diff --git a/erpnext/controllers/accounts_controller.py b/erpnext/controllers/accounts_controller.py
index 910c19c..ecbf59d 100644
--- a/erpnext/controllers/accounts_controller.py
+++ b/erpnext/controllers/accounts_controller.py
@@ -192,11 +192,13 @@
 							if (item.get(fieldname) is None or fieldname in force_item_fields):
 								item.set(fieldname, value)
 
-							elif fieldname == "cost_center" and not item.get("cost_center"):
+							elif fieldname in ['cost_center', 'conversion_factor'] and not item.get(fieldname):
 								item.set(fieldname, value)
 
-							elif fieldname == "conversion_factor" and not item.get("conversion_factor"):
-								item.set(fieldname, value)
+							elif fieldname == "serial_no":
+								stock_qty = item.get("stock_qty") * -1 if item.get("stock_qty") < 0 else item.get("stock_qty")
+								if stock_qty != len(item.get('serial_no').split('\n')):
+									item.set(fieldname, value)
 
 					if ret.get("pricing_rule"):
 						# if user changed the discount percentage then set user's discount percentage ?
diff --git a/erpnext/patches.txt b/erpnext/patches.txt
index 9c2b1c4..522c4fc 100644
--- a/erpnext/patches.txt
+++ b/erpnext/patches.txt
@@ -385,4 +385,5 @@
 execute:frappe.delete_doc('DocType', 'Purchase Common')
 erpnext.patches.v8_0.update_stock_qty_value_in_purchase_invoice
 erpnext.patches.v8_0.update_supplier_address_in_stock_entry
-erpnext.patches.v8_0.rename_is_sample_item_to_allow_zero_valuation_rate
\ No newline at end of file
+erpnext.patches.v8_0.rename_is_sample_item_to_allow_zero_valuation_rate
+erpnext.patches.v8_0.set_null_to_serial_nos_for_disabled_sales_invoices
\ No newline at end of file
diff --git a/erpnext/patches/v8_0/set_null_to_serial_nos_for_disabled_sales_invoices.py b/erpnext/patches/v8_0/set_null_to_serial_nos_for_disabled_sales_invoices.py
new file mode 100644
index 0000000..197d6de
--- /dev/null
+++ b/erpnext/patches/v8_0/set_null_to_serial_nos_for_disabled_sales_invoices.py
@@ -0,0 +1,14 @@
+# Copyright (c) 2013, Web Notes Technologies Pvt. Ltd. and Contributors
+# License: GNU General Public License v3. See license.txt
+
+from __future__ import unicode_literals
+import frappe
+from erpnext.stock.stock_balance import update_bin_qty, get_reserved_qty
+
+def execute():
+	frappe.db.sql("""
+		update 
+			`tabSales Invoice Item` 
+		set serial_no = NULL
+		where 
+			parent in (select name from `tabSales Invoice` where update_stock = 0 and docstatus = 1)""")
\ No newline at end of file
diff --git a/erpnext/public/js/controllers/transaction.js b/erpnext/public/js/controllers/transaction.js
index 7e0dccc..a583f7d 100644
--- a/erpnext/public/js/controllers/transaction.js
+++ b/erpnext/public/js/controllers/transaction.js
@@ -260,6 +260,7 @@
 							customer: me.frm.doc.customer,
 							supplier: me.frm.doc.supplier,
 							currency: me.frm.doc.currency,
+							update_stock: in_list(['Sales Invoice', 'Purchase Invoice'], me.frm.doc.doctype) ? cint(me.frm.doc.update_stock) : 0,
 							conversion_rate: me.frm.doc.conversion_rate,
 							price_list: me.frm.doc.selling_price_list ||
 								 me.frm.doc.buying_price_list,
@@ -275,7 +276,8 @@
 							name: me.frm.doc.name,
 							project: item.project || me.frm.doc.project,
 							qty: item.qty,
-							stock_qty: item.stock_qty
+							stock_qty: item.stock_qty,
+							conversion_factor: item.conversion_factor
 						}
 					},
 
@@ -762,7 +764,8 @@
 			"ignore_pricing_rule": me.frm.doc.ignore_pricing_rule,
 			"doctype": me.frm.doc.doctype,
 			"name": me.frm.doc.name,
-			"is_return": cint(me.frm.doc.is_return)
+			"is_return": cint(me.frm.doc.is_return),
+			"update_stock": in_list(['Sales Invoice', 'Purchase Invoice'], me.frm.doc.doctype) ? cint(me.frm.doc.update_stock) : 0,
 		};
 	},
 
@@ -781,7 +784,8 @@
 					"parent": d.parent,
 					"pricing_rule": d.pricing_rule,
 					"warehouse": d.warehouse,
-					"serial_no": d.serial_no
+					"serial_no": d.serial_no,
+					"conversion_factor": d.conversion_factor
 				});
 
 				// if doctype is Quotation Item / Sales Order Iten then add Margin Type and rate in item_list
diff --git a/erpnext/stock/get_item_details.py b/erpnext/stock/get_item_details.py
index 3ada10b..c2e77df 100644
--- a/erpnext/stock/get_item_details.py
+++ b/erpnext/stock/get_item_details.py
@@ -161,7 +161,7 @@
 		"min_order_qty": flt(item.min_order_qty) if args.doctype == "Material Request" else "",
 		"conversion_factor": 1.0,
 		"qty": args.qty or 1.0,
-		"stock_qty": 1.0,
+		"stock_qty": args.qty or 1.0,
 		"price_list_rate": 0.0,
 		"base_price_list_rate": 0.0,
 		"rate": 0.0,
@@ -172,10 +172,18 @@
 		"net_amount": 0.0,
 		"discount_percentage": 0.0,
 		"supplier": item.default_supplier,
+		"update_stock": args.get("update_stock") if args.get('doctype') in ['Sales Invoice', 'Purchase Invoice'] else 0,
 		"delivered_by_supplier": item.delivered_by_supplier if args.get("doctype") in ["Sales Order", "Sales Invoice"] else 0,
 		"is_fixed_asset": item.is_fixed_asset
 	})
 
+	# calculate conversion factor
+	conversion_factor = args.get("conversion_factor") or get_conversion_factor(item.item_code, args.uom).get("conversion_factor") or 1.0
+	out.update({
+		"conversion_factor": conversion_factor,
+		"stock_qty": out.qty * conversion_factor
+	})
+
 	# if default specified in item is for another company, fetch from company
 	for d in [["Account", "income_account", "default_income_account"],
 		["Account", "expense_account", "default_expense_account"],
@@ -532,6 +540,9 @@
 		args = json.loads(args)
 		args = frappe._dict(args)
 
+	if args.get('doctype') == 'Sales Invoice' and not args.get('update_stock'):
+		return ""
+
 	if args.get('warehouse') and args.get('stock_qty') and args.get('item_code'):
 
 		if frappe.get_value('Item', {'item_code': args.item_code}, "has_serial_no") == 1: