Why your mouse, headset or controller battery percentage jumps

You glance at your mouse battery: 100 %. An hour later, 90 %. Then nothing moves for an afternoon, and suddenly it reads 60 %. A headset sits at 75 % for days, then drops to 25 %. Nothing is broken: most wireless devices simply do not report their battery to the percent.

Three ways a device reports its battery

• A real percentage: the device measures its charge and sends a number from 0 to 100. Recent Logitech mice and keyboards, Razer mice and keyboards, Corsair's Slipstream mice and many headsets work this way, and the level moves one point at a time.
• A few steps: the device only sends a level out of 4, 5, 9 or 10. The PS5 DualSense reports steps of 10 %, an Arctis 7+ or a first-generation Arctis Nova 7 five levels, the original Corsair Dark Core RGB five levels too. The display then jumps from one step to the next.
• A voltage: some devices send the voltage of their lithium-ion cell, and the percentage has to be estimated from a discharge curve. Earlier Logitech Lightspeed mice (G502 Lightspeed, G703, G903…) and the Razer Nari headset work this way.

Why a voltage gives an uneven percentage

A lithium-ion battery does not lose voltage at a steady rate. Its voltage falls quickly at the top of the charge, stays almost flat through the middle, then drops sharply near the end. Converting voltage to a percentage takes a curve, and that curve is an average: two mice of the same model, with batteries of different ages, will not follow it exactly.

That is why a voltage-based level can sit at 60 % for hours, then fall to 30 % in one evening. The battery was not suddenly drained: the flat part of the curve was hiding the drop.

Load plays a part too. Under heavy use (bright lighting, rumble, a high polling rate) the voltage sags for a moment and the estimated level dips, then recovers at rest. A level that goes back up a little after a session is usually this, not a recharge.

Why two programs can show different numbers

When a device only gives a voltage, every program uses its own curve. The manufacturer's software has one, open-source projects such as Solaar or the Linux drivers have theirs, and the results can differ by a few points for the same reading. Neither is wrong: both estimate a value the device never measured.

With steps, the difference is in how each program labels them. A device reporting level 3 out of 4 can be shown as 75 %, as the middle of that step, or simply as good. The information underneath is the same.

How to read the level without being caught out

• Set the alert higher on devices that report steps or a voltage. At 20 %, a device with steps of 25 % may already be close to empty; 30 or 35 % leaves a margin.
• Watch the trend over a few days rather than a single jump. A drop from 60 to 30 % in an evening is normal for a voltage-based device leaving the flat part of its curve.
• Charge before the last step. On a device with five levels, the last one before empty can be short.
• Expect the level to settle after charging. Right after unplugging, the voltage is slightly higher than a few minutes later, so a voltage-based level can show 100 % and then 95 %.

For the PS5 controller specifically, see why the DualSense shows the wrong percentage. How precise each brand's level is, model by model, is detailed on its page: Logitech, SteelSeries, Corsair or Razer.