Flew for a couple hours today. During the last approach I got the warning above in the messages. Once I was on the ground and shut down I tried to troubleshoot. According to the error message on the HDX panel, the backup battery needs at least 12.5v to charge, but the buss voltage (according to the HDX) was 13.8 v for the whole 2 hours we flew. Is my backup battery dying already (the whole system is only 4 months old), or is there something that I need to check before I lay out $240 for a new battery? The smaller, 7", secondary, screen and the D10A seem to be ok; at least they're not giving the same warning.