ArduPilot Voltage connection

check the schematic for the shield. there is a voltage divider with a 240 and 100k resistors. so the voltage input from the pack is divided by 3.4 ( 240+100 / 100 ) and the resulting signal goes to the arduino input. you wouldn't want the result to be much over approx 5 volts, or really shouldn't have anything over what voltage the arduino sees for Vcc. If you're using a separate receiver pack and letting the receiver power ardupilot through the servo lines (the default setup), that voltage could go lower like 4. so I wouldn't put more than 3.4 * Vcc, could be as low as 13.6v.

is 18.2 your maximum pack voltage or your nominal pack voltage? an extra volt or two may not hurt anything, but not sure if it would goof up the analog inputs to have anything higher than Vcc.

A very simple solution: put another resistor in series with the battery pack sensing lead. so the divider divides the voltage down more. for example, another 240k resistor in line, would give (240 + 240 + 100) / 100, or a 5.8 division. so even if your supply to Vcc for the arduino went as low as say 4 volts, it should be perfectly fine to put 23 volts to the voltage sense input. more dividing will give less voltage measurement resolution, so don't put too large a resistor.

Another solution would be to add several diodes or leds in line. they would subtract approx 1.3 volts per diode, so that would be another simple way to keep the input low enough.

Either way, change code to calculate the voltage correctly, depend on what was added.

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Dale March 4, 2010 at 9:01pm

check the schematic for the shield. there is a voltage divider with a 240 and 100k resistors. so the voltage input from the pack is divided by 3.4 ( 240+100 / 100 ) and the resulting signal goes to the arduino input. you wouldn't want the result to be much over approx 5 volts, or really shouldn't have anything over what voltage the arduino sees for Vcc. If you're using a separate receiver pack and letting the receiver power ardupilot through the servo lines (the default setup), that voltage could go lower like 4. so I wouldn't put more than 3.4 * Vcc, could be as low as 13.6v.

is 18.2 your maximum pack voltage or your nominal pack voltage? an extra volt or two may not hurt anything, but not sure if it would goof up the analog inputs to have anything higher than Vcc.

A very simple solution: put another resistor in series with the battery pack sensing lead. so the divider divides the voltage down more. for example, another 240k resistor in line, would give (240 + 240 + 100) / 100, or a 5.8 division. so even if your supply to Vcc for the arduino went as low as say 4 volts, it should be perfectly fine to put 23 volts to the voltage sense input. more dividing will give less voltage measurement resolution, so don't put too large a resistor.

Another solution would be to add several diodes or leds in line. they would subtract approx 1.3 volts per diode, so that would be another simple way to keep the input low enough.

Either way, change code to calculate the voltage correctly, depend on what was added.
WhiteQueen March 4, 2010 at 7:25am

Let me correct my question.
It is the ArduShield that has the voltage monitor connection. Can someone confirm that 18.2 volts will work fine, and not fry the circuit?

This reply was deleted.

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ArduPilot Voltage connection

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