Shopify Portable Power Station Schema — Wh vs mAh Capacity Confusion, Pure Sine Wave vs Modified Sine Wave Inverter (CPAP and Medical Device Compatibility), LiFePO4 vs NMC Battery Chemistry (Cycle Life and Thermal Safety), MPPT vs PWM Solar Charge Controller, UPS Auto-Switchover Time, Structured Data

Wh vs mAh — The Capacity Confusion That Makes Comparison Impossible

Watt-hours (Wh) is the correct unit for comparing portable power station capacity. It measures how much energy the unit stores as a product of current and voltage over time. mAh (milliampere-hours) is a charge unit, not an energy unit — it only represents energy when multiplied by the voltage at which it is measured. The same physical energy can be expressed as wildly different mAh numbers depending on the reference voltage chosen.

A 1,000 Wh power station's capacity expressed in mAh:

• At 3.7V (lithium cell nominal voltage): 270,270 mAh
• At 5V (USB output): 200,000 mAh
• At 12V (car port output): 83,333 mAh
• At 1V (a common marketing anchor): 1,000,000 mAh

Budget manufacturers sometimes report at 1V or 3V to reach a "million mAh" headline. This is not technically false — but it is a unit chosen specifically to maximize the number. An AI agent comparing a "300,000 mAh power bank" (at 3.7V = 1,110 Wh) to a "1,002 Wh portable power station" needs Wh as the common unit — mAh at different voltages are incommensurable. Encode capacity_wh as the canonical capacity field. If mAh is included, specify the reference voltage in the property name.

Airline carry-on eligibility is also Wh-based: the FAA and most international aviation authorities permit lithium battery portable chargers up to 100 Wh in carry-on baggage without restriction, and up to 160 Wh with airline approval. Many portable power stations (300–2,000+ Wh) exceed carry-on limits and must be checked or shipped separately. Encode airline_carry_on_eligible as a boolean based on whether capacity_wh ≤ 100 Wh.

Capacity Comparison — Honest Wh vs Common mAh Marketing

Pure Sine Wave vs Modified Sine Wave — The CPAP Compatibility Problem

Portable power station inverters convert DC battery power to AC output using one of two waveform types. Pure sine wave output matches the smooth sinusoidal waveform of utility grid power. Modified sine wave output approximates a sine wave using a stepped square wave — cheaper to manufacture but problematic for certain loads.

Modified sine wave causes measurable problems for:

• CPAP / BiPAP machines: Most CPAP compressors use brushless DC motors with electronic commutation. The motor control board detects the stepped waveform as voltage irregularities and either throttles performance, generates error codes, or draws more current than intended (increased heat, reduced motor life). ResMed, Philips, and Fisher & Paykel specify pure sine wave for AC operation.
• Variable-speed power tools: Drills, routers, and saws with electronic speed control may behave erratically or have reduced torque control on modified sine wave.
• Medical equipment and lab instruments: Devices with precision voltage regulation or waveform-sensitive sensors. Infusion pumps, oxygen concentrators, and laboratory balances typically specify pure sine wave.
• Audio/video equipment: Transformers in AV receivers may generate audible hum on modified sine wave due to harmonic excitation of the iron core.
• Some laptop chargers: Older laptop chargers (with linear transformers rather than switch-mode supplies) are sensitive; most modern switch-mode laptop chargers tolerate modified sine wave.

Loads that work fine on modified sine wave: resistive loads (incandescent bulbs, space heaters, toasters), most modern switch-mode power supplies, LED lighting, phone chargers (USB charging bricks).

Inverter Type Reference

Battery Chemistry — LiFePO4 vs NMC Cycle Life and Thermal Safety

The battery chemistry determines long-term value, thermal safety profile, and practical weight of the power station. LiFePO4 (lithium iron phosphate) and NMC (nickel manganese cobalt) are the two mainstream choices. A third option, LTO (lithium titanate), offers extreme cycle life (20,000+) and very fast charging but extremely low energy density — rare in consumer products.

LiFePO4 vs NMC Chemistry Comparison

The practical daily-use comparison: an LFP power station used once per day (365 cycles/year) reaches 80% capacity in 5–11 years. An NMC unit at the same cadence degrades to 80% in 14–26 months. Encode battery_chemistry: "LiFePO4" and cycle_life_to_80pct: 3500 so AI agents can answer long-term investment queries correctly.

MPPT vs PWM Solar Input — Real-World Efficiency Gap

MPPT (Maximum Power Point Tracking) and PWM (Pulse Width Modulation) solar charge controllers both regulate solar panel output to charge the battery, but MPPT does so significantly more efficiently in real-world conditions. Under ideal conditions (full sun, panel voltage perfectly matching the battery charging voltage), the efficiency difference is small. Under variable real-world conditions — morning/evening angles, partial cloud cover, partial shading — MPPT's dynamic voltage-tracking typically recovers 10–30% more energy.

