diff --git a/technic/machines/LV/alloy_furnace.lua b/technic/machines/LV/alloy_furnace.lua
index bdf2f31..56f0037 100644
--- a/technic/machines/LV/alloy_furnace.lua
+++ b/technic/machines/LV/alloy_furnace.lua
@@ -10,5 +10,5 @@ minetest.register_craft({
 	}
 })
 
-technic.register_alloy_furnace({tier = "LV", speed = 1, demand = {300}})
+technic.register_alloy_furnace({tier = "LV", speed = 1, demand = 300})
 
diff --git a/technic/machines/LV/compressor.lua b/technic/machines/LV/compressor.lua
index e2bde40..3344615 100644
--- a/technic/machines/LV/compressor.lua
+++ b/technic/machines/LV/compressor.lua
@@ -10,4 +10,4 @@ minetest.register_craft({
 	}
 })
 
-technic.register_compressor({tier = "LV", demand = {300}, speed = 1})
+technic.register_compressor({tier = "LV", demand = 300, speed = 1})
diff --git a/technic/machines/LV/electric_furnace.lua b/technic/machines/LV/electric_furnace.lua
index cc4daff..c083e7e 100644
--- a/technic/machines/LV/electric_furnace.lua
+++ b/technic/machines/LV/electric_furnace.lua
@@ -11,6 +11,6 @@ minetest.register_craft({
 	}
 })
 
-technic.register_electric_furnace({tier="LV", demand={300}, speed = 2})
+technic.register_electric_furnace({tier="LV", demand=300, speed = 2})
 
 
diff --git a/technic/machines/LV/extractor.lua b/technic/machines/LV/extractor.lua
index 363d2e3..86aea5c 100644
--- a/technic/machines/LV/extractor.lua
+++ b/technic/machines/LV/extractor.lua
@@ -10,4 +10,4 @@ minetest.register_craft({
 	}
 })
 
-technic.register_extractor({tier = "LV", demand = {300}, speed = 1})
+technic.register_extractor({tier = "LV", demand = 300, speed = 1})
diff --git a/technic/machines/LV/grinder.lua b/technic/machines/LV/grinder.lua
index da9ea29..ba8aa92 100644
--- a/technic/machines/LV/grinder.lua
+++ b/technic/machines/LV/grinder.lua
@@ -9,5 +9,5 @@ minetest.register_craft({
 	}
 })
 
-technic.register_grinder({tier="LV", demand={200}, speed=1})
+technic.register_grinder({tier="LV", demand=200, speed=1})
 
diff --git a/technic/machines/MV/alloy_furnace.lua b/technic/machines/MV/alloy_furnace.lua
index a1918fd..ae08350 100644
--- a/technic/machines/MV/alloy_furnace.lua
+++ b/technic/machines/MV/alloy_furnace.lua
@@ -10,5 +10,5 @@ minetest.register_craft({
 })
 
 
-technic.register_alloy_furnace({tier = "MV", speed = 1.5, upgrade = 1, tube = 1, demand = {3000, 2000, 1000}})
+technic.register_alloy_furnace({tier = "MV", speed = 1.5, upgrade = 1, tube = 1, demand = 3000, demand_reduction_factor=0.65 })
 
diff --git a/technic/machines/MV/centrifuge.lua b/technic/machines/MV/centrifuge.lua
index 5bf24bf..087dd46 100644
--- a/technic/machines/MV/centrifuge.lua
+++ b/technic/machines/MV/centrifuge.lua
@@ -9,7 +9,8 @@ minetest.register_craft({
 
 technic.register_centrifuge({
 	tier = "MV",
-	demand = { 8000, 7000, 6000 },
+	demand = 8000,
+	demand_reduction_factor=0.25,
 	speed = 2,
 	upgrade = 1,
 	tube = 1,
diff --git a/technic/machines/MV/electric_furnace.lua b/technic/machines/MV/electric_furnace.lua
index 1f6b1c2..97f583f 100644
--- a/technic/machines/MV/electric_furnace.lua
+++ b/technic/machines/MV/electric_furnace.lua
@@ -9,10 +9,10 @@ minetest.register_craft({
 	output = 'technic:mv_electric_furnace',
 	recipe = {
 		{'technic:stainless_steel_ingot', 'technic:lv_electric_furnace', 'technic:stainless_steel_ingot'},
-		{'pipeworks:tube_1',         'technic:mv_transformer',      'pipeworks:tube_1'},
+		{'pipeworks:tube_1',              'technic:mv_transformer',      'pipeworks:tube_1'},
 		{'technic:stainless_steel_ingot', 'technic:mv_cable0',           'technic:stainless_steel_ingot'},
 	}
 })
 
