Can Two controllers be used to power a single motor?

[_GonZo_]

Hope you can solve the problems and make it work properly soon.

I just remember that we made something similar on a big airplane (over 6000W power) we run a double controller set up, not like yours but similar thing... and in order to make it work properly we fired up the controllers by turn first one, wait for the beeps and then second one. Do not know if you can make it but may be it helps.

I wanted to post a picture but they are too big 

[MonkeyMagic]

hey mate

Download fotosizer from here
http://www.fotosizer.com/

you can make your pictures smaller to attach here

[Bikemad]

listen, if you decide to go external, I've got alphawire  ecowire ill send you some meters for nowt....as a gift after the controller

Thanks for the kind offer Ginge, I may well take you up on it if both controllers turn out to be dead.

I'm still not sure whether the second controller was actually making any difference at all, perhaps it could have died when I initially connected the battery, and the 25% power increase may just have been the result of the shunt modification alone, as I still feel the second controller should have given nearer 100% increase if it was working correctly.

I also noticed that only one of the controllers beeped (the original one) to falsely indicate a hall sensor fault when I had the wheel apart, but this might be because it's an earlier circuit board and the fault warning criteria might be slightly different.

Prior to the failure of the hall sensor/s, it was running very nicely indeed, so perhaps both controllers trying to run in sensorless mode at the same time has damaged some of the FETs because the hall sensors were no longer able to synchronise them?

I'm still puzzled as to what actually caused the hall sensor/s to fail, as I don't think the hub was anywhere near hot enough for the sensors to have become heat damaged as the hub was barely warm to the touch. Perhaps the extra load of operating two controllers was just too much for the hall sensors to withstand?

Anyway, the novelty of walking the dog on foot has already worn off after just one day, so I'm going to throw a standard wheel back on for the time being and remind myself of how difficult pedalling up steep hills unaided actually is!

Alan
 

[DirtyGinge]

To be honest, it does sound like somehow there were some voltage instability, which shouldnt really be with either the shunt mod or the dual cotrollers.....

I wonder if the fets had a problem due to voltage coming back from the opposite controllers phase firing, if they were slighty out of sync ??....

Well, the controller sent had done many miles without hitch, as had yours, both were tried and tested, so I guess we sorta know the outcome......shame though

Wire up an external harness, get an infineon of some description on there...apart from the cruise which takes a little getting used too, you wont be dissapointed...and not that much more than an external GM controller

[Andrew]

I've just read the whole of this thread,   such a great idea and a very brave modification. Gutted for you Alan, all that grinding too!

[_GonZo_]

hey mate

Download fotosizer from here
http://www.fotosizer.com/

you can make your pictures smaller to attach here

Thank you but I use Mac and that program is not for OS.
I have to look for something similar thought...

[Bikemad]

The wheel was removed and dismantled today and revealed some debris loose inside the hub accompanied by a strong smell of burnt components.

Here's what the three small capacitors on the rear of my original controller look like:



and this is all that remains of the same capacitors on Ginge's (second) controller:
 


And this capacitor has also split its end open on Ginge's controller:



I unsoldered the interconnecting wires and removed the second controller and then powered up the original controller with the main harness left disconnected. I was expecting to hear the same five beeps as before, but for some strange reason I heard four beeps, indicating a brake fault.     So I hastily connected the main harness to eliminate throttle and brake faults and powered up again. This time it had reduced to two beeps (hall sensor failure), so I grabbed a magnet and voltmeter and started testing the three hall sensor outputs and was soon able to confirm that all three sensors have been killed.

I'm now pretty hopeful that my original controller is still working, but I'm tempted to throw the wheel back together just to confirm it still works in sensorless mode, just to put my mind at ease. 

I will post an update when I've either tried it as it is, or when I've replaced the sensors and tested it 100%.

Ginge, I have not yet ruled out the possibility of converting the wiring and using an external controller, so please don't use up all of your alphawire wire just yet.

Alan
 

[Bikemad]

I was going to throw the wheel back together and test as it was, but I thought it might be interesting to increase the thickness of my additional shunt, so I soldered on another thin wire loop and then decided to solder them both together to give an even larger cross sectional area.

I reassembled the wheel and put it securely in the bench vice and connected up a 7cell 5Ah LiPo pack measuring just under 29.4V.

After the two beeps, I spun the wheel slightly and twisted the throttle and she burst into life running as smooth as ever. I tested the throttle, cruise and the regen functions and all are working fine.

Now the really exciting bit; I put on a pair of heavy duty gloves and decided I'd do a stall test to see how much current it would draw in sensorless mode with the improved shunt mod. I opened the throttle and grabbed the tyre to slow the wheel down as much as possible, but I could not quite manage to stop it completely. There was a strong smell of burning rubber from the friction of the tyre against the leather gloves and then I noticed the reading on the Watt meter:





I bet you can imagine how I'm feeling right now?



If it draws 1458 Watts on 7 cells it should be at least 2916 Watts (3.9HP) on 14 cells, but I don't know how long the controller will last at 55 Amps, I'm pretty sure something is bound to expire (probably in a big way) sooner or later with this amount of power.

I just couldn't resist trying it:





... and it still lives!

I wonder if I can manage 4HP?

I'm still not sure whether the second controller was actually making any difference at all, perhaps it could have died when I initially connected the battery, and the 25% power increase may just have been the result of the shunt modification alone, as I still feel the second controller should have given nearer 100% increase if it was working correctly.

I think my initial feelings may well have been correct in this instance, but I'm still puzzled as to why all three hall sensors failed.

Alan
 

[DirtyGinge]

I feel really guilty for some reason...i know the controller was good, covered nearly 700 miles.......but yet im still feeling guilty...honest guv, it was alright when I took it out.....

Still for a capacitor to blow that bad, in a very short space of time, I think one controller dumped all its volts through the phase interconnect into the other, and if they were in sensorless mode, could explain the lack of sync....

No worries on the alphawire alan, ill reserve some for you

I think once you get on your pie at that power, you will want it to become a permanent mod......maybe the controller will last that long......personally if I were you, before you seal it up, maybe a good time to add a LOT of heatsink metal to take the heat off the fets

(still feeling guilty  )

[Bikemad]

I feel really guilty for some reason...i know the controller was good, covered nearly 700 miles.......but yet im still feeling guilty...honest guv, it was alright when I took it out.....
(still feeling guilty   )

There's no reason why you should feel bad at all, I knew I was taking a big risk by doing what had not been done before, and I half expected something to go wrong, but I just had to do it to test my theory. Anyway, I'm very pleased with the 56.41 Amps maximum that it now draws, and the 2929.9 Watts of power being consumed really does feel a lot when trying to stop it by hand! I could see my tyre being quite literally worn away within my gloved hands!

I don't suppose there are many people stupid enough to try a burnout with their bare hands, as I think bits of skin would have been removed instead of bits of rubber, if it wasn't for the heavy duty gloves I was wearing.

Disclaimer
Remember kids, this sort of testing should only be carried out by a fully trained and highly qualified idiot, and in a properly controlled environment, so "Please don't be tempted to try this at home!"

I initially thought about videoing it, but I do not want to be responsible for any loss of limbs!

It will be interesting to see how new hall sensors survive with just one controller again, I measured around 2mA per sensor to pull it down to 0V, so that's around 4mA per sensor when running both controllers. I wonder what the maximum current is likely to be on the GM hall sensors? Hopefully the Honeywell ones will be better.

I still think it may have been more successful if both controllers had been exactly the same model number, and programmed with identical parameters.

Alan