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YouTube videos citing top speed & then following that with exaggerated range claims.

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    YouTube videos citing top speed & then following that with exaggerated range claims.

    In examples such as https://www.youtube.com/watch?v=sFGMPshbOTY, https://www.youtube.com/watch?v=a-LWf51XGiA and https://www.youtube.com/watch?v=_0LytDZmHf4, the salesman cites a top speed and later cites an expected range, in miles.

    When I watch these videos, I multiply the capacity (in Ah) by the voltage of the battery to calculate the total Wh of the battery. I then divide this capacity of the battery by the claimed number of miles and I always get a similar result: a power consumption of about 18-23 Wh/mi.

    So...certainly one can ride an ebike at this rate of power consumption, but at what speed?! Someone new to ebikes (and here we finally arrive at my point) might be fooled into thinking that one could ride at a high speed and still get the advertised range.

    The other choice would be riding the bike at top speed and having the battery require recharging after 20 to 30 minutes, albeit a very exciting 20-30 minutes.

    So what speed are you guys getting at 18-23 Wh/mi?

    Finally, some of their claimed power ratings are clearly so high that they would heat up these motors very quickly.

    So if there are any potential ebike salespeople reading this, consider informing the customer of the battery's capacity in Wh, and then allow them to consider various maximum ranges based on different power levels (in Watts).
    Last edited by commuter ebikes; 09-09-2016, 03:57 PM.

    #2
    yeah i hate range questions as an ebike seller..... when i get the question how far will it go.... i say you need to go research yourself or go talk to someone else.... its almost like you gotta lie to compare to other sellers because almost every dealer exaaggerates range at this point......i think its par for the course that all ebike dealers kind of exxaggerate range claims.... and to compete you need to play that game.

    I can understand it but i wont play that game. i just try to get everyone to understand what watt hours is :)

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      #3
      I average around 18 Wh/mile when I ride. Sometimes as high as 21, or as low as 14, on 30 mile-ish typical rides. But the number 18 comes up a LOT for me. So at least the range claimed in your example isn't ridiculously exaggerated, probably very realistic for normal riding - faster than bikes, but not flying. I've seen much more optimistic range claims than that.

      But you are absolutely right about claims of range and top speed. I see the same thing on specification pages for ebikes and sometimes batteries. For a rookie it can be misleading. Then again, a car might be advertised with a top speed of 150 mph and a range of 300 miles. Also not possible, simultaneously. So, I guess it isn't just an ebike thing, most vehicles list max performance for each specification, but assume a 'normal' drive for range and efficiency numbers.

      With that understood, I think that if you want to sell ebikes or even kits to newbies, it's helpful to give some indication of performance and range on the product pages. The problem is coming up with good numbers and a simple, but not misleading, way to explain them.

      Sending customers with questions to the forum is OK, but not the easiest way for them.

      If the product pages instead provided a quick explanation of Wh in a pack, and a description of how buyers can estimate their OWN range, that might work better. Include a reference table of real Wh/mile examples, too.

      Something like this, but the below numbers are not real, just rough guesses for example purposes:
      Machine & Riding Condition Wh / Mile, typical
      BBSHD Road Bike, 15-20 mph level road 15-20
      BBSHD Fat bike, 15-20 mph level road 20-25
      BBSHD on any bike, top speed 40-60
      Then let users do the math.

      Table is intentionally vague. 'Good enough to help'. But general enough to enable using anecdotal range examples from users who post here, instead of having to run specific tests. Eventually enough info should show up on it's own. Pretty good start already.

      Then, send 'em to the Wh/mile thread if they want more discussion about it.

      Just a thought, since we're discussing it.

      Fabrication is fun! Build something today. Show someone. Let them help. Inspire and share. Spread the desire.

      Comment


        #4
        I'm sure watt hours are a more accurate way to measure battery consumption per mile, but...I use a general rule of thumb for Amp-hours (Ah).

        If I am using my hand-throttle (on my BBSHD), I can depend on getting at least the same number of miles as the Ah size of the battery. 15-Ah = 15-miles.

        If I am using a medium setting of PAS (where you must pedal to get power), I can count on getting two miles per Ah. 15-Ah = 30 miles. Both of these will get you home while still having a small reserve left in the battery...

        Comment


          #5
          I just tell people, you can either go fast, or far, but not both! ;-)

          If I piddle a long at slow relaxed bicycle speed, just unloading the drive-train while pedaling, I could easily make a 50 - 60 mile trip with my beastly Cro Motor mid-drive stretch cruiser.

          I have been able to make a 17 Mile trip while averaging only 9 Wh/Mile even with my 114lb beast! (this includes going back up the hill that is nearly 2 miles long and averages 5% grade)

          However, if I want to make closer to 15 MPH average, pull my 150lb work (mobile ebike repair) trailer, that will include some of my commute accelerating to around 30 MPH for a short 2 block stretch near the bike shop, I am going to burn closer to 26 Wh/Mile on average.

          So with a 72V (20s 4P) Li-Ion battery with a 11.6 AH capacity, (835 Watt Hours) sure if I used every "drop", I could on paper expect between 90 - 30 miles, reality is different. : )

          Be very careful when you calculate to factor in a "reserve" for that unexpected headwind, hot/cold weather that will affect battery performance, and never go below 20% capacity if you can to not only keep your battery's longevity, but just in general, the harder you cells are run, the more chance they will get out of balance easier, and the shorter their life expectancy is.

          I have some Turnigy Nano Tech LiPo that I can still use after about 7 yrs, however, they have only about 1/2 usable capacity.

          I also noticed recently that my new battery's BMS got testy with me after I had a bit too much fun seeing how fast I could get the bike to go with the trailer! 29 MPH with a gross weight of 444lbs is FUN (114lb bike, 180lb rider, 150lb trailer) but not practical with a relatively small capacity battery at that speed! :D

          I had to stop pushing it so hard even in the short term to not give the BMS fits (I charged up to 100% capacity and let it sit a while and that seemed to allow it to sort it's self out better).

          Any battery CAN and WILL fail if you push it too hard, so ya, don't believe all the hype from sellers who tell you can just go forever as fast as you want.

          I will hopefully be getting the 72v 26ah battery with the 100a BMS next (when I make some $$$ next spring maybe ! not anytime soon I'm afraid ;-) )

          And that will be more for track use, but one thing to keep in mind, it's NOT all just watts either, I have pushed batteries too hard and noticed that I got a LOT less resting voltage afterwards only using a "small" amount of Amp Hours, so just use common sense, if you need to go some distance, make sure you stick closer to bicycle speeds, if not, just remember, going "balls to the walls" just means a new battery is in your future much sooner than you think. ;-)

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