-technic.register_electric_furnace({tier="MV", upgrade=1, tube=1, demand={2000, 1000, 500}, speed=4})
+technic.register_electric_furnace({tier="MV", upgrade=1, tube=1, demand=2000, demand_reduction_factor=0.75, speed=4})
 
diff --git a/technic/machines/MV/extractor.lua b/technic/machines/MV/extractor.lua
index fdef5b2..e3103e0 100644
--- a/technic/machines/MV/extractor.lua
+++ b/technic/machines/MV/extractor.lua
@@ -9,4 +9,4 @@ minetest.register_craft({
 	}
 })
 
-technic.register_extractor({tier = "MV", demand = {800, 600, 400}, speed = 2, upgrade = 1, tube = 1})
+technic.register_extractor({tier = "MV", demand = 800, demand_reduction_factor=0.5, speed = 2, upgrade = 1, tube = 1})
diff --git a/technic/machines/MV/grinder.lua b/technic/machines/MV/grinder.lua
index dac536c..2a5f3cf 100644
--- a/technic/machines/MV/grinder.lua
+++ b/technic/machines/MV/grinder.lua
@@ -9,5 +9,5 @@ minetest.register_craft({
 	}
 })
 
-technic.register_grinder({tier="MV", demand={600, 450, 300}, speed=2, upgrade=1, tube=1})
+technic.register_grinder({tier="MV", demand=600, demand_reduction_factor=0.5, speed=2, upgrade=1, tube=1})
 
diff --git a/technic/machines/MV/tool_workshop.lua b/technic/machines/MV/tool_workshop.lua
index cc54001..3cdad4a 100644
--- a/technic/machines/MV/tool_workshop.lua
+++ b/technic/machines/MV/tool_workshop.lua
@@ -14,14 +14,15 @@ minetest.register_craft({
 	}
 })
 
-local workshop_demand = {5000, 3500, 2000}
+local workshop_demand = 5000
+local workshop_demand_reduction_factor = 0.6
+local num_upgrade_slots = 2
 
 local workshop_formspec =
 	"invsize[8,9;]"..
 	"list[current_name;src;3,1;1,1;]"..
 	"label[0,0;"..S("%s Tool Workshop"):format("MV").."]"..
-	"list[current_name;upgrade1;1,3;1,1;]"..
-	"list[current_name;upgrade2;2,3;1,1;]"..
+	"list[current_name;upgrades;1,3;" .. num_upgrade_slots .. ",1;]"..
 	"label[1,4;"..S("Upgrade Slots").."]"..
 	"list[current_player;main;0,5;8,4;]"..
 	"listring[current_player;main]"..
@@ -41,13 +42,20 @@ local run = function(pos, node)
 
 	-- Setup meta data if it does not exist.
 	if not eu_input then
-		meta:set_int("MV_EU_demand", workshop_demand[1])
+		meta:set_int("MV_EU_demand", workshop_demand)
 		meta:set_int("MV_EU_input", 0)
 		return
 	end
 
+	-- Do compatibility updates if needed.
+	technic.transfer_upgrades_to_new_upgrade_inventory(meta, formspec, num_upgrade_slots)
+
 	local EU_upgrade, tube_upgrade = technic.handle_machine_upgrades(meta)
 
+	-- Calculate the required EUs based on the normalized number of battery upgrades.
+	local norm_eu_upgrade = technic.normalize_value(EU_upgrade, 0, num_upgrade_slots)
+	local total_required_power = workshop_demand - ((workshop_demand * workshop_demand_reduction_factor) * norm_eu_upgrade)
+
 	local repairable = false
 	local srcstack = inv:get_stack("src", 1)
 	if not srcstack:is_empty() then
@@ -70,14 +78,14 @@ local run = function(pos, node)
 		return
 	end
 	
