Magic Pie II Dual Drive

[jupiterhenry]

Hi Yao,

My name's Jupiter, and I was just reading some posts about the dual drive Magic Pie II...at one point, you said in the forum, "I'd like to take this opportunity to make Dual Drive kits and Complete Dual Drive Bikes available for sale on the website", are those coming soon? Also, I saw you posted something about the MPII production being delayed, and I saw somebody else say something about 2012...what's the status on the MPII, if you don't mind me asking? Can you give me any updates?

I need to set up a dual drive system on my utility tricycle soon, and I don't know if I should wait for the MPII dual drive kit, or wait and buy two MPII's and wire it myself without the kit, or just go ahead and buy two MPI's and wire it myself without the kit. I've been doing tons of research on the Magic Pie and I can't wait to try it out, but I'd sure like to get the MPII if I could. Any news?

Thanks!

Jupiter

[Bob91403]

If you're running two pies at the same time, don't you have to be able to balance them against each other? Is there a way to do that in the programming? No two motors, or wheels for that matter, are exactly alike. Is one motor just being dragged by the other?

[Bikemad]

Bob,

If the wheels are the same size, and you are running the motors on the same voltage, there should be no problem at all using the same throttle to control both motors.



The controllers should be pretty closely matched, but it still wouldn't matter if one motor was working slightly harder than the other at light throttle, in fact it may even be advantageous to have just one motor doing all the work under low load conditions.
At full throttle, each motor will still be working 100%, unless the front wheel is in the air!
However something like my D.I.Y. chopper bike, which has significantly different sized wheels, might need a little bit of tweaking to provide an adjustable offset on the throttle output:



The dual drive is intended mainly for improved performance, i.e. faster acceleration and better hill climbing ability. The actual top speed on the level will only be slightly faster than a single motor.

Alan
 

[vapid2323]

Alan is correct I have a dual drive (about 200 miles so far) and it runs fine by simply splitting all the cables to send signals to both pies. I don't know the technical stuff but it works just fine.

[e-lmer]

I have been a long time buyer.

I am dying to upgrade to a 45V LiFeP04.

A battery special would be sweet!

[Leslie]

The only thing I would watch for with the dual drive is that it might need a battery and BMS rated to the maximum current a dual drive may need.  The 12ah 48v may be a little small for a dual drive setup, however I think it is Vapid reporting that the 48v battery is doing fine with a dual drive..

[vapid2323]

The only thing I would watch for with the dual drive is that it might need a battery and BMS rated to the maximum current a dual drive may need.  The 12ah 48v may be a little small for a dual drive setup, however I think it is Vapid reporting that the 48v battery is doing fine with a dual drive..

Yes I am working with a 48v

[GM Canada]

I am considering turning my JoyEbike into a Dual Pie Drive. I have seen many posts asking how can this be done. Has anyone ever come up with a definative answer? Can I just put them on two batteries and split the wites from the one throttle and one set of brake levers to both controllers? Im thinking all that would have to be split is the throttle signal to both controllers and the brake signal to both controllers. Every thing else should be the same.

Also currently I have 2 batteries wired in paralell running one Pie. Should I wire the batteries seperatly to each motor or can I just paralell in the 2nd wheel to what is already wired?

Gary

[Leslie]

Yes from what I read Gary its easy done.

I havent done it and the one member I know well of Vapid only used a single pack.

But I think with two packs you need to join the black throttle feed wires from the two controllers as you need a common ground. Even just a small wire from one packs ground wire to the other will do the job.

Give it a go and tell me how thing turn out.

[Leslie]

You could join both packs as one but that could cause charging and discharging issues between both packs and on could shut down from over current,

Yeah just a single wire the same size as the throttle wire between the two packs grounds is correct.  Makes it tidy and easier if both packs are put together.

Or just join the black throttle wires together leading to the throttle.


Think about the controller with no black wire running to it.

Can a single white wire run a controller?  You need the circuit to be grounded.

[GM Canada]

Well I did it! It was alot easier then I imagined. I spliced into the white and black from the throttle and added another black female plug with only the white and black in it. Then I spliced into the brake wires and added another blue female plug. With everything plugged in normally from the back wheel, I just plugged in the blue and black plugs from the front wheel and of it goes!! I'll have to add another plug for the cruise tommorow, it was getting to late today. Im not sure if I just stated that in a way that makes sence. Maybe Leslie can do up a diagram for us.

Anyway I took it out for a test drive and HOLY SH*T does it ever fuggin go! Wow! Wow! Wow!

After a few hard takeoffs I kicked out the batteries. plugging them in for a second turned them back on. I then used the USB plug and turned down the regen, I almost wiped out the first time I braked. It was way to strong with two motors. I also cut the amps back to 15 continuous and 20 peak to stop kicking out the batteries. We will see how it performs hauling the trailor ten miles up hill in the morning. I think it will be a blast!

I have to upload a few pictures tomorrow of my Dual Slice of the PIe!


Gary

[Leslie]

Really two packs to one controller should be separated by a diode on each pack to avoid them from discharging onto each other.  But this will block regen function

Its not as big an issue iof both packs are of equal size and age.

But the dual setup  unless the current path ways a perfectly in balance from both packs one wheel could draw more from one side of you parallel pack than the other making one pack go more flat.

When this occurs the higher charged pack is left unrestricted to another pack unrestricted and the current can exceed the rating of the BMS.


The dual pie on separate packs to separate controllers and no full circuit linked between the two packs  is by far a better solution than even two packs parallel on a single controller.

[Leslie]

Gary for what configuration do you want me to do the dual diagram for?

The Pie internal or the external one?

Both? 

I feel the internals will be phased out soon so any efforts may be best put towards the external one.  but I am willing to do both if you need this.

 

[Leslie]

EXPERIMENTAL

Use at own risk.




Here is what Ive done so far.

The regulators are switchmode.  Depending of the lil transofrmer their maybe isolation happening.

I cant be sure unless someone tests this.  


Once we have established isolation between the two packs there is no reason why one can not draw 25 amps  from each pack without it shutting down.

[Leslie]

Gary is there a reason why you need your pack full parallel?

See once ground is connected between the packs there is no need for any other connections than the signal splitters to each controller.



One pack peaked over 40 amps as both packs can not respond to the demand the same. This is why it shut down and you had to put the current down is my guess.

It not a healthy config you're doing here if both packs are in parallel like this unrestricted or not diode blocked.



Im not sure if you remove positive the bridge wire between the packs this would work, I have no schematics nor anything go on just some pictures.


I need your interaction here.

As you know I wait for my lovey pies you packed and sent me and even then they are both rear.  So this isn't even something I will do myself.

I keep thinking the positive bridge I put on the throttle is even needed.  I assumed that the switch mode may be isolated but seeing you used the black and whit wire and it worked my assumptions could be wrong.

You should be able to do 25 amps from each pack no problems with no shut down.  A true 2kw bike is the aim of a dual setup or else there isnt any point.  More of a loss with the added weight.