brushless Dc motor controllers

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Jimsorenson
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brushless Dc motor controllers

Post by Jimsorenson » Dec 27, 2017 1:44 am

I have a 1500 watt conhismotor (hallomotor) mounted in a 20"x 4" fatwheel..the controller it came with in the kit is junk in my opinion ...ive wasted quite a bit of money basically from not knowing what im doing i hate to admit..anyway im wanting advice to if i can achieve 30 mph at 48 volts with the right controller..or do i need to take it up to 60 or what..im ready to purchase a new controller but need to know also if i need to buy s higher voltage battery as well...any help with my stupudity on the issue would be greatly appreciated jim

DAND214
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Re: brushless Dc motor controllers

Post by DAND214 » Dec 27, 2017 10:52 am

In most cases a controller will not increase your speed.
What speed are you achieving with 48v and is it 48 nominal or 52?
Does the controller have a 3 speed switch?

Dan

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Drunkskunk
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Re: brushless Dc motor controllers

Post by Drunkskunk » Dec 28, 2017 4:57 pm

A motor's speed is based on the voltage supplied. And the speed is basically linear. If 10 volts gives you 10mph, 20 volts will give you 20mph. 100 volts will give you 100mph.... as long as you also have enough amps to cover the wattage needed to go that speed.

If you take the battery voltage you have now, and divide it by your current speed, then multiply that number by the speed you want to go, it will give you the battery voltage you need to reach that speed.

For example..if you have a 48 volt battery, and you can go 22mph, and you want to go 30...

48volts / 22mph = 2.181818.. (this is in volts per mph)
2.181818 X 30mph = 65.45454 volt

So you need a 66 volt battery to do 30mph, if those were the numbers you started with. You'll have to fill in your own current voltage and top speed.

Additionaly, you'll need a battery and controller that can handle 1000 to 1500 watts output to be able to go 30mph.
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markz
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Re: brushless Dc motor controllers

Post by markz » Dec 28, 2017 10:46 pm

Jimsorenson wrote:
Dec 27, 2017 1:44 am
Ithe controller it came with in the kit is junk in my opinion

wanting advice to if i can achieve 30 mph at 48 volts with the right controller

im ready to purchase a new controller
Buy a 72V 800W controller from ebay seller hksunwin
You wont be able to use the KT Display with it.

Also your battery, need more info. Where did you buy it, whats it Ah rating, whats it discharge rating. Maybe you can scavange it and rebuild it to make it 72V

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Lebowski
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Re: brushless Dc motor controllers

Post by Lebowski » Dec 29, 2017 3:29 am

Drunkskunk wrote:
Dec 28, 2017 4:57 pm
A motor's speed is based on the voltage supplied. And the speed is basically linear. If 10 volts gives you 10mph, 20 volts will give you 20mph. 100 volts will give you 100mph.... as long as you also have enough amps to cover the wattage needed to go that speed.

If you take the battery voltage you have now, and divide it by your current speed, then multiply that number by the speed you want to go, it will give you the battery voltage you need to reach that speed.

For example..if you have a 48 volt battery, and you can go 22mph, and you want to go 30...

48volts / 22mph = 2.181818.. (this is in volts per mph)
2.181818 X 30mph = 65.45454 volt

So you need a 66 volt battery to do 30mph, if those were the numbers you started with. You'll have to fill in your own current voltage and top speed.

Additionaly, you'll need a battery and controller that can handle 1000 to 1500 watts output to be able to go 30mph.
A good controller can get more speed than described here... but you're talking a few 100 $ then, not $35. Look for a controller that is 'FOC' and can do fieldweakening.

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dogman dan
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Re: brushless Dc motor controllers

Post by dogman dan » Jan 03, 2018 10:03 am

You aren't stupid, just new. Of course you expected 30 mph, and in 26 inch wheel and regular tires with 60 psi in them, you would just get that when the battery was very full. They just don't tell you in the ad that a fat soft tire and smaller diameter will cost you speed.

Just curious, what speed are you getting to? surely still close to 25 mph right out the gate, and 20 later on?

It could be also related to your battery. If your 48v, which I assume is charged to 54.6v, sags 8v under load, then you are running in effect, 40v. A stout battery that sags only 2v under load will go much faster.

But your smaller wheel is costing you a bit of top speed too, along with tire drag if you are running 10 psi or whatever. In general, you'd expect 25-27 mph with a hard skinny tire. But a soft fat one, another few mph gone.

I would think that 2000 watts will be enough power, but you might still have to bump up to 18 cells in series battery, (64v) or even 20s 72v to get the top speed you want, and not take forever to build up to that speed.

Good advice above to spend a bit on a higher volts controller, and enough amps to reach 2000w peak. Look for one with a broader range of voltages, like 48-72, and 30 to 40 amps.

Chances are though, your current battery can't even begin to handle more than 20 amps. :roll: so you need to ride slow awhile, till you are ready to ante up for the faster bike. Think another $500, or more.

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