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I was going to go with 48V for my motorcycle. 48V X 55ah = 2640 watt/hr. If I go with 72V X 38ah, I get 2738 watt/hr, roughly the same. I am assuming that purely from a range standpoint, the 72V system will go farther because of less current draw and therefore less Peukert effect. Or do I just go with their [nearly] equal total watt/hr and assume that their ranges will be [nearly] the same?

James
 

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If you use lets say 5kW to maintain speed. This means you draw a 104 amps from the 55Ah pack, which is almost 2C. And you will draw 70 amps from the 38Ah pack, also aproximaly 2C. So the peukert effect stays the same.
 

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Generally speaking the higher the voltage the better. Voltage is what forces current to flow into a given load. More of it means more current flow = more power.

Consider a 9V battery. People test it with their tongues. As the battery gets weaker the current it can force to flow decreases thus a weaker shock to the tongue. If you place it on your dry skin you won't feel a shock, even with a new battery. However if you get on 120V from your home power, it will shock you MUCH MORE even with dry skin because of the MUCH HIGHER VOLTAGE.

Another issue is the size of the wire. Higher voltage allows smaller wire for a given KW because less current is needed to produce a given speed. Smaller wire cost less and weighs less too!

Just had some time to kill... Hope this helps.
 

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higher voltage = higher RPM as well, so your top speed will be about 1/3 less at 48V than at 72V.
 
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