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  1. powermed

    Prius Batteries - How to make them work

    Tom, my thoughts go something like...."run, don't walk" to get a good quality meter you can depend on. Here's a clamp meter for $80 I rely on clamp meters exclusively to measure current going to each cell of my single cell LiPO chargers, it's just incredibly easy, and in general...
  2. powermed

    Prius Batteries - How to make them work

    Tom, no doubt if you have the extra capacity and it's working for you, no reason to change. I've left 8.3v on overnight once by accident and there was no issue, the cells were drawing milliamps, but no heat/defomation/gassing. A while back I set my charge to 8.35v and charge them in series...
  3. powermed

    Prius Batteries - How to make them work

    Yowsa, fantastic to see so much interest in Prius cells after all this time! I've been way too busy to post for quite a while. If anyone is interested, I still have my original ones working without any problems. I also noticed a lot of whole Prius batteries on ebay for pretty cheap money...
  4. powermed

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

    I should add, although I've not tested it, I think it would be dangerous to have a DC supply that can power up the Vicor's beyond the C rate of the cells. Those Vicor's can supply up to 20 amps if there's enough power coming from the input side. That's a 2C rate for a 10AH cell should the...
  5. powermed

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

    Hi Travis, The way I've used them (without any problem) is to work "backwards" with the math. I haven't seen any evidence of the vicor's attempting to draw more current from the power supply than the power supply can deliver in order to charge my cells. Not my area of expertise, but I...
  6. powermed

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

    here's a few for even less... http://cgi.ebay.com/Cisco-AIR-PWRINJ-48V-DC-Power-Injector-and-AC-Adapter_W0QQitemZ290285493982QQcmdZViewItemQQptZCOMP_EN_Routers?_trksid=p3286.m20.l1116
  7. powermed

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

    hi Travis, they're off via USPS... Here's what should be a pretty good fit...
  8. powermed

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

    Hi Travis, No onboard way I know to adjust current on these vicors (there might be one, but I've never tried). Someone confirm my math...A simple method is to multiply the number of cells (4) x the charge voltage you need (3.7?) x the max safe charge current (3.2) = the max wattage of the...
  9. powermed

    Prius Batteries - How to make them work

    Whoa...you are spot on...not sure what I was smoking... 168S it is.
  10. powermed

    Prius Batteries - How to make them work

    I am doing that for my packs - but my point was that each module (a single plastic unit) in the Prius pack is actually 6 cells in series - the module voltage is 7.2 nominal - so a Prius pack is essentially 28S6P. I'm not convinced you can't safely charge them in parallel - as long as you're not...
  11. powermed

    Prius Batteries - How to make them work

    That sounds true - if you're topping them off. I don't charge them fully / to the voltage drop. Each module is 6 cells in series, so they are in effect always being charged in parallel.
  12. powermed

    Prius Batteries - How to make them work

    Agreed. I've probably had a few dozen emails from folks wanting to know how to charge these cells in larger configurations than the stock Prius. I'm obviously very happy and comfortable with them compared to A123 cells. I've taken to charging them in series - they just don't seem to get out...
  13. powermed

    Yesa battery real world test - by this forum

    "when i took it and while i've manipulated it to put it on my bench, the rotation of it maked me to hear something strange inside this white box... When i move it i can hear a little part and few others smaller moving inside as i shake it " I'm wondering if you're not hearing a foil battery...
  14. powermed

    Discharge Curve: Headway 38120S (screw terminal) 10ah cell

    "I actually would tend to question if even these improved headway cells could really do anything over 3C continous once assembled into a complete pack" I wouldn't question it too much from my experience over the last week. Ran them deliberately hard the other day on my mid-engine at "24v" on a...
  15. powermed

    How does your ebike weight?

    "through - the - gears" does require a bit of common sense / trial and error, but c'mon, these forums are filled with people that do that everyday! If you look at the various pics on my site, other than the front freewheel and currie motor with planetary gearhead, weight claimps (could use U...
  16. powermed

    How does your ebike weight?

    Since I dropped to 29v from 44 (Prius pack), the whole shebang is just under 45 pounds without the coffee. I shed another 3 pounds with the 10AH Headway pack I just bought from Chad for kicks. Why all the hub motors? The key is using a through the gears drive and a 24" rear wheel - lots of...
  17. powermed

    Some advices to STORE YOUR BATTERY for the winter period

    Excellent advice. Another thing to keep in mind is that any attached device - such as a charger or DC converter may have a slight amp draw. Over time it can be enough to ruin a battery. If in doubt it's best to disconnect them entirely! z.
  18. powermed

    Grab these cheap battery packs!!!!!!!

    they are ok. AH ratings are suspect, need a bunch of chargers and or reconfigure packs. Overall, I was happy with the 36v (3 12v string) packs they sell after I rewired them for permanent charging. z.
  19. powermed

    Confirm, please, that this LiPo pack is a goner?

    Is there any voltage from the pack? I didn't see it in the thread - I fixed my brother's LiFePO4 pack which had a similar problem by giving it a partial charge directly from a low current 36v source. Sometimes (I think it was mentioned) chargers have a low voltage limit for safety. If they...
  20. powermed

    Making battery pack from cheap AA NiMH cells

    Consider it nipped in the bud...since at best you're only saving a few bucks it's hardly worth all the hassle, time, unhappy surprises and pain you will likely encounter. IMHO
  21. powermed

    Who's using Lipo without a BMS?

    No BMS on my old A123 dewalt packs, and no BMS on my current prius packs. No problems for the last 2 years. The key, as stated, is to know your ride, stop using battery power as soon as you notice any drop in performance, and not try to fully charge them - the mantra I go by is simply "don't...
  22. powermed

    Prius Batteries - How to make them work

    totally normal ride on my overnight pack. The details are beyond my current knowledge base, but the big picture is pretty clear - exceed the right charging voltage (somewhere around 8.3v) on those packs and you're in for an unpleasant event of some kind. the fact that your results on 8.4v at a...
  23. powermed

    Prius Batteries - How to make them work

    Well, I learned something last night, just not entirely sure what it was... For the first time since I've been doing this - some several hundred cycles - I left a pack charging over night. I saw the plug first, and with that gut wrenching feeling placed my hand into the bag to check the pack -...
  24. powermed

    Investing in a new battery

    Hi Kurt, can you charge in town? Getting a pack that can handle high amps charging, and charging in town for 30 minutes might make good sense. To that end, a pack based on A123 or Prius cells would do it easily. Your commute sounds much like mine. In town I stop at a coffee shop I like...
  25. powermed

    Prius Batteries - How to make them work

    "The application I was thinking about would a 40AH, 50 volt pack, or thereabouts, for an electric scooter. Still a lot of volume compared to LiFePO4. But if you don't need such large capacity this is the way to go. " Yeah, I think once you get over the 28 modules of 1 complete Prius battery...
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