Engineering report · reviewed against NEC 2026 & BS 7671:2018+A2
Engineering Breakdown: Running a ResMed AirSense 11 CPAP (With Heated Humidifier & Tube) on the EcoFlow Delta Pro 3
When pairing the EcoFlow Delta Pro 3 (4,096 Wh LiFePO4 capacity, 4,000 W continuous, 8,000 W surge) with a ResMed AirSense 11 CPAP (With Heated Humidifier & Tube) (65 W running, 90 W starting surge), the system operates at 2% of continuous inverter capacity on a 120 V North American circuit and 2% on a 230 V UK/EU/AU circuit. At a 100% duty cycle and 85% inverter efficiency, a full battery delivers roughly 53.6 hrs of off-grid runtime. Wiring the connection over a 25 ft run calls for a 15 A breaker and 14 AWG copper, terminated at a NEMA 5-15P connection.
1. Compatibility Verdict & Inverter Load Utilization
In North American mode the ResMed AirSense 11 CPAP (With Heated Humidifier & Tube) loads the EcoFlow Delta Pro 3's inverter to 2% of its 4,000 W continuous rating and 1% of its 8,000 W surge rating. Both figures are under the 80% sustained-load guideline, so this is a comfortable, verified match with 3,935 W of spare capacity for lights, a router or a refrigerator on the same unit.
| Check | Load requires | EcoFlow Delta Pro 3 provides | US/NA | UK/EU/AU |
|---|---|---|---|---|
| Continuous output | 65 W | 4,000 W | Pass | Pass |
| Start-up surge | 90 W | 8,000 W | Pass | Pass |
| Voltage | 120 V / 230 V | 120/240 V / 230 V | Pass | Pass |
| Connection | NEMA 5-15P | NEMA L14-30R / NEMA 6-20R / TT-30R | UK/EU/AU: BS 1363 13A / Schuko CEE 7/4 / AS/NZS 3112 10A | |
Critical loads value uptime over raw power. At 65 W, this equipment is small relative to the EcoFlow Delta Pro 3's 4,000 W inverter, so the deciding factors are runtime, pure-sine output quality and switchover time. Most modern power stations offer UPS or EPS pass-through with a 10–30 ms transfer, which is fast enough for CPAP machines, routers and servers with active-PFC power supplies. For medical devices, always confirm with the device manufacturer and keep a secondary backup plan; for CPAP specifically, a DC adapter can extend runtime by 20–30% by skipping inverter losses.
As a portable power station, the EcoFlow Delta Pro 3 integrates the LiFePO4 battery, inverter, MPPT solar controller and AC outlets in one chassis, so it can be wheeled to the load or connected to a transfer switch through its NEMA L14-30R / NEMA 6-20R / TT-30R outlet.
2. Real-World Runtime by Duty Cycle
Nameplate capacity is not usable capacity. DC-to-AC conversion, battery management overhead and cell protection reduce the 4,096 Wh rating to about 3,482 Wh of deliverable AC energy (85% system efficiency). Duty cycle is the share of each hour the load actually draws its running power — thermostats, pressure switches and intermittent use all lower it.
| Duty cycle | Average draw | Runtime (no solar) | Energy per 24 h |
|---|---|---|---|
| 25% | 16 W | 8.9 days | 0.4 kWh |
| 50% | 33 W | 4.5 days | 0.8 kWh |
| 65% | 42 W | 3.4 days | 1.0 kWh |
| 100% | 65 W | 53.6 hrs | 1.6 kWh |
At a 50% duty cycle the EcoFlow Delta Pro 3 covers a full day (4.5 days) without any recharge — ample for a typical overnight outage.
3. NEC 125% Breaker & Copper Wire Gauge Sizing
NEC 210.19(A) and 210.20(A) require conductors and overcurrent devices for continuous loads — anything running three hours or more, which includes EV charging and HVAC — to be rated at 125% of the load current. For this pairing: 65 W ÷ 120 V = 0.5 A, × 1.25 = 0.7 A, which rounds up to the next standard NEC 240.6 size of 15 A. The conductor must be protected by that breaker (75 °C ampacity at least 15 A) and keep round-trip voltage drop at or below 3%, so longer runs are upsized.
