Search found 14777 matches

by fechter
Jul 23 2021 10:02am
Forum: Battery Technology
Topic: Single cell voltage isolated chargers?
Replies: 2
Views: 36

Re: Single cell voltage isolated chargers?

I remember seeing one years ago that was used for LiFePO4 batteries. I don't see them around anymore. I have also seen DIY setups using a bunch of "wall wart" style single cell chargers. It tends to be much more bulky than a conventional charger setup but eliminates the need for a BMS duri...
by fechter
Jul 22 2021 8:55am
Forum: EBike Technical
Topic: How to make push button as throttle? +video
Replies: 11
Views: 212

Re: How to make push button as throttle? +video

pickworthi wrote:
Jul 21 2021 4:24pm
This post:
https://www.endless-sphere.com/forums/v ... 0#p1520695

.. has both a circuit and a physical implementation for your perusal.

My circuit is working fine after three months.
Thanks for posting that. Having everything adjustable should make it pretty universal.
by fechter
Jul 21 2021 3:52pm
Forum: EBike Technical
Topic: How to make push button as throttle? +video
Replies: 11
Views: 212

Re: How to make push button as throttle? +video

If the controller resistance is really 220 ohms (or much higher and you place a 220 ohm across it), Then R1= 1100 ohms and R2= 55 ohms. Finding these exact resistor values may be difficult depending on your sources. Sometimes you need to combine values you can actually get to make what you want. For...
by fechter
Jul 21 2021 3:36pm
Forum: EScooter/EMotorcycle Build Threads
Topic: Nova Cruz Voloci Scooter/Bike Info
Replies: 203
Views: 44662

Re: Nova Cruz Voloci Scooter/Bike Info

It sounds like a hall timing issue, but there are plenty of other things that it could be. One test is to measure the no-load, full speed current and compare to the stock controller. If the timing is correct, the no load current should be very close. There is a way to check statically the timing. Di...
by fechter
Jul 21 2021 8:28am
Forum: EBike Non-hub Motor Drives
Topic: Reverse Enginering Bafang m500 and m600 Firmwares and BESST
Replies: 7
Views: 196

Re: Reverse Enginering Bafang m500 and m600 Firmwares and BESST

I don't have a M600, but I do have a BBSHD. We have the firmware .bin files for those and good chance it's similar. BBSHD uses a ST microcontroller:
http://www.stcmicro.com/STC15W4K56S4.html
by fechter
Jul 21 2021 8:18am
Forum: EBike Technical
Topic: How to make push button as throttle? +video
Replies: 11
Views: 212

Re: How to make push button as throttle? +video

Yes, you need the throttle signal to stay between 0.8v and about 4.0v. Your circuit might work if you use the right resistors. The correct value will depend on your controller. If you have a voltmeter, you can change the resistor values until you see the right range. My guess is you need much larger...
by fechter
Jul 20 2021 10:27am
Forum: EBike General Discussion
Topic: is series 2x switchingmode power supplies safe for charging at 1C
Replies: 5
Views: 99

Re: is series 2x switchingmode power supplies safe for charging at 1C

If it didn't immediately blow up when you tested them in series, that's a good sign. An easy way to double check is to use an ohmmeter and measure resistance from the case to either output terminal. It should look like an open circuit if it is isolated. As long as the outputs are isolated, you can r...
by fechter
Jul 16 2021 10:53am
Forum: Bike Mechanical & Structural
Topic: e-scooter stability
Replies: 2
Views: 83

Re: e-scooter stability

I've had several scooters and have ridden hundreds of miles on them. There is a learning curve for the handling for sure. Your design is interesting. Actually riding it would be the real test. What you have is a lot of "trail" in the steering, which improves stability. I ended up modifying...
by fechter
Jul 16 2021 10:39am
Forum: EBike General Discussion
Topic: Ebike vs Escooter
Replies: 14
Views: 1136

Re: Ebike vs Escooter

I have both bikes and scooters. The scooter is definitely more dangerous and you really need to be alert when riding. What I really like the scooter for is when I travel by car and don't have room to carry the bike. Around here, scooters are allowed anywhere you can ride an ebike. I was pretty serio...
by fechter
Jul 16 2021 10:23am
Forum: EBike Troubleshooting
Topic: low current issue that i don't know how to solve
Replies: 3
Views: 70

Re: low current issue that i don't know how to solve

It sounds like the controller is going into "limp mode" when the battery voltage drops to a certain point. This is a common feature. Going slow is better than cutting off completely. But it doesn't make sense that switching to the higher voltage setting solves the issue. There may be a bug...
by fechter
Jul 16 2021 10:14am
Forum: EBike General Discussion
Topic: Hanging an e-bike from front tire - good idea or bad?
Replies: 4
Views: 129

Re: Hanging an e-bike from front tire - good idea or bad?

