Search found 41 matches

by busted_bike
Apr 03, 2013 10:57 am
Forum: General Discussion
Topic: Rube Goldberg engineering
Replies: 25
Views: 3680

Re: Rube Goldberg engineering

OK Go - This Too Shall Pass

http://www.youtube.com/watch?v=qybUFnY7Y8w
by busted_bike
Feb 15, 2013 3:57 pm
Forum: General Discussion
Topic: Car Goes Downwind 2.5 Times Faster Than the Wind
Replies: 268
Views: 18496

Re: Car Goes Downwind 2.5 Times Faster Than the Wind

It's not that hard. A balloon is powered by the wind, and can only be as fast as the wind. A wind vehicle in contact with the ground is powered by the wind AND the ground, and can move faster than the wind. And yet a vehicle powered only by the ground goes nowhere... :wink: Perhaps you're oversimpl...
by busted_bike
Feb 07, 2013 9:51 am
Forum: General Discussion
Topic: Car Goes Downwind 2.5 Times Faster Than the Wind
Replies: 268
Views: 18496

Re: Car Goes Downwind 2.5 Times Faster Than the Wind

Unfortunately, I neglected to look at the date when I read this post - I didn't realize I was complicit in thread necromancy. Nevertheless, I missed it the first time around and it is something interesting to ponder. But I agree with John - pitch-adjustable blades on the prop may be helpful, but are...
by busted_bike
Feb 06, 2013 11:51 am
Forum: General Discussion
Topic: Car Goes Downwind 2.5 Times Faster Than the Wind
Replies: 268
Views: 18496

Re: Car Goes Downwind 2.5 Times Faster Than the Wind

I haven't read the whole thread, but I think I get it - maybe - so I'll try my own twist on an explanation. Forgive me if someone has already taken the same tact on an explanation. First, it seems obvious that a tailwind turning a prop geared to the wheels would make the thing move forward, at least...
by busted_bike
Nov 15, 2011 11:44 am
Forum: Battery Technology
Topic: Accurate affordable RI meter for low impedance cells?
Replies: 28
Views: 2170

Re: Accurate affordable RI meter for low impedance cells?

LFP is pretty much spot on - I uploaded a simulation image that I created previously to explain why it's necessary to use the rebound voltage delta for calculating Ri, rather than droop. If you use droop rather than rebound, there is some voltage sag due to normal discharge effects that muddles up t...
by busted_bike
Aug 19, 2011 10:32 am
Forum: General Discussion
Topic: Help me write the ES wiki https://endless-sphere.com/w
Replies: 88
Views: 337202

Re: Help me write the ES wiki

ptd wrote:
Miles wrote:I vote for SI (MKS) to be used as the primary units system for the wiki. Using a coherent system makes understanding relationships so much easier....
would it be so difficult to just do both? coherent is kind of subjective
How many Coulombs is your battery? ;)
by busted_bike
Aug 19, 2011 10:25 am
Forum: General Discussion
Topic: Help me write the ES wiki https://endless-sphere.com/w
Replies: 88
Views: 337202

Re: Help me write the ES wiki

Just a suggestion - I suspect a lot of the material for an ES wiki has already been written, here and in other places. Basic electronics units, math, and theory is all over the web. Some of it is even well written. If someone can find this site, they can probably find another with excruciating detai...
by busted_bike
Jul 06, 2011 11:13 am
Forum: General Discussion
Topic: Rational transportation choices, or "My 3 ton SUV"
Replies: 86
Views: 7817

Re: Rational transportation choices, or "My 3 ton SUV"

Heh, why not a Peterbilt, or a Unimog? Fitting in a parking space and a garage is a consideration, and those kinds of vehicles fail miserably. Plus, I'd like something quiet and refined, not something with, well, a truck's interior. Pick up some nice aftermarket whale penis leather seats and park w...
by busted_bike
Jul 06, 2011 10:00 am
Forum: General Discussion
Topic: Rational transportation choices, or "My 3 ton SUV"
Replies: 86
Views: 7817

