The Schwinn Power Pac
The Schwinn Power Pac contains the latest battery technology going beyond lithium ion to lithium polymer (LiPo). The Schwinn Power Pac is one of the few systems available in a bike that use this technology.
Why is this better?
The Schwinn Power Pac 29.4-volt 10 Amp-Hour lithium polymer battery has about 5 times the power to weight ratio (specific energy) as lead acid, 4 times nickel cadmium, 2.5 times nickel metal hydride or 1.4 times the power to weight ratio of lithium ion.
This means more power for the same weight or the same power in a much lighter smaller space, or a combination of increased power and less weight.
When correctly controlled lithium polymer discharges at a more consistent voltage than other battery technologies so the power output is more predictable. Also, recharging is much faster. At less than 3 hours, a full recharge is accomplished in less than half the time of other battery types. Battery care is similar to a laptop computer, store the Schwinn Power Pac battery between 32 and 140 degrees Fahrenheit, and charge it up at least once every 2 months, or when there are 2 lights or less showing on the Schwinn Power Pac battery meter. Because the Schwinn Power Pac battery recharges so quickly, there is no need to leave the battery plugged into the charger for extended periods of time, this wastes energy and is not the best for the battery. All rechargeable batteries have a certain number of recharges before they are worn out. Lithium polymer batteries have 2 to 5 times the service life of other types of batteries so don’t worry, ride often!
Lithium polymer is not based on a liquid solvent like lithium ion and other technologies so it doesn’t need to be contained in a heavy metal shell. The gum-like substance that stores the electricity is also far safer than lithium ion since it is not a flammable liquid. It can also take on various shapes and be made very compact. You may even have a lithium polymer battery in your pocket right now if you have a relatively new cell phone.
The Schwinn lithium polymer Power Pac - lighter, smaller, safer, more reliable and worth the investment because it works!
The Schwinn Plug N’ Drive DC Brushless Hub Motor
The Schwinn Plug N’ Drive hub motor is light, small, powerful, durable, quiet and efficient.
The core of the system is the Schwinn Plug-n-Ride hub motor. The brushless design means there are no mechanical contact points (brushes) to cause drag, internal contaminating dust or wearable parts to be replaced. The brushless design uses “pulses” of electricity sent from the battery to create power. These pulses are triggered by the motor controller located just in front of the battery in the battery junction box. The junction box is the place the battery plugs into in the rack and where the “ignition” key is inserted. The controller is like the fuel injection system in a car metering out just the right amount of power efficiently at the right time based on rider input and road conditions (wind, terrain, speed etc.)
The motor is internally geared so it can be smaller and provide more torque than other motor designs. When there is no added power desired by the rider, or when bike speed exceeds the motor allowed speed, the hub simply spins silently with very little added drag.
The high efficiency output of the Schwinn Plug-n-Ride motor adds just the right amount of power at the right time for maximum range. Since 20% or more of the battery drain would happen when a rider starts from a dead stop, the automatic pedal assist feature kicks in the motor once the rider has reached 2-3 mph extending the overall range significantly. The rider may also choose to “boost” the pedal assist system by holding the thumb paddle down for about 10% more power when needed, of course this will reduce the range a bit. For safety, the motor will automatically cut out when either brake is applied.
The Schwinn Plug-n-Ride motor size and design was carefully chosen by Schwinn to supplement the bicyclist’s efforts extending the range and adventures, but keeping the bike a bike. Higher power electric bikes are available but are just too heavy to actually ride as a bicycle. One unexpected trip home experienced with a dead battery and the other older designs wind up getting left in the garage.
More on Electric bike terms and definitions
For many people an electric bike introduces us to a whole new world of terminology. Such terms as voltage, wattage, and amperage may sound like a foreign language. Keep reading if you want to learn more about the true details of what makes an electric bike an electric bike.
Voltage
The Schwinn Power Pac 29.4-volt 10 Amp-Hour lithium polymer battery has about 5 times the power to weight ratio (specific energy) as lead acid, 4 times nickel cadmium, 2.5 times nickel metal hydride or 1.4 times the power to weight ratio of lithium ion. This means more power for the same weight or the same power in a much lighter smaller space, or a combination of increased power and less weight.
Voltage
Voltage can be thought of as the pressure or strength of electric power. Imagine fuel flowing through a pipe with higher or lower pressure (voltage). The Schwinn Power Pac has a peak voltage of 29.4 volts.
