Easiest power loss fix ever... 3spd switch

Voltron · Mar 6, 2018

Just a little something to check before you go tearing things apart...
I've been having a slow drop off in power for a while, that I assumed was either my pack aging out, or my motor getting demagnetized, or controller etc. This particular controller had a real pronounced step up in power at about 25 mph, that I've read was where it's switching to sensorless mode, that I was starting to miss, and the top speed had dropped from 40ish to low 30s.
So anyway, finally decided to track down where the missing jump had gone, mentally ready for a full teardown and testing. Then it suddenly occurred to me that it was slowly starting to feel like it had when the three speed switch was in the medium position, like way back when I was testing it to figure out the wire colors and never used again. I used a bent over paperclip to jumper it on high back then, and this damp winter made it corrode just enough to add resistance slowly. A quick wiggle to get to shinier metal, and immediately back to full power!
I will probably hook in a switch, as it has enough jump again to make medium power a good idea for friends test rides, but I also want to test how much an even lower resistance connection boosts things.

amberwolf · Mar 7, 2018

If you mean lower resistance in the 3-speed switch connection, it doesn't matter once it reaches the point at which it causes the MCU to read that as "on", as the switch is a binary switch.

Usually there are three wires from teh switch, one of which is a common (either 5v or ground) and the other two go to the speed pads on the controller, which just accept either a ground or 5v input. Anything between those voltages is still considered one or the other until it reaches whatever threshold that unit uses.

So position 1 turns "on" the first speed pad, postion 3 turns on the other, and position 2 (middle, medium speed, etc) is open, so neither one is on.

It's possible that just the right resistance might make enough of a connection most of the time to have enough voltage (or a good enough ground) to bring up the full speed position, while at other times it fluctuates between that and the "off" 2nd position, so that it appears to be something between the two, but I"d expect some sort of change you could feel between the two (unless teh cotnroller ramps between them).

But I expect that's not happening, and it's either in one mode or the other, and while the switch makes it eaiser to change modes, it won't increase or decrease speed in the same mode because of the contact resistance vs the wire bit you've got in there now.

Voltron · Mar 7, 2018

Yes... It sure seemed like it felt somewhere in between the two settings with the increased resistance though, and the drop off was so gradual that it seemed like resistance was having an effect. Couldn't hurt to do a quick test I guess...

John in CR · Mar 11, 2018

That's why I always set my 3spd programming to default to max speed. ie the middle setting on the switch, which is the same as having no switch connected at all.

rollingreenhills · Mar 14, 2018

So a 3 speed switch is not a potentiometer?

Could you solder a three speed switch to the throttle cables, in order to produce stepped speeds?

My bike is too fast so I need to limit the throttle to about 50%. I have looked at a method using potentiometers. Also resistors.

Voltron · Mar 14, 2018

In this case the switch isn't affecting the throttle at all... its just telling the brain of the controller to limit the power, but not by limiting the throttle signal. So putting a regular three speed switch to the throttle wires wouldn't help. Putting in a potentiometer might work if your system doesn't have any way to limit power I suppose, but you would want it pretty foolproof I would imagine.

e-beach · Mar 14, 2018

rollingreenhills said:
So a 3 speed switch is not a potentiometer? ....Could you solder a three speed switch to the throttle cables, in order to produce stepped speeds?

It could be a couple of resistors or a couple of potentiometer set at a specific resistance with a switch involved. The purpose is to reduce the return voltage from the throttle to the controller so the controller thinks you are using less throttle.

So yes, a three speed built for your throttle type will work as a way to reduce your speed with the option to go faster at the flip of a switch.

Voltron · Mar 14, 2018

But just taking a regular off-the-shelf three speed switch and wiring it in won't work...

e-beach · Mar 14, 2018

Voltron said:
But just taking a regular off-the-shelf three speed switch and wiring it in won't work...

Sure it can. Depending on how the switch is made.

Voltron · Mar 14, 2018

The only off the shelf ones I've seen don't do that, and it would be abnormally odd to find one that did, so re. the guys question about just adding in a stock 3 speed switch, I think it's highly unlikely to work. But yes, you could engineer some way around that, and maybe somebody has... Maybe.

e-beach · Mar 14, 2018

Voltron said:
.......you could engineer some way around that, and maybe somebody has... Maybe.

I can't speak about your "off the shelf" kind that plug into a controller because I never hacked one open. I get the feeling though that they are a simple set of resistors connected to a switch. The controller is looking for a return voltage, but when switched it is receiving less of a return voltage then full voltage. Some early 3 speed switches that were being sold by ES members were simply two trim pots potted in epoxy and switched through a switch on the handlebars. They worked as I described earlier.

A variable speed switch for an e-bike throttle is as simple as splicing a potentiometer into the return wire from the throttle.
Or a series of trim pots through a switch.
Or predetermined resistors through a switch.

Voltron · Mar 14, 2018

If you Google ebike 3 speed switch, you'll see what I mean by off the shelf. While it might be switching between resistors inside the controller, the actual switch has no resistors, and has full signal voltage on two of the settings, and no connection on the other.
What you describe is surely out there, but if you order any of the first 50 or so generic ones that show up in a search, and wire it into a throttle, all it will do is work full power on two settings, and not work at all on one.
I'm trying to keep it simple for the question the guy asked, where there is a 99% chance a standard 3 speed switch isn't going to solve his problem because it won't do anything to reduce the throttle voltage, as that's not how most three power level controllers work.

So is a generic 3 speed switch a potentiometer? No.
Will adding one produce stepped speeds? No.

But some specialty solution might if he can find it or make it.

