step 2. make it a backpack mount and take power

code/datums/action.dm

@@ -253,6 +253,9 @@
 /datum/action/item_action/toggle_mister
 	name = "Toggle Mister"
 
+/datum/action/item_action/toggle_grinder
+	name = "Toggle Grinder"
+
 /datum/action/item_action/activate_injector
 	name = "Activate Injector"
 

code/datums/components/twohanded.dm

@@ -8,8 +8,8 @@
 	dupe_mode = COMPONENT_DUPE_UNIQUE_PASSARGS 		// Only one of the component can exist on an item
 	var/wielded = FALSE 							/// Are we holding the two handed item properly
 	var/force_multiplier = 0						/// The multiplier applied to force when wielded, does not work with force_wielded, and force_unwielded
-	var/force_wielded = 0	 						/// The force of the item when weilded
-	var/force_unwielded = 0		 					/// The force of the item when unweilded
+	var/force_wielded = 0	 						/// The force of the item when wielded
+	var/force_unwielded = 0		 					/// The force of the item when unwielded
 	var/wieldsound = FALSE 							/// Play sound when wielded
 	var/unwieldsound = FALSE 						/// Play sound when unwielded
 	var/attacksound = FALSE							/// Play sound on attack when wielded

code/modules/cargo/packs/tools.dm

@@ -107,9 +107,9 @@
 
 /datum/supply_pack/tools/anglegrinder
 	name = "Angle Grinder"
-	desc = "Contain one angle grinder, a tool used for quick structure deconstruction and salvaging"
-	cost = 1000
-	contains = list(/obj/item/anglegrinder)
+	desc = "Contains one angle grinder pack, a tool used for quick structure deconstruction and salvaging"
+	cost = 2000
+	contains = list(/obj/item/anglegrinderpack)
 	crate_name = "Angle Grinder"
 
 /*

code/modules/mining/equipment/angle_grinder.dm

@@ -1,43 +1,193 @@
-/*
- * Configure features by editing __DEFINES/anglegrinder.dm
-*/
+/obj/item/anglegrinderpack
+	name = "grinder pack"
+	desc = "Supplies the high voltage needed to run the attached grinder."
+	icon = 'icons/obj/mining.dmi'
+	item_state = "anglegrinderpack"
+	icon_state = "anglegrinderpack"
+	lefthand_file = 'icons/mob/inhands/equipment/backpack_lefthand.dmi'
+	righthand_file = 'icons/mob/inhands/equipment/backpack_righthand.dmi'
+	w_class = WEIGHT_CLASS_BULKY
+	slot_flags = ITEM_SLOT_BACK
+	slowdown = 1
+	actions_types = list(/datum/action/item_action/toggle_grinder)
+	max_integrity = 200
+	armor = list("melee" = 0, "bullet" = 0, "laser" = 0, "energy" = 0, "bomb" = 0, "bio" = 0, "rad" = 0, "fire" = 100, "acid" = 30)
+	resistance_flags = FIRE_PROOF
+	var/obj/item/anglegrinder/grinder
+	var/obj/item/stock_parts/cell/cell
+	var/preload_cell_type = /obj/item/stock_parts/cell/high
+	var/power_cost = 5
+
+/obj/item/anglegrinderpack/Initialize()
+	. = ..()
+	grinder = make_grinder()
+	if(preload_cell_type)
+		if(!ispath(preload_cell_type,/obj/item/stock_parts/cell))
+			log_mapping("[src] at [AREACOORD(src)] had an invalid preload_cell_type: [preload_cell_type].")
+		else
+			cell = new preload_cell_type(src)
+
+/obj/item/anglegrinderpack/Destroy()
+	QDEL_NULL(grinder)
+	return ..()
+
+/obj/item/anglegrinderpack/ui_action_click(mob/user)
+	toggle_grinder(user)
+
+/obj/item/anglegrinder/item_action_slot_check(slot, mob/user)
+	if(slot == user.getBackSlot())
+		return 1
+
+/obj/item/anglegrinderpack/proc/toggle_grinder(mob/living/user)
+	if(!istype(user))
+		return
+	if(user.get_item_by_slot(user.getBackSlot()) != src)
+		to_chat(user, "<span class='warning'>[src] must be worn properly to use!</span>")
+		return
+	if(user.incapacitated())
+		return
+	if(!cell || !cell.charge)
+		return
+
+	if(QDELETED(grinder))
+		grinder = make_grinder()
+	if(grinder in src)
+		//Detach the grinder into the user's hands
+		if(!user.put_in_hands(grinder))
+			to_chat(user, "<span class='warning'>You need a free hand to hold the grinder!</span>")
+			return
+	else
+		//Remove from their hands and put back "into" the pack
+		remove_grinder()
+
+/obj/item/anglegrinderpack/verb/toggle_grinder_verb()
+	set name = "Toggle Angle Grinder"
+	set category = "Object"
+	toggle_grinder(usr)
+
+/obj/item/anglegrinderpack/proc/make_grinder()
+	return new /obj/item/anglegrinder(src)
+
+/obj/item/anglegrinderpack/equipped(mob/user, slot)
+	..()
+	if(slot != ITEM_SLOT_BACK)
+		remove_grinder()
+
+/obj/item/anglegrinderpack/proc/remove_grinder()
+	if(!QDELETED(grinder))
+		if(ismob(grinder.loc))
+			var/mob/M = grinder.loc
+			M.temporarilyRemoveItemFromInventory(grinder, TRUE)
+		grinder.forceMove(src)
+
+/obj/item/anglegrinderpack/attack_hand(mob/user)
+	if (user.get_item_by_slot(user.getBackSlot()) == src)
+		toggle_grinder(user)
+	else
+		return ..()
+
+/obj/item/anglegrinderpack/MouseDrop(obj/over_object)
+	var/mob/M = loc
+	if(istype(M) && istype(over_object, /atom/movable/screen/inventory/hand))
+		var/atom/movable/screen/inventory/hand/H = over_object
+		M.putItemFromInventoryInHandIfPossible(src, H.held_index)
+	return ..()
+
+/obj/item/anglegrinderpack/attackby(obj/item/W, mob/user, params)
+	if(W == grinder)
+		remove_grinder()
+		return 1
+	else
+		return ..()
+
+/obj/item/anglegrinderpack/dropped(mob/user)
+	..()
+	remove_grinder()
+
+/obj/item/anglegrinderpack/proc/consume_charge(cost = power_cost)
+	if(cell.charge >= cost)
+		cell.charge -= cost
+		return TRUE
+	else
+		cell.charge = 0
+		remove_grinder()
+		return FALSE
+
+/obj/item/anglegrinderpack/attackby(obj/item/I, mob/living/user, params)
+	if(I.tool_behaviour == TOOL_SCREWDRIVER)
+		cell.update_appearance()
+		cell.forceMove(get_turf(src))
+		cell = null
+		to_chat(user, "<span class='notice'>You remove the cell from [src].</span>")
+		return
+	if(istype(I, /obj/item/stock_parts/cell))
+		var/obj/item/stock_parts/cell/newcell = I
+		if(cell)
+			to_chat(user, "<span class='warning'>[src] already has a cell!</span>")
+			return
+		else
+			if(newcell.maxcharge < power_cost)
+				to_chat(user, "<span class='notice'>[src] requires a higher capacity cell.</span>")
+				return
+		if(!user.transferItemToLoc(I, src))
+			return
+		cell = I
+		to_chat(user, "<span class='notice'>You install [cell] in [src].</span>")
+		return
+
+/obj/item/anglegrinderpack/examine(mob/user)
+	. = ..()
+	if(!cell)
+		. += "<spawn class='notice'>The cell is missing!</span>"
+	else
+		. += "<span class='notice'>[src] is [round(cell.percent())]% charged.</span>"
 
