UNDERSTANDING BATTERIES.

NI-CADS

NI-CAD batteries are the standard type rechargeable battery as usually found in your Transmitter and receiver.
These batteries can suffer from memory lock and need to be fully cycled on a regular basis.
To "Cycle" a battery means to discharge a pack to within 0.5 volts per cell and then to fully charge it.  If this is not done on a regular basis your battery WILL lose power.
Transmitter batteries are normally 8 cell so you will need to discharge down to 4 volts.  NEVER discharge a battery past this point.
For example, a 700Mah transmitter pack can drop to 200 - 300mah but if you cycle it properly it can come back up to 700 or even more.
 

NI-MH

These batteries are said not to suffer from memory lock but I think you should still treat them in the same way you do a NI-CAD but you will not need to "cycle" them as regular.
New batteries should not be charged on a DELTA PEAK (auto sensing full charge) charger the first couple of times as the batteries will false peak (say they are charged but they are not).  To charge these the first couple of times use your FUTABA charger for a set time.  The way to calculate the time is to look at the MAmps of the battery then divide it by the output of the charger.  For example, a Transmitter 8 cell pack of 2600 Mamps/hr on a FUTABA charger with an output of 108 mamps/hr will be 2600 divided by 108 =24.07 hours on charge.

LI_POLY

These batteries should be treated with a lot of respect.  They have a very good POWER to WEIGHT ratio and high output but you pay the penalty of them not being very forgiving.  Basically, NEVER over charge them, never fully discharge them, do not leave them discharged, and NEVER leave them on charge unattended as they can and do burst into flames.  A little tip is to charge them in a metal or Pyrex dish with a lid.  There is also a lot of confusion over the voltage and number of cells, this is easy, a one cell pack will be 3.6 volts, a two cell pack will be 7.2 volts and a three cell pack will be 11.1 volts.  (Multiply the number of cells by 3.6).
For more safety information go to the OVERLANDER site and look at the information there. http://www.overlander.co.uk/warning.asp
You can also download their latest catalogue for more information on charging (page 16).