Author Topic: Speed Control Question.  (Read 671 times)

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Offline ballbreakerTopic starter

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Speed Control Question.
« on: May 18, 2011, 03:07:23 PM »
Hi

I know that the speed controller changes the speed of the motor by basically turning it on and off really fast.

 i want to be able to run the motor when its on (like normal) but when its on the off phase to be able to charge the batteries pf the motor by an external source to make the batteries last longer. how can i do that?
thank you
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Offline Kylepowers

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Re: Speed Control Question.
« Reply #1 on: May 18, 2011, 03:37:52 PM »
What your talkimg about really wont give you much charge because the switching will be going so fast but if you want to do it. You would have to hook the motors to a seperate cirucit. Then it could work. I guess I need more details on your idea.

Offline ballbreakerTopic starter

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Re: Speed Control Question.
« Reply #2 on: May 18, 2011, 03:57:48 PM »
i know it wont give much charge but it will when its on hold and when on low rpm

basically i want the speed controller to be connected to the battery to the motor and to the external power source.

 when the speed controller is on the on phase then i want to give current from the battery to the motor.
else when the speed controller is on the off stage to give current from the external power source to the battery.
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Offline Billy

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Re: Speed Control Question.
« Reply #3 on: May 18, 2011, 06:49:42 PM »
else when the speed controller is on the off stage to give current from the external power source to the battery.

You can tie all three of these items to a common voltage bus without any switching other than motor PWM and it will do what you want. If the motor is drawing more current that the external supply can deliver, the bus will draw current from the battery to make up any short coming, and when the motor is not drawing current, the external supply can put current onto the bus that can be consumed by the battery.

You'll just need to make sure the external supply is current limited and that the battery and external supply voltage are compatible.

Keep in mind that the "really fast" you're talking about is usually in the 20-40 kHz range and the capacitors that are placed in properly designed circuits will likely prevent the current flow from doing what you're thinking.  But I've never tried it so if someone knows for sure, they can correct me.

Offline ballbreakerTopic starter

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Re: Speed Control Question.
« Reply #4 on: May 20, 2011, 11:56:56 AM »
thats what i was looking for except from the part that the capacitors that are placed in properly designed circuits will likely prevent the current flow from doing what you're thinking. can you be more specific in which way to connect them on the controller thank you
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