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  1. ahambone

    Verifying whether SPI is working for Linear Tech LTC6802

    Reading back all 0xFF indicates that the MISO pin on your MCU probably was pulled high the entire time. There are several things to check: 1) Make sure your MCU doesn't requore pull-up or pull-down resistors on its MOSI/MISO pins or it's SPI clock pins. This is uncommon but can happen. If...
  2. ahambone

    New Forum Section!

    Hey, I just noticed this new section! This is great. I'll throw up a build thread for my Cabrio here. Awesome! Cheers, --Adam
  3. ahambone

    Headway Pack Performance Analysis

    MrKang - thanks for the link to the program. That certainly will make things easier! Cheers, --Adam
  4. ahambone

    Headway Pack Performance Analysis

    Time to share some Headway data porn. The 120 cell Headway pack has been in "testing" use in the car for a few months now. I've determined that the 50-AHr (5p)x24s pack gives me just about 15.2 miles of range, taking the cells down to 64V total (~2.6V/cell) where my controller cuts me off...
  5. ahambone

    Headway Pack Builders thread

    The cad drawing is also missing the male/female trapezoid interlocks that hold the end caps together. Frodus is right - buy one if you want to clone it. They're only $1 at batteryspace, get 2 so you can feel how they interlock. http://www.batteryspace.com/search.aspx?find=BH2M Cheers, --Adam
  6. ahambone

    Most powerful EV battery pack ever?

    Very nice pack! I've been driving on a 3.6KWh pack (5px24s) pack for several months now. I'm about to take the plunge and expand it to a 48s pack, doubling the voltage. Nowhere near what this EV pack looks like, tho. Really impressive! :mrgreen: Cheers, --Adam
  7. ahambone

    Big Headway pack design

    Why the 8 AHr cells and not the 10 ahr screw-tab cells? What are you planning on using to interconnect the cells with? I'm using a 120 cell (24s x 5p) pack right now and am curious why you went with the tabbed cells. Maybe you have assembly machinery that I didn't have access to. (BTW, size...
  8. ahambone

    Advice Needed - Headway vs Thundersky

    flashedarling: Wow.. I'm blushing! :mrgreen: Thanks for the compliments on the battery pack. You are right - without access to local scrap yards for the copper and a friend's machine shop I wouldn't have been able to make my battery pack. I too have a garage that is mostly hand tools...
  9. ahambone

    Advice Needed - Headway vs Thundersky

    If you're planning on routinely pulling more than 3C (@60 ahrs = 180 amps) then I would suggest going Headway. If you're planning to stay under 3C then I'd vote with the bang-for-the-buck advantage and go with Thunder Sky cells. I have a 120 cell Headway pack in my EV and will soon have 2 of...
  10. ahambone

    Headway Battery Rust Issue

    I'd say about 5 of my 125 cells had rust spots when they arrived. I've had them in a car in Houston TX for the last 2 months and haven't noticed any expansion of the rust spots since I installed the cells. The cells are in the trunk compartment so they aren't directly exposed to the elements or...
  11. ahambone

    Bottom balancing?

    This is a highly scientific sample size of two. And I'm guessing that both of you periodically monitor the cells' voltages and/or never drive near the end of your range. In practice do you always drive only 60 AHrs into a 100 AHr pack? Do you have some kind of other instrumentation that tells...
  12. ahambone

    Bottom balancing?

    I just finished re-reading Jack's rant. I found this line particularly rich: This is right after railing Goodrum's calm and polite explanation. Didn't I read in another thread/comment somewhere that Mr. G. was an engineer/consultant working for Lockheed or the like? Not exactly piggly...
  13. ahambone

    Bottom balancing?

    Well, Jack's videos are at least fun to watch. :roll: Maybe we can take something good from this and gather in-EV-use "production" data from some LiFePO4 cells and publish the data/result graphs here (in a new thread, of course). I'm working on collecting some data like this from my...
  14. ahambone

    What's The Consensus Opinion On Sony 18650??

    The Telsa Motors config is 11S x 9S x 69P. So I guess 99s x (69p) is a accurate. We really need a standard for the associativity of the "s" and "p" characters in battery short-hand. To me "99p69s" implies 99 cells in parallel and then 69 of those in series - which is not what the tesla pack...
  15. ahambone

    EEStor ultracapacitor

    There is nothing new here. This is all the same smoke and mirrors from July 2009. Wake me up when a prototype on a test bench is photographed or videoed with monitoring equipment showing that it works. Until then this is snake oil from the ocean-front district of Utah. :wink: --Adam
  16. ahambone

    Linear Tech 12-cell battery monitor/BMS

    The LTC chips do look sexy. I'm not sure I'm ready to make the leap to surface mount yet. My hands just aren't quite that steady. :roll: I just ordered my first custom PCBs for battery monitoring stuff a couple of days ago (G/F BMS boards don't count). I'll see how that project works out...
  17. ahambone

    Linear Tech 12-cell battery monitor/BMS

    I too approve of the testing setup! 8) Arduinos are loads of fun. I have several of them around for various projects. I built a follow-the-sun solar panel tilt controller for a friend of mine based on an one. I love following this project. Those LT chips look awesome for monitoring 12s...
  18. ahambone

    Hypothetical: I want to Build a LifePo4 battery- But How?

    I've built a 72v 50Ahr pack from Headways. I go into some detail about it over in the Headway Pack Builder's thread around page 12: http://endless-sphere.com/forums/viewtopic.php?f=14&t=12320&start=165. That thread is a great thread to read of you are considering building a pack like this...
  19. ahambone

    Thundersky LFP activation charge why ?

    I suspect the "charge cells to 4.2V to break in" procedure is just as was said earlier - to make sure users balance their cells before making packs out of them. An implicit top-balance if you will. When I got my 125 Headway 38120S cells I placed them in parallel groups of 5 with short runs...
  20. ahambone

    Bottom balancing?

    That's quite true. Right now I'm running off of a Headway pack (might upgrade to SkyE/CALB later) that is 50 AHr pack, 72.8 v pack (5p x 24s). It's not the final pack for the car but it's what I've got to get me on the road and for testing. Flooring it from a dead stop on level ground I can...
  21. ahambone

    Headway Pack Builders thread

    Thanks, Otanet! :D I am just now realizing that I thought I was obsessed before. Now that the project rolls the obsession only gets worse. :P Cheers, --Adam
  22. ahambone

    Headway Pack Builders thread

    Hi Folks, I've uploaded a few videos to you tube of my car's first day on the road (test runs really). I don't want to junk up this thread with notes about my conversion, but here is a video that shows the pack driving the car on the road. 3 passengers, ~20 to 25 mph and hooked up with only...
  23. ahambone

    Headway Cell at 1.000 Volts

    Of the 125 headway 38120S cells I ordered through Frodus there was one cell that arrived at 1.77 volts. This was enough to scare me and so I labeled the cell with a big mailing-label that said "arrived 1.77, weak". I threw it on a VoltPhreaks charger and have charged it up slowly and have used...
  24. ahambone

    Thundersky cells and BMS

    Using the LVC detection leads in parallel is exactly what I plan on doing. In my finished car I'll have two 24 channel G/F BMS systems and two 24S packs attached in series to make my car a ~144 volt car. The LVC circuitry will be wired in parallel between the two BMS systems. When charging I...
  25. ahambone

    Headway Pack Builders thread

    I do have all the wire leads coming off the same side. I am fairly certain this is okay for my pack because the leads in my case are balancing, sensing, and shunting leads and not charging leads. If I recall correctly in your setup otanet you are using individual DC/DC converters to drive...
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