-	if eu_input < workshop_demand[EU_upgrade+1] then
+	if eu_input < total_required_power then
 		meta:set_string("infotext", S("%s Unpowered"):format(machine_name))
-	elseif eu_input >= workshop_demand[EU_upgrade+1] then
+	elseif eu_input >= total_required_power then
 		meta:set_string("infotext", S("%s Active"):format(machine_name))
 		srcstack:add_wear(-1000)
 		inv:set_stack("src", 1, srcstack)
 	end
-	meta:set_int("MV_EU_demand", workshop_demand[EU_upgrade+1])
+	meta:set_int("MV_EU_demand", total_required_power)
 end
 
 minetest.register_node("technic:tool_workshop", {
@@ -92,8 +100,7 @@ minetest.register_node("technic:tool_workshop", {
 		meta:set_string("formspec", workshop_formspec)
 		local inv = meta:get_inventory()
 		inv:set_size("src", 1)
-		inv:set_size("upgrade1", 1)
-		inv:set_size("upgrade2", 1)
+		inv:set_size("upgrades", num_upgrade_slots)
 	end,	
 	can_dig = technic.machine_can_dig,
 	allow_metadata_inventory_put = technic.machine_inventory_put,
diff --git a/technic/machines/register/battery_box.lua b/technic/machines/register/battery_box.lua
index 82edca0..ecf45ba 100644
--- a/technic/machines/register/battery_box.lua
+++ b/technic/machines/register/battery_box.lua
@@ -77,14 +77,13 @@ function technic.register_battery_box(data)
 		"listring[current_name;src]"..
 		"listring[current_player;main]"
 
+	local num_upgrade_slots = 2
+
 	if data.upgrade then
 		formspec = formspec..
-			"list[current_name;upgrade1;3.5,3;1,1;]"..
-			"list[current_name;upgrade2;4.5,3;1,1;]"..
-			"label[3.5,4;"..S("Upgrade Slots").."]"..
-			"listring[current_name;upgrade1]"..
-			"listring[current_player;main]"..
-			"listring[current_name;upgrade2]"..
+			"list[current_name;upgrades;3,3;"..num_upgrade_slots..",1;]"..
+			"label[3,4;"..S("Upgrade Slots").."]"..
+			"listring[current_name;upgrades]"..
 			"listring[current_player;main]"
 	end
 
@@ -93,12 +92,15 @@ function technic.register_battery_box(data)
 		local eu_input       = meta:get_int(tier.."_EU_input")
 		local current_charge = meta:get_int("internal_EU_charge")
 
+		-- Do compatibility updates if needed.
+		technic.transfer_upgrades_to_new_upgrade_inventory(meta, formspec, num_upgrade_slots)
+
 		local EU_upgrade, tube_upgrade = 0, 0
 		if data.upgrade then
 			EU_upgrade, tube_upgrade = technic.handle_machine_upgrades(meta)
 		end
 		local max_charge = data.max_charge * (1 + EU_upgrade / 10)
-			
+
 		-- Charge/discharge the battery with the input EUs
 		if eu_input >= 0 then
 			current_charge = math.min(current_charge + eu_input, max_charge)
@@ -113,7 +115,7 @@ function technic.register_battery_box(data)
 		current_charge, tool_empty = technic.discharge_tools(meta,
 				current_charge, data.discharge_step,
 				max_charge)
-			
+
 		if data.tube then
 			local inv = meta:get_inventory()
 			technic.handle_machine_pipeworks(pos, tube_upgrade,
@@ -173,10 +175,10 @@ function technic.register_battery_box(data)
 			description = S("%s Battery Box"):format(tier),
 			tiles = {"technic_"..ltier.."_battery_box_top.png",
 			         "technic_"..ltier.."_battery_box_bottom.png",
-				 "technic_"..ltier.."_battery_box_side.png^technic_power_meter"..i..".png",
-				 "technic_"..ltier.."_battery_box_side.png^technic_power_meter"..i..".png",
-				 "technic_"..ltier.."_battery_box_side.png^technic_power_meter"..i..".png",
-				 "technic_"..ltier.."_battery_box_side.png^technic_power_meter"..i..".png"},
+			         "technic_"..ltier.."_battery_box_side.png^technic_power_meter"..i..".png",
+			         "technic_"..ltier.."_battery_box_side.png^technic_power_meter"..i..".png",
+			         "technic_"..ltier.."_battery_box_side.png^technic_power_meter"..i..".png",
+			         "technic_"..ltier.."_battery_box_side.png^technic_power_meter"..i..".png"},
 			groups = groups,
 			tube = data.tube and tube or nil,
 			paramtype2 = "facedir",
@@ -195,8 +197,7 @@ function technic.register_battery_box(data)
 				meta:set_float("internal_EU_charge", 0)
 				inv:set_size("src", 1)
 				inv:set_size("dst", 1)
-				inv:set_size("upgrade1", 1)
-				inv:set_size("upgrade2", 1)
+				inv:set_size("upgrades", num_upgrade_slots)
 			end,
 			can_dig = technic.machine_can_dig,
 			allow_metadata_inventory_put = technic.machine_inventory_put,
diff --git a/technic/machines/register/common.lua b/technic/machines/register/common.lua
index aa8ec9c..e573d30 100644
--- a/technic/machines/register/common.lua
+++ b/technic/machines/register/common.lua
@@ -1,65 +1,134 @@
 
