diff --git a/de_react_auto b/de_react_auto
index 1180202..dd66d95 100644
--- a/de_react_auto
+++ b/de_react_auto
@@ -522,9 +522,9 @@ local function processStateMachine()
     end
 
     if reactorStatus == "running" then
-        local chargeThreshold = CONFIG.charge_field_target * 0.9
-        if fieldStrength < chargeThreshold then
-            setState(STATES.CHARGING, "field " .. fieldPct .. " < " .. formatPercent(chargeThreshold) .. " threshold")
+        local minThreshold = CONFIG.target_field_strength * 0.9  -- 90% of operational target (27% if target is 30%)
+        if fieldStrength < minThreshold then
+            setState(STATES.CHARGING, "field " .. fieldPct .. " < " .. formatPercent(minThreshold) .. " min threshold")
         elseif temp > CONFIG.critical_temperature then
             setState(STATES.COOLING, "temp " .. formatTemp(temp) .. " above critical " .. formatTemp(CONFIG.critical_temperature))
         else