#12V BATTERY VOLTAGE MONITOR HOW TO#
#12V BATTERY VOLTAGE MONITOR INSTALL#

This makes rawVolts = 3693 * (3.3 / 4095) = 2.976 and batteryVolts = 2.976 * (120000 + 33000) / 33000 = 13.8.If you ever wanted an inexpensive and accurate way to test your battery voltage, log the usage and something that extremely easy to install then this is the tool for you.Ĭheck your parked up boat or caravan batteries without going outside, app can monitor multiple batteries (individual bluetooth modules required), receive notifications once a day on the condition (toggle on or off), use the log to determine a failing battery, especially handy if you have two installed and cant identify the issue. Int rawVolts = analogRead(A0) * voltsPerBit //Calculate voltage at A0 inputĪt the typical battery voltage of 13.8V, you will get 2.976 volts at input A0 and an analogRead() value of about 3693. const float voltsPerBit = 3.3 / 4095 // Calculate volts per bit of ADC readingĬonst float ratioV = (120000 + 33000) / 33000 //Calculates to 4.636363 This gives a voltage-per-bit of 3.3v/4095. The Core has a 12bit ADC so at 3.3V, the ADC value will be 4095. Shows voltage information when user is close to the vehicle, no need to.

So, where you would read the analog voltage at A0 in your code, you would apply a ratio to calculate the equivalent battery voltage. 12V Car Battery Monitor via bluetooth 4.0 Voltage Meter Tester w/ auto Alarm BM2. With decent (1%) resistor, at 15V the analog input of the Core will be 3.235 volts. It prevents problems, if you forget in your parked car or boat a cool box or other 12-V devices from the power. You can do that using a voltage divider to step the higher voltage down to a max of 3.3V. When it comes to 12-V batteries, its important to understand the type of batteries you. The second part of the solution is monitoring the battery voltage (up to 15V) with the max 3.3V analog input of the Core. Typically, 12-volt batteries are the most commonly used storage devices. There are lots of other ways but you need to find the one you feel most comfortable with implementing. This can be done a few ways: with an efficient “step-down” switching regulator like this Polulu unit or using a cigarette lighter USB phone charger adapter with a suitable USB cable.

#12V BATTERY VOLTAGE MONITOR HOW TO#

The first is how to power the core from the 12V battery. If you are just trying to see the battery is charged or not, the simple divider will work and there are two parts to your solution. So depending on the accuracy and resolution that you need, you may want to consider an external ADC or an Op-Amp comparator. It is important to choose a current sensor that has an input common-mode voltage (VCM) rating that complies with the worst-case. Note that if you use the resistor divider and feed that directly into the Analog input, you will not have a very large change between a fully charged battery (13v?) and a flat battery (10v?). There are many others out there depending on your current requirement. I would suggest a Switching Regulator, for example To power the Spark from the same battery you could use a simple Linear regulator to drop the 12 V to a usable input for the Spark, however with a 12v input you will generate quite a lot of heat. These values should be quite high and you will need to take into account the input impedance of the Spark. The voltage divider will work but your top rail, the positive end will be connected to the battery voltage and you will need to calculate the resistor values required to achieve about a 3v value to feed into the Spark analog input when the battery is fully charged.

12v battery voltage monitor