Best way to communicate wirelessly

Can anyone recommend the best way to communicate a device's voltage wirelessly to Arduino Uno?

I have 8 remote control cars that require voltage monitoring. Each car uses its own lipo battery, I am looking for the best way to communicate the voltage with Arduino, which will be displayed to a serial monitor and I could assign actions based on the voltage.

The communication distance is less than 1 meter, all 8 cars will be 'parked' inside a display cabinet, and Arduino will be mounted behind it.

If you charge a lipo to its storage voltage it will hold that charge for probably well over a year and will certainly recharge when you need it any way. If keeping them stored longer than that I’d consider taking the batteries out so you can check for bulging etc .

Any device you connect to the cars will need powering - presumably discharging the cars , which otherwise would have held the charge , , Your UNO will need powering too ....

Each battery is in a constant drain, it is always plugged in and powering the car's wireless charging system, and headlights/taillights. I keep these lights on. I also added a power management board to avoid discharging/overcharging. Therefore a voltage monitor of each car is needed.

I am leaning towards NRF24L01 to be put in each car, it seems to be the most logical method for the application. It will be scalable in case more cars are involved.

I haven't used one, but the Wemos D1 often comes up in cases like this because they're a very cheap way to get wireless connectivity. They're small too, which will likely help.

They have a single analog input so you can measure battery voltage with a voltage divider.

You will need one for each car and another for them to send their data to.

I never heard of it, but it sounds great. I did a google image for Wemos D1 is almost as big as Arduino Uno, are you sure it is small?

How much room do you have inside those cars?

An NRF24 may do the job, but also needs an Arduino or other MCU to do the actual reading and communication.

The WeMOS D1R2 is the same form factor as the Uno. Avoid that board, it's a disaster. You have to look at the WeMOS D1 Mini, that's a much smaller one.

Thanks wvmarle - yes, I meant the mini.

Each car has very little room, it will fit an NRF24 or D1 Mini but not together with an Arduino Uno. I was hoping to use only a tx in each car, and the Arduino would sit outside as Rx. Will ESP-01 work also?

With the D1 mini, you don't need an Arduino in the car. It's a (much more) powerful micro controller in it's own right.

OK, then I will use a D1 mini in each car collecting voltage information, it seems like overkill for such a simple operation but it will work. Each D1 mini will broadcast information to a central receiver, then displaying the information to the serial monitor. Any suggestion for the receiver?

caineroad:
Any suggestion for the receiver?

How about a D1 mini :wink:

The ESP8266 uses WiFi so can connect to your router, or some external server, or even host its own web site...

The ESP01 module does not have the analog input broken out so not suitable for reading the battery voltage.

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