# Electric Scooter parts selection help ...



## mxmtech (Apr 21, 2009)

The battery you have selected only puts out 20 amps at 48 volts, unless my math is wrong that means the max motor size that you should use is 960 watts. The motor you are contemplating uses 150 amps. You would need 8 of the lithium batteries to use this motor to its capacity. A 960 watt motor would use up this battery to 100% discharged in an hour which would kill the battery very quickly. If you intend to run for an hour and a half on this battery you shouldn't exceed 450 watts and that is assuming 100% efficiency from the battery.


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## 280z1975 (Oct 2, 2008)

mxmtech said:


> The battery you have selected only puts out 20 amps at 48 volts, unless my math is wrong that means the max motor size that you should use is 960 watts. The motor you are contemplating uses 150 amps. You would need 8 of the lithium batteries to use this motor to its capacity. A 960 watt motor would use up this battery to 100% discharged in an hour which would kill the battery very quickly. If you intend to run for an hour and a half on this battery you shouldn't exceed 450 watts and that is assuming 100% efficiency from the battery.


As I understand it most LIFEPO4 batteries can go to 3C rate for short bursts and then remain at 1C for their stated capacity. This would give me a power of around 2880 watts for short bursts and long term constant wattage of 960 watts. These requirements should be well within the range of this motor. In the idea of my set-up, it's my batteries which may be the limiting factor (depends on the controller I choose).

http://www.diyelectriccar.com/forums/showpost.php?p=145491&postcount=4

This was from a previous thread I did about range. I do believe this estimate to be true as it's about 150 to 200 watts over what it would take to move a bicycle at that speed. 

That assumed, and an 80%DOD (.768kwh in the battery). I could theoretically go 1.4 hours (an hour and 20 minutes at that speed). Which is about where I would like to be (5 minutes out to the canal, 50 minutes motorpacing and then 5 minutes home). It cuts it close to my desired place range, but the jump to a 30ah battery is more than double the cost. My best thought was to just buy two of these batteries and string them together to get 40ah out of them at 48v (5,760 watts of max power, just under 3000 watts of constant speed potential). Since two of these is cheaper than one 40ah battery, plus I can charge them in the same time as the 20ah since I would have two chargers D). Then I would have around 2.8 hours of flat drive time, which is plenty to do a HARD 1.5 of motorpacing (sprints at 60kph, flat pacing at 50kph).


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## Amberwolf (May 29, 2009)

You may also want to go to the Endless Sphere forum and look at Recumpence's reduction drive, designed for use with high-speed heli/RC motors like that:
http://www.endless-sphere.com/forums/viewtopic.php?f=1&t=6163
Might also have more in this thread:
http://www.endless-sphere.com/forums/viewtopic.php?f=28&t=7180

There's also this one he did for Y-pedal:
http://www.endless-sphere.com/forums/viewtopic.php?f=28&t=9342

Also read up on the Vpower stuff while you're there. There have been good and bad reports about them, in various threads.

This thread may also have information useful to you:
http://www.endless-sphere.com/forums/viewtopic.php?f=28&t=4625
and this:
http://www.endless-sphere.com/forums/viewtopic.php?f=2&t=5594
________
Web Shows


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## 280z1975 (Oct 2, 2008)

Amberwolf said:


> You may also want to go to the Endless Sphere forum and look at Recumpence's reduction drive, designed for use with high-speed heli/RC motors like that:
> http://www.endless-sphere.com/forums/viewtopic.php?f=1&t=6163
> Might also have more in this thread:
> http://www.endless-sphere.com/forums/viewtopic.php?f=28&t=7180
> ...



Thanks for the links, will get after then when I get back from work.


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## mxmtech (Apr 21, 2009)

960 watts times 1.6 hours equals 32 AH


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## mxmtech (Apr 21, 2009)

I would MUCH rather replace my motor than my batteries. My little 450 watt motor will operate at 720 watts if I push it hard, but my batteries can handle it. The motor you're looking at will accept a demand of 11.2 KW and the batteries are not up to it. I have about $600 invested in my batteries but I figure I could replace the motor for $60. Plus I can smell the motor when I start cooking it and I can stop.


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