Power consumption when voltage at Li+ reduces

Hardware
#1

Hello community,

I am trying to analyze power consumption of a particle based device. The battery is connected to Li+ pin of the Particle electron u270. As device operates, the voltage will reduce, as the battery discharges.
Now, I am trying to calculate power consumption of different device operation periods. Each of these period has a list of same tasks for the particle to execute. For each task, I experimentally obtained the current consumption by particle, at a fixed voltage. My doubt is that, when voltage reduces at Li+ pin. does the power consumed by particle changes, even if it is doing same tasks?

Thanks in advance.

#2

Generally speaking, the Power (Watts) should only change based on the efficiency of the Voltage Regulator at each given Input Voltage and current. This isn’t normally a large variation across normal operating conditions.

Now assuming the Power is constant, the Current (Amps) must increase as the battery voltage drops, since Watts = Amps * Volts.
That’s why a “X” mA result really doesn’t have much meaning without also recording the Voltage at the time of the measurement.

If you perform your tests at 4.2V and say 3.6V, the Power (Watts) should be very similar.
The difference is mainly the regulator efficiency.

Just calculate the mW for each data point and don’t put the emphasis on the mA.

2 Likes
#3

Thank you @Rftop for the reply.