 local S = technic.getter
 
--- handles the machine upgrades every tick
-function technic.handle_machine_upgrades(meta)
-	-- Get the names of the upgrades
+
+
+-- A function to normalize a value. The output floating-point value should
+-- always be in the range [0, 1].
+function technic.normalize_value(value, lower, upper)
+	value = value - lower
+	upper = upper - lower
+	return value / upper
+end
+
+
+
+-- This function is defined because the same compatibility code needs to be run
+-- in three different places. This function can be removed once we are
+-- reasonably sure that everyone is updated.
+function technic.transfer_upgrades_to_new_upgrade_inventory(meta, new_formspec, new_inv_size)
 	local inv = meta:get_inventory()
 
-	local srcstack = inv:get_stack("upgrade1", 1)
-	local upg_item1 = srcstack and srcstack:get_name()
-
-	srcstack = inv:get_stack("upgrade2", 1)
-	local upg_item2 = srcstack and srcstack:get_name()
-
-	-- Save some power by installing battery upgrades.
-	-- Tube loading speed can be upgraded using control logic units.
-	local EU_upgrade = 0
-	local tube_upgrade = 0
-
-	if upg_item1 == "technic:control_logic_unit" then
-		tube_upgrade = tube_upgrade + 1
-	elseif upg_item1 == "technic:battery" then
-		EU_upgrade = EU_upgrade + 1
+	-- Compatibility code. Move upgrade items from the (now depreciated)
+	-- upgrade inventory lists into the new unified upgrade list. This code
+	-- assumes that the new upgrade inventory size is at least 2.
+	if inv:get_size("upgrade1") > 0 then
+		assert(new_inv_size >= 2)
+		local upg1 = "upgrade1"
+		local upg2 = "upgrade2"
+		local new_list = "upgrades"
+		inv:set_size(new_list, new_inv_size)
+		local stack1 = inv:get_stack(upg1, 1)
+		local stack2 = inv:get_stack(upg2, 1)
+		if stack1 and stack1:get_count() > 0 then
+			inv:set_stack(new_list, 1, stack1)
+			inv:remove_item(upg1, stack1)
+		end
+		if stack2 and stack2:get_count() > 0 then
+			inv:set_stack(new_list, 2, stack2)
+			inv:remove_item(upg2, stack2)
+		end
+		-- Update the formspec.
+		meta:set_string("formspec", new_formspec)
+		inv:set_size(upg1, 0)
+		inv:set_size(upg2, 0)
 	end
-
-	if upg_item2 == "technic:control_logic_unit" then
-		tube_upgrade = tube_upgrade + 1
-	elseif  upg_item2 == "technic:battery" then
-		EU_upgrade = EU_upgrade + 1
-	end
-
-	return EU_upgrade, tube_upgrade
 end
 
--- handles the machine upgrades when set or removed
-local function on_machine_upgrade(meta, stack)
-	local stack_name = stack:get_name()
-	if stack_name == "default:chest" then
-		meta:set_int("public", 1)
-		return 1
-	elseif stack_name ~= "technic:control_logic_unit"
-	   and stack_name ~= "technic:battery" then
-		return 0
-	end
-	return 1
-end
 
--- something is about to be removed
-local function on_machine_downgrade(meta, stack, list)
-	if stack:get_name() == "default:chest" then
-		local inv = meta:get_inventory()
-		local upg1, upg2 = inv:get_stack("upgrade1", 1), inv:get_stack("upgrade2", 1)
 
-		-- only set 0 if theres not another chest in the other list too
-		if (not upg1 or not upg2 or upg1:get_name() ~= upg2:get_name()) then
-			meta:set_int("public", 0)
+-- Calculates the number & type of machine upgrades.
+function technic.handle_machine_upgrades(meta)
+	local inv = meta:get_inventory()
+	local clu = "technic:control_logic_unit"
+	local bat = "technic:battery"
+	local bat_upgrades = 0
+	local clu_upgrades = 0
+	local upgrade_list = "upgrades"
+	local num_upgrade_slots = inv:get_size(upgrade_list)
+
+	for i = 1, num_upgrade_slots, 1 do
+		local stack = inv:get_stack(upgrade_list, i)
+		if stack then
+			local item = stack:get_name()
+			-- Assume that each inv slot cannot have more than 1 upgrade item.
+			if item == bat then bat_upgrades = bat_upgrades + 1 end
+			if item == clu then clu_upgrades = clu_upgrades + 1 end
 		end
 	end
-	return 1
+
+	return bat_upgrades, clu_upgrades
 end
 