If the wheel is strong enough to ride the bike on the ground, lifting it with a hook shouldn't be any more stressful. I would worry more about the thing falling.
by fechter
Jul 16 2021 10:12am
Forum: Motor Technology
Topic: Flux transfer coil calculations
Replies: 13
Views: 266

Re: Flux transfer coil calculations

I think the link for the video is wrong. It was about space boots. It seems like it should be easy to test whether this effect works or not by using a hall effect sensor on one of the pole ends. As far as I know, magnetism doesn't have any "inertia" and can change very rapidly under the ri...
by fechter
Jul 16 2021 8:48am
Forum: Large EV General Discussion
Topic: 1967 Ford Econoline Leaf conversion
Replies: 8
Views: 1281

Re: 1967 Ford Econoline Leaf conversion

How fast does it go?
by fechter
Jul 16 2021 8:45am
Forum: Motor Technology
Topic: Flux transfer coil calculations
Replies: 13
Views: 266

Re: Flux transfer coil calculations

The flux in the core will be a function of amp-turns and also time in the case of a pulse. Getting the flux up to the saturation point of the core, or close to it, is the most you need to shoot for. You can pick the number of coil turns. To get the flux to go from zero to saturation is going to take...
by fechter
Jul 16 2021 8:28am
Forum: General Discussion
Topic: la Nina rears her ugly head
Replies: 2136
Views: 148541

Re: la Nina rears her ugly head

The monsoons also bring the chance for dry lightning, which will start more fires. A bunch of huge fires were started by lightning last year. Rain, good. Lightning, bad.
by fechter
Jul 15 2021 9:24am
Forum: Motor Technology
Topic: Flux transfer coil calculations
Replies: 13
Views: 266

Re: Flux transfer coil calculations

I found this description of the Flynn motor: https://www.flynnresearch.net/technology/PPMT%20Technology.htm Not sure I totally buy the concept, but if it works, great. Seems like you'd want to discharge a HV capacitor into the coil to get the pulse. Use IGBTs that can handle the voltage. The size of...
by fechter
Jul 14 2021 2:47pm
Forum: EBike General Discussion
Topic: BBSHD gear ratios
Replies: 6
Views: 261

Re: BBSHD gear ratios

Do you have any issues with a 30T Chainring with the BBSHD and what is the offset? I have not had any issues with the 30t chain ring other than the chain line. I "edited" my cassette to keep the alignment reasonable. I have not measured the offset. It is a 10 speed cassette, but now I can...
by fechter
Jul 14 2021 8:49am
Forum: EBike General Discussion
Topic: BBSHD gear ratios
Replies: 6
Views: 261

Re: BBSHD gear ratios

The BBSHD likes low gearing. I use 30 tooth chain ring and I think 12t-42t cassette (with a few removed so the chain line stays OK). Even with the mini 30t chain ring, the motor can reach the bike's top speed limited by wind resistance and power in the top 3 gears. But the pedal cadence is crazy fas...
by fechter
Jul 14 2021 8:42am
Forum: EBike General Discussion
Topic: ebike speedometer
Replies: 5
Views: 158

Re: ebike speedometer

Either one of the motor hall sensors or an external wheel sensor. There's a huge difference in pulses per wheel revolution between the hall and wheel, so most of those are only going to work with one or the other.

Does it have a way to calibrate the speed?
by fechter
Jul 14 2021 8:39am
Forum: EBike Technical
Topic: Universal lcd display
Replies: 5
Views: 242

Re: Universal lcd display

What is it using for a speed sensor? If it's coming off a motor hall, the voltage may be out of range.
by fechter
Jul 14 2021 8:36am
Forum: General Discussion
Topic: la Nina rears her ugly head
Replies: 2136
Views: 148541

Re: la Nina rears her ugly head

I had a few days of hot weather, then the fog returned. They call the Golden Gate Bridge the world's largest air conditioner. Actually so cold I have to wear a jacket all day in SF. High today in SF is forecast to be 59 (and windy). A little warmer at home, but still pleasantly cool. Now, if we coul...
by fechter
Jul 14 2021 8:12am
Forum: Motor Technology
Topic: Flux transfer coil calculations
Replies: 13
Views: 266

Re: Flux transfer coil calculations

Is that some kind of switched reluctance motor?

If you want shorter pulses, you want fewer turns to reduce the inductance.
by fechter
Jul 14 2021 8:09am
Forum: EBike Build Threads
Topic: Hub motor as mid (illegalbike) 6000W / 33kg
Replies: 80
Views: 4703

Re: Hub motor as mid (illegalbike)

I like how you made the video in front of a gas station :wink:
by fechter
Jul 12 2021 2:01pm
Forum: Motor Technology
Topic: Flux transfer coil calculations
Replies: 13
Views: 266

Re: Flux transfer coil calculations

You might try this calculator: https://www.omnicalculator.com/physics/solenoid-magnetic-field or https://www.accelinstruments.com/Magnetic/Magnetic-field-calculator.html It's the amp-turns you need to calculate. You have flexibility in the actual number of turns as long as the amps x turns is what y...
by fechter
Jul 12 2021 1:51pm
Forum: EScooters/EMotorcycles
Topic: My new electric motorcycle
Replies: 29
Views: 1284

Re: My new electric motorcycle

That looks very interesting. I'd love to see a picture of the motor. 10kW is pretty good. I'm sure with a little hacking, it could be bumped up a bit.