The IQ4 will get the batteries to 14.6 stays there 15 minutes, then drops to 14.2 for 8 hours, then goes to 13.6
How long it takes to get to 14.6 depends on the charging rate and the initial SOC of course. Higher charging rate, faster time to get to 14.6 but at a lower SOC when it gets there, so the remaining SOC will be at the lower Absorption voltage.
Total gen time then depends on juggling the Bulk time and the Absorption times to create the shortest total time. That is what my old ugly graph was supposed to help with. (It still can help with that it is so clever! :) )
