Battery advice is passed around like folklore, and most of it was true of a different technology in a different decade. Here are the ones we hear most often, and what is actually going on.
1. Batteries need an eight-hour first charge
This dates from nickel-cadmium cells and old chargers. Modern lithium-ion and NiMH batteries arrive part-charged and stop accepting current when full. Leaving them plugged in for eight hours achieves nothing except a slightly warm battery.
2. Putting batteries in the freezer revives them
It does not. Cold slows the internal chemistry, so a chilled battery may briefly deliver a little more voltage, then less. Condensation when it warms up corrodes terminals, and moisture can damage the cell. Store batteries at room temperature instead.
3. You must fully drain a battery before recharging
That was reasonable for nickel-cadmium. It is actively harmful for lithium-ion, where deep discharge damages the cell. Modern batteries prefer shallow top-ups.
4. More mAh always means a better battery
Capacity is only useful if the device can use it. A higher-capacity cell of the same size usually trades away cycle life or current capability, and a device does not draw more power just because the battery is bigger.
Worse, buying a higher-capacity battery in the wrong voltage is a genuine safety risk, which is why the voltage matters more than the mAh on the label.
5. A dead battery means it is broken
A battery that reads 3.6V on a multimeter can still fail in a camera flash, because the device needs a burst of current and the cell's internal resistance has risen with age. Voltage alone tells you little about health under load.
6. Leaving a laptop plugged in destroys the battery
Modern devices stop charging at full and run from mains. The real damage comes from heat and from sitting at 100 percent in a hot room for months. Many laptops offer a charge limit for exactly this reason.
7. Brand-new batteries are always the best buy
Freshness matters more than the label for alkaline and coin cells, which lose charge on the shelf. Check the date code where there is one, and buy from shops with real turnover rather than a marketplace listing that has sat for years.
The short version
- Most battery folklore comes from nickel-cadmium era advice.
- Cold storage causes condensation and does not restore capacity.
- Shallow top-ups beat deep discharge for lithium-ion.
- Voltage and fit matter more than headline mAh.