INA260 Question

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Cyborg_delta1
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INA260 Question

Post by Cyborg_delta1 » Fri Sep 13, 2019 4:38 pm

Hello

I have an Arduino project that is powered by a 3.7v LiPoly battery via Power Boost 1000c, My project and code works fine but now I want to find a way to monitor the battery and the screen to show the remaining battery percentage. To get the Nextion display to show symbols and the Feather to change those symbols is easy but to correctly monitor the battery voltage is whats confusing me as there seems to be no clear way going about this as every corner of the internet either says its possible, not possible, do it this way, do it that way or do it wrong and you could start a small fire

But I then came across the Adafruit INA260 (No thanks to google) and it seems to tick the right box's but I am unsure of how to correctly wire it up, below is a very basic diagram of how I think it should be set up for my project:

Image

But will I still be able to charge the battery via the Powerboost as the + cable is going through the INA260 IC or would this damage the IC and the battery and as the + connection is going through the IC would this continue to drain the battery to the point of damaging it. The only other way I thought of wiring this project is to connect the INA260 to the BAT pin on the Powerboost but where should I go after that I can not connect it straight to ground?

I am sorry if this is a lot of questions but when it comes to power supply or power circuits I am very nervous especially with mains or LiPoly battery's

Cyborg_delta1
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Re: INA260 Question

Post by Cyborg_delta1 » Sun Sep 15, 2019 4:46 pm

Hello All

Just encase any one else needs to know this is the response I got from Adafruit:
That is the correct way to wire it. The battery current is not going through the INA260. It is going through a 0.1 ohm shunt resistor. The INA260 measures the voltage drop across that resistor and calculates the current flow via Ohm's Law.
Thank you, so charging wont be affected?
Charging should be fine. During the 'fast charge' phase, the charge current will be 1A, so there will b a 0.01v drop across the shunt resistor. Not enough to slow charging noticeably.

The last phase of the charge cycle is a constant-voltage 'trickle' charge to top-off the cell. The cell is fully charged when the charge current goes to zero. With zero current, there will be zero voltage drop across the shunt resistor, so the battery voltage will be a full 4.2v.

floppes
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Re: INA260 Question

Post by floppes » Mon Sep 16, 2019 5:15 am

The INA260 seems to be a very nice and powerful board. But I think it is a little too much for your needs. Do you really want to meaure the current?

To get the battery percentage, it is enough to measure the battery's voltage. This can be done with any of the Bluefuit's analog inputs. Just connect the positive side of the battery with a 10K resistor to an analog input. If the Bluefruit runs on 3.3 V logic level (which I think it does) you need to use a voltage divider to protect the input pin. Just add another 10K resistor to GND.

You can easily convert the analog value to volts by multiplying it with the analog reference voltage divided by the analog resolution (should be 3.3 V and 1024 for the 32U4). If you added the above voltage divider (which divides the voltage by 2), you need to multiply the result with 2.

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