Only one tower of ours has recorded relative humidity and ipack voltage at the same time (other towers have sensors occupying all channels). Unfortunately, the scenario that I described in the previous post does not apply to the RH5 on that tower, so I cannot offer more clues.
Let's say the iPack battery has ran out of power because of cloudy sky, and thus the RH5 readings go to zero. Is the RH5 supposed to be able to function properly again once the battery is recharged and the voltage goes back to 12V?