diff --git a/code/modules/clothing/spacesuits/rig/modules/computer.dm b/code/modules/clothing/spacesuits/rig/modules/computer.dm
index 9ec7d7e5d1..1b2befa59a 100644
--- a/code/modules/clothing/spacesuits/rig/modules/computer.dm
+++ b/code/modules/clothing/spacesuits/rig/modules/computer.dm
@@ -411,8 +411,14 @@
 		drain_complete(H)
 		return
 
-	// Attempts to drain up to 40kW
-	var/target_drained = interfaced_with.drain_power(0,0,40000)
+	if(holder.cell.fully_charged())
+		H << "<span class = 'warning'>Your power sink flashes an amber light; your rig cell is full.</span>"
+		drain_complete(H)
+		return
+
+	// Attempts to drain up to 40kW, determines this value from remaining cell capacity to ensure we don't drain too much..
+	var/to_drain = min(40000, ((holder.cell.maxcharge - holder.cell.charge) / CELLRATE))
+	var/target_drained = interfaced_with.drain_power(0,0,to_drain)
 	if(target_drained <= 0)
 		H << "<span class = 'danger'>Your power sink flashes a red light; there is no power left in [interfaced_with].</span>"
 		drain_complete(H)
@@ -421,19 +427,16 @@
 	holder.cell.give(target_drained * CELLRATE)
 	total_power_drained += target_drained
 
-	if(holder.cell.fully_charged())
-		H << "<span class = 'warning'>Your power sink flashes an amber light; your rig cell is full.</span>"
-		drain_complete(H)
-		return
+
 
 	return 1
 
 /obj/item/rig_module/power_sink/proc/drain_complete(var/mob/living/M)
 
 	if(!interfaced_with)
-		if(M) M << "<font color='blue'><b>Total power drained:</b> [total_power_drained]J.</font>"
+		if(M) M << "<font color='blue'><b>Total power drained:</b> [round(total_power_drained/1000)]kJ.</font>"
 	else
-		if(M) M << "<font color='blue'><b>Total power drained from [interfaced_with]:</b> [total_power_drained]J.</font>"
+		if(M) M << "<font color='blue'><b>Total power drained from [interfaced_with]:</b> [round(total_power_drained/1000)]kJ.</font>"
 		interfaced_with.drain_power(0,1,0) // Damage the victim.
 
 	interfaced_with = null
diff --git a/code/modules/power/cell.dm b/code/modules/power/cell.dm
index e6c7b0eec9..36ab1047a3 100644
--- a/code/modules/power/cell.dm
+++ b/code/modules/power/cell.dm
@@ -14,6 +14,9 @@
 	if(drain_check)
 		return 1
 
+	if(charge <= 0)
+		return 0
+
 	var/cell_amt = min((amount * CELLRATE), charge)
 	use(cell_amt)
 	return cell_amt / CELLRATE