diff --git a/backend/services/planning_engine.py b/backend/services/planning_engine.py
index 2c13f74..18f4b55 100644
--- a/backend/services/planning_engine.py
+++ b/backend/services/planning_engine.py
@@ -498,7 +498,13 @@ def solve_dispatch(
         soc_prev_expr = current_soc_wh if t == 0 else soc[t - 1]
         arb_t = arb_floor_series[t]
         soc_low_t = soc_min_series[t]
-        prob += soc_prev_expr >= (arb_t - (arb_t - soc_low_t) * (1 - w_arb[t]))
+        # Při relaxovaném dnu (soc_low pod DB min_soc Wh) nesmí větev w_arb=1 znovu vynutit arb_t
+        # (typicky ~rezerva 20 %) — jinak nejde „vypustit“ baterku k planner floor 5 %.
+        if soc_low_t < min_soc_wh - 1e-3:
+            arb_cap_t = min(arb_t, soc_low_t)
+        else:
+            arb_cap_t = arb_t
+        prob += soc_prev_expr >= (arb_cap_t - (arb_cap_t - soc_low_t) * (1 - w_arb[t]))
         prob += bd[t] <= (
             s.load_baseline_w
             + ev_total_t