belt drive - how to pick voltage/gearing for best efficiency
Replies: 18
Views: 2141

Re: 250W RC belt drive - how to pick voltage/gearing for best efficiency

Why exactly 'RC crank drive' is harder than belt wheel drive? I daresay they are equivalent, though you have 'virtual fixed gear' with former. I don't think that's bad though - I think that might actually be beneficial for biomechanics (like oval rings, for instance - you legs get 'pulled through' d...
by BalorNG
Nov 24 2019 3:00pm
Forum: E-Bike Non-hub Motor Drives
Topic: Internally geared BLDC motor
Replies: 17
Views: 1922

Re: Internally geared BLDC motor

I think you will be much better off buying a copter motor like one from drones: https://www.dji.com/ru/e2000/info (Peak efficiency of 90% at about 400 watts) And than machining an axle adapter to that gearbox. You should enclose it in some sort of shroud because case will be spinning, BUT it will ha...
by BalorNG
Nov 24 2019 2:50pm
Forum: E-Bike Non-hub Motor Drives
Topic: "Chain Puller" mid drive from industrial BLDC motor
Replies: 3
Views: 997

Re: "Chain Puller" mid drive from industrial BLDC motor

Ok, please don't repeat my mistake - this motor is an absolute shite. Here are tech docs of similar motors, I wish I've found them earlier: http://gemsmotor.com/nema-23-round-brushless-dc-motor A motor similar to mine has about PEAK 65% efficiency - which is pretty much what am I getting. WTF those ...
by BalorNG
Nov 21 2019 12:10am
Forum: E-Bike Non-hub Motor Drives
Topic: Internally geared BLDC motor
Replies: 17
Views: 1922

Re: Internally geared BLDC motor

I've bought this for a similar purpose: https://ru.aliexpress.com/item/32797544178.html 3 times heavier, but 3 times cheaper :) Unlikely to fit your though. Otherwise, this looks very good indeed, you can have something like 16T freewheel/36T chainring for a perfectly good cadence off 24v battery (d...
by BalorNG
Nov 16 2019 4:20am
Forum: E-Bike Non-hub Motor Drives
Topic: My RC Mid Drive with Single Stage Reduction
Replies: 351
Views: 44591

Re: My RC Mid Drive with Single Stage Reduction

We just need to compare peak chain tension with rated tension, leave a healthy margin and see results. Since this is a low-power ASSIST, not 3+wk beasts, and with a single stage reduction, it should theoretically suffice, there are precedents with using PURELY plastic chains in first stage reduction...
by BalorNG
Nov 15 2019 3:03pm
Forum: E-Bike Non-hub Motor Drives
Topic: My RC Mid Drive with Single Stage Reduction
Replies: 351
Views: 44591

Re: My RC Mid Drive with Single Stage Reduction

Have you considered a plastic chain? https://www.rollerchain4less.com/35p-acetal-plastic-roller-chain-10ft Silent, self-lubricating, and seems rated for what you desire. Lighter as well, obviously. Can be combined with a 3d printed plastic sprocket I presume. If I knew about existence of such chains...
by BalorNG
Nov 14 2019 11:25am
Forum: E-Bike Non-hub Motor Drives
Topic: "Chain Puller" mid drive from industrial BLDC motor
Replies: 3
Views: 997

Re: "Chain Puller" mid drive from industrial BLDC motor

Yup, on an RWD bent (and especially velo) you have quite a bit of freedom with transmission, though there are still limits. Admittedly, for maximum efficiency you'd want a chain reduction and a smaller KV motor, but I thought that a difference of about 2% does not warrant going with a system that is...
by BalorNG
Nov 12 2019 3:08am
Forum: Motor Technology
Topic: opensource 3d printable electronic shifting?
Replies: 42
Views: 3688

Re: opensource 3d printable electronic shifting?

You can see approximate motor and 'gearing' parameters on this vid: https://www.youtube.com/watch?v=uuCiaa6zUoM Using a 'linear worm screw' is the best idea because it has passive and has nearly indefinite 'holding torque', so no need to keep the system powered unless actually shifting. It also has ...
by BalorNG
Nov 11 2019 6:53pm
Forum: Motor Technology
Topic: KT motor controllers -- Flexible OpenSource firmware for BMSBattery S/Kunteng KT motor controllers (0.25kW up to 5kW)
Replies: 3924
Views: 347291

Re: KT motor controllers -- Flexible OpenSource firmware for BMSBattery S/Kunteng KT motor controllers (0.25kW up to 5kW

I'm building a low power 'nema 23' drive - mostly because I'm lazy and it has good gearbox options as compared to a typical RC drive, and rated 180w is more then enough to me. https://www.aliexpress.com/item/32797544178.html Will a cheap KT controller, or similar chinese e-bike controller work with ...
by BalorNG
Nov 10 2019 7:49pm
Forum: E-Bike Non-hub Motor Drives
Topic: "Chain Puller" mid drive from industrial BLDC motor
Replies: 3
Views: 997

"Chain Puller" mid drive from industrial BLDC motor

The HPV to be 'electified' is a DIY velomobile intended for long distance travel. I want a relatively low-power (about 150watts) efficient mid-drive that will integrate into transmission exactly like e-assist of Tetz: http://www.recumbents.com/mars/tetz/E-Assist.htm I've bought this motor spindle wi...