And a cutoff voltage about 23 volts where the power management card inside the battery pack shuts down the system to protect it from over discharge. This greatly extends the battery life.
Amps or Ampere
Amperage or amps can be thought of as the volume or quantity of electric power, or how much fuel is flowing through the pipe. Amps are measured in current load. Climbing a hill will cause the motor to draw more current load or “amps” to maintain the same bike speed. The maximum amps the Schwinn Plug N’ Drive motor controller will allow the motor to draw through the system is 15 amps, with the average current draw about 6.5 amps. The amps used by the hub motor vary widely according to rider weight, terrain, road conditions, desired speed, wind and amount of effort the rider contributes so the total run time of the battery also varies widely from 30-40 minutes under primarily electric power to 90 minutes or more depending on the power contribution of the cyclist.
Amp-Hour
A unit of electrical current equal to 1 amp discharged continuously over 1 hour.
A 10 Amp-Hour (10Ah) battery can supply, for example, 5 amps for 2 hours or 6.5 amps for about 1.5 hours
Watt
A unit of work or power that is the product of voltage multiplied by amps.
28 volts X 6.43 amps = 180 watts
746 watts = 1 horsepower
A bicyclist setting a world speed record for 1 hour needs to maintain about 475 watts.
The occasional recreational cyclist can maintain about 1/10th of a horsepower or 75 watts for 1 hour with bursts of 200 watts for a few minutes, more or less depending on the riders conditioning.
The Schwinn Plug N’ Drive motor more than doubles the recreational cyclists input with 150 watts of continuous power and 250 watts of momentary power to help get the recreational cyclist through the tough parts of the ride.
Watt-Hour
A unit of electrical energy equal to one watt of power for one hour
The Watt-Hours of a 29.4 volt 10 amp hour battery is
29.4 X 10 = 294 Watt-Hours in a Schwinn Power Pac.
Peak Watts Vs Nominal Continuous Watts
Peak Watts
The Schwinn Plug N’ Drive motor is designed to draw a peak load of 290 watts. Peak watts are calculated by multiplying the nominal motor amp draw (10) by the peak voltage (29) however, the motor can only sustain the peak output for a few moments before the speed controlling circuitry backs down the voltage to ensure a longer motor service life. Under certain situations the wattage can go even higher, but this happens rarely and is seldom used to rate motors.
Nominal Continuous Watts
This is the output that the engineers designed as optimal for maximum efficiency and durability.
The high efficiency Schwinn Plug N’ Drive motor is rated at nominal continuous output of 150 Watts of mechanical work.
Watt’s the difference?
A watt is a unit of power or work. But electrical and mechanical watts are a bit different. When the cyclist wants to maintain a speed of 16.5 MPH on a flat paved road with no additional wind resistance, this requires about 125 watts of mechanical work. If the bikes electrical motor provides all the power to maintain this speed, the motor must produce a mechanical output of 125 watts. The Schwinn Plug-n-Ride hub motor system is designed to be very efficient at about 80% (some competitors are less than 50% efficient). The electrical watts supplied to the motor need to be about 150 watts to produce 125 mechanical watts at 80% efficiency. This would draw about 5.2 amps at 29 volts through the Schwinn Plug N’ Drive electrical system.
Watt Confusion?
A watt is a measurement of work or power. But not necessarily a reliable way to compare competitors motors. An electrical motor is usually rated by the nominal continuous mechanical work output. Some motors are rated using the higher electrical input, or even the peak electrical input, even if the system will not support it.
An inefficient 400 watt bicycle motor system may not accelerate as fast as an efficient 200 watt bicycle motor system. Power can be wasted in many ways such as mechanical drag and heat, neither get power to the ground. A good example of modern technology creating efficiencies is the light bulb, also measured in watts. A 13 watt compact fluorescent light bulb can create the same amount of light or lumens as a 55 watt standard light bulb. The standard light bulb wastes 42 watts, or over 75% of the energy it consumes, as unnecessary heat.
Likewise, if a bicycle motor system is noisy or if there are added belts, gears or chains to link the motor to the bicycles drive train, there is probably mechanical drag wasting energy.
Excess system weight can quickly add up to require more power just to move the bike down the road, this can be a big waste of energy, both electrical and yours!
And, if a motor gets hot to the touch it’s not operating efficiently and wasting electrical energy as heat.
Poor quality bearings and motor materials, sloppy manufacturing tolerances, internal buildups of brush dust and mechanical drag from brush-type systems all draw more amps, increasing the watt listing but not getting power to the ground.