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# 18650 battery

Posts: 4
how can i control the discharge cureent of my 18650 battery

• Posts: 8,612
With a resistor or a current control circuit. Posting some more info about what you want to do with the battery and what it powers would help in providing a better answer.
• Posts: 22,754
The current out of a power source is solely dependent on the output voltage and the load. For simple resistive loads, Ohm's law applies:

I = E / R

If you need a constant current, regardless of the battery's output voltage, consider using a voltage regulator like the LM317 in a current-regulation configuration. (Look up any datasheet for this device for an example circuit.)

-Phil
• Posts: 4
edited 2019-10-14 - 05:45:43
so does it mean that if i put a voltage regulator with 1.5A max at the output of mt3608 module, the module will therefore suck 1.5A out of my battery ?
im trying to make diy power bank
• Posts: 8,612
seansean wrote: »
so does it mean that if i put a voltage regulator with 1.5A max at the output of mt3608 module, the module will therefore suck 1.5A out of my battery ?
im trying to make diy power bank

No. The mt3608 is a boost regulator and will boost the output voltage from the 18650 to whatever voltage it is set to output. The efficiency of the mt3608 and the circuit that is connected to the output of the mt3608 will determine the current draw.

Typical efficiency is 88 - 91%, so if you were to double the voltage (3.2V > 6.4V) and attach a circuit that draws 500mA the mt3608 would draw approximately 500 * 2/.9 = 1.1A from the battery assuming the efficiency was 90%.
• Posts: 22,754
seansean wrote:
so does it mean that if i put a voltage regulator with 1.5A max at the output of mt3608 module, the module will therefore suck 1.5A out of my battery ?
No. That's a fundamental misunderstanding about what a power source does. A power source provides voltage. Current is provided only on an as-needed basis. A load is required to draw current from the power source. Absent a load (i.e. a complete circuit), there is no current draw.

-Phil