When an engine
is running or genset, lead acid batteries will often see up to 14.4 volt, so lithium 13.4 Volt should work
. Hmmm, is 13.4 volt measured on the battery
terminal or at the inverter itself? If it is measured at the battery
, try to measure on the inverter; with all the changes there might be a enormous voltage drop somewhere now. However I have not seen an inverter that sounds a loud alarm
at low voltage. Has the polarity been changed inadvertently?
Whatever it is, a resistor is not the answer, in my opinion.
Maybe have a look at the inverters settings, there might be one that may need adjusting, although I cannot think of one.