Home Oxygen Concentrator Backup Power Planner

Medical & safety notice: This planner is for preparedness math only—not medical advice. Follow your clinician/DME provider’s instructions and your concentrator manufacturer’s manual. Keep a non-electric backup (portable oxygen cylinders) sized to your prescription. If the patient has breathing distress, confusion, chest pain, bluish lips/face, or low SpO₂ per your care plan, call emergency services.

What this backup power planner does

Home oxygen concentrators make oxygen by compressing room air and passing it through sieve beds. That compression step uses electricity, so a power outage can interrupt therapy unless you have backups. This calculator helps you estimate:

• Battery runtime based on usable battery energy (Wh) and inverter efficiency.
• Generator runtime based on fuel on hand and an estimated fuel burn rate.
• Portable cylinder coverage based on how many cylinders you have and how long each lasts at the prescribed flow setting.
• A combined plan for an outage duration goal (run batteries first, then generator, and keep cylinders as a non-electric reserve).

Inputs (what to enter)

• Concentrator power draw (watts): use the nameplate/label or manual value. Many units fall roughly in the 200–600 W range, but your device may differ.
• Compressor duty cycle (% runtime): the fraction of time the compressor actually runs. Some concentrators cycle on/off; others run nearly continuously. If unsure, start conservative (higher duty cycle).
• Battery bank usable capacity (Wh): energy you can safely use (after depth-of-discharge limits). If you only know Amp-hours, convert with: Wh ≈ V × Ah.
• Inverter efficiency (%): AC inverters waste some energy as heat. Typical real-world values are often ~85–95% depending on load.
• Generator continuous output (watts): the continuous (running) rating, not peak/surge.
• Fuel on hand (gallons) and Generator consumption (gal/hour at 50% load): use your generator manual if possible.
• Portable oxygen cylinders available and Minutes per cylinder at prescribed flow: use supplier tables for your cylinder size and your flow rate/device type.
• Plan for outage duration (hours): your target scenario (e.g., 24/48/72+ hours).

Core formulas (transparent math)

Let:

• P = concentrator rated watts
• d = duty cycle (%)
• E_b = usable battery capacity (Wh)
• η = inverter efficiency (%)
• F = fuel on hand (gal)
• f₅₀ = generator fuel burn (gal/hr) at 50% load
• N = cylinder count
• m = minutes per cylinder
• T = planned outage duration (hr)

Average electrical load from duty cycle

Battery runtime (hours) (includes inverter loss)

t_b = (E_b × (η/100)) / P_avg

Generator runtime (hours)

t_g = F / f₅₀

Note: this uses your provided “gal/hr at 50% load” as a simple estimate. Real fuel burn changes with load, temperature, engine condition, and fuel type.

Cylinder coverage (hours)

t_c = (N × m) / 60

Plan check against your target outage

• Battery gap: max(0, T − t_b)
• Generator gap: max(0, T − t_g)
• Cylinder gap: max(0, T − t_c)

Some versions of this planner also show a simple “combined coverage” sequence (batteries → generator → cylinders) as an upper-bound planning number. In practice, many households reserve cylinders for transport/evacuation and use generator/batteries for primary coverage.

How to interpret the results

• If battery runtime is short: you may need more usable Wh, a higher-efficiency inverter, or to reduce other loads on the same battery system.
• If generator runtime is short: you need more fuel, a lower burn rate (often by reducing load), or a resupply plan.
• If cylinders are short: you need additional cylinders, larger cylinders, or confirmed access to refills during the outage window.
• If generator watts are below your expected load: treat it as a red flag; overload can trip breakers, stall the generator, or damage equipment.

Worked example (end-to-end)

Scenario: A patient uses a concentrator labeled 350 W. The compressor cycles, so you estimate a 60% duty cycle. You have a 3000 Wh usable battery bank with a 92% efficient inverter. You also have a 2000 W continuous generator with 10 gallons of fuel. The generator manual (or your best estimate) suggests 0.4 gal/hr at 50% load. You keep 4 portable cylinders that last about 120 minutes each at the prescribed flow. You want to plan for 72 hours.

1. Average concentrator watts: P_avg = 350 × 0.60 = 210 W
2. Battery runtime: t_b = (3000 × 0.92) / 210 ≈ 13.14 hours
3. Generator runtime: t_g = 10 / 0.4 = 25 hours (rough estimate)
4. Cylinder coverage: t_c = (4 × 120) / 60 = 8 hours
5. Compare to 72 hours:
   • Batteries alone: short by ~58.9 hours
   • Generator alone: short by 47 hours
   • Cylinders alone: short by 64 hours

Interpretation: In this scenario, a 72-hour outage is not covered by any single backup. You’d need a fuel resupply plan (or additional fuel storage within safety/legal limits), more battery energy, additional cylinders, or an evacuation plan. Also consider that if you run other household loads (refrigerator, furnace fan, lights), the generator fuel burn will likely be higher than the 50% load estimate.

Comparison table (at-a-glance)

Assumptions & limitations (read before relying on outputs)

• Device variability: concentrator wattage and behavior vary by model, flow setting, altitude, and filter condition. Some devices have higher startup/surge power than their steady draw.
• Duty cycle is an estimate: if you underestimate duty cycle, you will overestimate runtime. When in doubt, choose a higher duty cycle.
• Battery “usable Wh” matters: nameplate battery capacity is not always safely usable due to depth-of-discharge limits, aging, cold temperatures, and BMS cutoffs.
• Inverter efficiency is load-dependent: efficiency can drop at very low or very high loads.
• Generator fuel burn is load-dependent: “gal/hr at 50% load” is a rough anchor. Actual burn may be higher if you power additional appliances or if conditions are harsh (heat, altitude, maintenance state).
• Generator output derating: continuous watt ratings may reduce with altitude/temperature; some generators cannot sustain their advertised output.
• Cylinder duration depends on prescription and equipment: continuous-flow vs pulse-dose devices can change cylinder life significantly; use your supplier’s tables for your setup.
• No guarantee of safety/adequacy: use results to identify gaps, then confirm your plan with your DME provider/emergency plan. Maintain smoke/CO detectors and follow safe generator practices (never run indoors).

Practical planning tips

• Register for your utility’s medical baseline/priority restoration program if available.
• Keep written instructions for switching between concentrator, battery/inverter, generator, and cylinders.
• Plan for refills/resupply: identify pharmacies/DME suppliers and routes that may remain open during outages.
• Consider redundancy: two smaller batteries vs one, extra extension cords rated for load, spare filters, and maintenance supplies.