Quote:
Originally Posted by Bill
For your system, there are others much more competent than I am, so I will leave the details and final answer to them. My first reaction, though, is that you say you shut down the solar system for a month, leaving no source of charge current. Like most RVs, a TM has a number of parasitic loads - devices which continue to draw small but non-zero current even when everything is nominally OFF. The sum of these currents will draw a Group 27 lead-acid battery to zero in less than a month. Perhaps it pulled your lithiums down pretty far, so they were hungry when you tried to charge them with the genny?
Bill
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Good question, but his "pre-generator" picture shows "12V" voltage of 13.12 volts in a state of slight discharge. That's between 60% and 70% State of Charge for LFP batteries at normal temperatures.
In spite of moderatately high SOC, however, LFP batteries ARE willing accept very high input current and power with only a small voltage diiferential, because they have low internal resistance. If you give them a good voltage differential, they're ALWAYS "hungry".
Internal resistance of the cells is utterly inadequate to protect them from an excessive rate of charge, a protective limit needs to be enforced by external BMS unit. The BMS units in the '100Ah" batteries should allow at least 25A into each battery pack, and a 50A value would be appropriate for some of the better kinds of cells (EVE cells, for example). If each pack allows 50A, the 'bulk' charging limit will be the 60A limit of the WildKat.