Cell phone batteries come in all different varieties and sizes and they all have varying capacities.  The cell phone battery you get when you purchase your new cell phone is unlikely to fit your previous cell phone unless you have bought the same brand, but if your old phone is a few years old then it is also unlikely that it will be a match as these types of batteries are constantly being adapted to improve cell phone performance and the battery life of your cell phone.

When you purchase a brand new cell phone, in most cases you will need to charge your battery before you can use your phone.  You should do this as per the instructions that came with your new phone.  Correct charging of your phone can extend the battery life significantly.  It is advised that you allow your cell phone battery to charge to full capacity before first use.  Once you have charged your battery fully you can then use your new cell phone but be aware that a new battery that has gone unused for some time will need several full charges and drains to reach full performance, meaning that the first few times you use your battery it may not last as long as expected, this is normal and you should not assume you have a defective battery.  If however it does not improve and your cell phone batteries life is not what you expected you can, in most cases, contact the manufacturer for a replacement battery.

To keep your cell phone battery optimized for best performance and to get the longest life possible from your battery you should only charge it when the battery has fully drained.  Most people fail to do this, tending instead to charge their cell phone as soon as it has run down two thirds.  This can result in a shorter life span of your battery because you are not allowing your battery to fully charge at any time.  This is caused by the battery “memory” in batteries such as NiCad or NIMH batteries. 

These types of batteries remember their usual discharge point and cause the battery to need charging once it reaches the “remembered “ point.  In other words, if you only ever let your battery run down to half charged before you plug it in to charge again, the battery will mistakenly assume that when your battery gets to the halfway bar it is empty and will need to charge again.  Doing this effectively cuts your battery life in half.  The memory effect does not apply to LiION (Lithium Ion) cell phone batteries.

This is commonly referred to as talk-time and standby time, talk time refers to the length of time that the battery will last while the phone is in use, in other words how long you will be able to talk on your cell phone from a fully charged battery (note, you will only get the estimated talk time described for your cell phone by following the battery care guide that accompanied your cell phone)

Standby refers to the duration of the battery  (from fully charged) while your cell phone is not in use.  This can range from as low as 12 hours to 36 hours, although the standby time will reduce if you use your phone even for short periods during the specified time.

Looking after your cell phone battery will improve your batteries performance but most people are unaware of this and many people complain that the talk time and standby time quoted for their cell phone were misleading when in fact this problem is usually caused by incorrect charging or failing to follow the cell phone batteries care instructions.  If you want to get the maximum lifespan from your battery read the manufactures guidelines carefully.