ROBBE Power Peak E1 Manual De Uso página 49

20. Lithium batteries (LiPo, LiIo, LiFe)
There are several basic types of Lithium
battery:
1. Lithium-Ion batteries containing fluid
electrolyte, with a nominal voltage of 3.6
Volts. This is the first generation of Lit-
hium cell, and is not often used for
modelling applications.
(Battery type select: LION)
2. Lithium-Ion batteries containing fluid
electrolyte, with a nominal voltage of 3.7
Volts. This is the second generation of
Lithium cell, and is housed in a metal
can.
(Battery type select: LIPO)
3. Lithium-Ion-Polymer batteries (LiPo)
containing gel-form electrolyte, with a
nominal voltage of 3.7 Volts. This is the
current generation of Lithium cell, and
they have also become known as Li-po or
Li-poly batteries. The gel electrolyte
results in a reduced pressure build-up in
the cell during charging and discharging,
for which reason a foil housing is ade-
quate. This cell has rapidly become very
popular for model purposes due to its low
weight and high energy density.
(Battery type select: LIPO)
4. 4. Lithium-Ferrum (phosphor) batte-
ries with a nominal voltage of 3.3 Volts.
This is currently the latest generation of
Lithium batteries, also known as A123
cells. These batteries are likely to
become very widespread in modelling
circles due to their good energy density
and ability to tolerate high peak disch-
arge currents.
(Battery type select: LIFE)
We recommend the following charge
rates for Lithium batteries:
Lithium batteries are usually charged at a
rate of 1C, although many types of cell can
Operating instructions
Power Peak E1
be charged at 1.5 to 2C, and the latest types
at 5C. Please observe the maximum charge
current stated by the battery manufacturer.
The final discharge voltage of LiPo and LiIo
batteries should be set to 3.0 Volts.
LiFe batteries should be set to a final disch-
arge voltage of 2.7 Volts.
CAPACITY DIFFERENCES
If several cells are assembled to form a bat-
tery which is then discharged at a fairly high
current, the cells will heat up to different
extents as the cell or cells on the inside are
unable to dissipate heat effectively.
This results in changes to the cells' internal
resistance, which in turn reduces their
discharge capacity. The cell concerned will
then be discharged more quickly, with the
danger that it will eventually be discharged
below the permissible final discharge volta-
ge of 2.5 Volts.
Considerable differences in capacity can
occur when external temperatures are very
low.
For example, if a Li-poly pack is flown in an
electric helicopter, the front cell will be coo-
led very effectively by the normal airflow,
while the inner cells become significantly
warmer.
The colder cell will lose effective capacity,
with the danger that it will be discharged
below the permissible final discharge volta-
ge.
To avoid the danger of permanent cell
damage we recommend that Li-poly cells
should only be discharged down to a final
discharge voltage of about 3 to 3.3 Volts. It
is also essential that the cells should be
charged up to the same level next time the
pack is recharged. Always connect the vol-
tage sensor lead!
21
Order No.
8471