Are you wondering how volts affects the performance of an electric unicycle? When choosing an EUC, most people might focus on the size, or power of the wheel (torque or battery capacity). However, voltage seems to be a generally misunderstood factor in EUC performance. Voltage certainly factors into overall power output of an electric unicycle, but it also gives you insight into the efficiency of the overall system. Voltage effects your EUC’s top speed, total range with your battery size, and even how much heat your electric unicycle produces over time. Do you know what voltage sag is? Or, other electrical related “issues” in an EUC? Let’s find out!
In this article we’ll shed some light on the subject and hopefully help you make a better decision when choosing your next electric unicycle! Or, if you already have one, I hope this info will allow you to understand how your EUC works a tad better!
Three Popular High Voltage Electric Unicycles
Disclaimer: I’m not an electrical engineer or anything related. Rather, I’m an enthusiastic EUC rider/collector. If you have a question, or if I missed something, please let me know. I’m happy to do more digging.🖖
What is Voltage in an Electric Unicycle?
First things first. Let’s brush up on our electrical background.
Voltage is the potential difference of electric charge between two points in a circuit (source: Mammoth Memory ). It also refers to the magnitude of that current flowing through something like, say, an electric unicycle. Energy can be transferred through a circuit over time. The amount of energy transferred is measured in the unit of “watt-seconds” or Joules (source).
In other terms, voltage is the amount of potential energy stored in an electric system (e.g., an EUC’s battery).
Continue reading to learn more about how Voltage plays into how your EUC performs in real-world situations. However, to understand this, I think it’s also important to know how Voltage (V) is related to the other variables in the electrical system of an electric unicycle.
Amps, Volts, and Resistance
Let’s take a look at Ohm’s Law, which describes the relationship between Current (Amps, or “I”), Electrical Potential (Volts), and Resistance (R).
or Electrical Potential equals Current times Resistance
Voltage is a Measure of Battery Potential Energy
Voltage is the potential difference between two points in a circuit (source). The unit of voltage is “volt” (V).
Voltage is a way to understand the electrical system of any EUC. You can also see volts as a way to describe how much electrical “pressure” can be contained in a battery. The voltage that your EUC uses is based on the potential energy, or electrical pressure stored in its battery packs.
This also means that an EUC motor can run using different battery voltages. So, it’s important to understand that a 100V EUC and a 126V EUC may be completely different in terms of performance even with the same hub motor watt rating. See more about “watts”, or the ability of a motor to perform work below.
Battery electrical potential in an EUC is often noted as 84V, 100V, 126V, and 134V (theoretical), which is determined in part by a battery pack’s configuration and capacity of cells (which I do not get into here). The most common voltage for a performance EUC is currently 100V. When electric unicycles first came to market, they generally started with volt ratings of around 67V (or lower). Over time, EUCs became more powerful, more efficient, and required components to handle the increased “electrical pressure” or volts driving the entire system.
A quick note on the voltage you’ll need for your EUC. In a performance e-bike, a 48V battery is commonplace. In an EUC, 84V or 100V provides a lot more potential power–more than enough for most–to provide power to self-balance the wheel and generate the torque (e.g., for acceleration and hill-climbing) need to travel.
With more voltage, you’ll have more potential output from the battery in a given amount of time. 🏎
Watts in an EUC Motor is a Power Rating to Do “Work” or Ability to Move
A watt rating of the an EUC motor is one way to measure an EUC’s performance. The watt is a unit of power, and is defined as one joule per second (1 J/sec). Fun fact: 1 horsepower is equal to 750 watts. Some performance EUCs can produce up to 10 horse power at peak output.
The greater the wattage in an EUC motor, the more work that motor can do if provided with enough electrical energy (generated through amps, driven by electrical potential (volts) stored in the batteries). Watt ratings are either continuous or peak, and it’s crucial to understand which type you’re comparing when analyzing specifications.
Motors with the same Watt ratings may have a completely different amount of power, depending on the EUC’s design, which includes battery voltage and capacity. In part, much of this is also governed by the EUC controller (e.g., the “computer” that governs electrical current/power to the motor). You can read more in this article about torque and why it is important for EUC riders.
