Would someone know how long of battery life I’d have with one AAA battery powering an Arduino Pro Mini (5 volt) via the NCP1400-5V Step-Up Breakout.
All the Arduino will be doing is monitoring 1 sensor, and send a TX signal. The sensor, an EZ1 rangefinder, only uses 2 ma.
If this is unknown, is there a way to figure out the mAH of the step up board? A Duracell AAA about 1100 maH, so how many mah would you have at 5 volt from the NCP1400-5V Step-Up Breakout?
Bottom line: if my project can last at least 3-4 hours on 1 AAA, it’ll suffice. There’s not room to go with a AA battery!
Thanks,
The NCP1400 efficiency varies from 30% (.9V input) to almost 80% (1.5V input). Let’s assume an easy guess of 50% average efficiency. If your circuit draws a total of 10mA (8 for the Arduino and 2 for the rangefinder), then draw from the battery will be 20mA. An 1100mAH battery should last 55 hours. You’ve got enough juice left over for a few leds before you run into your 4 hour limit.
Looking at it from another perspective, 4 hours from an 1100mAH battery is approx. 275mA/Hour. Allowing for the inefficiency of the converter, you could probably safely pull 100mA and the battery will last 4 hours, which turns out to be the maximum current available from the NCP1400.
Dave Mueller:
The NCP1400 efficiency varies from 30% (.9V input) to almost 80% (1.5V input). Let’s assume an easy guess of 50% average efficiency. If your circuit draws a total of 10mA (8 for the Arduino and 2 for the rangefinder), then draw from the battery will be 20mA.
That would be true if the NCP1400 were 50% efficient and it had the same input and output voltages. The stated efficiencies of such devices are stated, AFAIK, in terms of power, not current. Therefore:
Iin * Vin *efficiency = Iout * Vout
Rearranging:
Iin = (Iout *Vout)/(Vin * efficiency)
Inserting our values:
Iin = (10 mA * 5 V)/(1.5 V * 50%) = 67 mA
Dave Mueller:
An 1100mAH battery should last 55 hours.
1100 mA-H/67 mA = 16 H
Dave Mueller:
You’ve got enough juice left over for a few leds before you run into your 4 hour limit.
Looking at it from another perspective, 4 hours from an 1100mAH battery is approx. 275mA/Hour.
1100 mA-H/4 H = 275 mA, not “mA/hour”.
Dave Mueller:
Allowing for the inefficiency of the converter, you could probably safely pull 100mA and the battery will last 4 hours, which turns out to be the maximum current available from the NCP1400.
At 100 mA, 5 V output:
Iin = (Iout *Vout)/(Vin * efficiency)
Inserting our values:
Iin = (100 mA * 5 V)/(1.5 V * 50%) = 670 mA
1100 mA-H/670 mA = 1.6 H
Yours in the interest of respecting the first law of thermodynamics,
Eric
The datasheet curves are efficiency vs current at various input voltages.
However, I did read the wrong graph. The 5.0V output efficiency is closer to a 70 to 80% average. In any case, I think 3-4 hours is easily attainable.