Okay kiddo, let me explain what memory effect is in a very simple way.
Picture this: you have a toy car that runs on batteries. Every time you play with it, you use it for a little bit and then put it away. But eventually, the batteries start to lose their energy and the car runs slower or stops completely.
Now, if you always use the toy car until the batteries are totally dead before recharging them, you might notice that they don't last as long as they used to. This is because of something called memory effect.
Memory effect happens when rechargeable batteries, like the ones in the toy car, don't get fully charged and discharged regularly. That means if you only use half the battery's energy before recharging it, the battery might "remember" that and start to act like it only has half the power after that.
It's kind of like if you always wear the same shoes to school and only ever walk on one side of the hallway. Eventually, the soles of your shoes might start to wear down unevenly because you're always using them in the same way.
So, to keep your toy car (and your rechargeable batteries) working their best, it's a good idea to use them all the way until they're empty and then recharge them all the way until they're full. This helps prevent memory effect and keeps the batteries working their best for longer!