Will a 36V 500W ebike with a 36V 17.5Ah battery go farther and faster than a 36V 250W ebike with a 36V 10Ah battery, or will I give up something by doubling that wattage?

  • You can roughly gauge the total energy stored in a battery (equivalent to gas in a gas tank) by multiplying the voltage by the amp-hour rating. Wattage gives you a rough equivalent to "horsepower". As with a hot rod, you can end up with a combo that can (figuratively) burn rubber but "run out of gas" in a half mile. – Daniel R Hicks Mar 26 '19 at 2:13
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    A 500W motor is not legal in some jurisdictions, meaning you may have to leave the battery behind. Its entirely possible the 250W will go much further and faster. – mattnz Mar 26 '19 at 5:04
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    @Andy and any close voters, I suggest that this is more related to the riding experience of different rated ebikes than some of the recently migrated, very technical electronic questions. worth keeping – Swifty Mar 26 '19 at 11:20
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    @DanielRHicks Actually power measure in watts is an exact equivalent of power measured in horsepower. – Argenti Apparatus Mar 26 '19 at 12:36
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    1 horsepower is 745 Watts from memory, so I'm 1/4 horsepower on a great day, or a sixth of my lawnmower's capacity, or just over 1 dogpower. – Criggie Mar 26 '19 at 12:41

The 500W bike will be able to go faster than the 250W one (unless the bikes assistance is speed limited). Note that it will not go twice as fast as the power required to overcome aerodynamic drag is proportional to velocity to the third power.

Higher power motor and battery combinations are not intrinsically less efficient than lower power ones, so the bike with the higher battery capacity would have greater range, if both bike were ridden on the same route at equal speed (and have the same mass, drag coefficient, frontal area etc.)

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    Speed limiting is a thing for many ebikes. Max speed may be 20 or 25 mph, but the higher wattage bike can do that up a hill whereas the lower wattage bike may not get to that speed cap on the same gradient. – Criggie Mar 26 '19 at 12:38

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