I'd like to create a voltage meter that can measure battery voltage and PV panel voltage. The only problem is that the PV input and Battery I/O doesn't share ground. I'm not sure if tying the grounds is a good idea then. Would I be able to achieve my goal using ADS1115 where battery is measured single ended compared to circuit ground and PV as differential measurement?

crude schematic

  • \$\begingroup\$ Making a differential measurement DOES NOT mean you don't need a common ground. For example, the inputs to the AD1115 may be used differentially but the input leakage currents are still to ground. Like most differential signals there is almost always an implied ground. \$\endgroup\$ – Jack Creasey Jun 7 '19 at 18:19
  • \$\begingroup\$ @JackCreasey so what are other viable choices? Easiest thing would be to tie the PV and Bat grounds together, but I'm not sure what would happen. \$\endgroup\$ – Pangu Jun 8 '19 at 10:33

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