What does overvolting mean?

E-driver_

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So I have seen lots of videos and threads about "overvolting". But I don't quite understand what they mean when they say that.

I have seen people talk about soldering the shunts of their controllers to make them draw more amps. But this is not the same as overvolting right? This is just making more current and amps going through the controller. It is not really the same thing as overvolting?

Is the definition of overvolting that you are using a battery that is above the written/recommended volt on the controller and motor?

So for example if I have a controller that is 36volt and a motor of 250w recommended for 36volt, then I am over volting the system when I am using a battery of 48 volts?
Have I understood that correctly? :)
 
Overvolting refers to giving more volts to the motor to make it spin faster, also to get more power at the same current as before without overheating it.
To overvolt a motor you'll need a new battery and controller.
 
Hmm ok

So overvolting means using a battery that has a higher voltage that what the motor is set for basically?

For example using a 48 volt battery for a motor set to 36volt is overvolting?
 
Yes, it's running more volts thru the motor, usually to get more rpms out of it for higher speed.

Motors usually don't care too much what voltage they're fed, as long as it's not up in the hundred of volts zone.

But controllers do care, so it's just a motor thing.
 
Voltron said:
Motors usually don't care too much what voltage they're fed, as long as it's not up in the hundred of volts zone.
How much is the life diminished of a 36V 350W hub motor (with 20A Controller) by overvolting with a 13s6p 48V battery that's now feeding a 30A Controller? With a 20A Controller no problem ... just not making good use of a 13s6p high energy battery feeding a 30A Controller with a 750W or 1000W motor.

In part it depends on the quality of the motor. Do you really want to shorten the life of a 350W motor by overvolting because you can't afford a 500W or 750W hub motor.

Battery + Motor (Flat Terrain 165lb Male) Maximum Speed (without overvolting?)
  • 250W 20mph ... 500W 25mph ... 750W 28mph ... 1000W 35mph
dogman dan said:
It gets very confusing. A 350w motor that has 350w max power will not go much faster than 30 kph (22mph) with typical speed/rpm wind. Wind resistance means more speed needs more watts. This is not the motor limiting speed, it's drag limiting it. But if you give that same motor 750w it can go 40 kph (25mph). But 40 kph is pushing the small motors pretty hard. You can do this in mild climates, but not in the desert where I live. It may overheat if pushed too hard by heavy riders.

A 500w rated motor may have the same speed wind, but it can be pushed much harder and still get away with it in my climate. So 45kph (28mph) is quite common when you give that 500w motor 48v. at 36v, 35kph (22mph) is typical.

If you want a system that can grow,, then get the 500w motor. you may choose to run it at very low power now for various reasons, your controller is weak, or maybe your battery is weak. But later on, you can upgrade to 48v and 1000w if you want, using the same motor.
If your riding requires sustained hilly terrain with a heavy load even a 500W hub motor will overheat with overvolting. If that's the terrain need an energetic battery + 40A controller feeding a 1000W motor.
 
Voltron said:
Yes, it's running more volts thru the motor, usually to get more rpms out of it for higher speed.

Motors usually don't care too much what voltage they're fed, as long as it's not up in the hundred of volts zone.

But controllers do care, so it's just a motor thing.

Hmm ok interesting.

Why is it that I see some people using statorade and stuff on youtube to cool the motor if the motor don't really care about it?

Is that for some other reason they do that then?
 
But controllers do care, so it's just a motor thing

Hmm ok.

Is it possible to increase torque power and speed by just changing the controller as well? For example if I have a 250w motor. And a 36 volt controller and a 36volt battery..

If I now change ONLY the controller, into a 48V controller., will that controller then pull more power out of that battery into the motor? Even if it is the same 36V-battery?
 
Usually, a 48v controller won't run on a 36v battery, as it thinks it's a really low voltage 48v battery, and there's usually an automatic low voltage cutout built into a controller to prevent that.

And what I meant by the motor not caring as much, is that if you just switch controller and battery to be higher voltage but less amps, it will work, and not immediately vaporize.
The winding insulation can withstand hundreds of volts, unlike electric components in a controller like the capacitors, that an extra 10 or 20 volts with blow up immediately.

You could also run it at higher voltage, and higher amps, and as long as you use sense about letting it cool off, it will again not immediately vaporize.

But if you want to run it at high voltage and high amps, and run it hard up mountains with no cool down, then yes it will shorten the life span, and yes, you might benefit from statorade and hubsinks.

But you probably shouldn't be doing that on any internal geared hub motor, they're terrible candidates for overvolting and hodrodding usually as they trap lots of heat in the shell, and the gears get soft, etc...
 
Voltron said:
You could also run it at higher voltage, and higher amps, and as long as you use sense about letting it cool off, it will again not immediately vaporize.

Aha. So if I run it at the same amps but higher voltage it will not get significantly hotter than before? But If I also raise the amps I could be in trouble?

Does it have to be less amps to work? Or could it be the same amps as before only higher voltage?
 
Voltron said:
But you probably shouldn't be doing that on any internal geared hub motor, they're terrible candidates for overvolting and hodrodding usually as they trap lots of heat in the shell, and the gears get soft, etc...

It is an old 250w hub-motor from Shengyi or something like that.

Therefore I look at this as a fun project potentially.

If it burns it burns :)

Would you go with higher controller and battery but lower(same?) amps?

Or could it work just as well, but cheaper, to do some soldering of the shunt in the 36volt controller, as I've seen a few guys do online. To make it draw more power into the motor I mean.
 
E-driver_ said:
Aha. So if I run it at the same amps but higher voltage it will not get significantly hotter than before? But If I also raise the amps I could be in trouble?

Does it have to be less amps to work? Or could it be the same amps as before only higher voltage?

There are two ratings that you have to consider. Changing voltage or current affects the power. Power (losses, inefficiencies) will affect heat, so higher current with the same voltage will still create more heat, as will higher voltage with the same current. Power limits involve a time component (continuous > forever; or may have a time based rating, good for X Power for Y minutes).

The voltage rating of the components, however, is a hard limit that can't be exceeded (the comment about vaporizing the component). You can't overvolt a capacitor or a MOSFET, for instance (vaporize/fry). But if the components in a controller can handle higher voltages, you can overvolt a controller (run a 36V controller at 48V), but if you do, you still need to keep an eye on the power timing element (it may not be able to run continuous at the higher level before cooking it, but for a limited time could be fine).
 
E-driver_ said:
Why is it that I see some people using statorade and stuff on youtube to cool the motor if the motor don't really care about it?
If you load up the motor too much (ex. trying to climb too steep a hill with too much weight) it will overheat internally and fry the wiring. Adding the statorade helps transfer that inner heat to the outer shell that can conduct the heat away to the surrounding outside air. Tight-fitting aluminum fins mounted on the motor outer circumference can help a little more as well.

Kind of like with a ICE car that starts to overheat climbing a mountain pass in the hot summer, the extra radiator fan turns on to help remove the excess heat generated by the engine.
 
Since '20amp' controller (when it comes to battery amps) will usually push more phase current though the motor with a higher voltage battery, 'overvolting' is also 'overcurrenting' the motor, unless your controller allows to control phase currents as well.

You get higher torque and higher top speed - but at lower efficiency and greater chance of frying the motor and stripping gears.
 
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