Each type of lithium battery has a maximum power, if the maximum power is exceeded, heat will be obvious. Also, I have never heard of 4000MAH 18650 batteries. They are all around 2000 in China, and the best ones are closer to 3000MAH. Those above 3000 are all imported (I understand the biggest one is only around 3200MAH). there are a lot of them in China, but actually they say there are 4000. Isn't that funny?
Yes, here's how to replace the built-in battery. The battery must have positive and negative polarity and cannot. be connected backwards. The built-in batteries have eye-catching colors. Usually the positive electrode is red and the negative electrode is black. The newly purchased battery can be installed in the battery compartment. Try to choose one with a larger capacity. the batteries with the same color wires and replace the old battery.
TheProtection board is a small and thin printed circuit board. It is usually packaged with the positive polarity of the battery, brings out the positive and negative electrodes, and is wrapped in heat shrink tubing for added protection.