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Thread: How much LifePO4 battery and What would be the range for AC-23

              
   
   
  1. #11
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    Quote Originally Posted by milton View Post
    Sorry my mistake. I miss-read lbs as kgs. I am basing the weight on my Victory hammer since it has a 250 rear tire.
    lol - that makes more sense alright.

  2. #12
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    Quote Originally Posted by milton View Post
    What lifePo4 cells have you used Skahle?
    I use a 24-cell CALB 70AH pack and as others have pointed out they sag more than the Leaf packs under similar loads which reduces my maximum discharge rate once they get a bit depleted. I chose the LiFePO4 chemistry and prismatic case hoping it would be more robust in a minor accident. I thought a pouch format would mean more weight spent boxing them and more work welding the tabs on lots of cells.

    (As Hugues mentions I would be careful using off brand cells as they may have quality issues which could be a problem, especially in a 10p configuration.)

    BTW: You are mixing AH and A in your posts which is confusing

  3. #13
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    Is there a problem using these liPo batteries or does it make sense to use these batteries?

    http://www.hobbyking.com/hobbyking/s...Approved_.html

    They give 90C with nominal cap of 7.5Ah thats 675A so 16 batteries in serial would give 120 volts and 2 parallel would give about 1300A.. and the weight would be about 25 lbs or 11kgs...

    I won't go for CALB anyways cause they are expensive and I need atleast 96v pack and with 2-3c its going to stress out the battery on highway if the motor is pulling 400amps continually. I need something that would give me atleast 120 miles with CALB that arrangement would break my budget.
    Last edited by milton; 10 February 2016 at 0809.

  4. #14
    Senior Member Hugues's Avatar
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    Quote Originally Posted by milton View Post
    Is there a problem using these liPo batteries or does it make sense to use these batteries?

    http://www.hobbyking.com/hobbyking/s...Approved_.html

    They give 90C with nominal cap of 7.5 thats 675A so 16 batteries in serial would give 120 volts and 2 parallel would give about 1300A.. and the weight would be about 25 lbs or 11kgs...

    I won't go for CALB anyways cause they are expensive and I need atleast 96v pack and with 2-3c its going to stress out the battery on highway if the motor is pulling 400amps continually. I need something that would give me atleast 120 miles with CALB that arrangement would break my budget.
    you can use these batteries, just make sure you don't let them over charge or discharge too deeply.

    But something's not right with your numbers, you cannot get 120 miles range on a motorbike with 11 kgs of batteries, whatever chemistry. Or maybe i misunderstood your post. YOu are also not likely to pull 400 amps continuously on highway, that's way too much. I don't go often on highway but that would be less than 100 amps. Or what speed you have in mind when you say highway ?
    Regards from Switzerland
    My 2.5 Upgrade Thread

  5. #15
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    I am in US. So the average highway speed would be about 60 mph thats 96kph. I assume at that speed the motor would be rotating at about 3000 RPM with direct drive!! (Hugues, you would know better since you already have a motorcycle with about the same motor in there).

    The website says the following about the battery and I am not sure if the 7.5 kw/kg is correct either. Thats a lot of energy per kg. If that is correct then I would get 82 kW with 16 batteries (11 kgs):
    Advantages over traditional Lipoly batteries;
    • Power density reaches 7.5 kw/kg.
    • Less Voltage sag during high rate discharge, giving more power under load.
    • Internal impedance can reach as low as 1.2mO compared to that of 3mO of a standard Lipoly.
    • Greater thermal control, pack usually doesn’t exceed 60degC
    • Swelling during heavy load doesn’t exceed 5%, compared to 15% of a normal Lipoly.
    • Higher capacity during heavy discharge. More than 90% at 100% C rate.
    • Fast charge capable, up to 15C on some batteries.
    • Longer Cycle Life, almost double that of standard lipoly technology.

    Huges,

    These parameters would really help to determine what size of battery would be needed and what would be range, since you already have a ready motorbike:
    • Whats the initial AMP usage from full stop and at what torque (If you have that information, otherwise the motorbikes gwt is sufficient which you have already provided)
    • Whats the AMP usage during hill climb at what angle of steep (approx) and whats speed
    • Whats the AMP usage at 45 mph (72 km) and 65 mph (104 km)

    I understand you don't have to provide all these info but It would be great help. And thank you for sharing your knowledge and experience and helping me any others who have not been able to determine how much to spend on the battery or what size of battery to get for their EV.

    I will post my experiences and share my knowledge as well when I start building my motorcycle.

