I have 3,3V pro mini with NTC and rf24l01 running on 18650 battery. How to make some sort of a switch so when battery goes under some level power gets cut off so i don't damage it?
There are units available on ebay to do that or you could use an A to D pin and readmthe voltage and have the Arduino shut down at the required voltage. Even alert you before it shuts down.
It can not be done by Arduino, because Arduino will have to shut down himself. Some circuit i need to put it before pro mini that will let power on above some voltage, and off below some voltage.
Not sure what to seek. It must be cheap, though.
There are lots of circuits out there to have an Arduino switch off itself. Usually built with two or three transistors, look for latching power supplies. You use a push button to switch it on, the same button or a signal from the Arduino to switch it off again. These circuits are quite simple and cheap to build.
To read the voltage of the battery you need a voltage divider to bring down the maximum voltage your batteries can produce (normally 4.2-4.3V for a nominal 3.7V battery) to <1V and use the internal 1V reference for the ADC to read the actual voltage. Note that you can't use the default reference, as that'd be the very voltage you try to measure. Again a very cheap circuit, as all you need is two resistors (use large resistors as otherwise you're leaking too much voltage - 500k total or so) and a small cap for stability (between the pin and GND - 10-100 nF should work for this).
This look so nice while i read you typed in. But, point to some tutorial would be nice. All is a bit confused to me.
Beside, i don't say you are not right, i just think that some circuit between battery and pro mini would do the job. Again, some tutorial would be nice.
There are indeed circuits that can just cut off the power - the batteries Adafruit supplies come with that included.
I don't have links to specific tutorials. Google is your friend for that. Tutorials, schematics, etc.
I believe these should do the job?
who_took_my_nick:
I believe these should do the job?
Depends, what the low voltage battery cutoff ?
For long life and safety you want the battery cut off to be 3.0 to 3.3V, that appears to be the recommended cut off.
Then what is the suggestion?
Suggestion: Do your own research, don’t expect us to do it for you.
We’re happy to review what you’re learning and thinking, but why would we do that learning and thinking for you?
lastchancename:
Suggestion: Do your own research, don’t expect us to do it for you.
We’re happy to review what you’re learning and thinking, but why would we do that learning and thinking for you?
If i do research and researching find solution then i wouldn't ask here. And posting here is some kind of a research. I don't expect from you to do research for me, but i do expect if someone had similar problem, can offer his solution, suggestion. If you do not have a solution, why posting in the first place?
You are obviously here to talk much and says nothing. Just please don't learn or think for me.
[gloves_off]
So what research or discovery have you brought to the thread?
Post #6 was a good start
What did you learn from Reply #7 ?
[/gloves_off]
Throw something in to the conversation, don’t just ask for results without trying to help yourself.
And yes - I do contribute to various topics.
Once you get this project running, you can move on to the Tutorials section. (Its early!)
People who do there reserch come here and post " Hi i am trying to do this, i have product 'A' and am trying to use it but am having problems! This and this is happening, Can someone help"
Others come here and go.
"Hi i am new and trying to do this, could someone please post a circuit and program for me to 'Help'" and then nomatter what someone says they tell you they tried it and did not work.
Then they repeat the same line above. It is very depressing as it indicates they just came here to get someone to do it all for them.
Now what did you think of the sujestion in post number 6 as i looked at the board and it does what you want 'Cuts off the power before the battery is damaged'.
Did you google the board model and see what others think.
When you post think of exactly what you want and describe it to the group.
EG. I am running an arduino with other boards attached and when the power begins to fail i would like it to first turn off the other boards then put its self to sleep.
Or
I want it to save all parameters and then disconnect from the power.
Or
I would like would like it to disconnect the power compleatly.
Help us to help you. At least describe your project and what you hope to achieve.
Daz