About e-bike's motor, what is the difference between 500W and 350W????

Discussion in 'Electric Bicycles' started by Morgan bro, Nov 23, 2016.

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  1. Morgan bro

    Morgan bro New Member

    Ready to buy electric bike! And see there are two kinds of motor 500W and 350W in the market! I would like to ask you guys:

    1) 500W and 350W, which one is large power consumption in the same gentle road and driving the same speed.
    2) 500W and 350W, which one can live longer?
    3) After the battery discharge a 50% or less of power, about the endurance and climbing ability? 500W and 350W, which one is more stong?
     

  2. zippinaround

    zippinaround Active Member

    Is this some kind of trick question?
    1) 500 w
    2) they can live just as long if maintained
    3) 500 w will still be stronger because it's more powerful
     
  3. bakaneko

    bakaneko Active Member

    1. Watt (W) or power is defined as in terms of e-bikes mass (rider, bike weight) and length, time (speed). The higher the W the faster the e-bike will take you. But, if you go the same speed on the 350W and 500W, it will consume the same power. Higher power also requires a better battery and controller

    2. always go for the highest power you can get financially and legally. they both last the same

    3. 500w is more powerful but maybe your question is more about the battery. there are two popular battery choices SLA and Lithium Polymer (LiPo4). while on paper both might have the same energy (amp hour), the difference is in the rated discharge rate. LiPo4 has a higher discharge rate which means you can go near 100% power and the discharge from the aH will be near constant. However, for SLA, the discharge rate for 100% power is dramatically higher and log or ^2, which means if you can go fast but not very far. Also, the LiPo4 is about 3-4 times as light, which matters. Never discharge your battery below 10-15%.

    If you are buying a e-bike most likely it will come with a LiP04 battery, but check the discharge rate of the battery and manufacturer. You would want the rated discharge (not peak discharge) to be near the power (W) of your motor. This will allow you to push your bike to the max without worrying about harming your battery. China batteries are usually lower quality than Japanese (Panasonic). I'd go for 500w too.
     
  4. KB_UK

    KB_UK Member

    Watts have nothing to do with the mass of the bike or the rider, a Watt is always 1 Joule of energy per second. Can be a nuclear power station or a bicycle doesn't matter. 1W always = 1J/s

    so:

    1) Watt rating is a maximum, at full throttle. If both a 350w and 500w bike are travelling the same speed, with the same load, they use the same power.
    2) They're the same.
    3) If the battery can still deliver the correct current and voltage, the 500W. This is a matter of the battery.
     
  5. bakaneko

    bakaneko Active Member

    yeah, i am just trying to relate it to his situation (bike and rider mass and speed). maybe, i am expressing it wrong but a watt is J / s = (N * m)/s or (kg * m^2)/s^3. Here I think kg is the rider + bike, m/s^2 is acceleration of the bike to some speed (velocity), and m is distance per second. i mean that a higher watt bike will be able to accelerate him to a higher speed than a lower watt system.
     
  6. Street Ryderz

    Street Ryderz Active Member

    you guys are wack! the watt rating is not the max but the average constant! I use a 500w set up on 60v and its peak draw is over 1600w! When its running at speed within 20 percent of its free spin then it draws 500 w on average.And sla batteries have way less output amperage then li-po batteries my li-po cells will put out 225 amps constant no problem good luck getting even close to that with an sla!
     
  7. Street Ryderz

    Street Ryderz Active Member

    Go use grin ebike simulator and look at the graph you can see everything and learn alot about how to get the most from your ride!
     
  8. Street Ryderz

    Street Ryderz Active Member

    www.ebikes.ca/tools/simulator.html
    Here is the site!
     
  9. bakaneko

    bakaneko Active Member

    yes, i heard that. i thought it ws closer to 1000w max on a 500w. but, it seems like you have a great bike.
     
  10. Street Ryderz

    Street Ryderz Active Member

    My batteries only weigh 5 lbs huge difference from carring 60 plus lbs and all in weight is 80 lbs,and it uses a 45 amp controller witch is the real factor of how much power you ultimately get not the motor!
     
  11. Street Ryderz

    Street Ryderz Active Member

    2014-05-13 21.31.14.jpg
     

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  12. Street Ryderz

    Street Ryderz Active Member

    Above is my ebike it gets lots of comments when out around town!hauls me and my girl to 56 kph no problem.
     