 
+
+-- Machine upgrade callback. Called when something is about to be added. Returns
+-- 'true' if the upgrade can be added, 'false' if not.
+local function on_machine_upgrade(player, meta, to_index, stack)
+	local clu = "technic:control_logic_unit"
+	local bat = "technic:battery"
+	local chest = "default:chest"
+	local player_name = player:get_player_name()
+	local inv = meta:get_inventory()
+
+	local item = stack:get_name()
+	if item == chest then
+		meta:set_int("public", 1)
+		return true
+	elseif item == clu then 
+		return true
+	elseif item == bat then 
+		return true
+	end
+
+	minetest.chat_send_player(player_name, S("That is not a valid upgrade item!"))
+	return false
+end
+
+
+
+-- Machine downgrade callback. Called just before something is removed.
+local function on_machine_downgrade(player, meta, from_index, stack)
+	local chest = "default:chest"
+	if stack:get_name() == chest then
+		local inv = meta:get_inventory()
+
+		local upgrade_list = "upgrades"
+		local num_upgrade_slots = inv:get_size(upgrade_list)
+
+		-- Check if any of the upgrade slots contain a chest.
+		local has_chest = false
+		for i = 1, num_upgrade_slots, 1 do
+			if i ~= from_index then -- Skip the chest that's about to be removed.
+				local stack = inv:get_stack(upgrade_list, i)
+				if stack then
+					local item = stack:get_name()
+					if item == chest then 
+						has_chest = true
+						break -- If one chest is found, we don't need to look for more.
+					end
+				end
+			end
+		end
+
+		-- If none of the upgrade slots contains a chest, the machine is no longer
+		-- publicly accessible.
+		if has_chest == false then meta:set_int("public", 0) end
+	end
+end
+
+
+
 function technic.send_items(pos, x_velocity, z_velocity, output_name, item_count)
 	-- Send items on their way in the pipe system.
 	if output_name == nil then
@@ -136,8 +205,8 @@ function technic.handle_machine_pipeworks(pos, tube_upgrade, send_function, item
 	local eject_count = meta:get_int("eject_count") + items_processed_this_cycle
 	meta:set_int("eject_count", eject_count)
 
-	local tube_upgrade_max = 2
-	local norm_tube_upgrade = tube_upgrade / tube_upgrade_max
+	local num_upgrade_slots = inv:get_size("upgrades")
+	local norm_tube_upgrade = technic.normalize_value(tube_upgrade, 0, num_upgrade_slots)
 	local stack_size = 11
 	local tube_time = meta:get_int("tube_time") + 1
 
@@ -174,10 +243,12 @@ end
 function technic.machine_can_dig(pos, player)
 	local meta = minetest.get_meta(pos)
 	local inv = meta:get_inventory()
+
 	if not inv:is_empty("src") or not inv:is_empty("dst") then
 		if player then
-			minetest.chat_send_player(player:get_player_name(),
-				S("Machine cannot be removed because it is not empty"))
+			local name = player:get_player_name()
+			minetest.chat_send_player(
+				name, S("Machine cannot be removed because it is not empty"))
 		end
 		return false
 	end
@@ -187,16 +258,15 @@ end
 
 function technic.machine_after_dig_node(pos, oldnode, oldmetadata, player)
 	if oldmetadata.inventory then
-		if oldmetadata.inventory.upgrade1 and oldmetadata.inventory.upgrade1[1] then
-			local stack = ItemStack(oldmetadata.inventory.upgrade1[1])
-			if not stack:is_empty() then
-				minetest.item_drop(stack, "", pos)
-			end
-		end
-		if oldmetadata.inventory.upgrade2 and oldmetadata.inventory.upgrade2[1] then
-			local stack = ItemStack(oldmetadata.inventory.upgrade2[1])
-			if not stack:is_empty() then
-				minetest.item_drop(stack, "", pos)
+		if oldmetadata.inventory.upgrades then
+			local num_upgrade_slots = #(oldmetadata.inventory.upgrades)
+			for i = 1, num_upgrade_slots, 1 do
+				if oldmetadata.inventory.upgrades[i] then
+					local stack = ItemStack(oldmetadata.inventory.upgrades[i])
+					if not stack:is_empty() then
+						minetest.add_item(pos, stack)
+					end
+				end
 			end
 		end
 	end
@@ -206,42 +276,52 @@ function technic.machine_after_dig_node(pos, oldnode, oldmetadata, player)
 	end
 end
 
