In our experience "cheap" batteries from the Far East are a poor investment. They don't tend to use "matched cells" which can cause the cell with the lowest resistance to deliver the majority of power and become more discharged than the others. Though they may be initially cheaper they end up being a false economy, not last as long or deliver as much power.

Good quality cells from manufacturers like Flight power, Overlander, Outrage and Thunder Power to name a few cost more initially but will easily out perform and outlast the cheaper cells, as with most things in life you get what you pay for!

Important information about Li-po batteries

Li-po and Li-on batteries designed for mobile phones and laptops have revolutionised the hobby and have made Ni-mh and Ni-cad batteries redundant.

There are pages and pages of information, scare stories, do's and guides on Li-po's and there use in electric models, i am not going to bore you with science of heavy maths (I couldn't if i wanted to) anyway here are a couple of basic things you should know:

1: in layman's  terms - The voltage of the battery defines how fast it will turn the motor, the capacity will basically define how long you can fly for and the C value defines how hard you can fly

2: Li-po batteries are supplied in different "C" value, the C value defines the amount of current the battery can deliver so for example; a 2000MAh 20C battery can sustain 40 amp (that's 20 x 2000MAH) where as the same capacity 30C battery can sustain 60 amps (30 x 2000MAh)

3: To get the best life out of your batteries, Li-po batteries should not be discharged below 3.2V (at no load) per cell, so for an example a 3 cell battery should not go below 9.6V

4: Do not charge li-po batteries at more than 1C so for example a 2000MAh battery should be charged at 2 Amps

5: To extend the life of your Li-po batteries only discharge them to 50% for the first 5 - 10 flights, after that take them down to 85%

6: Don't panic when charging li-po's when you see them charge to a higher voltage for example; 2 cell batteries will charge to 8.4V, 3 cell to 12.6V and 6 cell to 25.2 Volts.

7: Always charge using a balancer to equalize the voltage across all the cells

Li-po batteries can be dangerous an do explode very spectacularly (as I have learnt to my own experience) however you have to be pretty careless and or stupid to blow them up!

Batteries Required for Flying

Transmitter - Your radio transmitter will usually be supplied with a 9.6V Ni-cad, this is sufficient for 1 days flying and should be charged before each days flying, replacement 3 cell Li-po transmitter batteries are now available which can last for up to a month (flying each weekend).

Nitro Flight Battery - Nitro helicopters require a 4.8V - 6V battery to power all the electrics in the helicopter, a high capacity (3000+MAh) NI-MH battery will provide an afternoons flying on a general setup however they do need to be charged in between flying days, again Li-po alternatives are available however they require a voltage regulator to reduce there output from 7.4V - 4.8V.

Nitro Starter Battery - A battery is required to power your nitro engine starter, typically this is a 12V lead acid battery, a 7Ah is a good low cost option as a starter battery. as an alternative some people use 2 6 cell Ni-mh or Ni-cd batteries connected in series strapped to the bottom of the bottom of the starter.

450 Size Flight Battery - Most 450 size Helicopters use a 3 cell Li-po battery delivering 11.1V typically with a capacity of 2000MAh - 2500MAh and able to sustain 20 - 30C (depending on the type of flying)

500 Size Battery - Most 500 size helicopters use a 6 cell Li-po battery delivering 22.2V typically with a capacity of 2100MAh to 3200MAh and sustain 20 to 30C. it is possible to use 2 450 size batteries wired in series if required.

600 Size Battery - Most 600 size helicopters use a 6 cell Li-po battery delivering 22.2V typically with a capacity  of 4800MAH - 6000MAh and able to sustain 20 - 30C

Chargers

A good quality charger is a great investment, if you are flying electric helicopters it is highly recommended to get 2 x 6 cell or higher chargers so you can have 2 batteries on charge at any time.

As outlined above you should charge Li-po batteries a no more than 1C (1 x their capacity eg: 2000MAh battery should be charged at no more than 2 amps (2000MAh = 2Ah)) charging at 1C means it will take an hour to charge a battery (it will actually take slightly longer as the amps reduce as he battery reaches capacity & it balances the cells also) in general terms allow 1 hour 30 mins to charge a battery at 1C.

Don't be tempted with cheaper chargers like the Imax B6 and GT power 6 cell chargers only provide 50 Watts of power, again not to get to much into maths but watts are volts x amps so a 50 watt charger can only charge a 6 cell battery at 2 amps (25V x 2 amps = 50watts) this is ok for smaller capacity 6 cell 500 size batteries or lower voltage 2 or 3 cell batteries.

For 600 size batteries it is recommended to get a 150 Watt charger which can charge a 6 cell battery at up to 6 amps (25V x 6 amps = 150 watts).

Most chargers work of 12 volts which is great for charging at the field however you may want to get either a separate mains power supply or a dual power charger so you can charge your batteries before you get to the field.