  13. KCvale

    KCvale Motorized Bicycle Vendor

    I suggest you go back a couple steps Morgan and start with what YOUR NEEDS are now first.

    Just forget about money, it's about what do you need the bike to do day to day.
    Get you to work on time every day, or go fetch some snacks at the store on a nice day?

    Once you find what would be Prefect for you, you start making cuts to fit the budget, but in the long run you will know what those 'little things' are you might want to upgrade latter on, or not and be done with it which many are hehehe ;-}
     
  14. Pablo

    Pablo Motored Bikes Sponsor


    This seems most correct.

    To the OP there are more choices than 350W or 500W. As a practical matter, very rare (never) does someone say they had purchased a lower watt motor. It happens ALL the time when people say, I should have paid a few dollars more and got a higher rated motor.
     
  15. KB_UK

    KB_UK Member

    The Watt rating is the continuous maximum, which is different than a peak. You can have the thing wide open throttle, and yeah, you'll get a temporary burst of 1600W. But like you say it settles down to 500W within a second or two. What the controller lets you peak at says nothing about your actual continuous max power, which is what's actually relevant to a constant cruising speed, i.e the question actually asked.
     
  16. libranskeptic

    libranskeptic Member

    Whatever, very unclear query, but a few things:
    I find it odd folks ofte say "i need it for specific terrain". BS. A vehicle is a vehicle. Why have one that cant cope with unplanned demands?

    Done as intended, ebikes are just bicyles - wonderful fine tuned light machines to leverage human power.

    Ask too much of them and they will give problems, as with all things.

    i am from Oz, with EU rules, so its different from USA.

    I ride a 23kg alloy MTB mid drive, 3kg battery, me, 70kg, bike max load is 120kg btw.

    Because it is nominally legal to sell in the vast but upmarket (as opposed to china domestic market), you can buy mass produced classy bikes if they fit that general pattern of bike.

    the eu market all have to make do with low power, lets say 250w.

    my point is, if u keep power modest enough (like a 450-500w mid-drive), then you place uself in the maistream of the euro bike offerings (made in china, but suited to a legal variant in europe, and a usa 500w version).

    Above 500w on a mid-drive, you may be asking a lot of the chain drive and gears.

    Most cheat a little and its simple to hot them up to 350w, or even 500w - identical bike, just set up differently.

    Dont be too put off by 36v. It copes with up to 500w pretty well, so the euro market dont fuss about 48v so much..

    because mid drive drives the chain via gears, pedaling is ~always optional, even w/ 250w.

    mine is 350w, but I rarely use full power as I dont rush & ride smooth.

    Do get a generous battery, even if it adds a few kilos. a ~500wh lifepo4 pouch cell pack would be my choice - from a separate supplier. About an hour of 500w hard throttle or peace of mind long range.

    A powerful motor ise asy. A battery to feed it is hard.

    The general alternate view in usa, whe 750w is mostly legal, & ignored anyway, is a 75ow+ heavy steel cruiser hubmotor bike. heavy, dearer heavier battery, powerful, more comfortable on bad roads at speed, , no gears - so they hate low rpm starts and hard hills. a sorta harley bicycle.

    Their weak spot is the axle brackets of the forks. They cop a lot of stress.

    In short, a production euro friendly 350w mid drive MTB is a good choice if u r are under 95kg, then figure how to get the 500w version (an alternate controller usually - more amps) and suitable battery, and ridden right, 350w is fine & have 150w in reserve if needed.

    I am party pooping. This site is a DIY site :(:).

    DIY, a mid drive 500w bafang. Stacks of tips and how toS here & around the net.
     
  17. Street Ryderz

    Street Ryderz Active Member

    please if you have a 500w motor and a 45 amp controller on 60v the possible max is 60 times 45 2700w peak but since a 500 w motor wont draw 45 amp normally and voltage falls under load it not that high!The 500w is continuous Average my 60v system with 45 amp controller draw 27 amps at high load and voltage is around 56v so 1512watts continuously.
     
  18. KB_UK

    KB_UK Member

    Then you have a 1512W continuous max system, not a 500W one.
     
  19. Street Ryderz

    Street Ryderz Active Member

    No I have 2700w system with a 500w motor! that runs around 500w as a constant AVERAGE! Like I said go use ebike.ca simulator you will see that any setup will draw more then its rated for!
     
  20. KB_UK

    KB_UK Member

    Make your mind up, 500w continuous or 1512w continuous. You say both in the same post.
     
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