Why even use a controller?

8 posts / 0 new
Last post
deronmoped
Offline
Last seen: 13 years 6 months ago
Joined: Tuesday, December 25, 2007 - 08:18
Points: 342
Why even use a controller?

I was out testing my Pedelec today just using a heavy duty push button, it seemed to work pretty good. I would just select the gear I wanted, start pedaling and hit the button. On my other Pedelec that I ride all the time, it seems like I use full throttle almost all the time, what would I be missing if I did not use a controller? I know the bike would be at least 5% more efficient without the controller which would be a big plus.

Deron.

LinkOfHyrule
LinkOfHyrule's picture
Offline
Last seen: 12 years 11 months ago
Joined: Wednesday, October 17, 2007 - 14:54
Points: 730
Re: Why even use a controller?

LOL, that's pretty ghetto.

Well, obviously, you'd have no amp limit, so run a greater risk of frying the motor, and you're going to have to pedal if you want low speeds. Probably pretty hard on the batteries, and no LVC.

And if you ride WOT all the time, you aren't going to see a 5% increase in efficiency.

I guess you could if you wanted to, but I can't see a minuscule difference in efficiency making up for all the downsides. And that's assuming the very high amp draw at low speeds doesn't offset it or even make it worse overall, which there's a good chance it does. :/

The author of this post isn't responsible for any injury, disability or dismemberment, death, financial loss, illness, addiction, hereditary disease, or any other undesirable consequence or general misfortune resulting from use of the "information" contai

deronmoped
Offline
Last seen: 13 years 6 months ago
Joined: Tuesday, December 25, 2007 - 08:18
Points: 342
Re: Why even use a controller?

You know what would be better then a controller limiting the amps, would be a temperature sensor on the motor. A controller does not know how many amps a motor can handle, especially on the modified bikes some of us are building. If I bought a controller for my bike motor I would just be trying to take a educated guess at the cut off amperage. If I was to use a temperature sensor, I could find out what is a safe heat limit for motors in general. That is what we are shooting for is it not, run the motor as hard as we can get away with, without overheating it.

As for "real" low speeds, I find that I really do not need the motors assistance. Not sure how I would like riding the bike at moderate speeds, I would be modulating the push button to keep from going too fast. My stock Gaint LaFree control system does that for me right now, using the torque sensor on the crank, it turns on and off the motor with pedal pushes.

If the controllers are only 95% efficient at full throttle and even less efficient at part throttle, why would I not see a increase in efficiency when I bypass it, for the same amount of work out of the system?

The way I see it is, these bikes are so underpowered why would you want to throttle them? I know ICE's are most efficient at full throttle, not sure if that applies to motors. Just run the motor at full throttle all the time, just push the button as you need the extra power. I mean you pedal if you want to go and apply the brakes if you want to slow down, how much harder can it be to just modulate a button. Are we that lazy to need a controller :)

Deron.

LinkOfHyrule
LinkOfHyrule's picture
Offline
Last seen: 12 years 11 months ago
Joined: Wednesday, October 17, 2007 - 14:54
Points: 730
Re: Why even use a controller?

If the controllers are only 95% efficient at full throttle and even less efficient at part throttle, why would I not see a increase in efficiency when I bypass it, for the same amount of work out of the system?

How efficient they are at full throttle depends almost solely on the FETs used. If say, you had two 4110s in parallel (I do), that's something like 1.5mΩ of resistance. The motor will probably be at several hundred times that.

You know what would be better then a controller limiting the amps, would be a temperature sensor on the motor. A controller does not know how many amps a motor can handle, especially on the modified bikes some of us are building. If I bought a controller for my bike motor I would just be trying to take a educated guess at the cut off amperage. If I was to use a temperature sensor, I could find out what is a safe heat limit for motors in general. That is what we are shooting for is it not, run the motor as hard as we can get away with, without overheating it.

Thing is, while a thermometer can tell you how hot a motor's getting, it can't limit amps. So, you still have the issue of it wasting loads of power when accelerating, negating the gain in peak efficiency when not using a controller.

The way I see it is, these bikes are so underpowered why would you want to throttle them? I know ICE's are most efficient at full throttle, not sure if that applies to motors. Just run the motor at full throttle all the time, just push the button as you need the extra power. I mean you pedal if you want to go and apply the brakes if you want to slow down, how much harder can it be to just modulate a button. Are we that lazy to need a controller?

Because not all bikes are underpowered. I definitely wouldn't wan't to be riding the equivalent of Doc Bass's 7kw+ bike with just a push button. I wouldn't even want to ride my comparatively weak Golden Motor setup like that. Not to mention modulating speed would be really annoying, since you'd lurch forward every time you hit the button. And dangerous. Front wheel setups would run the risk of losing traction if it suddenly started drawing the maximum amperage a given voltage would allow (especially on wet/sandy roads O_O), and rear wheel ones would risk wheelies, assuming a torquey enough motor.

More importantly, a majority of hubs are brushless, meaning you HAVE to have a controller. They simply cannot run without one.

The author of this post isn't responsible for any injury, disability or dismemberment, death, financial loss, illness, addiction, hereditary disease, or any other undesirable consequence or general misfortune resulting from use of the "information" contai

deronmoped
Offline
Last seen: 13 years 6 months ago
Joined: Tuesday, December 25, 2007 - 08:18
Points: 342
Re: Why even use a controller?

I'm going to try the bike I'm building without a controller first. In my first test with just a push button it seemed to do what I needed it to do. I was even riding my other bike and paying more attention to how I used the power and it was full throttle all the time. There is a torque sensor in the circuit so that may be limiting the amount of power I was getting from the motor.

Yeah, I was thinking it might be dangerous if I let someone else ride the bike and did not know how to use the power. But then again, I would operate a high current relay with the push button, incorporate brake kill switches, a thermal overload switch on the motor and a fuse.

Deron.

Krilson
Offline
Last seen: 4 years 6 months ago
Joined: Tuesday, September 9, 2008 - 15:17
Points: 15
Re: Why even use a controller?

If you are using a series wound motor, then the efficiency increases with speed.
Motor, switch, battery. That's all you need if the motor is sized to fit the load

generic3
Offline
Last seen: 13 years 2 months ago
Joined: Monday, March 2, 2009 - 15:38
Points: 1
Re: Why even use a controller?

THe Hienzmann motor has a temp. sensor on the motorstock .

dogman
dogman's picture
Offline
Last seen: 12 years 6 months ago
Joined: Tuesday, April 29, 2008 - 15:41
Points: 830
Re: Why even use a controller?

A readout of the motors temperature is a good idea, and I plan to install one next time I have the covers off. Definitely before riding in above 90 F weather again. As for the switch, have fun when it welds itself together in the on position. A really simple controller like those found on the old golf carts could be made like the heater fan switch in your car. Three positions, with two different resistors and no resistors. So you get slow medium and fast. Those cart motors were fan cooled though. Brushed motors of course.

Be the pack leader.
36 volt sla schwinn beach cruiser
36 volt lifepo4 mongoose mtb
24 volt sla + nicad EV Global

Log in or register to post comments


Who's online

There are currently 0 users online.

Who's new

  • Conmac065
  • MalachiKldho
  • leastk
  • aymgoa
  • wodnik7

Support V is for Voltage