Julie, Jim is correct.
Take a look at this schematic from the GoPower user manual. What may be confusing you is, there are references to "battery 1" and to "battery 2". When two 6v batteries are wired together in series, you have one battery "bank". Each bank
of batteries would be wired to the controller as in the figure. Your dual 6v batteries make up one bank
, and are wired to the terminals marked "battery 1" as mine are. So, "battery 2" would only have a reading if you had a 2nd bank
of batteries wired to it.
Bottom line, there's nothing wrong with the display showing no reading for battery 2. Think of it as "battery bank 1" and "battery bank 2". You don't have a 2nd bank, so no reading.
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