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Why gyroboards are said to run so long on one battery charge...

  1. Sep 9, 2016 #1
    Hello
    Ads say a gyroboard with the battery 48V 4.4AH, and the motor 700 Wt will run for 2 hours at the speed of 20km/h ! But - simple physics - will not the motor drawing about 10-15 Amp exhaust the battery in just some 20 minutes !? Do ads lie ?
     
  2. jcsd
  3. Sep 9, 2016 #2

    jedishrfu

    Staff: Mentor

    Yes, ads lie or at least they take the best scenario possible like coasting downhill for two hours if that possible with a gyroboard with a very light weight person riding it.

    I tend to use the range as a better limiting factor as I wouldn't want to get stranded and have to carry the board back home but that's just me. I think the range for these is about 13 mi or about 20km on level ground.

    http://www.toptenthebest.com/beauty-sport/top-10-best-hoverboards/

    Some reviews say 10mi per charge and 7mph maximum speed.
     
    Last edited: Sep 9, 2016
  4. Sep 9, 2016 #3
    My scooter powered by 24V 7AH battery, the (brushed) motor 250 W runs 4 mi. I have added more 7AH batteries (so 14AH now), so am having now 8 mi range.
    But how on earth anything powered 48V 4.4AH, the (even brushles) motor 700W could run 10 mi (let alone 13mi) ?
     
  5. Sep 26, 2016 #4
    According to the article from Hoverbly, http://hoverbly.com/best-hoverboards-for-sale-ultimate-buyers-guide the Powerboard is able to drive with a top speed of 10 km/h, and your battery can last for up to six hours. I dont know if thats true but it seems to me that driving 6 hours at that speed might require pretty strong battery.
     
  6. Sep 26, 2016 #5
    That sounds like a liberal estimate. Not sure how much power it takes to run at 10 km/hr, but from my experience with model aircraft power consumption can be quite high when demanding performance. What do those scooters have like 200 Watt-hours. I doubt it takes any less than 50W to propel that board at any appreciable speed, probably more. Even with that conservative estimate of power required that's only four hours run time. They were putting poor quality batteries in those scooters so the Watt-hour rating was greatly optimistic anyway.

    There were incidents of battery fires due to those poor quality packs which gave the scooters a bad rep. I don't see them advertised at all anymore and I don't think anyone is buying them now. It's funny, I happened to see HSN advertising a sale on them and they kept emphasizing the brand was "improved" with safety features to eliminate the fire hazard. They probably still didn't sell any.
     
  7. Sep 26, 2016 #6

    OmCheeto

    User Avatar
    Gold Member
    2016 Award

    This sounds about right.
    From my research, a hoverboard should consume about 80 watts at a speed of 20 km/hr.
    The 700 watts is the maximum power rating.
    Yes, it is simple physics. Unfortunately, you did your physics wrong.
    It would if there were not a speed limiter. At 700 watts, I calculate your top speed at around 46 km/hr.
    Aerodynamic power consumed varies by the cube of the speed. Rolling resistance varies linearly.

    My equation, based on wikipedia's bicycle power at speed graph is: watts = 0.0066*(kph^3) + 1.384*kph
    I concur with the following:

    But, bad physics lies more, IMHO.

    ps. The Swagtron T1 hoverboard stats seem about right:
    watt hours: 155
    rated speed: 12.9 km/hr
    rated time: 2.5 hours

    my interpolation of a 100% efficient system:
    rated time: 4.9 hours
     
  8. Sep 26, 2016 #7

    rbelli1

    User Avatar
    Gold Member

    It is not necessarily lying (it all depends on what the definition of is is. I mean lying is.). It implies (but definitely does not promise) that you can go the fastest speed for the longest run time. If you listen to the exact wording you will find some weasel words caveating the crap out of the statements.

    Read the fine print. Its still probably lying-ish but you get what you pay for.

    BoB

    PS: OK. I'm playing devils advocate. It is lying in the nicest possible manner.
     
  9. May 8, 2017 #8
    it's not always about speed but battery life is also something that matters a lot because if you are continuosly charging you hoverborad at every 6 miles (coz you are a speed freak and will spend most of your battery in it)..then it's of no use...i am not discouraging you from buying as hoverboard if you really want to buy a hoverboard then you can get one for yourself from here.
     
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