Why do batteries use steel

data.lua

@@ -42,6 +42,9 @@ data.raw["recipe"]["fast-transport-belt"].ingredients = {
 data.raw["recipe"]["solar-panel"].ingredients = {
   {type="item", name="iron-gear-wheel", amount=5}
 }
+data.raw["recipe"]["solar-panel-equipment"].ingredients = {
+  {type="item", name="iron-gear-wheel", amount=5}
+}
  
 --Change electric poles
 --realistically this would short circut
@@ -96,3 +99,18 @@ data.raw["module"]["speed-module-3"].stack_size = 5
 data.raw["recipe"]["landfill"].ingredients = {
   {type="item", name="stone", amount=25}
 }
+--make personal roboport cheaper
+data.raw["recipe"]["personal-roboport-equipment"].ingredients = {
+  {type="item", name="advanced-circuit", amount=5},
+  {type="item", name="battery", amount=20},
+  {type="item", name="iron-gear-wheel", amount=20}
+}
+--mk.2
+data.raw["recipe"]["personal-mk2-equipment"].ingredients = {
+  {type="item", name="advanced-circuit", amount=10},
+  {type="item", name="battery", amount=40},
+  {type="item", name="iron-gear-wheel", amount=40}
+}
+data.raw["recipe"]["battery-equipment"].ingredients = {
+  {type = "item", name = "iron-plate", amount = 10}
+}