-local function inv_change(pos, player, count, from_list, to_list, stack)
-	local playername = player:get_player_name()
-	local meta = minetest.get_meta(pos);
-	local public = (meta:get_int("public") == 1)
-	local to_upgrade = to_list == "upgrade1" or to_list == "upgrade2"
-	local from_upgrade = from_list == "upgrade1" or from_list == "upgrade2"
 
-	if (not public or to_upgrade or from_upgrade) and minetest.is_protected(pos, playername) then
-		minetest.chat_send_player(playername, S("Inventory move disallowed due to protection"))
+
+local function inv_change(pos, player, count, from_list, from_index, to_list, to_index, stack)
+	local player_name = player:get_player_name()
+	local meta = minetest.get_meta(pos)
+	local public = (meta:get_int("public") == 1)
+	local is_upgrade = (to_list == "upgrades")
+	local is_downgrade = (from_list == "upgrades")
+
+	if (not public or is_upgrade or is_downgrade) and minetest.is_protected(pos, player_name) then
+		minetest.chat_send_player(player_name, S("Inventory move disallowed due to protection"))
 		return 0
 	end
-	if to_upgrade then
-		-- only place a single item into it, if it's empty
-		local empty = meta:get_inventory():is_empty(to_list)
-		if empty then
-			return on_machine_upgrade(meta, stack)
+
+	if is_upgrade then
+		local previous_stack = meta:get_inventory():get_stack("upgrades", to_index)
+		-- Only place a single item into the upgrade slot, if it is empty.
+		if previous_stack:get_count() == 0 then
+			if on_machine_upgrade(player, meta, to_index, stack) then
+				count = 1
+			else
+				count = 0
+			end
+		else
+			count = 0
 		end
-		return 0
-	elseif from_upgrade then
-		-- only called on take (not move)
-		on_machine_downgrade(meta, stack, from_list)
+	elseif is_downgrade then
+		-- Only called on take (not move).
+		on_machine_downgrade(player, meta, from_index, stack)
 	end
+
 	return count
 end
 
-function technic.machine_inventory_put(pos, listname, index, stack, player)
-	return inv_change(pos, player, stack:get_count(), nil, listname, stack)
+
+
+function technic.machine_inventory_put(pos, to_list, to_index, stack, player)
+	return inv_change(pos, player, stack:get_count(), nil, nil, to_list, to_index, stack)
 end
 
-function technic.machine_inventory_take(pos, listname, index, stack, player)
-	return inv_change(pos, player, stack:get_count(), listname, nil, stack)
+function technic.machine_inventory_take(pos, from_list, from_index, stack, player)
+	return inv_change(pos, player, stack:get_count(), from_list, from_index, nil, nil, stack)
 end
 
-function technic.machine_inventory_move(pos, from_list, from_index,
-		to_list, to_index, count, player)
+function technic.machine_inventory_move(pos, from_list, from_index, to_list, to_index, count, player)
 	local stack = minetest.get_meta(pos):get_inventory():get_stack(from_list, from_index)
-	return inv_change(pos, player, count, from_list, to_list, stack)
+	return inv_change(pos, player, count, from_list, from_index, to_list, to_index, stack)
 end
 
diff --git a/technic/machines/register/machine_base.lua b/technic/machines/register/machine_base.lua
index 361f491..9062c42 100644
--- a/technic/machines/register/machine_base.lua
+++ b/technic/machines/register/machine_base.lua
@@ -26,6 +26,7 @@ function technic.register_base_machine(data)
 	local machine_desc = data.machine_desc
 	local tier = data.tier
 	local ltier = string.lower(tier)
+	local num_upgrade_slots = data.upgrade_slots or 2
 
 	local groups = {cracky = 2, technic_machine = 1}
 	local active_groups = {cracky = 2, technic_machine = 1, not_in_creative_inventory = 1}
@@ -36,7 +37,6 @@ function technic.register_base_machine(data)
 		active_groups.tubedevice_receiver = 1
 	end
 
-
 	local formspec =
 		"invsize[8,9;]"..
 		"list[current_name;src;"..(4-input_size)..",1;"..input_size..",1;]"..
@@ -49,12 +49,9 @@ function technic.register_base_machine(data)
 		"listring[current_player;main]"
 	if data.upgrade then
 		formspec = formspec..
-			"list[current_name;upgrade1;1,3;1,1;]"..
-			"list[current_name;upgrade2;2,3;1,1;]"..
-			"label[1,4;"..S("Upgrade Slots").."]"..
-			"listring[current_name;upgrade1]"..
-			"listring[current_player;main]"..
-			"listring[current_name;upgrade2]"..
+			"list[current_name;upgrades;0,3;"..num_upgrade_slots..",1;]"..
+			"label[0,4;"..S("Upgrade Slots").."]"..
+			"listring[current_name;upgrades]"..
 			"listring[current_player;main]"
 	end
 
