The battery stops charging, or reports its state of charge, below full even when a full charge seems to have finished. On SMA Sunny Island systems, look in the event log for the change to full charge. If SOC is still below 100% afterwards, the loads may have drawn too much power before the full charge ended. For that case, set a longer full charge time, also called the absorption period. Check the charge limit settings first. A maximum or cut-off charge SOC, or a time-slot charge SOC, set below 100% makes the battery stop charging at that value. On the Sunny Boy Storage SBS2.5-1VL-10, older firmware does not allow the self-consumption range above 75%. Updating to firmware 3.11.10.R or later sets it to 90%. Seasonal self-consumption ranges also change automatically how much of the battery capacity is used through the year. Incorrect battery parameters can also be the cause, such as the battery type, the nominal capacity or the full and equalization charge settings, so compare them with the battery manufacturer's recommendations. The SOC shown is an estimate from ampere-hour counting plus voltage recalibration. The goal of a full charge is a state of charge of at least 95%, not exactly 100%.
<!-- review notes
observed_asc1 verified · fact SOC below 100% after full charge proposed
The displayed battery SOC stays under 100% even though the full-charge phase has finished. The SMA documents say loads drew so much power before the full charge ended that the battery could not reach 100%.
sec=h979 h=2a543f30380csec=h850 h=ee387738d66fsec=h192 h=81126f37319bsec=h592 h=1c911f608962verified by: review-workflowverified on: 2026-10-24
c2 drafted · lead Full charge status event proposed
SMA event 9321 or E205 marks the change to full charge. Use it to confirm that a full charge was actually started before reading a capped SOC as abnormal.
tbl=76.r12 h=17df887c13dctbl=72.r12 h=17df887c13dctbl=38.r2 h=bfc8cc968771tbl=133.r4 h=71f3d966459dreview note: support check: partial - Events 9321 and E205 mark the change to full charge, but the passages do not say to use them to confirm a full charge before judging a capped SOC.; review: partial - Events 9321 and E205 do mark the change to full charge, but the passages never say to use them to confirm a full charge before treating a capped SOC as abnormal.
c3 verified · fact Max charge SOC setpoint reached proposed
Charging stops at the configured maximum or cut-off SOC, or at a time-slot charge SOC. Generac's MaxSoCAbs can be set from 10 to 100% and defaults to 100%.
tbl=20.r2 h=8ec93b949f11tbl=19.r6 h=26535068e24dtbl=21.r3 h=016b064975ebsec=h294 h=fda63069986bverified by: review-workflowverified on: 2026-10-24