I believe cars normally charge at 14V; and a backup alt should be set to kick in at 13V?  (on my 28V system, the batt is 24, main alt is 28, and backup alt is 26)

Spikes to 16 probably not a problem, but sustained high voltage increases current everywhere, thus heating everything more than normal -- system components and the battery itself, which sees a significant increase in charging current. On Jan 23, 2013, at 7:36 PM, Paul Miller wrote:

BandC.biz has lots of data on regulators, says 13-15 is normal range.  I think 16v to the battery is too high a charge value for any 12v system I'm familiar with.  Bill at BandC is the expert, always happy to talk on the phone (at length) and can set you up with the best voltages for your battery, regulator and probably the maximum value where a warning would trigger.   I would call him.

Paul