Front 24V brushed hub, rear gas drive, on-demand recharge.

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augidog   10 W

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Front 24V brushed hub, rear gas drive, on-demand recharge.

Post by augidog » Jan 07 2016 7:49pm

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Chalo   100 GW

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Re: Front 24V brushed hub, how to regen?

Post by Chalo » Jan 07 2016 8:30pm

First thing: Regen is only going to happen on your system when the back EMF of your hub exceeds the battery voltage. It'll be like a brake that comes on to limit your speed to slightly more than the no-load speed of the electric motor. Below that speed, there will be no effect, and no regen current.

Second thing: You have an inefficient gas motor and an inefficient electric motor (which you can operate as an inefficient generator). Why the heck do you want to burn more gas to charge the battery a little bit, when you'd get more miles from the same fuel by powering the bike directly?
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augidog   10 W

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Re: Front 24V brushed hub, how to regen?

Post by augidog » Jan 07 2016 8:46pm

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Rassy   1 MW

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Re: Front 24V brushed hub, how to regen?

Post by Rassy » Jan 07 2016 9:19pm

Hi Augidog, interesting set up. Don't know anything about your gas system, but those old WE brushed motors worked pretty good.

About 10 years ago I purchased several BD36 kits with 35Amp controllers and SLA batteries. Eventually they were all run on 48V with no problems. Two of them that I know of are still in use, both using Ping 48V LiFePO4 batteries. One gets heavy use laced into a 16" wheel on a pusher trailer for a friend's handcycle trike. It easily pushes the trike over 20 MPH, never been opened up so is still on the original brushes. The other Is in a 20" front wheel on my daughter-in-law's delta trike. It also still runs good, but doesn't get a lot of use.

Anyway, I lived on a 15% grade when I was using these motors and I experimented with some plug brakes, first just some tail lights, then with a 35' coil of wire. I temporarily hooked up a volt meter and remember seeing that the voltage produced varied considerably, and unless you had some sort of regulator would probably not be very effective for battery charging, although I never tried charging my batteries.

My setup had a low voltage toggle on the handlebar that would trigger relays to activate the plug brakes. One problem I encountered was when I flipped the toggle to turn off the brakes the relays would not always release and would eventually be ruined by arcing during the release.
-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
https://endless-sphere.com/forums/viewt ... 0#p1291260

augidog   10 W

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Re: Front 24V brushed hub, how to regen?

Post by augidog » Jan 07 2016 9:45pm

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Rassy   1 MW

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Re: Front 24V brushed hub, how to regen?

Post by Rassy » Jan 07 2016 10:43pm

I didn't quite follow your previous post about push buttons and relays, but a thought occurred, what would happen if you continued to hold the throttle on the electric system at WOT while the gas system accelerated beyond the 15 MPH max of the electric system?

Of course you are risking frying something in the controller, since, for one thing that hub motor will soon be producing more than 24 volts, and of course as many amps as it can to the battery, if that's what happens. I do remember that when using my BD36 on my old recumbent bike and pedaling along, such as just after cresting a hill, there would be a point where the bike would be easier to pedal when I released the throttle. i.e., I had reached the speed where the motor was working as a generator and (probably) charging the battery, hence creating a little braking resistance. Not very scientific test, and if I said something wrong I don't take credit for it. :D

Reedsport? Went to school in Waldport (few years ago, I'm 75 now), Lived in Port Orford since retirement, until 2 years ago. Friend with the handcycle lives at Myrtle Point and I try to get down there a couple of times every year to ride with him.
-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
https://endless-sphere.com/forums/viewt ... 0#p1291260

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Chalo   100 GW

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Re: Front 24V brushed hub, how to regen?

Post by Chalo » Jan 07 2016 11:12pm

If you use a relay to bypass the controller, and a power diode on that bypass circuit to prevent the battery from driving the motor, then you have a passive means to charge the battery-- if and only if the motor is being turned faster than it will turn when connected directly to the battery with no load. This threshold speed is a function of the battery's voltage, and thus it will change as the battery goes deeper into its discharge curve.