@@ -67,19 +64,31 @@ function technic.register_base_machine(data)
 		local machine_node      = "technic:"..ltier.."_"..machine_name
 		local machine_demand    = data.demand
 
+		-- This is the percentage by which the base demand may be reduced by a
+		-- complete complement of battery upgrades. Fewer battery upgrades than the
+		-- maximum possible will reduce the total demand by less than this.
+		local machine_demand_reduction_factor = data.demand_reduction_factor or 0.0
+
 		-- Setup meta data if it does not exist.
 		if not eu_input then
-			meta:set_int(tier.."_EU_demand", machine_demand[1])
+			meta:set_int(tier.."_EU_demand", machine_demand)
 			meta:set_int(tier.."_EU_input", 0)
 			return
 		end
 
+		-- Do compatibility updates if needed.
+		technic.transfer_upgrades_to_new_upgrade_inventory(meta, formspec, num_upgrade_slots)
+
 		local EU_upgrade, tube_upgrade = 0, 0
 		if data.upgrade then
 			EU_upgrade, tube_upgrade = technic.handle_machine_upgrades(meta)
 		end
 
-		local powered = eu_input >= machine_demand[EU_upgrade+1]
+		-- Calculate the required EUs based on the normalized number of battery upgrades.
+		local norm_eu_upgrade = technic.normalize_value(EU_upgrade, 0, num_upgrade_slots)
+		local total_required_power = machine_demand - ((machine_demand * machine_demand_reduction_factor) * norm_eu_upgrade)
+
+		local powered = eu_input >= total_required_power
 		if powered then
 			meta:set_int("src_time", meta:get_int("src_time") + round(data.speed*10))
 		end
@@ -95,7 +104,7 @@ function technic.register_base_machine(data)
 				meta:set_int("src_time", 0)
 				break
 			end
-			meta:set_int(tier.."_EU_demand", machine_demand[EU_upgrade+1])
+			meta:set_int(tier.."_EU_demand", total_required_power)
 			technic.swap_node(pos, machine_node.."_active")
 			meta:set_string("infotext", S("%s Active"):format(machine_desc_tier))
 			if meta:get_int("src_time") < round(result.time*10) then
@@ -158,8 +167,7 @@ function technic.register_base_machine(data)
 			local inv = meta:get_inventory()
 			inv:set_size("src", input_size)
 			inv:set_size("dst", 4)
-			inv:set_size("upgrade1", 1)
-			inv:set_size("upgrade2", 1)
+			inv:set_size("upgrades", num_upgrade_slots)
 		end,
 		can_dig = technic.machine_can_dig,
 		allow_metadata_inventory_put = technic.machine_inventory_put,
diff --git a/wrench/technic.lua b/wrench/technic.lua
index c404180..22460df 100644
--- a/wrench/technic.lua
+++ b/wrench/technic.lua
@@ -75,7 +75,7 @@ wrench:register_node("technic:lv_electric_furnace_active", {
 		src_time = INT},
 })
 wrench:register_node("technic:mv_electric_furnace", {
-	lists = {"src", "dst", "upgrade1", "upgrade2"},
+	lists = {"src", "dst", "upgrade1", "upgrade2", "upgrades"},
 	metas = {infotext = STRING,
 		formspec = STRING,
 		MV_EU_demand = INT,
@@ -84,7 +84,7 @@ wrench:register_node("technic:mv_electric_furnace", {
 		src_time = INT},
 })
 wrench:register_node("technic:mv_electric_furnace_active", {
-	lists = {"src", "dst", "upgrade1", "upgrade2"},
+	lists = {"src", "dst", "upgrade1", "upgrade2", "upgrades"},
 	metas = {infotext = STRING,
 		formspec = STRING,
 		MV_EU_demand = INT,
@@ -127,7 +127,7 @@ wrench:register_node("technic:alloy_furnace_active", {
 		src_time = INT},
 })
 wrench:register_node("technic:mv_alloy_furnace", {
-	lists = {"src", "dst", "upgrade1", "upgrade2"},
+	lists = {"src", "dst", "upgrade1", "upgrade2", "upgrades"},
