Wh to Ah Power-Bank Comparator

The first portable USB power bank for mobile phones was introduced in 2001 by Sansui as a small case holding two AA alkaline cells with a 5 V boost converter and a USB-A output. Capacity was about 5 Wh; phone batteries of the era were 3-4 Wh, so a single recharge consumed most of the bank. The 2007 launch of the iPhone created mass demand for portable charging because the original iPhone had no removable battery - a deliberate Apple decision that effectively created the modern power-bank market overnight.

Anker founded in 2011 became the defining brand of the early power-bank era, shipping the original Astro line: 5200, 7800, and 10,000 mAh banks using 18650 cells at 3.7 V (19, 29, and 37 Wh respectively). The 10,000 mAh form factor became the industry standard because it fits in a jacket pocket and delivers roughly two iPhone charges. Pricing fell from 80 USD in 2011 to 25 USD by 2018 as 18650 cell prices collapsed during the EV battery scale-up.

The FAA 100 Wh / 160 Wh rule was codified in 2008 in response to lithium-ion fire incidents on aircraft, including a 2007 cargo fire of a UPS shipment of laptop batteries. The rule was based on IATA Dangerous Goods Regulation 49 CFR 175.10: below 100 Wh is "contained" and self-extinguishing; 100-160 Wh requires airline approval; above 160 Wh is treated as Class 9 hazardous material and forbidden on passenger aircraft. The exact 100 / 160 cutoff was an engineering compromise; subsequent UL 9540A testing has largely validated it for modern Li-ion cells, with newer LFP chemistry being safer at the same Wh.

The 27,000 mAh / 99 Wh power bank emerged as the market sweet spot around 2018. At 3.7 V x 27,000 mAh = 99.9 Wh, this bank sits exactly below the 100 Wh limit and delivers maximum legal travel capacity. Anker PowerCore+ 26800 (99.16 Wh), RAVPower 27000 (99.9 Wh), Mophie Powerstation Pro (99 Wh), and ZMI 20 (99 Wh) all converge on the same architecture. The market has essentially saturated this constraint and competes on PD output speed, USB-C count, weight, and brand.

USB Power Delivery (PD) launched in 2012 and reached 100 W max in PD 3.0 (2015), transforming power banks from phone-charging devices into laptop chargers. The 100 W PD bank typically uses six 18650 cells in 6s1p or 3s2p arrangement to deliver 20 V at 5 A. By 2024, PD 3.1 extended max output to 240 W (48 V at 5 A) - enough for a 16-inch MacBook Pro at full throttle. The Anker 737 (24,000 mAh, 99 Wh, 140 W PD output) is the canonical laptop-class bank as of 2026.

LFP power banks emerged in 2023 as the safety-first response to the Boeing 787 grounding and the various airline lithium-fire incidents of 2018-2022. LFP cells (3.2 V) tolerate puncture, overcharge, and short-circuit much better than NMC - they thermal-runaway at 270 C versus NMC's 200 C, and they do not propagate cell-to-cell as readily. The Anker 100W LiFePO4 and EcoFlow River Mini are mainstream LFP banks; they weigh 15-25 percent more per Wh but accept 3000+ cycles vs NMC's 800-1000.

Solar power banks remain a small niche - the 1-3 percent recharge rate from a 6 W folded solar panel means a 30,000 mAh bank takes 30+ hours of full sun to recharge. They are useful for multi-day backcountry hiking where there is no outlet to plug into, but as an everyday product they are dominated by wall-charged banks. The 2024 BLAVOR Solar 30,000 mAh and Anker 21W solar panels represent the current state of the art; 50 W foldable panels (Goal Zero Boulder) are heavy but recharge a 100 Wh bank in 2-3 hours of midday sun.