Search found 767 matches

by jag
May 07 2017 11:04am
Forum: E-Bike General Discussion
Topic: 48 - 265V 500 Lumen $1 eBike light from hardware store parts
Replies: 1
Views: 369

48 - 265V 500 Lumen $1 eBike light from hardware store parts

I tested about a dozen different LED bulbs, 5 brands from 3 hardware stores, to see over what voltage range they would function. LED bulbs have a built in PWM step-down voltage to current converter that is set to different voltages for different bulbs. Many of these voltage converters are "universal...
by jag
Nov 23 2014 5:35pm
Forum: Motor Technology
Topic: Help suggest low cogging outrunner for Univ robotics project
Replies: 8
Views: 1026

Re: Help suggest low cogging outrunner for Univ robotics pro

Hi Martin, One significant factor is the lowest common multiple of the slot/pole combination. This is what determines the number of detents per revolution. More steps and therefore less peak force for each step being better, of course. Looking at the list of motors on your link, they have a motor w...
by jag
Nov 22 2014 10:01pm
Forum: Motor Technology
Topic: Help suggest low cogging outrunner for Univ robotics project
Replies: 8
Views: 1026

Help suggest low cogging outrunner for Univ robotics project

We have a haptic robotics project at school. It involves designing and making a force reflective robot wrist. The application is in tele-robotics, where a human moves one motorized arm, and those motions are replicated by an identical robot arm at a remote site. Here is an example picture and video ...
by jag
Nov 13 2014 12:06pm
Forum: E-Bike Non-hub Motor Drives
Topic: Split-crank Electric Tricycle
Replies: 10
Views: 1135

Re: Split-crank Electric Tricycle

Is the purpose of the drive just for aiding with propulsion? Or does it specifically have to drive both the left and right chain and cranks (as you suggest with the proposed application of two GNG drives), e.g. for rehabilitation of a person with lower body disability? If you tell us a bit more abou...
by jag
Jul 22 2013 12:27pm
Forum: E-Bike Build Threads / Photos & Video
Topic: recumbent build with homemade triple stator AF motor
Replies: 23
Views: 4629

Re: recumbent build with homemade triple stator AF motor

I'm amazed and impressed what you can do with basic tools and materials! (My own attempts tend to have +-0.5mm error and assembled results end up distorted :( I have a recumbent with a similar jackshaft and chainring setup under the seat. One problem I have is that the jackshaft flexes a bit too muc...
by jag
Jul 01 2013 4:42pm
Forum: Battery Technology
Topic: what is a safe limit for battery temperature during use?
Replies: 14
Views: 1245

Re: what is a safe limit for battery temperature during use?

Hi dh, Thanks for your good advice. I would like to ask what you consider "charge too fast" at low temp to be? Cold is not a problem (meaning damage of risk to the cell) until you get to about -20C (-4F) and you try to charge too fast--this plates Li. dh To be more specific, I have a 16s pack of 20A...
by jag
Jun 28 2013 5:55pm
Forum: General Discussion
Topic: Help me find a job in the Bay Area!
Replies: 36
Views: 2139

Re: Help me find a job in the Bay Area!

not the guy who is going to show up in a pressed suit. I am looking for *real work* with a *real* group of people. T-Shirt kind of people. You tried both big (Sandia) and small (your own business). How about medium? Startups or small companies with 5-25 people are less bogged down by administrators...
by jag
Apr 19 2013 6:49pm
Forum: General Discussion
Topic: Aosom bike trailer
Replies: 16
Views: 3833

Re: Aosom bike trailer

I agree with the previous poster that you should pester both the company and Amazon to actually support their product. If you bought with a credit card you could also see if it has an extended warranty or the CC company will do anything else. While these efforts may not succeed, at least the compani...
by jag
Feb 10 2013 1:24pm
Forum: Motor Technology
Topic: Worlds Worst Dyno - Version 2
Replies: 154
Views: 12181

