Battery capacity is listed in Ah or Wh depending on the brand — this converts between them at your battery's voltage.
12V batteries are common in RVs and off-grid setups; many portable power stations and EV packs use higher voltages, so always check the nameplate.
Amp-hours tell you how long a battery can supply a given current, but that's meaningless without knowing the voltage — a 100Ah battery at 12V stores half the energy of a 100Ah battery at 24V. Watt-hours fix that by baking voltage into the number, which is why comparing batteries across brands is easiest in Wh, not Ah.
This conversion matters most when comparing batteries from different product categories — a car battery, a solar battery bank, and a laptop battery are all commonly rated in different combinations of Ah, Wh, and voltage, and Wh is the only unit that lets you compare stored energy across all three on equal footing.
Lead-acid and many lithium packs traditionally use Ah since it dates back to simple battery ratings, while portable power stations increasingly use Wh because it's directly comparable across different voltage systems.
Yes — convert both to Wh (1200Wh each in this example) and you'll see they store the same total energy despite very different Ah ratings.
Only at the same voltage — a 100Ah battery at 24V stores twice the energy of a 100Ah battery at 12V, which is why comparing Ah alone across different-voltage batteries can be misleading.