mAh vs mWh: The Only Fair Way to Compare Rechargeable AA Batteries

If you’ve ever stared at two rechargeable AA batteries on Amazon — one labeled “2,800 mAh” and one labeled “3,600 mWh” — and wondered which is bigger, you’re not alone. The labels measure different things, and most product pages don’t explain the difference. This guide does.

Short answer: mAh measures charge, mWh measures energy. Devices consume energy. So mWh is the only fair way to compare batteries that operate at different voltages — which is exactly the situation with modern AA rechargeables (1.5V lithium vs 1.2V NiMH).

What Does mAh Actually Measure?

mAh stands for milliamp-hours — a unit of electric charge.

If a battery has a capacity of 2,800 mAh, it can deliver:

• 2,800 milliamps for 1 hour, or
• 1,400 milliamps for 2 hours, or
• 280 milliamps for 10 hours

In all three cases, the total charge moved through the circuit is the same: 2,800 mAh.

What mAh does not tell you is how much work that charge does. Work depends on voltage. A car that drives 50 miles on the highway and a car that drives 50 miles up a 10% grade have traveled the same distance but done very different amounts of work. mAh is the distance; mWh is the work.

What Does mWh Actually Measure?

mWh stands for milliwatt-hours — a unit of energy.

The formula is simple:

mWh = Voltage (V) × mAh

For a NiMH AA rated at 1.2V and 2,800 mAh:

2,800 mAh × 1.2V = 3,360 mWh

For a 1.5V lithium AA rated at 2,960 mAh:

2,960 mAh × 1.5V = 4,440 mWh

The lithium AA has only 6% more mAh, but 32% more mWh — because each unit of charge does more work at 1.5V than at 1.2V.

Why Devices Care About mWh, Not mAh

When you turn on a flashlight, the LED needs a certain amount of power (mW) to produce light. Power equals voltage times current:

Power (mW) = Voltage (V) × Current (mA)

Suppose the LED needs 300 mW. Here’s what each battery has to do:

• 1.5V lithium: 300 mW ÷ 1.5V = 200 mA of current required
• 1.2V NiMH: 300 mW ÷ 1.2V = 250 mA of current required

To produce the same brightness, the NiMH cell must push 25% more current. That means it depletes its mAh faster — by 25%. So even at the same mAh rating, the NiMH battery runs your device for less time than the lithium battery, because the device consumes energy (mWh), not charge (mAh).

This is exactly why mAh-to-mAh comparisons across chemistries are misleading, and why responsible battery brands publish mWh.

Real-World Examples: Same mAh, Different Energy

The chart below shows what happens when two rechargeable AA batteries have similar mAh but different voltages:

Alkaline isn’t in the table. Its delivered capacity depends heavily on the load, the temperature and the cut-off voltage, so there is no single mAh figure to put in it: Duracell, for example, publishes discharge curves for its Coppertop AA rather than one capacity.

Two observations stand out:

1. Pale Blue’s Voyager AA has fewer mAh than Eneloop Pro (about 2,200 vs about 2,600, about 15% fewer), but its higher voltage more than makes up the difference: it lists 3,300 mWh against about 3,120, about 6% more. Pale Blue gives only the mWh figure; the 2,200 mAh is 3,300 mWh ÷ 1.5V. mAh alone would suggest Eneloop wins; mWh shows the opposite.
2. SCIGOLD AA wins outright because it combines high mAh (2,960) with high voltage (1.5V). This is the only honest way to demonstrate the 4,440 mWh capacity advantage.

When mAh Is Fine to Use

mAh is a perfectly valid metric — when you’re comparing batteries of identical chemistry and voltage.

• Two NiMH AAs: compare by mAh ✓
• Two 1.5V lithium AAs: compare by mAh ✓
• One NiMH (1.2V) vs one lithium (1.5V) AA: use mWh ✓
• AA vs AAA: use mWh (different physical sizes can have different voltages)
• Phone batteries vs laptop batteries: use mWh (very different voltages)

Laptop makers such as Apple and Dell publish battery capacity in Wh (watt-hours, the bigger-unit version of mWh) for exactly this reason. The smartphone industry has been slower to adopt mWh, which is part of why phone-battery comparisons remain confusing.

How to Spot Misleading Battery Claims

A few patterns to watch for in rechargeable AA marketing:

Red flag 1: “2,800 mAh!” with no voltage stated. Without voltage, mAh is meaningless for cross-brand comparison. Always check the spec sheet for nominal voltage.

Red flag 2: Marketing “Lithium AA” without publishing mWh. Lithium AAs are 1.5V, so they get a free 25% energy boost over NiMH at the same mAh — but only if you advertise both numbers honestly. Brands that publish only mAh are often hiding mediocre energy density behind the voltage advantage.

Red flag 3: “Up to” specs without standard or sample size. “Up to 3,000 mAh” with no IEC 61960 reference and no batch size disclosure usually means the manufacturer cherry-picked their best cell. Look for third-party verification (SGS, TÜV, Intertek) and an explicit sample size: how many cells, from how many production batches.

Green flag: Third-party verified mWh with sample size and standard. Example: “SCIGOLD AA 4,440 mWh, verified by SGS Testing Services under IEC 61960-3, sample size 50 cells across 3 batches.” That’s the level of disclosure you should expect from a serious brand.

The Bottom Line

If you only remember one thing from this article:

Compare batteries by mWh, not mAh, whenever they operate at different voltages.

Modern rechargeable AAs come in two voltages — 1.2V NiMH and 1.5V lithium — so mWh is the only way to make a fair comparison. The SCIGOLD AA at 4,440 mWh verified by SGS is the highest capacity rechargeable AA we have found. The next time you see an AA marketed only by mAh, multiply by voltage and see what you actually get.