Re: Worlds Worst Dyno - Version 2

I measured input volts & amps, output torque and speed. So that gives the overall system efficiency. Which was typically up around 86-88% at full throttle, dropping to 77-80% at 50% throttle/speed. Now the data showed that we had more heat at the higher PWM frequency. So my money is on the hysteres...
by jag
Feb 09 2013 10:29pm
Forum: Motor Technology
Topic: Worlds Worst Dyno - Version 2
Replies: 154
Views: 12181

Re: Worlds Worst Dyno - Version 2

Hi Adrian, Hats off to you for one of the most informative threads on ES recently! Excellent job. Can you explain why? "Expected", for me, because I've seen other references to it. I've never seen a detailed analysis, though. I've just assumed that, if the motor inductance or the PWM frequency aren'...
by jag
Feb 07 2013 10:59am
Forum: E-Bike General Discussion
Topic: DC residents: Is this plan crazy? *update* No it's not
Replies: 16
Views: 583

Re: DC area residents: Is this plan crazy?

I have a 3 day work trip to the Coast Guard operations System Center in Martinsburg, WV. I'll be flying into and out of Dulles. I have a non-motorized folding bike that - if disassembled will fit in a large hard side suit case. I'm tempted to fly down with that bike, assemble it, ditch the suitcase...
by jag
Dec 11 2012 8:22pm
Forum: Motor Technology
Topic: Worlds Worst Dyno - Version 2
Replies: 154
Views: 12181

Re: Worlds Worst Dyno - Version 2

Ignoring the waste heat in just turning over the regen motor, then the power the regen controller puts out when in regen, compared to the extra power required to create it sits in the 78-82% efficiency, with the rest heating up the controller based on the temp rise I saw. So I guess it isn't that b...
by jag
Dec 10 2012 7:51pm
Forum: Motor Technology
Topic: Worlds Worst Dyno - Version 2
Replies: 154
Views: 12181

Re: Worlds Worst Dyno - Version 2

Hi Adrian, I'll second Miles comment: Great setup. I'd be curious about the efficiency of the regen part of it, and how it varies with rpm and regen current. I don't think real world regen efficiency has been tested/posted for these types of controllers and motors. Probably motor/controller run in b...
by jag
Nov 01 2012 2:49pm
Forum: E-Bike General Discussion
Topic: Lightweight folder - build thread
Replies: 140
Views: 18764

Re: Lightweight folder - build thread

The bike all up weight is just over 16kg, which is heavier than I wanted, TBH. My ideal "back of the car ebike" would be around 12kg, which is a tall order, but possibly do-able with care and one of the little 1.6kg Keyde motors. Hi Jeremy, For those of us building small folders it would be interes...
by jag
Dec 02 2011 6:20pm
Forum: E-Vehicles General Discussion
Topic: Aptera is gone for good. :'(
Replies: 105
Views: 9521

Re: Aptera is gone for good. :'(

To bad to see a visionary company close. But not unexpected. If it was easy to start auto manufacturing we would have seen more new companies grow in the past 50 years, and less dominance by the old big ones. If there was an "experimental" class for cars, just like for planes, then maybe new designs...
by jag
Nov 30 2011 5:47pm
Forum: E-Bike General Discussion
Topic: Heavy cargo hauler project
Replies: 173
Views: 12635

Re: Planning a heavy cargo hauler. Input welcome.

Hi Tom, I love that classic cargo bike and don't want to dissuade you from the build. However a 25km daily commute may not be ideal on it. After a while you'll probably long for a bike that is lighter, faster and more agile at swerving around pedestrians, bikes and cars. Think about it: How much doe...
by jag
Nov 10 2011 1:40am
Forum: E-Bike General Discussion
Topic: Good Deal? Or Rip Off?
Replies: 26
Views: 3169

Re: Good Deal? Or Rip Off?

Edit: Added some cost estimates in text below I pm'd Steveo and posted a reply here but nothing - oh well, thanks anyway all who did post and try to help me, You can always try to post with a specific title like "Help with ebike wanted in Toronto, ON area, Canada". Or you could just ask if some nea...
by jag
Nov 08 2011 11:32am
Forum: General Discussion
Topic: Any College drop outs on ES? Care to narrate?
Replies: 63
Views: 3939

Re: Any College drop outs on ES? Care to narrate?

