Arduino Solar Shield v 2.2 read battery percentage

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#1

Hi all,
First of all, I’m not an expert.
For my Arduino project I’m using solar panels and this Arduino Solar Shield in order to charge the battery.

On the same page it seems possible to read the battery voltage. I have 2 questions about it:

  • What’s means “In order to connect the VBAT pin to Analog pin A0, so that we can read the data from A0 pin, we need to Short R7 using a 0ohm resistor as shown in the figure”
    What do I have to do?
  • Is it possible in some ways to obtain the percentage of the battery charge?
#2

Sorry, I apologize for our misrepresentation. The phrase means please short the two pads on the R7.
As for the percentage, you can do it yourself by writing a program with the following idea: read the current voltage value, and the ratio of the voltage when it is fully charged.

#3

Hi @Citric
thanks for your info…
I have a doubt:
I just added this shield on my Arduino (with the battery) and I loaded the code in order to read the voltage on A0 pin. I haven’t changed anything on the R7 and I’m able to read the value.
If I try to short the two pads on the R7 I read a different value (slightly higher to the previous test).
So, without changing the R7, what am I reading?
Why is it necessary to short the two pads on the R7?

#4

Here’s the thing, if you short R7, then VBAT will be connected to the A0 pin. Reading the value of the analog pin A0 is equivalent to reading the value of VBAT.

#5

Do I need to add a 0 Ohm resistor or just a piece of wire to short R7? Is it enough?
In case I need to use a 0 Ohm resistor, could you suggest the type that I should purchase? (Sorry, but I’m not an electronics expert.)

#6

Yes, you need to use a piece of wire to short R7. it is enough

#7

I conducted some tests to understand how I can retrieve the battery charge percentage level.
Firstly, as you suggested, I shorted the R7.
I charged the battery to its maximum capacity and began retrieving the VBAT values using the sketch provided on the Solar Shield page.

Starting from this point, I recorded the following values:
The highest recorded value was 417 (when the battery was completly charged).
Just before the Arduino turned off due to low battery charge, the VBAT value was 280.

To calculate the battery level percentage, do I need to consider these maximum and minimum values?

Additional question: Is there a way to determine if the battery is charging?