Dual drive bike lost all regen braking after low brake lost 5V supply during re-wiring bike

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Roguenite   1 µW

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Dual drive bike lost all regen braking after low brake lost 5V supply during re-wiring bike

Post by Roguenite » Apr 05 2021 7:41am

Hello everyone,

I have a 2 wheel drive bike.
2 x 1000W Voilamart motors
2 x 48V 13ah batteries (not parallel)
2 x Voilamart Sinewave controllers
2 x Greentime Squarewave controllers

I think some of you guys won't approve my build because I run 2 motors with 4 controllers.
But I have been riding to work everyday for over a year with this build with no issues. I use an ON/OFF/ON flick switch (3 speed switch on Aliexpress throttle) to change between the throttles of 2 sinewave controllers and 2 squarewave controllers. So only 1 controller's throttle is active for 1 motor at any time. However all 4 controllers are ON at the same time.

The reason I built it like this is because the regen braking I got by jumping pins in the Voilamart sinewavers is rubbish compared to the regen stopping power of greentime squarewave. But I prefer to drive with sinewave. (It was a cheaper way than getting the expensive controllers)

Everything had been working perfectly for over a year. After all the trials, fails and fixes were over, I finally decided to re-wire absolutely everything and make the bike look more clean.

After the re-wiring, and during testing I noticed rear motor doesnt cutoff on brake pull and has no regen. The reason was low brake wire had 1V present. It was not shorting with ground or anything else. I found a PIN on the greentime controller labelled as 4.3V and jumped it to the low brake pin. That solved the no brake cutoff issue but still no regen.

I decided to just be happy with front motor regen as I'm too tired from rebuilding the bike already. But now front motor works only if both motors are active. (I had added an isolation switch for the 2 wheel ignitions in case I need to troubleshoot just one.) If i switch only front motor controllers, i hear the first click in the motor and but no response on throttle. Turns out after I joined the 4.3V pin to the rear wheel low brake, front controllers have gone to 0V and would only work using that 4.3V supply of rear controller. Hence rear ignition is off, front low brake is at 0V. (Low brake wires of all 4 controllers are joined together).

Now I gave 5V from throttle to low brake wire of front controllers and both wheels work fine on throttle and cuts off on low brake trigger. Except no-regen from either wheel.

I re-wired everything the same way as they were for the past year except I made the wires much shorter. Is it possible that I've blown the pull up resistors by making the wires too short? I read about pull up resistor on some threads here.

If anyone has some idea on what exactly is wrong with my low brake triggers and shed some light on how I can get my regen back I would really appreciate it.

Thanks
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amberwolf   100 GW

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Re: Dual drive bike lost all regen braking after low brake lost 5V supply during re-wiring bike

Post by amberwolf » Apr 07 2021 9:43pm

Roguenite wrote:
Apr 05 2021 7:41am
But I have been riding to work everyday for over a year with this build with no issues. I use an ON/OFF/ON flick switch (3 speed switch on Aliexpress throttle) to change between the throttles of 2 sinewave controllers and 2 squarewave controllers. So only 1 controller's throttle is active for 1 motor at any time. However all 4 controllers are ON at the same time.
Presumably you switch between them when you are about to brake, so that you can then control braking proportionally with the throttle? If so, you can make that much more effective and easy to use, in one of two ways:

The first is pretty simple, by using a 3PDT relay driven by the ebrake switch. The ebrake would turn on the relay when starting to brake. That relay switches three things. WHen off, it leaves the ebrake line open, and leaves each throttle connected to the respective driving controller. When on, it closes the ebrake line to the braking controllers, and switches the throttle signals over to the respective braking controller.

The second is much like the first, except there is no switching of throttles, and instead you use a single cable-operated throttle that is pulled by the brake lever itself, and the ebrake switch goes directly to the braking controllers as it does now. (if you are using a mechanical cable operated brake as well, then simply use a dual-cable-pull lever, with the barrels adjusted so the mechanical brake doesn't engage until after you've run out of regen braking power increase.) This throttle is connected only to the braking controllers, and you just brake normally without worrying about manipulating the regular throttle during braking. More intuitive, and quicker and easier to control.

If you don't have proportional (variable) regen braking, then the above doesn't matter, and you also don't need a switch to go between the throttles. (if you are not using the braking controllers for driving; if you do use them for driving, then the switch make sense and the second method above won't work, but the first will).

After the re-wiring, and during testing I noticed rear motor doesnt cutoff on brake pull and has no regen. The reason was low brake wire had 1V present. It was not shorting with ground or anything else. I found a PIN on the greentime controller labelled as 4.3V and jumped it to the low brake pin. That solved the no brake cutoff issue but still no regen.
By "low brake wire" do you mean the actual signal wire for low brake? If so, it means the internal 5v pullup, or 5v supply, in that controller has failed for whatever reason. Most often that happens from an incorrect voltage applied to the line that's higher than what it can handle. It only has to be momentary in many cases, like an accidental brush of one wire against another with power applied, or even just a sufficiently-still-charged capacitor.

If the MCU input itself was damaged in the process (also possible) then that could also be the problem.

If you are not using pullup resistors (5kohm to 10kohm) between the brake signal wire and the 5v (or 4.3v) supply you've rerouted to it, then when you pull the brake lever to short the brake signal wire to ground, you are also shorting out the 5v line on the controller(s) to ground, which turns the controller off, which would prevent regen from working because the controller isn't "awake" to do it.

It will also damage or destroy the 5v regulator eventually.


Another possible cause is if you tied the 5v lines of controllers together at any point, the slight differences in the regulators in each one can cause current flows from one to the other that either interfere with or even damage the regulators in others. This can leave the controller unable to power on by itself, or acting "wierd", depending on the extent of the problem. The 5v lines on any controller should always remain independent of all the others.

It can also help to not connect grounds, except at the battery negatives they all share, because you can end up with ground loops.

So if you have a throttle that runs more than one controller, you would hook up the 5v, signal, and ground to one of the controllers, and *only* the signal wire to the other(s). It does mean that the throttle will only work if that controller is powered on, but since you already run them all at the same time you already have that situation. :)
I re-wired everything the same way as they were for the past year except I made the wires much shorter. Is it possible that I've blown the pull up resistors by making the wires too short? I read about pull up resistor on some threads here.
Wire length won't affect the operation the way you're seeing. (too long a wire could degrade a signal...but shorter wires would *help*, rather than degrade).



It may be helpful if you trace out all of your wiring *as it is right now* (not as it *should* be, but what it actually really is wire for wire, measured and traced out one wire at a time), and draw it out on paper, labelling each wire for function and color, it may help you see what is different now than how it had been before. Also, you can post that here in this thread, and we can see it and also look thru it for potential issues.

And then it will also help others setup their bikes like yours, if they want to do that. It is an interesting idea to use a different controller for braking than driving; I have seen threads for using two controllers always parallleled and running for both (which can result in failure of one or both), but not separated by function.

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