bosparra
Junior Member level 1
I am in the process of designing an intelligent battery monitor. Its for an RV where a freezer will be running off a 12V lead acid deep cycle battery. Just monitoring the voltage is not enough, since it will report a run down battery after the fact. I want to monitor the current draw of the load, to calculate an estimated time before the battery runs down.
My question is this: using a shunt resistor is not practical because the resistor will have to be huge. A 1ohm shunt resistor measuring 4 amp on a 12V battery will already have to handle 48W! Then we haven't even started measuring charging currents of at least 6A. What other way is there to measure up to 20A-30A in this environment, without using a shunt resistor?
I have looked at hall effect sensors, but is there another cheaper and more practical way of measuring DC current accurately?
My question is this: using a shunt resistor is not practical because the resistor will have to be huge. A 1ohm shunt resistor measuring 4 amp on a 12V battery will already have to handle 48W! Then we haven't even started measuring charging currents of at least 6A. What other way is there to measure up to 20A-30A in this environment, without using a shunt resistor?
I have looked at hall effect sensors, but is there another cheaper and more practical way of measuring DC current accurately?