Search found 41 matches

by busted_bike
Sep 27 2010 7:35pm
Forum: Battery Technology
Topic: Looking for help with an unusual battery application
Replies: 10
Views: 758

Re: Looking for help with an unusual battery application

Perhaps dumping the load power as heat or mechanical energy is not such a bad idea. What you need to do is find a constructive use for that heat/power... Yep, that was my first intuition. Once I wrap a control loop and some diagnostic circuitry around a heating element and then add some fans (which...
by busted_bike
Sep 27 2010 12:03pm
Forum: Battery Technology
Topic: Looking for help with an unusual battery application
Replies: 10
Views: 758

Re: Looking for help with an unusual battery application

Thanks - unfortunately, I seem to have left out some relevant information: the duration during which the load can act as an energy source isn't well bounded. In the extreme case, it could be hours. Worst case current spikes are around 100A, operating Voltage is flexible... but lets say 24V-27V opera...
by busted_bike
Sep 27 2010 11:35am
Forum: Battery Technology
Topic: Looking for help with an unusual battery application
Replies: 10
Views: 758

Looking for help with an unusual battery application

I have an application in mind for a battery pack as short-term energy absorption. It has little to do with EVs, but I figured I’d ask the question here since the folks on this forum have, collectively, as much battery knowledge as I’ve seen just about anywhere. Anyway, I’m worki...
by busted_bike
Aug 19 2010 12:55pm
Forum: General Discussion
Topic: went to school today...
Replies: 5
Views: 608

Re: went to school today...

Congrats! I've been working as an EE for ~15years now. Mostly microelectronics - these motor thingies are more of a hobby. Your first year should be more of a general education, applicable to just about any engineering field. The narrowly focused classes don't really start until the third year. If t...
by busted_bike
Aug 17 2010 9:08am
Forum: E-Bike General Discussion
Topic: Wondering if I should succomb to a hub motor
Replies: 30
Views: 1905

Re: Wondering if I should succomb to a hub motor

I basically agree with LFP - it's all about the tradeoffs you want to make. I'm using a geared front hub motor on my commuting bike, and am perfectly happy with it. Advantages, as I see it: - Freewheels when not under power. I do a lot of pedaling, and found the cogging torque of a DD hub to be very...
by busted_bike
Aug 08 2010 12:48pm
Forum: E-Bike Technical
Topic: Using a PDA as a bike computer?
Replies: 15
Views: 2557

Re: Using a PDA as a bike computer?

I use older PalmOS 3.x devices like the m100 with VeloAce, which does what a good bike computer would do. But it doesn't have any ebike-specific capabilities. It just monitors a simple serial input (either from the dock serial port using any reed switch and magnet, or from IR, if you build a little...
by busted_bike
Aug 08 2010 8:06am
Forum: E-Bike Technical
Topic: Using a PDA as a bike computer?
Replies: 15
Views: 2557

Re: Using a PDA as a bike computer?

Hrmmm... check out this Apple patent. How novel. http://www.freepatentsonline.com/y2010/0198453.html What is claimed is: 1. A system for communicating riding characteristics among a plurality of bicycles, comprising: a first electronic device coupled to a first bicycle, the first electronic device o...
by busted_bike
Aug 06 2010 3:02pm
Forum: E-Bike Technical
Topic: Using a PDA as a bike computer?
Replies: 15
Views: 2557

Re: Using a PDA as a bike computer?

but just having USB OTG support doesn't mean that its easy to add hardware. You need a driver written for that specific device. Most of the support thus far is for keyboards and flash memory. Yup. Clearly, there would be some work to do... analog sensors (I, V, temp?), driver, and UI. But I suspect...
by busted_bike
Aug 06 2010 1:04pm
Forum: E-Bike Technical
Topic: Using a PDA as a bike computer?
Replies: 15
Views: 2557

Re: Using a PDA as a bike computer?

I'm surprised there isn't more interest in this. USB host capability is built into the hardware of a lot of newer smartphones (USB On-The-Go). Software support is a hot feature request for the Android platform. Maybe some day soon... http://code.google.com/p/android/issues/detail?id=738&colspec=ID%2...
by busted_bike
Jul 25 2010 1:52pm
Forum: Battery Technology
Topic: A123 Internal Resistance Question
Replies: 19
Views: 1425

Re: A123 Internal Resistance Question

If I understood half of what you just said.... Sounds cool though. I'm a fan of automatic testing, all the decimals get carried properly, I just come back later and it's done. Now, if someone will just make one that tests (and graphs) 10 at a time. Katou http://www.maccor.com/formationequipment.php...
by busted_bike
Jul 24 2010 2:15pm
Forum: Battery Technology
Topic: A123 Internal Resistance Question
Replies: 19
Views: 1425

Re: A123 Internal Resistance Question

I believe some industrial systems superimpose an AC current waveform on top of the (DC) discharge current and LPF the sensed Voltage in order to measure Ri throughout a full charge or discharge cycle. If it were to stop and start the discharge process, and measure the current level and the voltage d...
by busted_bike
Jul 20 2010 8:45am
Forum: General Discussion
Topic: What does your commute cost?
Replies: 21
Views: 1274

Re: What does your commute cost?

I've calculated the burdened cost for my 9yo VW Jetta at approximately $0.38/mi, including amortized purchase price, insurance, repairs, gas, etc... My commute is 47 miles round trip.

So every day I leave the car in the garage is an extra $17 in my pocket.
by busted_bike
Jul 16 2010 8:47am
Forum: Battery Technology
Topic: Got me a pufffy
Replies: 23
Views: 2435

Re: Got me a pufffy

The organic solvent inside the pouch is critical to cell function, an will evaporate out if it's not sealed. Also, at least in theory, if oxygen and water vapor get inside the pouch, it should do bad things, yet in practice the most reaction I got was just mild warming. Based on my understanding fr...
by busted_bike
Jul 14 2010 1:05pm
Forum: Battery Technology
Topic: Combining Batteries Of Different Discharge Rates
Replies: 22
Views: 1869

Re: Combining Batteries Of Different Discharge Rates

I don't know that they would necessarily try to instantly equalize the SOC, but for sure there would be current flow from the low C cells to the high C cells. I would have thought that the cells would just try to equalize voltage and current would flow to the point with the lowest potential, the hi...
by busted_bike
Jul 14 2010 11:51am
Forum: Battery Technology
Topic: Combining Batteries Of Different Discharge Rates
Replies: 22
Views: 1869

Re: Combining Batteries Of Different Discharge Rates

My concern is not what happens when under load, it's what happens when the load is removed. If you have a scenario where you have a large low C group of cells with a smaller high C group of cells, the high C cells will get more deeply discharged quite quickly when under a heavy load. If the no load...
by busted_bike
Jul 14 2010 8:20am
Forum: Battery Technology
Topic: Combining Batteries Of Different Discharge Rates
Replies: 22
Views: 1869

Re: Combining Batteries Of Different Discharge Rates

Funny, I was wondering the same thing recently - basically thinking about optimizing cost/energy/power/price/safety/weight by combining different types of cells (even different chemistries) in parallel. For example, I'm thinking of putting together a relatively small pack (36V*5Ah) for my bike. I'd ...