Most of the better transmitters have a meter to show you the battery level. For keeping an eye on the reciever batterys I buy something called "Voltwatch". They are inexpensive and you check the led indications before and after every flight. They work very well and at the price, I install them in all my new planes. Follow the link below to check them out. I checked and see that you are in Canada. For buying in Canada the best placew to buy from is called Great Hobbies. There prices are very good and good people to deal with. [8D]
http://www2.towerhobbies.com/cgi-bin...&I=LXMZ56&P=ML
http://www.greathobbies.com/