sunshine_eggo
Happy Breffast!
Why does the manual instruct that float and bulk be set to the same voltage when using lithium batteries on the "user" (user input numbers and user supplied lithium batteries without compatible bms)?
Because they're idiots and have incorrectly applied the idea of "LFP batteries don't need to be floated." Even big battery does this on many of their products - specify the same absorption and float voltages.
Without knowing more, their recommendation results in holding batteries at the absorption voltage potentially for hours at a time. This results in daily over-charge as tail current clearly will drop well below 0.05C.
I won't rule out that it may in some way change the logic to something more sensible, but I would never intentionally allow a battery to be held above 3.45V/cell all day.
If the voltages are set differently, then what strategy does growatt use to transfer to float? Time spent at boost voltage? The amps decay in amps flowing into the battery once boost voltage is reached?
This has been a mystery since people have been putting DIY or unmanaged BMS LFP batteries on them. Whatever the logic, given that it appears to work for many folks, it seems to be far more reasonable than, "hold battery at max voltage for as long as you can."
If this is normal behavior for these chargers, they should not be used for DIY LFP.