Those upstairs are also mixed with flashlights. Say hello first∩_∩
7.4 is a dilithium discharge platform. The only way to achieve stability is to use a step-up and step-down circuit.
But it seems that your machine itself is made of dilithium. Simply connect two 18650 cells in series to the battery compartment. The operating voltage of the machine is floating. It does not need to be 7.4V. two batteries with a dilithium protection board. ~You can use the original charger for charging. If it cannot be charged, it will be tested, which is another matter...
If you use an external power supply. Interface, it is best to use a single lithium-ion battery. For the voltage circuit, connect multiple 18650s in parallel. The efficiency of a single 7.4 V lithium booster is estimated at around 80. The choice of booster card may requireer one without. output protection or delay protection. The camera's starting current is relatively large...
Each type of lithium battery has a maximum power, and heat will be obvious if it exceeds the maximum power. 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). a lot in China, but in reality you say there are 4,000, it's not a joke