 	metas = {infotext = STRING,
 		formspec = STRING,
 		MV_EU_demand = INT,
@@ -136,7 +136,7 @@ wrench:register_node("technic:mv_alloy_furnace", {
 		src_time = INT},
 })
 wrench:register_node("technic:mv_alloy_furnace_active", {
-	lists = {"src", "dst", "upgrade1", "upgrade2"},
+	lists = {"src", "dst", "upgrade1", "upgrade2", "upgrades"},
 	metas = {infotext = STRING,
 		formspec = STRING,
 		MV_EU_demand = INT,
@@ -145,7 +145,7 @@ wrench:register_node("technic:mv_alloy_furnace_active", {
 		src_time = INT},
 })
 wrench:register_node("technic:tool_workshop", {
-	lists = {"src", "upgrade1", "upgrade2"},
+	lists = {"src", "upgrade1", "upgrade2", "upgrades"},
 	metas = {infotext = STRING,
 		formspec = STRING,
 		MV_EU_demand = INT,
@@ -169,7 +169,7 @@ wrench:register_node("technic:grinder_active", {
 		src_time = INT},
 })
 wrench:register_node("technic:mv_grinder", {
-	lists = {"src", "dst", "upgrade1", "upgrade2"},
+	lists = {"src", "dst", "upgrade1", "upgrade2", "upgrades"},
 	metas = {infotext = STRING,
 		formspec = STRING,
 		MV_EU_demand = INT,
@@ -178,7 +178,7 @@ wrench:register_node("technic:mv_grinder", {
 		src_time = INT},
 })
 wrench:register_node("technic:mv_grinder_active", {
-	lists = {"src", "dst", "upgrade1", "upgrade2"},
+	lists = {"src", "dst", "upgrade1", "upgrade2", "upgrades"},
 	metas = {infotext = STRING,
 		formspec = STRING,
 		MV_EU_demand = INT,
@@ -203,7 +203,7 @@ wrench:register_node("technic:extractor_active", {
 		src_time = INT},
 })
 wrench:register_node("technic:mv_extractor", {
-	lists = {"src", "dst", "upgrade1", "upgrade2"},
+	lists = {"src", "dst", "upgrade1", "upgrade2", "upgrades"},
 	metas = {infotext = STRING,
 		formspec = STRING,
 		MV_EU_demand = INT,
@@ -212,7 +212,7 @@ wrench:register_node("technic:mv_extractor", {
 		src_time = INT},
 })
 wrench:register_node("technic:mv_extractor_active", {
-	lists = {"src", "dst", "upgrade1", "upgrade2"},
+	lists = {"src", "dst", "upgrade1", "upgrade2", "upgrades"},
 	metas = {infotext = STRING,
 		formspec = STRING,
 		MV_EU_demand = INT,
@@ -237,7 +237,7 @@ wrench:register_node("technic:compressor_active", {
 		src_time = INT},
 })
 wrench:register_node("technic:mv_compressor", {
-	lists = {"src", "dst", "upgrade1", "upgrade2"},
+	lists = {"src", "dst", "upgrade1", "upgrade2", "upgrades"},
 	metas = {infotext = STRING,
 		formspec = STRING,
 		MV_EU_demand = INT,
@@ -246,7 +246,7 @@ wrench:register_node("technic:mv_compressor", {
 		src_time = INT},
 })
 wrench:register_node("technic:mv_compressor_active", {
-	lists = {"src", "dst", "upgrade1", "upgrade2"},
+	lists = {"src", "dst", "upgrade1", "upgrade2", "upgrades"},
 	metas = {infotext = STRING,
 		formspec = STRING,
 		MV_EU_demand = INT,
@@ -273,7 +273,7 @@ wrench:register_node("technic:cnc_active", {
 		cnc_product = STRING},
 })
 wrench:register_node("technic:mv_centrifuge", {
-	lists = {"src", "dst", "upgrade1", "upgrade2"},
+	lists = {"src", "dst", "upgrade1", "upgrade2", "upgrades"},
 	metas = {infotext = STRING,
 		formspec = STRING,
 		MV_EU_demand = INT,
@@ -282,7 +282,7 @@ wrench:register_node("technic:mv_centrifuge", {
 		src_time = INT},
 })
 wrench:register_node("technic:mv_centrifuge_active", {
-	lists = {"src", "dst", "upgrade1", "upgrade2"},
+	lists = {"src", "dst", "upgrade1", "upgrade2", "upgrades"},
 	metas = {infotext = STRING,
 		formspec = STRING,
 		MV_EU_demand = INT,