Watt-Hours (Wh) is the “Capacity of a Battery” to Produce an Electrical Current
A watt-hour (Wh) is the standard unit of energy. It is equal to the work done by a power of 1 watt for 1 hour. This is related to lithium batteries as their energy capacity is measured in watt-hours. Lithium batteries will not be able to power an EUC at their maximum rating for long periods of time–the battery is draining!–So, it’s important to consider the amount of watt hours (energy storage) your battery can hold and how quickly that energy is expended while riding.
You can calculate watt-hours by multiplying the number of amps with the battery voltage. So, 3.7V battery with a 840ah capacity (amp-hour) has a 3108 watt-hour (wh) capacity.
Interestingly, if you remember the Sofirn flashlight I showed you above that runs on 3.7V batteries, then knowing the per battery cell capacity could tell you how many of those cells you would need to make a “battery pack” big enough to generate the power needed to run an EUC with a 1000watt motor for, say, 2 hours.
The higher the watt-hour capacity of your EUC battery pack, the longer your electrical system will run before needing to be recharged. The number of watt hours in your battery determines the size of your EUC’s gas tank, which obviously determines the range of your EUC.
A key point about how watt-hours (wh) of a battery affect voltage is related to “voltage sag” (see below). In general, the bigger your EUC battery with a greater wh rating, the longer you can ride without voltage sag affecting your overall EUC’s performance. This is because larger batteries contain more electrical potential energy (noted as volts).
What is “Voltage Sag”?
A battery’s voltage will “sag” (or decrease) when it drains under load–when amps are drawn away from the battery cells. This is common in all battery-powered electrical systems. “Sag” refers to the decrease in voltage (or electrical potential) from a battery.
If you want to see what happens when voltage sag forces an EUC motor to stop working, check out this cutout video from Adam Malicki at Wrong Way.
If you use a balloon, as an example, as air escapes the balloon, the internal pressure decreases. As your EUC demands more “air” or electrical current (amps), the internal pressure or electrical potential in your battery will decrease, or “sag”.
As more amps are required in the EUC motor (governed through the controller), the voltage will drop in your battery packs. And, if the electrical demand is high, this can result in a loss of performance (e.g., 20mph instead of 25mph) because there is less and less electrical potential to generate the amps required to the turn the motor. Go to far, voltage drops to the point that there is no electrical current at all, aka a cut-off.
As your battery packs drain, voltage sag becomes more and more of a problem. This is because your battery is losing its capacity to produce amps. In the “less air” in the balloon analogy above, the greater the risk of a voltage sag becomes.
The degree to which a battery sags depends on the quality of your battery, but also various other factors including how much power your EUC requires at any given moment during acceleration or climbing hills.
How does the watt-hour size of a battery affect voltage sag or EUC performance over time?
A larger battery contains more total electrical potential (which is divided into “cells”, each with their own voltage measures). This means that a larger watt-hour battery will experience voltage sag, or loss spread across it’s entire “a larger mass of cells”. This makes this higher capacity battery resilient to voltage sag, even during times of high peak demand from a EUC rider.
In other words, using the balloon above, a larger balloon will contain more air. In such a scenario, the loss of some air in a large balloon does not affect the overall pressure in the ballon as much as it would in a smaller balloon.
Of course, with a battery, it is a bit different, but the general principle applies. At some point, voltage in your EUC battery drops as electrical current demands increase from the motor-controller.
Choosing an EUC with a larger watt-hour battery pack will allow such an EUC to perform at peak output (e.g., generate higher torque, maintain higher speeds, carry a heavier rider) for longer periods of time, and more often during a ride, without voltage sag threatening a cut-off.
What Makes Voltage Sag Worse in an Electric Unicycle?