Voltage drop % = (2 × L × I × R) ÷ V × 100
North America (NEC, THHN copper, 75 °C)
| One-way distance | Breaker | Min. copper | Voltage drop | Note |
|---|---|---|---|---|
| 25 ft (7.6 m) | 15 A | 14 AWG | 0.07% | Sized by ampacity |
| 50 ft (15.2 m) | 15 A | 14 AWG | 0.14% | Sized by ampacity |
| 75 ft (22.9 m) | 15 A | 14 AWG | 0.21% | Sized by ampacity |
| 100 ft (30.5 m) | 15 A | 14 AWG | 0.28% | Sized by ampacity |
UK / EU / Australia (IEC 60364 / BS 7671, PVC copper, method C)
IEC-based codes size protection by design current rather than a blanket 125% multiplier: Ib ≤ In ≤ Iz. At 230 V the load draws 0.3 A, so a 6 A Type B/C MCB with RCD protection applies. In the UK, BS 7671 Section 722 additionally requires a dedicated circuit and Type A or Type B RCD for EV charge points.
| One-way distance | MCB | Min. cable | Voltage drop |
|---|---|---|---|
| 7.5 m (25 ft) | 6 A | 1.5 mm² | 0.02% |
| 15 m (49 ft) | 6 A | 1.5 mm² | 0.04% |
| 22.5 m (74 ft) | 6 A | 1.5 mm² | 0.07% |
| 30 m (98 ft) | 6 A | 1.5 mm² | 0.09% |
Because the current is modest, 14 AWG copper stays within the voltage-drop target all the way to 100 ft.
4. Solar Array Recharge Time Breakdown
The EcoFlow Delta Pro 3 accepts up to 2,600 W of photovoltaic input. Real arrays rarely deliver nameplate output, so we apply an 80% harvest factor for MPPT conversion, cell temperature and soiling, and convert hours to days using 4.5 peak-sun-hours — a conservative annual average for the US, southern Europe and Australia (UK winters can fall below 1.5).
| PV array | Real harvest | 0–100% recharge | Sun-days @ 4.5 PSH | Net with load @ 50% |
|---|---|---|---|---|
| 400 W | 320 W | 12.8 hrs | 2.8 | +288 W |
| 800 W | 640 W | 6.4 hrs | 1.4 | +608 W |
| 1,600 W | 1,280 W | 3.2 hrs | 0.7 | +1,248 W |
| 2,600 W | 2,080 W | 2.0 hrs | 0.4 | +2,048 W |
A typical 800 W portable array refills the battery in about 6.4 hrs of strong sun, while maxing out the 2,600 W input cuts that to 2.0 hrs. To fully offset the ResMed AirSense 11 CPAP (With Heated Humidifier & Tube) at a 50% duty cycle (33 W average) during daylight you need roughly 50 W of panels, which this unit can accept.
5. Frequently Asked Questions
Can the EcoFlow Delta Pro 3 run a ResMed AirSense 11 CPAP (With Heated Humidifier & Tube)?
Yes. The EcoFlow Delta Pro 3 delivers 4,000 W continuous and 8,000 W surge, covering the ResMed AirSense 11 CPAP (With Heated Humidifier & Tube)'s 65 W running and 90 W start-up draw at 2% inverter utilization.
How long will the EcoFlow Delta Pro 3 run a ResMed AirSense 11 CPAP (With Heated Humidifier & Tube)?
With 4,096 Wh of capacity and 85% inverter efficiency, expect about 53.6 hrs of continuous operation and 4.5 days at a 50% duty cycle. Adding solar input during the day extends this further.
What breaker and wire size do I need to connect a ResMed AirSense 11 CPAP (With Heated Humidifier & Tube) to the EcoFlow Delta Pro 3?
In the US, 65 W at 120 V is 0.5 A; applying the NEC 125% continuous-load rule gives 0.7 A, so use a 15 A breaker and 14 AWG copper for runs up to 25 ft (0.1% voltage drop). In 230 V markets the load draws 0.3 A, protected by a 6 A MCB on 1.5 mm² cable for runs up to 7.5 m. Receptacle: NEMA 5-15P (US) or BS 1363 13A / Schuko CEE 7/4 / AS/NZS 3112 10A (UK/EU/AU).
How long does it take to recharge the EcoFlow Delta Pro 3 with solar panels?
With an 800 W array and an 80% real-world harvest factor, a full recharge takes about 6.4 hrs of peak sun (1.4 days at 4.5 peak-sun-hours). At its maximum 2,600 W solar input it drops to 2.0 hrs.
Methodology & safety note
Specifications come from manufacturer datasheets in our open dataset; ampacity and resistance values follow NEC Table 310.16 and Chapter 9 Table 8, and BS 7671 Appendix 4. Calculations assume copper conductors, 30 °C ambient and no bundling derating. Inverter-to-panel connections require a listed transfer switch or interlock to prevent back-feeding the grid. These results are an engineering estimate, not a substitute for a licensed electrician and local permit. See our methodology and safety disclaimer.