Above that speed, resistance in the motor will build rapidly with small increases in speed, effectively limiting the bike's speed to just a little more than the no load speed and diverting portion of any excess power to the battery.

This is the same principle I used when I made a stationary generator bike-- pedal up the generator, the relay switches on at about 7V, the power diode allows current to enter the battery when the voltage surpasses the sum of the actual battery voltage and the forward voltage of the power diode. At that point, the resistance at the pedals really piles on hard.

If you use a boost converter on the relay-controlled circuit, then you can get the battery to charge at a lower speed, possibly even low enough to be useful as a brake. But in that case, charge current (and braking power) would be limited to the capacity of the boost converter. And there would be a further efficiency toll on the system.
This is to express my gratitude to Justin of Grin Technologies for his extraordinary measures to save this forum for the benefit of all.

augidog   10 W

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Re: Front 24V brushed hub, how to regen?

Post by augidog » Jan 08 2016 1:28am

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Chalo   100 GW

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Re: Front 24V brushed hub, how to regen?

Post by Chalo » Jan 08 2016 3:25am

augidog wrote:a diode between the controller and motor will protect the controller during overspeed, correct?
Yes, that works because your motor is DC. But it will prevent the passive regen Rassy and I are taking about. If you use a DPDT relay, you can take the controller out of the circuit on demand, and substitute a circuit that contains a diode preventing the battery from driving the motor. That circuit would allow passive regen at speeds above the no-load speed.

Keep in mind that every diode you add drops more or less a volt from whatever you feed through it. A volt times 25A means you have to dissipate 25W of heat somehow. So it's best for both range and reliability to only put a power diode in where you really need one, and provide plenty of heat sinking and air flow.

When I bring up efficiency, it's not as some sort of goal in itself. What I was getting at is that for every mile worth of electric power you stash away by using the gas motor and regen, you probably could go four or five miles if you just used the same amount of fuel to propel the bike. You're almost certainly hurting your range of operation by trying to employ regen.
This is to express my gratitude to Justin of Grin Technologies for his extraordinary measures to save this forum for the benefit of all.

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Re: Front 24V brushed hub, how to regen?

Post by amberwolf » Jan 08 2016 3:40am

Just to emphasize that range loss, keep in mind that "regen" is usually a short form of the phrase "Regenerative Braking". ;)

(because while you are using it, it is taking forward motion and "recovering" some energy from it, wasting some more as heat, and slowing down that forward motion (which in your case you'd be replenishing with the ICE, at the cost of the extra gasoline it burns at the higher load of regen braking *plus* maintaining forward motion)).


There's nothing inherently wrong with doing this, but if you are doing it to extend your range, it won't--it'll significantly *shorten* that range instead.


(there are lots of discussions around here about that, most of them in the Alternative Energy subforum, which explain exactly why this is the case, if you're interested).

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Re: Front 24V brushed hub, how to regen?

Post by 999zip999 » Jan 08 2016 3:48am

A three phase motor is much more efficient then a bushed motor and more regen.

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Re: Front 24V brushed hub, how to regen?

Post by amberwolf » Jan 08 2016 3:50am

Harder to do the regen; requires either regen-capable BLDC controller or more complicated relay/diode setup.

Will not be any more efficient in any practical amount vs brushed, in this case, as there is already so much efficiency loss in the conversions from the raw gasoline. ;)

All other things identical wouldn't really be any more regen just for being brushless. depends on it's own no-load speed, etc.

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Chalo   100 GW

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Re: Front 24V brushed hub, how to regen?

Post by Chalo » Jan 08 2016 3:54am

999zip999 wrote:A three phase motor is much more efficient then a bushed motor and more regen.
He's been very clear that efficiency isn't his bag, man.

Since he only has three means of propulsion on his bike, I'm thinking maybe an alcohol powered microjet on the back. And sails.
This is to express my gratitude to Justin of Grin Technologies for his extraordinary measures to save this forum for the benefit of all.

augidog   10 W

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Re: Front 24V brushed hub, how to regen?

