Just about all battery chargers, including the best car battery charger, do have one main thing in common: they function by loading electrical power into batteries for a certain time hoping that the cells within the battery will maintain some of the power transferred through it. That is approximately where the likeness of chargers starts and ends.
The most affordable, crudest technology in battery chargers make use of either a continuous voltage or continuous current which are then applied to the batteries when turned on. There are two scenarios that could happen when charging a battery – either you overcharge it or under charge it. Better chargers make use of a significantly lower, milder charge, possibly 3–5 % of the battery’s optimum rated current, for a significantly extended time period.
Learning how batteries work
Batteries really are a lot like a luggage: the more you pack in, the harder and longer it takes. That’s very easy to grasp if you bear in mind that charging a battery primarily requires slowing down the chemical responses occurring when it powers your laptop or desktop as school equipment.
Example: a laptop battery discharging and charging, it involves shunting back and forth the atoms missing electrons (lithium ions), from one electrode to the other. All ions have a positive charge and therefore it makes it easier to shove them to the otherwise empty electrode at the very start. Since they begin to increase there, it becomes more difficult to group more of them in where later phases of charging are more difficult than in the first stage.
Overcharging is usually more dangerous compared to undercharging. When batteries are completely charged and then it continues to pump in more power, the battery will need to remove that extra energy being fed by heating up and building pressure inside. This can result to rupture, chemicals or leaking, and possibly explode.
More advanced timer chargers switch off on their own following a set period of time. However, that does not always stop overcharging or undercharging as the best charging time differs for many different reasons. The very best chargers function intelligently, making use of microchip-based electric powered circuits to make a good sense of the amount of power had been stored in the battery. It figures out when the charging time is actually done and then switches off all current going into the battery.