A portable oxygen concentrator (POC) is a medical device that filters nitrogen from the surrounding air to provide a user with highly concentrated oxygen. Unlike bulky home units, POCs are designed for mobility, meaning their power consumption, measured in watts, is limited to conserve battery life. Understanding the relationship between the machine’s wattage draw and its oxygen delivery method is a primary concern for users planning daily activities or travel. The total power requirement of a POC varies significantly based on the technology it uses and the prescribed oxygen setting.
Understanding Power Draw: Pulse Dose vs. Continuous Flow
The instantaneous wattage a portable concentrator uses is largely determined by its delivery method: pulse dose or continuous flow. Pulse dose (PD) technology is energy-efficient because it detects the user’s inhalation and delivers a quick burst of oxygen, allowing the internal compressor to rest between breaths. These concentrators typically operate at a low wattage, drawing as little as 10 to 20 watts at their lowest setting.
As the prescribed setting increases, the pulse dose machine must deliver a larger oxygen bolus, requiring the compressor to run more often and with greater intensity. At higher flow settings, a pulse dose POC may draw up to 50 to 70 watts. Continuous flow (CF) portable units are less common and less efficient for battery use because they deliver a steady stream of oxygen regardless of the user’s breathing pattern. This constant operation demands a higher, more consistent power draw, often ranging from 70 to 120 watts.
The flow setting directly impacts the power consumption for both types. For example, increasing a pulse dose model from setting 1 to setting 6 can more than quadruple the power draw, demanding more work from the motor and electronics. POCs ensure their overall wattage remains low compared to stationary home units, which can draw 300 to 600 watts.
Translating Wattage to Battery Run Time
The wattage consumption translates directly into how long a user can remain mobile before needing to recharge. Battery capacity is measured in Watt-Hours (Wh), which represents the total energy stored. Dividing the battery’s Watt-Hour capacity by the machine’s Watt usage provides the approximate run time in hours. For instance, a battery rated at 50 Wh powering a machine drawing 25 W will last for two hours.
The flow setting is the most important factor affecting this calculation. A pulse dose unit at a low setting may last six and a half hours on a standard battery, but the same battery may only last one and a half hours when the setting is increased to its maximum. This reduction is due to the increased wattage draw required to deliver the higher prescribed oxygen volume. Users seeking extended mobility often utilize external or extended batteries, which effectively double the Watt-Hour capacity and the run time.
A practical challenge to run time is the power requirement when the concentrator is operating and charging simultaneously. When plugged into an AC or DC source, the machine prioritizes running the oxygen compressor while also directing power to recharge the battery. This combined load slightly increases the total power draw from the external source compared to simply running the machine without charging.
Managing Power Sources and Operational Costs
Portable oxygen concentrators are designed to run and charge using both Alternating Current (AC) from a standard wall outlet and Direct Current (DC) from a vehicle or airplane power port. When operating from a wall outlet, the machine’s power supply converts the AC house current to the DC power required by the internal components and battery. Using a DC power cord in a car works similarly, drawing 12-volt DC power from the vehicle and converting it to the machine’s specific voltage.
DC charging in a vehicle may be less efficient than AC charging because the power conversion process results in some energy loss. Furthermore, a vehicle’s charging port may not supply enough amperage to both run the concentrator at a high setting and charge the battery simultaneously. In such cases, the DC power may only maintain the current battery charge level. For long-term use at home, the operational cost of a POC is minimal, often adding only a dollar or two to a monthly utility bill, depending on local rates.
To calculate the cost, the machine’s wattage is converted to kilowatts (kW) by dividing by 1,000, and this figure is multiplied by the hours of use and the utility rate. Considering backup power, a POC requires a power source like a generator or uninterruptible power supply (UPS) that can handle the machine’s wattage plus a margin for the startup surge of the motor. This ensures uninterrupted oxygen therapy during a power outage.