Lower voltage

[rodriguise]

Would this work with 3.3v systems?

[rlogiacco]

Sure, you need to adapt your setup to your configuration: every time you read 5V in the README you should consider it as 3.3V and you are good to go.
So, if your project is powered by a LiPo (3.7-4.2V) you are in a Higher than 5V context...

[rlogiacco]

BTW, when I say device, I mean the MIC29150, when I say MCU I mean your Arduino, or whatever device you are using

[yasiriqbal92]

"you should stop using the battery at 3.3V (your operating voltage) + 0.6V (the voltage drop) = 3.9V." I understand this but currently my battery is at 3.7 V so would I have to continuously measure battery output ?
Secondly, in discharging curves, how would i know the x-axis which is current capacity? I mean do I need to see total current capacity of battery using series ammeter?

[rlogiacco]

I don't think I get your question: why are you now speaking of current in terms of electrical current?

You want to measure your battery (at its terminals) periodically: how frequently depends on your specific requirements, the battery will get lower in voltage while getting depleted.

Regarding the discharging curves, if you are referring to the diagram I've put on the project readme, the battery capacity is measured in mAH (milliampere per hour) non in mA (milliamperes, measurable by an ammeter)...

Please, keep the discussion focused on the library and its usage: if you need a broader set of information, StackOverflow or a good EE forum might be better.

[yasiriqbal92]

Hello,
Sorry to question you again. I set up a voltage divider before my device (MIC29150) for 3.3V and input this (3.3v) to A0 of my MCU and I uploaded the battery monitor code. I have verified the voltage at sense pin which is 3.3V. But I am getting this 5000 value. Can you please guide me why I am not getting exact voltage? THanks

[rlogiacco]

First of all, you are reading 5000 as for 5000 mV so 5.0V and that's because you setup your battery instance with value 5000, which is wrong for your device, which is 3.3 V... so the first value of the begin function should be 3300 as stated in the README.md, How To section:

The sense pin wiring can vary depending on your battery configuration, but here are a few examples based on the assumption you are using a 5V board: in case of a 3.3V board you should be performing the necessary adjustments.

The begin function call contains also another error, because you have set up your voltage divider ratio to 1, which means NO VOLTAGE DIVIDER... Use the formula as per the README.md description, Voltage divider ratio section:

The voltage divider ratio is determined by the formula (R1 + R2) / R2: if you use two resistors of the same value the ratio will be 2, which can be interpreted as whatever value we read it will be half of the actual value. This allows us to sense batteries up to 10V. If you use a 22k Ohm resistor for R1 and a 10k Ohm for R2 than your voltage ratio will be 3.2 and you will be able to safely monitor a 12-15V battery.

Please note all the examples refer to a 5V device, so you have to adjust your calculations to a 3.3V one: you can measure batteries up to 6.6V with a divider ratio of 2 and up to 10.5V with a divider ratio of 3.2!

Finally, if you need further assistance, please post a schematics of your circuit: you can use this website (which also has a simulator) or Upverter or any other tool you prefer.

Hope this helps!