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  1. #1
    Senior Member 15rms's Avatar
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    Bionx 48 volt system

    I see Bionx is going to be selling a 48 volt 350 watt kit starting in Feb. For those that understand this better than I, I have a question. Would the 48 volt battery hold 33% more energy than a 36 volt battery? And assuming so would you expect the bike to go 33% further on a charge or would the extra power and acceleration eat up the benifit?

    http://www.greenspeed.us/bionx_PL350...l_edition.html

  2. #2
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    It doesn't say the AH of the battery.

    Here is the calculations you need...

    Volts times Amp Hours = Watt/Hours
    More volts = more speed.
    More AHs = more distance.
    Wattage of motor = Pulling Power (torque)

    So everything hinges on those calc...

    Example....
    36v 10ah = 360 w/h
    36v 20ah = 720 w/h = more distance
    48v 10ah = 480 w/h (compared to 36v 10ah) = more speed and distance
    48v 20ah = 960 w/h (compared to 48v 10ah) = more distance.

    Given equal batteries(lets say 36v 20ah), a 250w motor will use up all the battery in ~3 hrs. (720wh / 250w)
    A 500 watt motor will give much better torque, but can use up twice as much power as the 250w one will. (720wh / 500w)

    Given different voltages, it gets a little trickier...
    A 36v 20ah running a 250w motor = a little less than 3 hours. (see above calc)
    A 48v 20ah running a 250w motor = more speed and a little less than FOUR hours. (960wh \ 250w)
    You'll notice the batteries have the same "AH" but you'll see that the 48v will give you more speed and distance.
    A 48v 20ah running a 500w motor = even more speed, more torque, and less time (960wh / 500w = a little less than TWO hours.

    Hope this helps.

  3. #3
    Senior Member 15rms's Avatar
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    Thanks Sangesf.
    Last edited by 15rms; 12-01-10 at 10:24 AM.

  4. #4
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    Given different voltages, it gets a little trickier...
    A 36v 20ah running a 250w motor = a little less than 3 hours. (see above calc)
    My 500w hub motor kit came with a 36v10ah battery and was advertised to go 20 miles on a charge with a top speed of 20mph. But 360 watt-hours (batt) / 500 watts (hub motor) = 0.72 hours and 0.72 hours x 20mph = 14.4 miles! (My maximum range on a charge) Did I calculate right or did I get taken for a ride?

  5. #5
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    The fly in the ointment is the fact that batteries should not be drawn down fully before recharging so count on less ah than advertised.

    If you want to get the best mileage, pedal along with the power.

  6. #6
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    Quote Originally Posted by edcastrovalley View Post
    My 500w hub motor kit came with a 36v10ah battery and was advertised to go 20 miles on a charge with a top speed of 20mph. But 360 watt-hours (batt) / 500 watts (hub motor) = 0.72 hours and 0.72 hours x 20mph = 14.4 miles! (My maximum range on a charge) Did I calculate right or did I get taken for a ride?
    Well 20 miles on 10ah is a bit optimistic.

    On 36v I average 7 miles for every 5ah. (at 22mph)
    (LiFePo4)

  7. #7
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    Quote Originally Posted by Sangesf View Post
    Well 20 miles on 10ah is a bit optimistic.

    On 36v I average 7 miles for every 5ah. (at 22mph)
    (LiFePo4)
    7 miles for 5 ah sounds good! (especially at 22mph) On my longest ride I went 16 miles total without any signs of slowing down. I'm good with that.

  8. #8
    Senior Member GTALuigi's Avatar
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    hmm... very informative.

    I just learned something new today

    Thanks!

    Quote Originally Posted by Sangesf View Post
    It doesn't say the AH of the battery.

    Here is the calculations you need...

    Volts times Amp Hours = Watt/Hours
    More volts = more speed.
    More AHs = more distance.
    Wattage of motor = Pulling Power (torque)

    So everything hinges on those calc...

    Example....
    36v 10ah = 360 w/h
    36v 20ah = 720 w/h = more distance
    48v 10ah = 480 w/h (compared to 36v 10ah) = more speed and distance
    48v 20ah = 960 w/h (compared to 48v 10ah) = more distance.

    Given equal batteries(lets say 36v 20ah), a 250w motor will use up all the battery in ~3 hrs. (720wh / 250w)
    A 500 watt motor will give much better torque, but can use up twice as much power as the 250w one will. (720wh / 500w)

    Given different voltages, it gets a little trickier...
    A 36v 20ah running a 250w motor = a little less than 3 hours. (see above calc)
    A 48v 20ah running a 250w motor = more speed and a little less than FOUR hours. (960wh \ 250w)
    You'll notice the batteries have the same "AH" but you'll see that the 48v will give you more speed and distance.
    A 48v 20ah running a 500w motor = even more speed, more torque, and less time (960wh / 500w = a little less than TWO hours.

    Hope this helps.
    Mu SL Gone in 10 sec!
    Matrix The perfect commuter bike for all terrain!

  9. #9
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    Always glad to help... Any more questions?

  10. #10
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    Who builds the best controller and motors? What makes one motor better than another? What do you see as the ideal combination of power Motor(W) and Battery V/A? Seems people forget that as you increase both, you also increase weight and balance on the bike. That much I know, but I am a newbie here.

  11. #11
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    I always like to use 250w-350w motors because I don't need speed or power..
    I always like as much distance..
    I'm in south florida so it's all flat around here. If you live in a slightly hilly area, go with 500-750w motors.
    If you live in very hilly areas, then an 800w+ motor is for you.

    Just about any motor will do for me because I only run 250w-350w continuous and most motors handle that easily.
    36v IMO is the best for price per weight.
    Smaller wheels provide more torque and more speed compared to larger wheels...

    I use Goldenmotor controllers, they run voltages 24-60v and when used with 24/36v they only pull 25a max. They have regen, cruise control, reverse, programable, alarm, horn, etc, etc all in one controller

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