 /obj/item/anglegrinder
 	name = "angle grinder"
-	desc = "A powerful salvage tool used to cut apart walls and airlocks. A peeling hazard sticker recommends ear and eye protection."
+	desc = "A powerful salvage tool used to cut apart walls and airlocks. A hazard sticker recommends ear and eye protection."
 	icon = 'icons/obj/mining.dmi'
 	icon_state = "anglegrinder_off"
 	lefthand_file = 'icons/mob/inhands/weapons/chainsaw_lefthand.dmi'
 	righthand_file = 'icons/mob/inhands/weapons/chainsaw_righthand.dmi'
 	flags_1 = CONDUCT_1
 	force = 13
 	w_class = WEIGHT_CLASS_HUGE
-	slot_flags = ITEM_SLOT_BACK
-	slowdown = 1
-	throwforce = 13
-	throw_speed = 2
-	throw_range = 4
-	custom_materials = list(/datum/material/iron=13000)
+	item_flags = ABSTRACT
 	attack_verb = list("sliced", "torn", "cut", "chopped", "diced")
 	hitsound = 'sound/weapons/anglegrinder.ogg'
 	usesound = 'sound/weapons/anglegrinder.ogg'
 	sharpness = IS_SHARP
-	tool_behaviour = null // is set to TOOL_DECONSTRUCT once weildedk
+	tool_behaviour = null // is set to TOOL_DECONSTRUCT once wielded
 	toolspeed = 1
 	var/wielded = FALSE // track wielded status on item
+	var/obj/item/anglegrinderpack/pack
 
 // Trick to make the deconstruction that need a lit welder work. (bypassing fuel test)
 /obj/item/anglegrinder/tool_use_check(mob/living/user, amount)
-	return TRUE
+	if(pack.consume_charge())
+		return TRUE
+	else
+		to_chat(user, "<span class='warning'>You need more charge to complete this task!</span>")
+		return FALSE
 
 /obj/item/anglegrinder/use(used)
 	return TRUE
 
 /obj/item/anglegrinder/Initialize()
 	. = ..()
+	pack = loc
+	if(!istype(pack))
+		return INITIALIZE_HINT_QDEL
 	RegisterSignal(src, COMSIG_TWOHANDED_WIELD, PROC_REF(on_wield))
 	RegisterSignal(src, COMSIG_TWOHANDED_UNWIELD, PROC_REF(on_unwield))
 
+/obj/item/anglegrinder/doMove(atom/destination)
+	if(destination && (destination != pack.loc || !ismob(destination)))
+		if (loc != pack)
+			to_chat(pack.loc, "<span class='notice'>[src] snaps back onto [pack].</span>")
+		destination = pack
+	..()
+
 /obj/item/anglegrinder/ComponentInitialize()
 	. = ..()
 	AddComponent(/datum/component/butchering, 30, 100, 0, 'sound/weapons/anglegrinder.ogg', TRUE)