Hey everyone,
I would like to supply my Mkr Nb1500 with power via a battery pack, but also display the capacity as a percentage at the same time. It would be best to display this in the IoT cloud in the dashboard. The picture shows how it all looks at the moment.
Any ideas how this could work? I would appreciate any help 
Estimating the remaining capacity could be difficult, unless that battery module you show has an output for that purpose. You can't estimate the remaining capacity from the 5V outputs because the boost converter circuit in the battery module keeps the output at 5V whatever the remaining capacity. You need an output that shows the true battery voltage, which will vary from around 4.2V when fully charged to around 2.8~3.0V when discharged.
1 Like
I see... means there's nothing to be done?
I don't know, you have not given enough information about the battery module.
Perhaps you can solder a wire directly to the battery+ terminal. Then use a voltage divider to reduce that voltage to below 3.3V so that the Arduino can measure it.
1 Like
I have just checked. 3.329v comes out of the 3v output and 5.060v comes out of the 5v output
What voltage will be shown as 0%?
The 5V does not reflect the battery voltage.
The "3V" MAY - or more likely not.
As @PaulRB says you NEED the battery terminal voltage - by soldering a wire to the battery + on the battery holder.
Connect it via a suitable RRC divider and filter to an analog input
where exactly should I solder it?
Turn the battery so you can see which is the + terminal and solder to the point on the battery holder next to it.
I'm sorry, but I don't quite understand what the point is 
You might want to connect your potential divider after the on-off switch, so that you don't continue to discharge the cell when the power is switched off.
Can you supply us with more photographs of just the battery holder, both sides of the PCB, and perhaps with the battery removed, so that we can indicate to you where the best place to make a connection would be?
At the big solder blob next to the big + sign.
to measure the battery voltage you need to make a connection to it.
Then use a potential divider to reduce the voltage to whatever the ADC on your board will handle.
Like this
Two years ago I bought a kit that will do just that. It places a known resistive load on the battery and monitors the voltage drop over time at the known load. You could do the same.
1 Like
Another thing to think about is a lot of these boost circuits have an inverted output , so the 0v on the battery may not be 0v on the output .
1 Like
That should be easy to check with a multimeter.
1 Like
This topic was automatically closed 180 days after the last reply. New replies are no longer allowed.