Re: Rational transportation choices, or "My 3 ton SUV"

Cliffs Notes: Given the right set of inputs even a very rational individual can come to the conclusion that driving a barge of an SUV is the proper choice. I get it - externalities aren't your problem. I also suspect you've read one too many "Freakonomics" books. :wink: Also, since your reasoning s...
by busted_bike
Jul 01, 2011 1:02 pm
Forum: E-Bike Technical
Topic: What Motor for coasting? _edited title_
Replies: 32
Views: 1964

Re: What Motor for coasting? _edited title_

I understand that you have an idea in mind that you're running with, but I'm going to reiterate what others in this thread have already stated: regen on a bike is useless in practice. Here's a link that does a reasonable job of explaining why. http://www.ecospeed.com/regenbraking.pdf Now - if you're...
by busted_bike
Dec 16, 2010 12:09 pm
Forum: General Discussion
Topic: DC microgrids - from the people who brought you the USBCell
Replies: 7
Views: 545

Re: DC microgrids - from the people who brought you the USBC

How does it deal with the fact that my laptop wants 19.5V, my router wants 12V, and my cell phone wants 5V?

Goodness knows what else I have laying around that wants 18V / 24V / 48V...
by busted_bike
Dec 06, 2010 9:16 am
Forum: General Discussion
Topic: Over-Unity achieved !
Replies: 18
Views: 1187

Re: Over-Unity achieved !

At what charge status did you test the LiFePo4 cell(s)? At full charge I would expect different results, though I may be off base. My pack is a well used LiMN pack 20s and about 20ah. I doubt the pack saw anywhere near 20°C temperature change, because it started at about a 20°C ambient temp, and ...
by busted_bike
Dec 06, 2010 9:03 am
Forum: Battery Technology
Topic: lithium shipping hazmat fees
Replies: 73
Views: 4752

Re: lithium shipping hazmat fees

As I recall, about 2/3 of the energy released for virtually any lithium chemistry cell on ignition is due to combustion of the electrolyte. So even a completely drained LiFeP04 cell represents a potential fire hazard under the right circumstances. So I'm with Jeremy on this one.
by busted_bike
Dec 03, 2010 2:54 pm
Forum: General Discussion
Topic: Over-Unity achieved !
Replies: 18
Views: 1187

Re: Over-Unity achieved !

I've measured the tempco of a LiFeP04 cell at 50uV/degC (single cell, from 23C-40C). I don't know what your pack consists of, so lets assume a hypothetical 22 cell series connection and a 20C temperature rise. 50uV/degC * 22 cells * 20C = 22mV Your pack Voltage rose by an order of magnitude more tha...
by busted_bike
Dec 03, 2010 10:30 am
Forum: E-Bike Technical
Topic: Rules of Thumb: Estimating Range
Replies: 6
Views: 551

Re: Rules of Thumb: Estimating Range

So the rule for me simplifies even further: to estimate the difficulty of a new route, add a kilometre for every 20 metres climbed, and add or subtract another kilometre for each 20 metres the finish is above or below the start. That's not so difficult, is it? :wink: Now that's a rule of thumb!
by busted_bike
Nov 03, 2010 8:41 am
Forum: Battery Technology
Topic: This has to be BS; Audi EV can recharge in 6 minutes!
Replies: 66
Views: 3242

Re: This has to be BS; Audi EV can recharge in 6 minutes!

