Indoor medical backup power with LiFePO4 stations

How much battery do my medical devices actually need?

Most sizing calculators look only at running wattage. Accurate runtime needs duty cycle and conversion efficiency, so we split equipment into resistive heating loads, steady compressor loads and intermittent motor cycles.

Runtime (hours) = Battery Wh × 0.90 usable depth of discharge × conversion efficiency (0.85 for AC inverter output, 0.95 for DC ports) ÷ continuous load (W).

CPAP and BiPAP machines (ResMed AirSense 10/11, Philips DreamStation)

• The humidifier multiplier. At around 10 cmH₂O with the heated humidifier and tube off, a typical CPAP draws roughly 15–25 W (120–200 Wh per 8-hour night). With heat on, consumption commonly rises to 60–90 W (480–720 Wh per night). Planning estimate
• The DC-to-DC advantage. Through the AC plug, the station inverts DC to 120 V AC and the CPAP brick converts it back to DC. Using the CPAP maker's approved 12 V/24 V DC cord avoids that loss. Reserve models AC at 0.85 and DC at 0.95 efficiency, which is roughly a 12% runtime gain from the cord alone, more when it also lets the AC inverter switch off.

Oxygen concentrators: home vs portable

• Continuous-flow home units (e.g., Inogen At Home, Philips EverFlo) commonly draw 280–350 W. At 300 W on AC, a 2,048 Wh station runs about 5.22 hours. Calculated
• Pulse-dose portables such as the Inogen One G5 draw roughly 18–45 W depending on setting. At 25 W on DC, a 2,048 Wh station runs about 70.04 hours. Calculated

Motorized lift chairs and hospital beds

Actuators pull roughly 150–250 W while moving and essentially nothing at rest. Use is brief, so energy is small, but follow the maker's power requirements; pure sine output is the safe default for actuator controls.

How long will a 2 kWh or 4 kWh station run each device?

Which power stations are benchmarks for indoor medical backup?

Tier 1 favours lithium iron phosphate (LiFePO4). Compared with nickel-manganese-cobalt (NMC) cells in many older consumer units, LiFePO4 is more thermally stable and is commonly rated for thousands of cycles (makers often cite 3,000–4,000 cycles to 80% capacity). More stable is not the same as fire-proof.

BLUETTI AC200L

Base capacity ........ 2,048 Wh (expandable with B300-series packs)
Continuous output .... 2,400 W pure sine wave
UPS-style transfer ... ≤ 20 ms
DC ports ............. 48 V and 12 V outputs

EcoFlow DELTA Pro 3

Base capacity ........ 4,096 Wh (expandable with extra batteries)
Continuous output .... 4,000 W, 120 V / 240 V
UPS-style transfer ... ≤ 10 ms (switchover, not a true online UPS)
Noise ................ quiet at moderate load; fans run under heavy load

Pending verification These two models' figures have not yet been tied to an official document on this site. Verify them on the manufacturers' current pages before purchase.

Is UPS pass-through mode good enough for life-critical equipment?

Both benchmark units support pass-through charging, so equipment stays plugged in when the grid drops:

1. Plug the power station into a wall outlet.
2. Plug the CPAP, concentrator or router into the station.
3. On grid power, the station passes power through and keeps its battery charged.
4. When the grid drops, an internal relay switches the load to battery, typically within 10–20 ms per maker claims.

How do I recharge a battery during a week-long outage?

A battery is a finite tank. For 5–7 day outages, stored energy must be replenished without bringing combustion indoors.

Portable folding solar arrays (200–400 W)

Set up on a south-facing deck, balcony or yard. A 400 W array might deliver roughly 1.2–1.6 kWh on a clear day, depending on season, angle and shading. Planning estimate Silent and fuel-free.

Vehicle 12 V/24 V auxiliary input

When cloud rules out solar, a 12 V car charging cable can feed the station's DC input at roughly 100–200 W. The vehicle must be outdoors in the open, never in an attached garage, even with the door up. About 3 hours of charging might restore roughly 450 Wh. Planning estimate

The hybrid gas-battery routine

Rather than running a generator all day, run a compact inverter generator outdoors, at least 20 ft from doors, windows and vents with exhaust pointed away, for a short daily window and charge the station at its maximum rated AC input, then shut the generator off. Use CO alarms indoors. CDC — Carbon monoxide poisoning prevention

Which accessories should I buy with a Tier 1 system?

• Device maker's 12 V/24 V DC CPAP adapter, specific to your model (e.g., ResMed's DC converter for AirSense 11).
• Solar extension cables (MC4 / XT60, 10 AWG) to limit voltage drop. Route through a window without pinching the cable or blocking egress.
• Plug-in watt meter to measure real running and idle draw before an outage.
• Battery-backed CO alarms if any combustion recharge method is part of your plan.