Why does battery powered electronics (such as a remote or an electrical toothbrush) lose power as the battery is weakened and not work at full power till the battery is dead?
In: Technology
Batteries work by chemical reactions in a liquid; as concentrations of the chemicals drop, there are fewer opportunities for the different chemicals to “find” each other and react, so you get fewer reactions, releasing fewer electrons, and thus get less voltage.
Coin cell batteries used to have liquid mercury as one of the chemicals, and they worked at basically 100% until they ran out and then voltage dropped to zero pretty much all at once. That’s because unlike a chemical floating in a liquid, the liquid was 100% active chemical the Hg itself).
Most devices have something that is running 24/7, drawing microamps of power. Then there is also the chemical breakdown of the battery chemistry, it only has a shelf life of a few years.
A battery’s voltage decreases as it is drained of energy.
Think of voltage (electrical potential) as water pressure. You hang up a bucket of water and open a hole on the bottom to shower. The water pressure at the start is strong from the weight of water pressing down. However, as the water drains, the pressure weakens and it gets more difficult to wash yourself.
This is the same thing that happens with the motors and lights powered by batteries. As the battery drains, these parts lose power gradually until they stop working.
One way to prevent this is to put in regulators that fix the pressure/voltage at some level rather than have it decrease over time. Newer electric toothbrushes have this. They will run at full power and only start weakening when they are low on battery.
If the question wasn’t too understandable (English is not my native language), what I was trying to ask is why i.e. when your remote’s batteries are almost dead the signal weakens instead of working full power until there is no power left in the battery?
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