Overnight charging and 100mi range would be acceptable for my commuter car. I think my family is a pretty typical American family - we live in the suburbs, two kids, two cars. One car is a road tripper / kid-hauler, the other is a commuter. The commuter could easily be replaced by a range & charge l...
by busted_bike
Oct 14, 2010 11:37 am
Forum: E-Bike General Discussion
Topic: Looking to buy an e-bike
Replies: 18
Views: 972

Re: Looking to buy an e-bike

36V * 15Ah is probably about right if you plan on minimal pedaling to assist the motor. I have a 36V*12Ah battery and a 16.5mi (one way) commute to work. I keep a charger at home and at work. If you plan on pedaling hard, you can probably get away with a smaller battery (lighter, lower cost). For my...
by busted_bike
Oct 12, 2010 3:00 pm
Forum: E-Bike Technical
Topic: Looking for help designing torque-based throttle alternative
Replies: 34
Views: 3031

Re: Looking for help designing torque-based throttle alterna

You're probably right. I also don't recall any noticeable torque ripple once I got going. They might have traded off the latency for low ripple though, via a more complex control algorithm. If you find that the bang-bang controller produces noticeable torque ripple, you might consider something less...
by busted_bike
Oct 12, 2010 12:03 pm
Forum: E-Bike Technical
Topic: Looking for help designing torque-based throttle alternative
Replies: 34
Views: 3031

Re: Looking for help designing torque-based throttle alterna

The PID loop needs to work fast enough to prevent the torque/power overshooting and undershooting the demand and so probably needs to run at a speed of at least 10Hz to be reasonably free from jerkiness. What I need to avoid is the situation where the rider demands power, the controller applies too...
by busted_bike
Oct 12, 2010 11:28 am
Forum: E-Bike Technical
Topic: Looking for help designing torque-based throttle alternative
Replies: 34
Views: 3031

Re: Looking for help designing torque-based throttle alterna

Bandwidth is the problem though, mainly in the A-D conversion and the subsequent code. It's one of those areas where an analogue design may actually have the edge, as getting the code to run fast enough in a microcontroller is a challenge, even for the 40MHz clock chips. Out of curiosity... what so...
by busted_bike
Oct 04, 2010 12:49 pm
Forum: E-Bike Technical
Topic: Cycle computer as battery meter?
Replies: 5
Views: 391

Re: Cycle computer as battery meter?

I recall seeing it on the ampedbikes forums. TI has a new microcontroller development kit for <$5 that should work: http://processors.wiki.ti.com/index.php/MSP430_LaunchPad_%28MSP-EXP430G2%29?DCMP=launchpad&HQS=Other+OT+launchpadwiki A more analog-ish alternative would be to use a VFC as the heart o...
by busted_bike
Oct 04, 2010 9:02 am
Forum: Battery Technology
Topic: Combining A123 M1´s & low C rate lifepo4 questions
Replies: 7
Views: 414

Re: Combining A123 M1´s & low C rate lifepo4 questions

Unfortunately, there are a lot of unknowables. IMO, the only way to difinitively answer your questions is to build and characterize it. I suspect that as long as your peak power * duty cycle is less than the continuous output power rating on the cheap cells, you'll be fine. The most practical way to...
by busted_bike
Sep 29, 2010 1:36 pm
Forum: Battery Technology
Topic: hybrid fuel cell.
Replies: 12
Views: 793

Re: hybrid fuel cell.

I didn't realize fuel cells were that readily available. I found them on sale at this site:

http://www.outdoorgb.com/p/Efoy_Fuel_Cell/

18.7lb / 65W / $4750

Doesn't appear to make sense to carry it around on anything I can plug in at the end of the day or after a ride.
by busted_bike
Sep 29, 2010 8:25 am
Forum: Battery Technology
Topic: hybrid fuel cell.
Replies: 12
Views: 793

Re: hybrid fuel cell.

Hillhater wrote:..And the price is ....????
Agreed... it sounds cool though. I wonder how long 'till we're able to pick up power tool fuel cells at Home Depot?
by busted_bike
Sep 29, 2010 8:16 am
Forum: Battery Technology
Topic: Looking for help with an unusual battery application
Replies: 10
Views: 653

Re: Looking for help with an unusual battery application

How about powering an electrolytic hydrogen generator? One can have endless fun with stochiometric mixes of hyrdrogen and oxygen. :twisted: Heh. I'm no chemist... what sort of input bandwidth does a system like that have? Can you ramp hydrogen production up as an energy sink and then back down agai...