Hi All,
I am measuring a 140VDC battery, and displaying the value on a LCD. I have the battery voltage working well, using a voltage divider and powering the unit via a special DC to DC. I am also monitoring the battery continuity between the battery negative pole and the battery case which also works well. I now need to measure the battery pole positive to the machine case for a positive ground fault. I am having problems with this as I have used another isolated DC to DC to step the voltage down to a LM7805 for the PIC to detect +5V or 0V if the voltage flows from the positve battery pole to the machine case. This works ok but once I place a short between the battery positive pole and the machine case the unit does not work again I suspect we are getting a large amount of amps flowing causing damage. Does anyone know of a better way of doing this?
I am measuring a 140VDC battery, and displaying the value on a LCD. I have the battery voltage working well, using a voltage divider and powering the unit via a special DC to DC. I am also monitoring the battery continuity between the battery negative pole and the battery case which also works well. I now need to measure the battery pole positive to the machine case for a positive ground fault. I am having problems with this as I have used another isolated DC to DC to step the voltage down to a LM7805 for the PIC to detect +5V or 0V if the voltage flows from the positve battery pole to the machine case. This works ok but once I place a short between the battery positive pole and the machine case the unit does not work again I suspect we are getting a large amount of amps flowing causing damage. Does anyone know of a better way of doing this?