Specifications

damage. Be sure to wash your hands after handling nicad batteries. Also, nicad
batteries MUST be disposed of properly. See Section 30.9.4, “NiCad/NiMH/LiPo
Battery disposal”.
30.9.2. Nickel-metal-hydride (NiMH) batteries
Nickel-metal-hydride batteries are a newer battery type than nickel-cadmium. They have a
higher energy capacity than nicad, but have a much shorter life (about 100 charge/discharge
cycles), and they are more easily damaged by overcharging and vibration.
NiMH batteries can be charged at a maximum rate of 1C, however, some people claim the
Sanyo HR2600SC can be charged at 2C rates. This warms up the cell for maximum perform-
ance prior to flying. Chargers will fail to properly terminate the charge when NiMH cells are
charged at rates less than 0.4C, so slow charges must be carefully timed to avoid overchar-
ging the cells.
NiMH batteries can be left either charged or discharged at the end of a flying day. When stored
long-term they should be stored in a cool storage area. After storage, they should be cycled a
few times to restore capacity.
30.9.3. Lithium-Polymer (LiPo) batteries
Lithium polymer is the newest battery type. They have up to four times the battery capacity of
nicad batteries, but they are very fragile. They contain lithium which is a metal which ignites on
contact with air, so if the battery balloons and the covering pops or the covering of the battery
is punctured, it will ignite and explode.
LiPo batteries can be charged at a maximum rate of 1C.
LiPo batteries are very sensitive to overcharging. They should NEVER be overcharged, and
ALWAYS be charged in a fireproof container and should ALWAYS be attended because they
have been known to ignite in some circumstances.
LiPo batteries should not be discharged below 3 volts per cell because they can be damaged
by overdischarging. A LiPo battery should not be discharged below 80% capacity if possible
because this stresses the cell and reduces the cell lifetime (number of charge/discharge cycles
before cell capacity degrades significantly). They should not be fully discharged at the end of
the day; you should leave some charge in them. Thunder Power recommends long-term stor-
age with about a 40% charge left in the cell; this minimizes cell deterioration and prevents the
cell's voltage from dropping too low. They should be stored in a cool place in a fireproof con-
tainer.
LiPo batteries are fairly fragile. You should avoid dropping them (especially onto concrete or
asphalt) because this can cause cell damage. LiPo batteries have beeen damaged in a crash
and have spontaneously ignited up to 30 minutes later. Any LiPo batteries which have been in
a helicopter that has crashed should be kept in a fireproof container for a few hours for obser-
vation.
Do not attempt to charge or discharge a ballooned battery pack. The proper way to dispose of
a bad lipo cell is to take a container and fill it with water, then keep adding salt and stirring until
no more salt will dissolve (reached saturation). Drop in the cell and leave for at least TWO
WEEKS. Also, please search for "lipo disposal" in the RC Groups forums for the latest safety
information on this technique.
30.9.4. NiCad/NiMH/LiPo Battery disposal
Technical Appendix
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