KF's story tops my list of best ever ES post (2nd one is LFP's encounter with Mustang and Camaro guy from some years ago). I had plenty of experiences like KF's with narrow minded types. In one early assignment we were to design a garage floor engine crane. I did my design so there were no bending m...
by jag
Oct 29 2011 1:35pm
Forum: E-Bike General Discussion
Topic: Good Deal? Or Rip Off?
Replies: 26
Views: 3169

Re: Good Deal? Or Rip Off?

I also think your old bike has a lot going for it: http://www.green-cruiser.com/bay-street-angel-2.html http://www.green-cruiser.com/media/catalog/product/cache/1/thumbnail/50x50/9df78eab33525d08d6e5fb8d27136e95/f/i/file_10.jpg A geared Bafang hub in a 20" wheel is going to be better on your hilly r...
by jag
Oct 29 2011 10:21am
Forum: Battery Technology
Topic: Edit: solved! HK screwing me on Nanotech order. What do?
Replies: 12
Views: 905

Re: Hobbyking screwing me on Nanotech order. What to do?

Success at last. After 1 month of wrangling, 10 or so emails, HK finally agreed to fill missing/out of stock pieces in the order I had paid for a month ago with the next better parts and get it shipped. I'm hoping it ships in the next couple of days so I'll have the gear next week. Rachel, Oct-29 14...
by jag
Oct 28 2011 7:44pm
Forum: General Discussion
Topic: Occupy REI!
Replies: 77
Views: 6078

Re: Occupy REI!

http://media.economist.com/sites/all/themes/econfinal/images/the-economist-logo.gif “AS THOUSANDS have gathered in Lower Manhattan, passionately expressing their deep discontent with the status quo, we have taken note of these protests,” wrote Lloyd Blankfein, the boss of Goldman Sachs, in a recent...
by jag
Oct 28 2011 2:53pm
Forum: General Discussion
Topic: Hobbyking Customer Service.
Replies: 225
Views: 5256

Re: up your f***** ass, HobbyKing!

I have a similar problem with Hobbyking. (Reported in a separate ES thread) I think your plan sounds good: Report to Paypal. Racking up a bad record with Paypal is not going to be a good thing for them. Still, you might have to continue following their instructions, however ridiculous, so you can sh...
by jag
Oct 28 2011 3:05am
Forum: Battery Technology
Topic: Edit: solved! HK screwing me on Nanotech order. What do?
Replies: 12
Views: 905

Re: Hobbyking screwing me on Nanotech order. What to do?

Hi, Hobbyking customer service is giving me a runaround with an order of 45-90C Nanotech LiPo. I ordered nearly a month ago and they have still not shipped. Lousy Hobbyking customer service :shock:? What do you think? Should I fork out the $50 extra? I hate to say this but if your time is worth any...
by jag
Oct 28 2011 2:59am
Forum: Battery Technology
Topic: Edit: solved! HK screwing me on Nanotech order. What do?
Replies: 12
Views: 905

Re: Hobbyking screwing me on Nanotech order. What to do?

edit: my guess on the extra shipping is the extra weight Thats cheeky for the extra 200gms ! :shock: Battery packs weigh the same, but they hiked the nominal shipping weight for the new 5.0. If they were honest they should be wrapping them in 200g more of protective covering. Otherwise they are jus...
by jag
Oct 27 2011 6:56pm
Forum: Battery Technology
Topic: Edit: solved! HK screwing me on Nanotech order. What do?
Replies: 12
Views: 905

Edit: solved! HK screwing me on Nanotech order. What do?

Edit: After nearly a month of wrangling and customer support emails it's now finally solved. They will ship similar batteries with a different part number at no extra cost. See last post. Hobbyking customer service is giving me a runaround with an order of 45-90C Nanotech LiPo. I ordered nearly a m...