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  1. powermed

    Prius Batteries - How to make them work

    That was a mix up. The original dimensions was for all 6 of the Prius modules as shown - I edited the post, thanks. The width of each cell is .75" The form factor is actually perfect for virtually all the nice rear rack bags such as Topeak. I could easily fit an 8 module pack in the medium...
  2. powermed

    Prius Batteries - How to make them work

    Prius cell talking points, in my opinion (and in no particular order), are charging speed / convenience, deliverable power, form factor, known quality, life span, and durability. The charging method is just "different" than folks are familiar with. I'm really trying to emulate (not duplicate)...
  3. powermed

    Prius Batteries - How to make them work

    Hi Alan, I think it's fair to say a good SLA will deliver up to 50% of it's capacity at good power before fade time. Figure 80 - 90% for Prius NiMH and A123, so I think you'd probably see close to the same range all other things being equal - if those are good SLA's. However given the 20% bump...
  4. powermed

    Battery Needed

    You might want to consider Prius cells - your bike and distance is perfect for an 6 (44.4v) or 8 (59.2v) module pack. 6.5AH and will deliver every amp you need going up those hills. The really nice part is they can be recharged in an hour. You might want to see my post in Batteries "Prius...
  5. powermed

    Prius Batteries - How to make them work

    honored for the stickyfication... 6.5AH is the tech spec, but regrets - no wattsmeter. Having the same ride day in and day out for several years, and owning and using Dewalt and Tenergy's, I can make the following empiric statements; 1. vs Tenergy sub C NiMH (3.8 AH) packs: Those packs...
  6. powermed

    Prius Batteries - How to make them work

    I'm posting this separately since it might be too far buried in other threads - mostly about Prius failures. There's been quite a bit of mystery and misunderstanding about these amazing cells. It's no coincidence that Toyota has been using them successfully for almost a decade, and decided to...
  7. powermed

    Prius battery pack

    Hi Kurt, The resting voltage has always been above 7v in my experience. I stop using the batteries as soon as I notice a drop in performance, which should correspond to about 80% drain by the technical paper if all cells are balanced (and they are). I've also become quite comfortable riding...
  8. powermed

    Prius battery pack

    I've experienced no such swelling under either high load, or charging at 4.5A to 8.3v or delta T via infrared thermometer. Swelling is a function of internal gas production which typically occurs during over-charge. My brother who's ruined more than his fair share of Gen III cells has even...
  9. powermed

    Prius battery pack

    Folks looking for high performance commuting distances from 5 - 10 miles might strongly consider newer (gen III) prius cells. I've been using them exclusively on a daily basis for months now, they perform very much like A123 cells which I've had, but no longer use due to lower voltages...
  10. powermed

    Prius battery pack

    kurt, I think those batts are toast. z.
  11. powermed

    which gauge wire to use?

    Here's a good table that covers it. At the bottom is a calculator for voltage drop. http://www.powerstream.com/Wire_Size.htm I've used a lot of very heavy gauge (as low as 4) for my electric boat, unexposed to sunlight audio cable is exceptional stuff and can be found cheap sometimes. It's...
  12. powermed

    Prius battery to power e-bike?

    Whoops, I said 10% to the upside - should have said from 2 - 5% on the upside. Found what I thought was all the tech stuff I'd need, a paper written by the team that brought you the prius battery...Journal of Power Sources Volume 100, Issues 1-2, 30 November 2001, Pages 117-124 Development...
  13. powermed

    Prius battery to power e-bike?

    Someone jump on me if I'm wrong, but unloaded voltage should be the one that counts Kurt, that is if the charger has a constant current (CC) output. Most chargers do for the bulk of their charge cycle. I'd be wary of most SLA chargers unless they are of known high quality such as a soneil -...
  14. powermed

    Prius battery to power e-bike?

    Just got home after a 5 cell (36v) round trip to work on my summer ride (mid-engine-through-the-gears). Extremely satisfying with the ability to accelerate in any gear, even going uphill. I think I'm forming a few (no watt-meter type) conclusions of my own. I've summarized them as follows...
  15. powermed

    Prius battery to power e-bike?

    Good luck Kurt - from your description the cells sound over volted and under charged. I've pretty much set LiFeP04 aside since I can buy a 36v pack of these (5 cells / 6.5 ah) for under $150 that bolts together...Criminy....what am I missing? That's at least as good as 3 dewalts - and I truly...
  16. powermed

    Prius battery to power e-bike?

    Jeremy, I haven't had much luck deciphering what little technical info I've found on the prius cells, some of the more detailed sites I found are still pretty slim... http://www.99mpg.com/resources/articlesandblogs/batterypacksexpose/ http://hiwaay.net/~bzwilson/prius/pri_batt.html - this...
  17. powermed

    Prius battery to power e-bike?

    I've run a number of empirical tests on my generation 2 or 3 cells and would share a couple of personal observations with them. First, I think it's important to state they are all from the same car, only 2 or 3 years old, and arrived at my door at 7.4v each cell. I have no reason to think they...
  18. powermed

    Prius battery to power e-bike?

    Bummer Kurt. I've no problems running a 7 module pack flat out and fast charging it. Not a hint of warmth, or swelling, tons of power - as much as my A123's....mine are more recent vintage with aluminized sides on each module.
  19. powermed

    LiFePO4 C ratings and "Quality"

    Hi Gary, you're right about the possibility of singular cell weakness hiding amongst the cells. I've a single voltmeter and the cells are all on tap via a small 10 position DP rotary switch. That plus the larger bats keeps me safe on my usual jaunts since I know my territory and range very...
  20. powermed

    a DC-DC to charge li-ion... GREAT!!

    should have mentioned, the yellow wires are the parallel signal wires, purple and green are for switching on and off, deans in and deans out. z.
  21. powermed

    a DC-DC to charge li-ion... GREAT!!

    ok, previous pic was one of the charge converters, here's a few of the drive converters - a 28v array capable of providing up to 1600 watts. A second array will be in series with this one. z.
  22. powermed

    LiFePO4 C ratings and "Quality"

    Hi Gary, "what are you using for controllers? " - I use a very nice Zahn servo amplifer I picked it up on ebay for a song a few years ago. Ridiculous capacity, something like 5000 watts. I've run it close to that limit in the ocean and it never even got warm (I was seeing 100 amps on my...
  23. powermed

    Prius battery to power e-bike?

    I'm pretty sure that's a 1st gen battery - supposed to have some tendency to problems but I can't remember what. The one I have is 2nd gen and may be preferred. Gen 1 had 38 cells, Gen 2 has 28. z.
  24. powermed

    Prius battery to power e-bike?

    Sorry mitch - meant to add the cells are 7.2v nominal, 6.5 AH, maybe 12x5x1 in size? z.
  25. powermed

    Prius battery to power e-bike?

    forgot to add, I keep a voltmeter on my packs during charging so I can manually decide to end or continue a bit.
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