Post by augidog » Jan 08 2016 6:12am

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augidog   10 W

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Re: Front 24V brushed hub, how to regen?

Post by augidog » Jan 08 2016 6:45am

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Re: Front 24V brushed hub, how to regen?

Post by Ykick » Jan 08 2016 6:55am

Nevermind "efficiency" but BLDC front hub and controller would probably make what you wanna do much easier, IMO. Almost any BLDC controller's ready to handle regen and you'll never, ever need to replace brushes which will likely wear much faster when loading them in both directions.
Talent must not be wasted.... Those who have talent must hug it, embrace it, nurture it and share it lest it be taken away from you as fast as it was loaned to you.

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augidog   10 W

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Re: Front 24V brushed hub, how to regen?

Post by augidog » Jan 08 2016 7:03am

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Re: Front 24V brushed hub, how to regen?

Post by Ykick » Jan 08 2016 7:05am

augidog wrote:
Ykick wrote:Nevermind "efficiency" but BLDC front hub and controller would probably make what you wanna do much easier, IMO. Almost any BLDC controller's ready to handle regen and you'll never, ever need to replace brushes which will likely wear much faster when loading them in both directions.
I have what I have and want to make the most of it, and truth be told, I'm enjoying the old-school feel.
Of course, enjoy the ride!
Talent must not be wasted.... Those who have talent must hug it, embrace it, nurture it and share it lest it be taken away from you as fast as it was loaned to you.

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augidog   10 W

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Re: Front 24V brushed hub, how to regen?

Post by augidog » Jan 08 2016 7:35am

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gogo   10 MW

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Re: Front 24V brushed hub, how to regen?

Post by gogo » Jan 08 2016 9:21am

If you want a brushed controller that has regen capability check out the Kelly or 4QD.
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Re: Front 24V brushed hub, how to regen?

Post by 999zip999 » Jan 08 2016 12:27pm

Lot's of kits have a push on, release off horn button maybe on the same side as the throttle ? Maybe someone has a spare.
I get your rig. Where you live ?

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Rassy   1 MW

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Re: Front 24V brushed hub, how to regen?

Post by Rassy » Jan 08 2016 2:11pm

wait one. don't pwm controllers apply pulse at the negative side of the circuit, and the positive connection is a pass-through, and therefore the controller doesn't need diode protection? did this just get complicated again, or simpler, or am I overthinking
I don't think the diode that was mentioned was to protect the controller. It might be needed to keep the battery from running the motor when the controller is bypassed. If you only hit the push button when the motor speed is greater than the battery would drive it, maybe no diode is needed. If you continued to hold the button down as the bike slowed, there would be a point where the motor would basically be running at WOT. I would just figure all this out with a little trial and error testing after you determine at about what speed the motor produces something between 24 and 30 volts.

Speaking of the push button, I would be tempted to use a double throw toggle switch with an ON/OFF/ON so in one ON position the normal system works and in the other ON position the controller bypass/regen system works via whatever relays are required. That way you can't activate both at the same time and you don't have to hold the button down while still operating the gas system.

Anyway, good luck with your regen project. I'll enjoy seeing how it all works out for you.
-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
https://endless-sphere.com/forums/viewt ... 0#p1291260

augidog   10 W

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Re: Front 24V brushed hub, how to regen?

Post by augidog » Jan 08 2016 2:39pm

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Rassy   1 MW

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Re: Front 24V brushed hub, how to regen?

Post by Rassy » Jan 08 2016 3:35pm

Augidog, I have one of these ebrake buttons you can have. The wires were removed and used on a latching button instead of the original momentary button:

http://em3ev.com/store/index.php?route= ... uct_id=198

pm me with a mailing address and I'll send it to you.
-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
https://endless-sphere.com/forums/viewt ... 0#p1291260

augidog   10 W

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Re: Front 24V brushed hub, how to regen?

Post by augidog » Jan 08 2016 3:43pm

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