diff --git a/de_react_auto b/de_react_auto
index e355b93..e2f02fe 100644
--- a/de_react_auto
+++ b/de_react_auto
@@ -326,7 +326,12 @@ local function calculateFieldInput()
 
     local drainRate = reactorInfo.fieldDrainRate
     local currentStrength = reactorInfo.fieldStrength / reactorInfo.maxFieldStrength
+
+    -- Use charge target during warmup/charging, operational target when running
     local targetStrength = CONFIG.target_field_strength
+    if state == STATES.CHARGING or state == STATES.WARMING_UP then
+        targetStrength = CONFIG.charge_field_target
+    end
 
     -- Base input = drain rate to maintain current level
     local baseInput = drainRate
@@ -339,8 +344,8 @@ local function calculateFieldInput()
     local totalInput = baseInput + correction
 
     -- SAFETY: Never return less than the drain rate (would cause field to drop)
-    -- Add 10% safety margin
-    local minimumInput = drainRate * 1.1
+    -- Add 10% safety margin, but ensure minimum of 1M RF/t during warmup when drain is 0
+    local minimumInput = math.max(drainRate * 1.1, 1000000)
 
     return math.max(minimumInput, math.floor(totalInput))
 end
@@ -567,7 +572,13 @@ local function controlReactor()
 
     elseif state == STATES.WARMING_UP then
         -- WARMING UP: Maintain field, slowly ramp output
-        inputRate = calculateFieldInput()
+        local maxField = reactorInfo.maxFieldStrength or 0
+        if maxField > 0 then
+            inputRate = calculateFieldInput()
+        else
+            -- maxFieldStrength not available yet - use emergency input
+            inputRate = CONFIG.emergency_field_input
+        end
         outputRate = calculateOutputRate()
 
     elseif state == STATES.RUNNING then