I'm looking for a 2 channel (or more) data acquisition unit at a relatively low cost for monitoring charge in and current draw out from a battery bank charged from solar panels and feeding a mains inverter. One channel will be used to monitor battery voltage (10-15v DC) and another channel to monitor current by means of an ammeter shunt.
Reading battery voltage isn't an issue....any unipolar voltage ADC will work, with attenuating resistors to modify the FSD.
Here is the slight problem. The shunt is rated 200mV at 20A and is designed to convert a DVM with full scale reading of 1.999V into a 20A meter. Measuring this using a data acquisition unit is simple enough, but when charging, a maximum of 2A flows into the battery, and when powering the inverter, a maximum of 15A flows in the opposite direction.
The current monitoring input therefore needs to be bi-polar. With the currents indicated above, that would mean a voltage range of -20mV to +150mV
8 bit resolution is more than good enough....I just need to take readings of voltage and current at five minute intervals.
Suggest a product please!!