  6. #16
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    Quote Originally Posted by Skahle View Post
    I use a 24-cell CALB 70AH pack and as others have pointed out they sag more than the Leaf packs under similar loads which reduces my maximum discharge rate once they get a bit depleted. I chose the LiFePO4 chemistry and prismatic case hoping it would be more robust in a minor accident. I thought a pouch format would mean more weight spent boxing them and more work welding the tabs on lots of cells.

    (As Hugues mentions I would be careful using off brand cells as they may have quality issues which could be a problem, especially in a 10p configuration.)

    BTW: You are mixing AH and A in your posts which is confusing
    Sorry about that Skahle. I am still learning the concepts of electronics and electrical. I am from economics background so all this has been gibberish for me till few months ago.

  7. #17
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    I just realized with the above battery 7.5Ah and pulling at 30C or mure will only give me few seconds of current unless I place the batteries in parallel to give me atleast 70-80ah that's 10+ batteries in parallel and 16 in series.

  8. #18
    Senior Member Hugues's Avatar
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    Quote Originally Posted by milton View Post
    ...

    Huges,

    These parameters would really help to determine what size of battery would be needed and what would be range, since you already have a ready motorbike:
    Whats the initial AMP usage from full stop and at what torque (If you have that information, otherwise the motorbikes gwt is sufficient which you have already provided)
    Whats the AMP usage during hill climb at what angle of steep (approx) and whats speed
    Whats the AMP usage at 45 mph (72 km) and 65 mph (104 km)

    I understand you don't have to provide all these info but It would be great help. And thank you for sharing your knowledge and experience and helping me any others who have not been able to determine how much to spend on the battery or what size of battery to get for their EV.

    I will post my experiences and share my knowledge as well when I start building my motorcycle.
    you probably found them but just in case, AC-20 amps , torque and power graphs versus rpm can be found here:
    http://www.hpevs.com/HPEVS-AC-Electr...aphs-ac-20.htm

    I think they have the same graph for AC-23

    I did record some data from my rides last summer. The 2 graphs below could be interesting, showing lowest cell V versus battery amps and speed versus battery amps. You see at which amps most of my driving is done, i only pull 400 amps occasionally for a few seconds only.

    YOu can download the raw data here:
    https://docs.google.com/spreadsheets...it?usp=sharing
    you will see GPS speed, altitude, acceleration on x,y and Z axis, as well as battery amps and cells V. SO you can get a good idea about the questions you ask above. Hope this helps.

    I saw your correction post about battery capacity you need, seems closer to reality now. With small cells like these, the problem is that you need many and wiring them becomes tricky.

    lowest cell V versus battery amps.jpg
    speed (m:s) versus battery amps.jpg
    Regards from Switzerland
    My 2.5 Upgrade Thread

  9. #19
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    Milton, You want to build a beast...copy Hugues design. He has the best heavy cruiser on the site. Hugues, great data set! Looks like you have a time offset between speed and current in that speed goes up a few seconds before current goes up. Would be nice to see some constant throttle, constant speed for a few scenarios like; steady 20m/s (~45mph) no incline, same thing up a hill (grade of 5% is fairly steep where grade = 100(rise/run), 8% is quite steep). You are on and off the throttle which would make your passenger bump helmets but is fine solo...be smooth!

    Would be fun to see a 0-27m/s (0-60mph) run on no incline!

    Cruisers plow through the air above about 45mph and get inefficient due to lack of streamlining of bike and rider position. I love them anyway!

  10. #20
    Senior Member Hugues's Avatar
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    Quote Originally Posted by Skahle View Post
    ... Hugues, great data set! Looks like you have a time offset between speed and current in that speed goes up a few seconds before current goes up.
    ...
    well spotted. I need to work on that this season. I think i'm recording too much data and there is a bottleneck in my system somwhere, not sure which part yet.

    Quote Originally Posted by Skahle View Post
    ... .. You are on and off the throttle which would make your passenger bump helmets but is fine solo...be smooth!

    Would be fun to see a 0-27m/s (0-60mph) run on no incline!

    ...
    LOL, now i know why my wife's helmet is bumping into mine !

    I wanted to record a 0-60 mph run properly, but i have yet to get good data. The thing is, i'm scared, really. When i pass the ~50 mph mark at full throttle, it scares the sh.. out of me. This constant torque thing is scary. On a gas engine, you can feel your engine running out of torque before changing gear, hence accelerating less fast, but with an electric motor, it just bloody accelerates, it's scary. Ok, i'm just 2 years into my new driving license...

    I think i do 0-60 mph below 5 sec, closer to 4. But, i know, without proof in numbers, i'm just bragging.
    Last edited by Hugues; 11 February 2016 at 1205.
    Regards from Switzerland
    My 2.5 Upgrade Thread

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