Voltron · Mar 14, 2018

Some of those early ES ones were also throttle tamers, where you could adjust the ramp up of the throttle, which these days is usually programmable thru the controller, just like the three speed, so nowadays the switch is usually just a switch, with no voltage reduction between the positions.
A simple test on how it works is just jumpering the pins in the plug by shoving a bent over piece of wire in it. You get the three power levels, with no variable resistance required.

And again, yes, you could find or make something... But it will require more than a normal 3 speed switch.

e-beach · Mar 14, 2018

Voltron said:
.......

So is a generic 3 speed switch a potentiometer? No.
Will adding one produce stepped speeds? No.

........

I never said a your generic 3 speed switch was a potentiometer. That is your straw-man.

I said that if somebody wants to create a variable or stepped speed switch for there throttle then they could add one or more pots depending how the switch is wired. It has been done before regardless of your lack of knowledge about it.

Voltron · Mar 15, 2018

Nobody said you asked that, but it sure seems like you're just being an argumentative ass, who's so busy trying to be right they aren't even hearing the original questions anymore. Those were the two questions asked by rollingreenhills that I was responding to. No straw men needed.

And I've agreed several times that such a thing could be built... and the guy who asked the question mentioned already that he was looking into another method using resistors or potentiometers.

You also mention that you've never actually messed with a three speed switch, and you just have 'feelings' they might have some resistors in there. Maybe actually buy a couple and see how they work?

e-beach · Mar 15, 2018

Voltron said:
Nobody said you asked that, but it sure seems like you're just being an argumentative ass,

All I can say about that is there is a lot of psychological projection comming from you.

No straw men needed.

Yet you used one anyway.

And I've agreed several times that such a thing could be built...

Such a thing has been built.

and the guy who asked the question mentioned already that he was looking into another method using resistors or potentiometers.

Which is why I said it can be done because it has been done. But apparently you don't know that yet.

You also mention that you've never actually messed with a three speed switch,

Not the kind that plugs into a controller, but I have on multiple occasions put resistors and pots inline on the return wire from controllers to determine if I wanted a speed reducer to allow for wot while saving wh's. I eventually abandoned the idea as I developed the philosophy that less components means less to go wrong. With my riding style I just don't need one.

As for buying one why don't you buy the kind that reduces the return voltage on the throttle wire so you can quit being so argumentative.

Voltron · Mar 15, 2018

It's not projection to recognize when somebody is an ass. It's unfortunately a necessary skill in today's world.

And again, sure, they have been built. Feel free to point out where I've said it couldn't be or hasn't been done. But that's not what the guy's question was.

e-beach · Mar 16, 2018

Voltron said:
It's not projection to recognize when somebody is an ass. It's unfortunately a necessary skill in today's world.

Which is why I recognize it in you, but it is clear to see you don't recognize it in yourself.

And again, sure, they have been built. Feel free to point out where I've said it couldn't be or hasn't been done. But that's not what the guy's question was.

I am glad you are off the Maybe... and into the "they have been"
(for any body else who wants to see how, start here: https://endless-sphere.com/forums/viewtopic.php?t=41240)

As for the rollinggreenhills' quetion:

Could you solder a three speed switch to the throttle cables, in order to produce stepped speeds? My bike is too fast so I need to limit the throttle to about 50%. I have looked at a method using potentiometers. Also resistors.

The answer is still yes depending on how the switch is made. And in fact the adaptation of an "off the shelf" three speed switch to cut the throttle voltage in half (or really about 3vdc) is a simple build. All it takes is a pot and some wire splicing.

Voltron · Mar 16, 2018

If you have to go adapting it, it's not really off the shelf anymore.
It's obvious from his question, he knows it can be done with resistors or a pot, so you're not really helping him out with any new knowledge.

So back to his really basic questions... Is a 3 speed switch a potentiometer? No, unless you search out a special one that's different from 99% of normal ones, or built one yourself.

Will adding a normal one give you stepped speeds? Again, no.

e-beach · Mar 16, 2018

Voltron said:
If you have to go adapting it, it's not really off the shelf anymore.
It's obvious from his question, he knows it can be done with resistors or a pot, so you're not really helping him out with any new knowledge.

Except I explained to him what to do. But since you like throwing your rattle on the floor lets go one step further. Take an off the shelf 3 speed switch and hook it up like this.

So back to his really basic questions... Is a 3 speed switch a potentiometer? No, unless you search out a special one that's different from 99% of normal ones, or built one yourself.

Boy, smart as a bag of hammers...... :roll:

Back to the snowman...... :roll:

Voltron · Mar 17, 2018

That sure doesn't look like an off the shelf 3 speed switch, and no matter how many times you blather on about your cool idea, that's not what the question was...
Great topic for another thread tho... Even though there's a bunch of them already, I'm sure you have something to add...

e-beach · Mar 17, 2018

Voltron said:
That sure doesn't look like an off the shelf 3 speed switch,........

That because it is a schematic. :wink:

Voltron · Mar 17, 2018

You do recognize you keep beating the drum on a question that wasn't asked right?

John in CR · Mar 17, 2018

Every "off the shelf" 3 speed switch I've seen, and I spent quite a few grand on different "kits" and parts, was simply a 2 way switch with 3 wires going into it. One wire goes to neg on the controller board, and the other 2 go to "hi" ad "low" on the controller board, so High and Low positions on the switch are a short to ground of the applicable wire, and the mid position on the switch doesn't complete any circuit. The effect of these on the controller always seemed to be a spreading of the throttle response over the applicable throttle range, so if you used say a 50% setting in the controller programming, not only do you get that limited top speed, but low speed response is much smoother. Be careful with this on high powered rigs, because if you forget to let off the throttle when switching to a higher speed on the switch, it's quite easy to find yourself in an unintended wheelie.

rollingreenhills · Mar 23, 2018

Thanks guys. I appreciate all of the info, equally from all involved. :shock:

Easiest power loss fix ever... 3spd switch

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