Hi all,
I have made a simple voltage divider that will allow me to measure the output voltage of my battery using the analog pins on my arduino. The quick details of my voltage divider are as follows: V_in ->15kohm -> V_out -> 10kohm -> gnd. The resistors are only rated for 1/4 W. Will hooking up my lipo battery to this voltage divider cause a fire with the tiny resistors I am using? If so, what resistors would be good for something like this?
Thank you
They’ll be fine, but you really need to understand voltage & power (watts) and how current plays into that.
Read up on ohm’s law.
It's time for Ohm's law and stuff.
voltage 3*4.2 = 12.6 maximum
voltage across the 15K resistor is 15 / 25 * 12.6 or 7.6 volts.
current = voltage / resistance
current = 7.6 / 15000 0.51 mA (0.00051 A)
power watts = voltage * current or 0.004
Looks good.
On the other hand, it's never too soon to start calibrating your finger. Wire it up and enjoy the show if they blow up, don't do that again! or when they don't, put your finger on the resistor and see if it's cold or warm or hot.
a7
I did calculations myself, but I had a hard time trusting them. Something about hooking up a big battery to these little resistors seemed scary. I will be sure to look into the finger calibration... /s
Thank you for the reassurance,
Dom