Voltage sag gets worse under certain conditions, which can lead to the risk for motor/EUC failure. Here are a few variables you may want to be aware of that could exacerbate voltage sag (or the loss of electrical potential) in an EUC battery:
- Battery age/wear
- Natural heat build-up
- Riding uphill or over higher resistance hills (such as when climbing)
- Riding off road, dirt roads
- Riding over 80% of maximum speed (rated by the manufacturer)
- Operating in extreme cold conditions vs. warm conditions
How Voltage Affects Efficiency in an EUC?
Voltage is electrical pressure that your battery can provide to your EUC’s motor. The higher the voltage rating the more electrical power that can be delivered to your motor with less amperage (or current).
A closer look:
You can think of voltage (V) in an EUC as it relates to watts ( w) and amperage (A). The formula is:
A = W/V
For example, if you have an EUC with a motor power of 1000W running at 50V, the current is 1000W / 50V = 20A. An EUC with the same 1000W motor running at 100V will have a current of only 10A. Lower amperage means better efficiency with caveats as noted below.
If you use this watt-volt-amp formula, you’ll see that as the voltage rating of your EUC goes up, your amperage value decreases. This means that higher voltage EUC’s will require less electrical current to produce the same amount of work (watts) from the motor.
Another way to state this: High voltage EUC’s can turn your EUC motor with less electrical current (amps), which means less heat, less problems with voltage sag (due to reduced current load/draw), and overall less resistance. In the latter, a high voltage EUC must have a design to handle higher voltage to ensure that amperage is maintained without a concomitant increase in resistance. We can deduce the latter from Ohm’s Law (V=IR).
That’s why you’ll always see high performance EUCs, electric bikes and e-scooters with higher voltage electrical systems. Higher voltage provides more efficiency in the form of faster acceleration, faster top speeds and better torque.
However, it’s important to reiterate the need to control heat generation in a high volt system. Too much voltage without proper lower resistance components can lead to excessive heat and thermal issues. For an EUC engineer, this may mean using larger, thicker wires, for example.
How Does a Higher Voltage Electric Unicycle Differ From a Lower Voltage EUC?
Voltage doesn’t determine an EUC’s range. Instead, the voltage of your battery determines how much electrical potential is available to generate work or watts to turn the motor. Higher voltage batteries (in high performance EUCs) will provide more power (or torque) at any given battery charge than a lower-voltage rated EUC.
In other words, your 126V Kingsong s20 will still provide you with more torque (hill climbing and acceleration) at 20% battery charge, than an 84V EUC with a similar battery size drained to the same amount.
Frequently Asked Questions (FAQ)
How do I choose the right voltage for my electric unicycle?
There is no one-size-fits-all answer to this question, as the voltage that is right for you will depend on your needs and preferences. Some things to consider when choosing the right voltage include:
- Type of terrain you’ll be riding on
- Weight of the rider
- Desired speed and range
- Amount of power you need
What is the difference between a high and low voltage electric unicycle?
High voltage electric unicycles have more power and are more efficient than low voltage electric unicycles. Low voltage electric unicycles are better for smaller riders or those who mainly ride on flat terrain. High voltage electric unicycles can handle more strenuous riding and are better for larger riders or those who want more speed and range.
What are the benefits of a high voltage electric unicycle?
Standard benefits (potential, depending on EUC model and engineering):
- Higher top speed and range
- Less heat generated to achieve desired speeds and ranges
- More efficient (less heat, less voltage sag)
- Feel like you’re riding a supercar
How does a higher voltage electric unicycle affect an EUC?
Voltage doesn’t determine an EUC’s range (necessarily). Instead, you could simplify the idea about how voltage affects your overall performance with speed. A higher voltage EUC can provide you with more overall top speed than a lower voltage EUC.
Let’s put it together:
High voltage EUCs are more efficient than lower-voltage rated EUCs. This is because higher voltages will require less current (amperage) in order to turn the motor. This has the beneficial side effect of also protecting you from voltage sag when your battery drains lower and lower as you ride. With a higher voltage rated EUC, you can continue to demand motor torque for a longer period of time.
Did you find this article helpful? I’d love to get your feedback (good or bad). Leave me a comment below!