Use motor hub for charging?

Electric Motors and Controllers
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ford442
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Use motor hub for charging?

Post by ford442 » Sep 03, 2017 6:09 pm

Hey,
Does someone want to explain how difficult it is to use a hub motor to generate power while rolling?
I have a 60v / 1000w scooter with an extra hub motor. Attaching the rear motor wheel to the front fork would be unusual and I would get help, but what would I have to do beyond that to start pulling power back into a battery when the front wheel spins? I am aware that it would add some resistance to the wheel, but when it is rolling downhill, etc, it seems really worth trying to me. Rather than solar panels alone to charge while driving/parked.

dustNbone
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Re: Use motor hub for charging?

Post by dustNbone » Sep 03, 2017 8:39 pm

If it already has a hub motor in the rear, just use that (with an appropriate controller) to do the regen. No need for a separate motor, you're only doing one thing at a time, either powering or generating.

ford442
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Re: Use motor hub for charging?

Post by ford442 » Sep 03, 2017 9:03 pm

Oh yes?
So, I could use a secondary motor, secondary controller and battery without any hand electrical modification? Wow!
I will try to find a source for exact regen controller.
I am not as confident changing the stock controller to a regen one, but I would then have 2 motors in regen mode going downhill.
I'm hoping to see a pretty good output to help charge during driving and gain distance. Then I am slowly working toward putting solar panels onboard as well. :D

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Rassy
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Re: Use motor hub for charging?

Post by Rassy » Sep 03, 2017 9:48 pm

I may be missing something, and I understand you want to use regen when going downhill or slowing down (i.e. when braking), but it seems you expect to get some "free" regen from your front wheel while powering your scooter with the rear wheel motor. You will never get back as much from your secondary "generator" wheel as you lose from the extra power required from the main motor. This has been discussed many times, but keeps coming up again and again (i.e. that would be a perpetual motion machine, which doesn't exist).

Your best bet is to do what was suggested above and install a regen controller to your existing system. And this will only work if the existing hub motor is direct drive ( i.e. doesn't have an internal freewheel).
-Rassy-
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ford442
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Re: Use motor hub for charging?

Post by ford442 » Sep 03, 2017 9:59 pm

I am trying to picture it like having a dynamo generator that lights a bicycle headlight. Not trying to add power all of the time, but I have a lot of downhill parts of trips where I can drift for 1 - 3 miles! If one or both of the motors could charge the battery then and mostly then is my idea. To extend range...
I read that in 1930's Hungaria - trains used regenerative braking on steep mountains during downhill to gain power for the rest of their journey..

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Rassy
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Re: Use motor hub for charging?

Post by Rassy » Sep 03, 2017 10:22 pm

I am trying to picture it like having a dynamo generator that lights a bicycle headlight. Not trying to add power all of the time, but I have a lot of downhill parts of trips where I can drift for 1 - 3 miles! If one or both of the motors could charge the battery then and mostly then is my idea. To extend range...
I read that in 1930's Hungaria - trains used regenerative braking on steep mountains during downhill to gain power for the rest of their journey..
I'm not sure if you are just trying to justify your idea here, but the answer is still the same as above. The easiest, cheapest, most practical, etc. is to upgrade your controller to one that supports regen. Even then, your "drift for 1 - 3 miles" may be reduced to very slow or almost stopped by any regen system, whether it's from your rear wheel or from a front wheel, or from both. Compared to just cars, let alone trains, bikes and scooters have such a small mass that most have found it hard to get even 10% regen and thus are better off just having a larger or extra battery if extra range is required. Those that like regen the most usually have lots of steep hills and the use of regen can save a lot on braking requirements.
-Rassy-
One Tadpole Trike equipped with a Bafang BBS02
https://endless-sphere.com/forums/viewt ... 28&t=69419
One Delta Trike equipped with a Bafang BBS02
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ford442
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Re: Use motor hub for charging?

Post by ford442 » Nov 14, 2017 6:45 pm

To clarify, I am talking about adding a dedicated motor just like the rear wheel one. Either replacing the front wheel or attaching it to a sort of trailer/cart.
I see how to form the 3 phase rectifier bridge from AC to DC now.
Does that hook up to the motor with 3 wires?
I have the extra motor to test and the rectifiers to form the bridge, but what else am I missing to try this out?
What is the third wire to hook up to the rectifier from the motor?
I just want to turn the motor/wheel and see what comes out. Does anyone have an article with these things explained?

Addy
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Re: Use motor hub for charging?

Post by Addy » Nov 14, 2017 8:40 pm

ford442 wrote:I see how to form the 3 phase rectifier bridge from AC to DC now.
Does that hook up to the motor with 3 wires?
Yes, you could use a 3 phase rectifier like this. One quirk of using this method is that the motor must be spinning above a minimum speed in order to charge the battery. If you are below this speed, no power is generated and there is no braking force provided. This would not be a good brake.

On the other hand, an appropriate motor controller has a better way to generate power. Without going into the exact details, a good motor controller will connect and disconnect the motor's phases at just the right moments to generate power at any speed.

The controller to look for is one that supports variable regen - this way you can apply the correct amount of brake that will allow you to keep going down the hill at a constant speed instead of coming to a full stop. If you got a good controller like this, there would be no need to modify your motor or add a secondary motor and you would have proper braking too.

ford442
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Re: Use motor hub for charging?

Post by ford442 » Nov 19, 2017 6:11 pm

OK.
I will have to wait until I can afford to buy a good regen capable controller.
For now, I have the 1 1/2 rectifiers to form the 3-phase rectifier and try it with my spare 1000W 60V motor right here.
I am just in the dark as to why there are 3 connections to the motor?
I am to connect POS + NEG + which?

ford442
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Escooter hub motor to generate while riding?

Post by ford442 » Nov 21, 2017 5:28 pm

I am working based on this youtuber's mothed - https://www.youtube.com/watch?v=OD1gSx92DuM
Seeing this method of generating a DC current has gotten me interested and I have the bridge rectifiers in front of me to test with a 1000W uumotor 10" 60V scooter motor, but I feel like I am in the dark as to the last step which is to connect to the motor with output only. I don't see how there are 3 leads to connect from the motor to the rectifier bridge. Do you see what I am missing?

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