Quote Originally Posted by CatFan View Post
Your problem is likely that the battery BMS is shutting the battery down for excess current, disconnecting the battery from the system. Since the battery load plays a big part in the operation of regulating the alternator output, his results in the charging system losing regulation and high voltage. This is why Mercury has recommended against lithium-ion cranking batteries for most motors until recently when they issued a service bulletin with battery parameters and a list of engines that can work with lithium-ion batteries.
In the original post he stated the units would cut off on long runs on plane even before he switched to Lithium. That's why I suspect it's not a lithium/BMS issue, but a connection issue in the circuit that powers the Helixes. I hope he figures it out and shares the finding as Super Dave is intrigued and watching...