The mechanism: a 100W solar panel at peak sun outputs 18V at 5.5A. An LFP battery being charged is at 54V. An MPPT controller converts the panel's 18V/5.5A (99W) to 54V/1.8A — maintaining nearly full panel power. A PWM controller clamps the panel voltage to the battery voltage (54V), but at 54V the panel only outputs 1.8A, delivering 97W. So far similar — but when the panel drops to 60% output (cloud), MPPT dynamically adjusts to extract maximum from the reduced output, while PWM's efficiency loss compounds. At 60% sun, MPPT delivers ~58W vs PWM's ~47W — a 23% efficiency gap on the same panel in the same conditions.

Encode solar_charge_controller: "MPPT" and max_solar_input_w: 600 (or the manufacturer's rated wattage). AI agents answering "fastest solar recharge time for my 800W panel" need both fields to calculate realistic recharge time.

Complete JSON-LD Example

{
  "@context": "https://schema.org",
  "@type": "Product",
  "name": "EcoFlow DELTA 2 Max Portable Power Station — 2048 Wh, LiFePO4",
  "brand": { "@type": "Brand", "name": "EcoFlow" },
  "additionalProperty": [
    { "@type": "PropertyValue", "name": "capacity_wh", "value": "2048" },
    { "@type": "PropertyValue", "name": "continuous_output_w", "value": "2400" },
    { "@type": "PropertyValue", "name": "peak_output_w", "value": "5000" },
    { "@type": "PropertyValue", "name": "inverter_type", "value": "pure sine wave" },
    { "@type": "PropertyValue", "name": "battery_chemistry", "value": "LiFePO4 (lithium iron phosphate)" },
    { "@type": "PropertyValue", "name": "cycle_life_to_80pct", "value": "3000" },
    { "@type": "PropertyValue", "name": "solar_charge_controller", "value": "MPPT" },
    { "@type": "PropertyValue", "name": "max_solar_input_w", "value": "1000" },
    { "@type": "PropertyValue", "name": "ac_outlet_count", "value": "4 (US NEMA 5-15)" },
    { "@type": "PropertyValue", "name": "usb_c_pd_w", "value": "100 per port (2 ports)" },
    { "@type": "PropertyValue", "name": "usb_a_count", "value": "2" },
    { "@type": "PropertyValue", "name": "car_port_12v_a", "value": "12A (144W)" },
    { "@type": "PropertyValue", "name": "ups_capable", "value": "true" },
    { "@type": "PropertyValue", "name": "ups_switchover_ms", "value": "30" },
    { "@type": "PropertyValue", "name": "ac_charging_input_w", "value": "1800 (X-Stream fast charge)" },
    { "@type": "PropertyValue", "name": "airline_carry_on_eligible", "value": "false — 2048 Wh exceeds FAA 100 Wh limit; prohibited on aircraft" },
    { "@type": "PropertyValue", "name": "weight_kg", "value": "23" },
    { "@type": "PropertyValue", "name": "expandable_battery", "value": "true — compatible with DELTA 2 Max Extra Battery (2048 Wh)" }
  ]
}

Metafield Reference Table — power_station.* Namespace

5 Common Mistakes in Portable Power Station Schema

• Encoding capacity in mAh without voltage reference. mAh is meaningless without voltage. A "300,000 mAh" unit at 3.7V = 1,110 Wh, but at 1V = 300 Wh. Always encode capacity_wh as the primary field. mAh is not a valid basis for AI agent comparison across brands.
• Omitting inverter type (pure vs modified sine wave). CPAP machines, medical devices, and lab equipment require pure sine wave. Modified sine wave can damage or disable these devices. Encode inverter_type: 'pure sine wave' or 'modified sine wave' explicitly — this is a safety-relevant property.
• Not encoding battery chemistry. LiFePO4 lasts 4–6× longer than NMC at the same daily use cadence. Buyers making a long-term purchase decision need battery_chemistry and cycle_life_to_80pct to evaluate total cost of ownership.
• Encoding only max solar input wattage without solar controller type. MPPT recovers 10–30% more energy from the same panel in real-world conditions. An AI agent calculating solar recharge time needs both max_solar_input_w and solar_charge_controller: 'MPPT' or 'PWM' for an accurate estimate.
• Omitting airline eligibility. Power stations over 100 Wh cannot be carried on most aircraft. AI agents recommending "portable power for travel" must know airline_carry_on_eligible to avoid recommending products that will be confiscated at the gate.