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Thread: Choosing my Battery Pack!

              
   
   
  1. #1
    I should be working! furyphoto's Avatar
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    Choosing my Battery Pack!

    A thread to follow my decision process on choosing a battery pack for my bike

    Already decided:


    1. LITHIUM!
    2. 72v - 90v pack
    3. 4.3 - 9.7 KWH Depending on cells chosen and budget! (See my performance/range goals HERE)
    4. BMS - Cell level monitoring with no active balancing, (shunts get hot, and burn down bikes) Probably will use this one. but maybe something else.
    5. Will bulk charge the pack normally, and use my icharger 208B to balance when needed.


    Here are the contenders:

    • CALB CA cells

    CA60FI2 (Copy).jpg
    • RC LiPo

    TurnigyHC_4S_5000_20c__74659.1318395669.1000.1000 (Copy).JPG
    • A123 20AH prismatic cells (Genuine)


    • A123 20AH prismatic cells (No Label seconds form China)

    A123_20Ah_Automotive_Class_Lithium_Ion_Cell (Copy).jpg


    I already have a few RC 4s Hardcase packs from HobbyKing for my RC helicopters so I am familiar with them, they will get some testing done to them as soon as my icharger arrives.

    I have ordered 3 A123 "No-Label) cells from China to test as well. While these "seconds" cells may not live up to the full potential of the original A123's, they are the best priced Li batteries per/KWH and if their limits are designed into the system, they could work well. Testing will be rigorous, and hopefully provide for a clear decision.

    Let me know what you think.
    -Andrew

    http://www.andrewdoran.com
    mail(at)andrewdoran.com

    My ElMoto Project "Electric Hurricane" - 1987 Honda CBR600 F1: Check out my Build ALBUM
    My ICE Cafe Racer Project "My Precious" - 1983 Honda CM400 Classic

  2. #2
    Seņor Member podolefsky's Avatar
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    If you're not building a race bike, and are worried about burning your bike up, don't use RC lipo. Go with LiFePO4. CALB are good, GBS are also good. I like my GBS cells a lot. A123 prismatic cells are nice, but harder to assemble since you need to build them in series/parallel to get up to the 60-100 Ah range.

    I've never heard of shunts getting hot and catching cells on fire, at least not LiFePO4 with a reputable BMS. Maybe a cheap lipo BMS? Bulk charging and balancing with the iCharger is fine, it's just more work and it's not actively monitoring your cells (so you won't know if you're killing one while you're out riding).

    Safest, most reliable, and easiest route are large format LiFePO4 with a well established BMS.
    - Noah Podolefsky -
    The GSX-E

  3. #3
    Senior Member Hugues's Avatar
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    I've read your range and speed expectations in your other post, pretty similar to mine, with hills riding.

    9 kwh of RC Lipo is asking for trouble. I've got about 1 kwh on my mountain bike for the past two years , that's 20s and I would not like to have to monitor more than this really.

    A123 is really a huge job to assemble for that kind of pack.

    I agree with Noah's conclusion above.
    Regards from Switzerland
    My 2.5 Upgrade Thread

  4. #4
    I should be working! furyphoto's Avatar
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    I think one of the benefits of A123 or Lipo is the ability to start with a smaller AH pack and then expand. With the large format cells you pretty much have to go for broke from the get go. You can't reaally upgrade from the 60ah to the 100ah, you have to get it all from the start.

    I was thinking about getting it on the road for short around town trips, and then building on the pack to meet the ultimate goals later on.
    -Andrew

    http://www.andrewdoran.com
    mail(at)andrewdoran.com

    My ElMoto Project "Electric Hurricane" - 1987 Honda CBR600 F1: Check out my Build ALBUM
    My ICE Cafe Racer Project "My Precious" - 1983 Honda CM400 Classic

  5. #5
    teddillard
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    I have a small RC lipo pack with the hardcase 4s Turnigy. I also just finished a 40ah CALB pack and took a ride last night. Let's just say it's a considerable difference.

    The CALB pack is way heavier, and I've made some changes to the bike that added weight, but it's a LOT slower off the line. I was kind of afraid of that.. I'm pretty sure it's not as much due to the weight, but more the chemistry. I'm going to be testing that theory out as soon as I tighten up a few details.

    Granted, the RC lipo is a handful, but if you're looking to go fast, it's awesome. Of course, the A123 are good for that too, but as has been said, more work to set up.

  6. #6
    Seņor Member podolefsky's Avatar
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    For sure, A123 of lipo are lighter, can give more amps, and yeah, you can build them up in stages. Although, you want to match the cells when you put them in parallel, and that's going to be harder to do if some of the cells are used and you add ones that are fresh off the shelf.

    It's true, though, with large format you have to buy the whole thing, and then you're pretty much stuck with it (pretty much...there are things you can do, like booster packs).

    I'm going to guess the main reason Ted's bike feels slower is weight - you probably added, what, 75 lb to a 200 lb bike? The other thing is the output of those 40Ah calb cells. You'd really be pushing them to get 400A. With your 1003 and Altrax, you can easily pull over 450A, so you're sort of starving the drive system.

    Although, right off the line you're not pulling that many amps from the cells since you're at low RPM (where battery amps < motor amps). The calbs should be able to supply all the current the controller is asking for at WOT up to about 30 mph (give or take depending on your gearing).
    - Noah Podolefsky -
    The GSX-E

  7. #7
    teddillard
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    Nope, more like a net gain of less than 50lbs. I'm pulling the old pack off (25lbs) and adding maybe 60lbs. But the voltage sag is pretty big... the 80V pack is dropping below 60V when I'm honkin' on bobo.

    But we'll see. I'm going to pull half the pack out and put the lipo back in. The weight will be close, then, and I can see how it goes.
    Last edited by teddillard; 18 May 2013 at 1105. Reason: bad maths

  8. #8
    Seņor Member podolefsky's Avatar
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    Quote Originally Posted by teddillard View Post
    Nope, more like a net gain of less than 50lbs. I'm pulling the old pack off (25lbs) and adding maybe 60lbs. But the voltage sag is pretty big... the 80V pack is dropping below 60V when I'm honkin' on bobo.

    But we'll see. I'm going to pull half the pack out and put the lipo back in. The weight will be close, then, and I can see how it goes.

    Oh, yeah, that's a lot of sag. If you have the Alltrax at max current, you're asking over 11C of your calbs at full throttle. They're not going to like that.
    - Noah Podolefsky -
    The GSX-E

  9. #9
    teddillard
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    Right, as I said, they're much different. Ironically, (and to the point) though, as I went to top up my lipo pack I found another pack has given up the ghost... So yeah. A handful.

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  11. #10
    Senior Member Remotecontact's Avatar
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    I strongly disagree. If you have a bit of know how and follow a few simple rules an RC Lipo pack can give you years of amazing performance, energy density, and $/kwh.

    I've been riding with my Turnigy Lipo pack for two and a half years and it's still going strong.

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