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Sharing Throttle, Brake and PAS with 2 contrs and 2 bats

Posted: Mar 28 2017 4:20pm
by RyanC
Reading over all the 2wd wiring diagrams I can find, most are focused on single battery setups-

The short version of my question is can I use one controllers 5v and ground and then parallel only the signal cables to the 2nd controller? And/or would I need to share grounds between the two batteries? Right now I am not wiring the batteries in either series or parallel, just each battery feeds it's own controller.

Basically I started with a stock radwagon, added a q100h to the front with a 2nd battery pack using the integrated 18a controller. This way I have been running it with a 2nd throttle for the front, and no PAS or brake sensors up front.

Now I picked up a q128c + s12s and am converting the drivetrain to 1x10 with shadow+ zee rear and a 54t chainring. I could keep it the same as it has been, but if it's not too big of a hassle I'd like to try a setup where it's possible to have 2 LCDs, 2 controllers, and 2 batteries, but have the 2 controllers share PAS, brake sensors and throttles. Ultimately then the battery for the front would also be connected to a 12v voltage converter for lights turn signals and horn.

It seems a lot of the posts on these recomend at least trying to share 5v and ground and see if there is any contention that way...so I thought I'd give it a thought. Worse case I have no problem going back to throttle only on the front.

Thanks-

Re: Sharing Throttle, Brake and PAS with 2 contrs and 2 bats

Posted: Mar 29 2017 1:56am
by amberwolf
There has to be a reference for the signal, so you have to have a ground, too, if the batteries are separate so that the battery grounds are not shared between controllers.

Re: Sharing Throttle, Brake and PAS with 2 contrs and 2 bats

Posted: Mar 29 2017 8:42am
by RyanC
amberwolf wrote:There has to be a reference for the signal, so you have to have a ground, too, if the batteries are separate so that the battery grounds are not shared between controllers.
Right that makes sense-

So can I try to parallel the signal wires, as well as the ground wires, but use only one of the 5V sources? And would this still be OK if the batteries aren't charged to the same level?

I guess it might be easier to parallel both batteries together, I'm trying to avoid that as ultimately my wife's bike will also end up with one dolphin, and maybe we would have a 4th battery and have the flexibility to rotate them around as needed on 2 bikes to facilitate more miles in one day.

I do understand that there is a potential for contention between the motors, I don't mind taking that chance. I just don't want to try something that results in an expensive battery fire. Thanks-

Re: Sharing Throttle, Brake and PAS with 2 contrs and 2 bats

Posted: Mar 29 2017 2:34pm
by amberwolf
As long as the grounds are the same, there should be no need to share the 5v or battery positives.

You could avoid even the ground sharing, but it would require isolating the "extra" system electrically, for all of the signals, like with some sort of optoisolator setup or similar. Could get complicated and the more complicated the more failure prone it could be.

I considered the latter for my own SB Cruiser, because I have some DC-DCs for lighting that will only work if I series two of my battery packs...but the controllers can't handle that. :/ So the only option to use the DC-DCs is to have each controller system totally independent (presently they share ebrake wires and the CA Shunt), with the only connection between them the positive of one being the negative of the second, and then the DC-DC wired across the whole setup. Anything that goes wrong with a phase wire or winding that shorts to the frame risks shorting an entire battery pack if there is already a similar short on the other system somehow, so for that and other reasons I've pretty well decided against this idea.

Re: Sharing Throttle, Brake and PAS with 2 contrs and 2 bats

Posted: Mar 29 2017 11:23pm
by motomech
I'm totally confused what the O.P.is trying to do, but if it's any help I once ran two controllers off one throttle. I simply split the signal out and ran the controllers w/ a SHORT common ground, less than 6 inches.
It worked ok, but I could sense some inter-action between controllers and degraded the throttle "feel".

Re: Sharing Throttle, Brake and PAS with 2 contrs and 2 bats

Posted: Apr 06 2017 7:44am
by RyanC
Thanks guys-

Apologies it's a little confusing. I'm trying to run 2 controllers (each with it's own battery, LCD and motor) from one throttle, pas and brake sensors and I would like to do it without paralleling the batteries together. After thinking about it, I can probably just add a 2nd PAS sensor on the left side of the BB, and I would guess(?) that the 5v brake signal won't have any issues being just a switch if I use one 5v source to feed both controllers?

So then maybe I'm only looking for an opto-isolator to share the throttle, is there a simple one out there that is known to work for this? Or if I go that route, does anyone know if any opto isolator boards that could be used to isolate all 3 (throttle, pas sensor, brakes)?

Thanks again-