2025 Buying Guide: How to Choose the Best Power Bank

1) Why an external battery in 2025?

Between brighter screens, 5G, GPS, photo/video, and onboard AI, smartphone batteries are under greater strain. On the computer side, USB-C Power Delivery has standardized charging and now allows up to 240W on PD 3.1-compatible cables and chargers—enough to power most modern laptops and power-hungry accessories. :contentReference[oaicite:0]{index=0}

Another strong trend is the widespread adoption of USB-C in the EU . As of December 28, 2024 , the majority of devices sold in Europe must adopt USB-C (laptops by 2026 at the latest). The result: fewer different chargers and greater compatibility between brands. :contentReference[oaicite:1]{index=1}

2) Capacity: mAh vs Wh (and how many actual recharges)

The advertised capacity of a power bank is often in mAh at the nominal internal voltage of the cell (≈ 3.6/3.7 V). To compare with airplane rules or computer needs, it is better to convert to Wh : Wh = (mAh × V) / 1000 . Examples: 10,000 mAh ≈ 37 Wh; 20,000 mAh ≈ 74 Wh; 30,000 mAh ≈ 111 Wh (at 3.7 V). :contentReference[oaicite:2]{index=2}

Why isn't your phone receiving 100% of its capacity? This is due to conversion losses (electronics, voltage rise, heat, cable). In practice, the usable capacity delivered to the phone is around 60–70% of the advertised capacity. This is normal and observed by manufacturers. :contentReference[oaicite:3]{index=3}

3) Power & protocols: USB-C PD, PPS, QC, Qi/Qi2

USB-C Power Delivery (PD) & PD 3.1

The gold standard for modern wired charging is USB-C Power Delivery . PD 3.1 extends the maximum power to 240W (up to 48V × 5A) via EPR cables (see Cables section). This is what more and more laptops and “high-power” chargers are incorporating. :contentReference[oaicite:4]{index=4}

PPS (Programmable Power Supply)

PPS (PD 3.0/3.1 option) finely adjusts voltage and current in real time to optimize performance and heating (useful, among other things, on many Samsung “Super Fast Charging” smartphones). For a “universal” purchase, choose a PD + PPS power bank. :contentReference[oaicite:5]{index=5}

Quick Charge & other protocols

Quick Charge (Qualcomm) and proprietary protocols still exist. Many power banks support both PD and QC for broad compatibility, but PD/PPS remains the most sustainable and cross-brand bet. :contentReference[oaicite:6]{index=6}

Wireless charging: Qi & Qi2

For a magnetic power bank or wireless module, look for Qi (general) or Qi2 (faster and with MagSafe-like magnetism). In 2025, the 25W Qi2 was made official, significantly speeding up certified wireless charging. :contentReference[oaicite:7]{index=7}

4) Cables, 100–240 W & e-marker: don’t limit your load

A cable can limit the power. Above 3 A (≈60 W), a 5 A cable with an e-marker chip is required; for PD 3.1 (EPR) up to 240 W, cables must meet additional requirements and be explicitly marked 240 W. :contentReference[oaicite:8]{index=8}

• Up to 60W : “standard” 3A USB-C cable.
• 100–140 W : 5 A USB-C cable with e-marker (SPR 20 V/5 A or PD 3.1 28 V/5 A).
• 180–240 W : 240 W EPR cable (36/48 V), e-marker required. :contentReference[oaicite:9]{index=9}

5) Which profile for which use?

6) Flying with a power bank: the 2025 rules

• Cabin only (never in the hold) for batteries/power banks.
• ≤ 100 Wh : authorized in the cabin (reasonable quantities).
• 101–160 Wh : in cabin, but subject to airline approval (often limited to 2 units).
• > 160 Wh : generally prohibited as a passenger.
• Protect the terminals (case/bag, tape) against short circuit.

Always check your airline's policy before departure. Official references: IATA & FAA. :contentReference[oaicite:14]{index=14}

7) Safety, standards & guarantees (EU 2 years)

Standards & best practices

• UN 38.3 : Air transport tests for lithium batteries (mandatory). :contentReference[oaicite:15]{index=15}
• IEC 62133 : Safety requirements for portable Li-ion secondary batteries. :contentReference[oaicite:16]{index=16}
• Temperatures : Avoid heat and charging below 0°C; ideally, charge between 10–30°C and store at around 40–60% at ~20°C. :contentReference[oaicite:17]{index=17}
• Pass-through (charging a device while the power bank is charging): Use only if authorized by the manufacturer, as this may increase the temperature of the product. :contentReference[oaicite:18]{index=18}

Reminders & vigilance

In 2024–2025, several power bank models were subject to safety recalls (risk of overheating/fire). Check the official lists (CPSC/OPSS/ACCC) if you have an older model or are buying used. :contentReference[oaicite:19]{index=19}

Guarantees in Europe

In the EU (including France), you benefit from a 2-year legal guarantee of conformity from the seller for all consumer purchases — in addition to any commercial guarantees. :contentReference[oaicite:20]{index=20}

8) Express checklist before buying

1. Need : smartphone, tablet, PC, drone, photo? (determines the power).
2. Capacity : 10–20k for smartphone, 20–30k for tablet/light PC.
3. Power : 20–30 W (smartphone), 45–65 W (tablet/ultrabook), 100–140 W+ (laptop). :contentReference[oaicite:21]{index=21}
4. Protocols : USB-C PD with PPS if possible; Qi/Qi2 for wireless. :contentReference[oaicite:22]{index=22}
5. Suitable cable : 5 A e-marker / EPR 240 W if necessary. :contentReference[oaicite:23]{index=23}
6. Safety : UN38.3/IEC 62133, reputable brand, usage temperature.
7. Airplane : Wh <=100 (or 101–160 Wh with agreement). :contentReference[oaicite:24]{index=24}

9) FAQ

mAh or Wh: which one to look at?

For battery life, mAh is used for smartphones. For airplanes and PCs, Wh is more relevant (and required by regulations). :contentReference[oaicite:25]{index=25}

How many top-ups for my phone?

Estimate “usable capacity” ≈ 60–70% of the advertised value, then divide by your phone’s capacity. Example: 20,000 mAh × 0.65 ≈ 13,000 mAh → ~3 charges of a 4,500 mAh. :contentReference[oaicite:26]{index=26}

Is Qi2 essential?

No, but it's a real convenience for magnetic use and wireless speed (up to 25W certified in 2025). For maximum efficiency, wired PD remains ahead. :contentReference[oaicite:27]{index=27}

Pass-through: Can I charge the power bank and my phone at the same time?

Only if the manufacturer mentions it (otherwise, there is an increased risk of overheating). Even when it is indicated, avoid doing it for hours on end. :contentReference[oaicite:28]{index=28}

Temperature: Are there any limits?

Avoid charging below 0°C, prefer 10–30°C, and store around 40–60% charged in a cool, dry place. :contentReference[oaicite:29]{index=29}