Electronics Interview Question:

Why does charging batteries take lengthy periods? What can be done to quicken the speed?

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Batteries work through a chemical process, some kind of ion exchange where the battery contains two elements that want to combine ions and give up an electron to cause current flow. They do this energy release all by themselves with no energy added, it wants this exchange to happen it is more stable after the reaction. Therefore, to charge the battery you are forcing things to go backwards, which the reaction does not like. By adding a current, you are making the reaction reverse. This is not an efficient process, and usually takes more energy than is given back, like more than twice as much takes (depends on the battery type). Where does the extra energy go? It is into heat mostly.

Therefore, the problem with fast charging is you cannot put so much energy back that you get the battery too hot and melt it down. You can charge a battery at a much higher rate than you discharge it, so you can make the charge cycle take less time than the discharge (this depends on the discharge rate as well, of course). However, you are limited by the heat, so a 1-minute charge of your electric car just is not possible.
Submitted by: Administrator