diff --git a/code/modules/mob/living/living_defense.dm b/code/modules/mob/living/living_defense.dm
index caa9a676cb2..a7af152daa9 100644
--- a/code/modules/mob/living/living_defense.dm
+++ b/code/modules/mob/living/living_defense.dm
@@ -202,8 +202,33 @@
 /mob/living/proc/electrocute_act(var/shock_damage, var/obj/source, var/siemens_coeff = 1.0, var/def_zone = null, var/tesla_shock = 0, var/ground_zero)
 	return 0 //only carbon liveforms have this proc
 
+/**
+ * Called a living mob is hit with an EMP effect. Returns the blocked result.
+ * Energy armor can downgrade or negate the effects of an EMP, and is checked here.
+ * The chance to reduce the effect is based on the average energy armor of the mob.
+ * A heavy EMP can only be downgraded to a light EMP.
+ * A light EMP can either be negated entirely, or only affect the mob's contents.
+ * Each step down is another chance equal to the average energy armor.
+ */
 /mob/living/emp_act(severity)
 	. = ..()
+	var/total_energy_armor = 0
+	var/limb_size_weight = 0
+
+	for (var/def_zone in BP_ALL_LIMBS)
+		var/list/armors = get_armors_by_zone(def_zone, DAMAGE_BURN, null)
+		for(var/datum/component/armor/armor_datum in armors)
+			total_energy_armor += armor_datum.get_value(ENERGY) * GLOB.organ_rel_size[def_zone]
+		limb_size_weight += GLOB.organ_rel_size[def_zone]
+
+	var/average_energy_armor = total_energy_armor / limb_size_weight
+
+	if(severity == EMP_LIGHT && prob(average_energy_armor))
+		if(prob(average_energy_armor))
+			return EMP_PROTECT_ALL
+		return EMP_PROTECT_CONTENTS
+	if(severity == EMP_HEAVY && prob(average_energy_armor))
+		severity = EMP_LIGHT
 
 	//If no protection of the contents, apply the EMP effect to the contents
 	if(!(. & EMP_PROTECT_CONTENTS))
diff --git a/code/modules/power/cell.dm b/code/modules/power/cell.dm
index b03b8fae665..bda3cf513d7 100644
--- a/code/modules/power/cell.dm
+++ b/code/modules/power/cell.dm
@@ -192,6 +192,7 @@
 	if (prob(10))
 		rigged = 1 //broken batterys are dangerous
 
+///A cell loses a random amount of charge, up to it's maxcharge, when it takes a heavy EMP, up to half it's maxcharge if hit by a light EMP.
 /obj/item/cell/emp_act(severity)
 	. = ..()
 
@@ -200,7 +201,8 @@
 		var/mob/living/silicon/robot/R = loc
 		severity *= R.cell_emp_mult
 
-	charge -= maxcharge / severity
+	if(severity)
+		charge -= rand(0, (maxcharge / severity))
 	if (charge < 0)
 		charge = 0
 	SEND_SIGNAL(src, COMSIG_CELL_CHARGE, charge)
diff --git a/html/changelogs/Fenodyree-EMPArmourChecksAndNerf.yml b/html/changelogs/Fenodyree-EMPArmourChecksAndNerf.yml
new file mode 100644
index 00000000000..f43c32815b0
--- /dev/null
+++ b/html/changelogs/Fenodyree-EMPArmourChecksAndNerf.yml
@@ -0,0 +1,7 @@
+author: Fenodyree
+
+delete-after: True
+
+changes:
+  - rscadd: "EMPs once again check energy armour. A heavy EMP can be downgraded to a light EMP, and a light EMP can be negated entirely or only affect the mob's contents. This chance is based on the average energy armour of the mob, weighted by limb size."
+  - balance: "The effect of an EMP on a power cell is now random. A light EMP can drain up to half the max charge, and a heavy EMP can drain up to the full max charge. Previously heavy would always drain the full max charge, and light would always drain half the max charge."