ROBBE POWER PEAK ULTIMATE 2 Manual De Uso página 63

No.
Operating instructions
8470
POWER PEAK ULTIMATE 2
MEMORY EFFECT, CELL CAPACITY
Li-poly cells do not suffer from the memory (lazy battery) effect, so the standard proce-
dure with NC and NiMH batteries of discharging before recharging (cycle charging, cell
balancing) is not necessary. Indeed, it is actually better to avoid discharging the cells
before recharging.
Each charge process reduces the capacity of the Li-poly pack slightly, so this would
lead to an unnecessary loss of capacity.
ASSEMBLING BATTERY PACKS
Li-poly cells can be wired together in series or in parallel in order to increase pack volta-
ge or capacity, but this does present problems due to variations in charge voltage and
capacity.
For this reason it is important to use selected cells exclusively if they are to be wired
together to form a battery.
CHARGING BATTERY PACKS
INTEGRATED CHARGE PROTECTION CIRCUIT
Each Li-poly cell usually contains a voltage monitor module to protect it from overchar-
ging, deep-discharging or excessive currents. However, for modelling applications it is
usual to draw high load currents, which means that the monitor module would very often
trip to protect the cells. For this very reason most battery packs do not include this fea-
ture.
The lack of the protective circuit can produce problems in the charging of series-wired Li-
poly cells. As mentioned earlier, individual cells in the pack may well have slightly diffe-
rent charge states and voltages. In this case the overall final charge voltage is not distri-
buted evenly amongst the individual cells, with the result that cells featuring higher volta-
ge can easily be overcharged.
To avoid this, the individual cells must be brought up to the final charge voltage of 4.2
Volts.
Charging parallel-wired cells does not present problems, as the total charge current is
distributed to the individual cells according to their voltage.
We wish to point out expressly at this point that, in the interests of safety, Li-poly batte-
ries may only be charged using the Power Peak Ultimate 2 charger if each individual cell
is fitted with a voltage monitor module. We accept absolutely no liability for damage cau-
sed by incorrect or incompetent handling of the cells. Please be sure to read and obser-
ve the safety notes.
Temperature differences always occur during the discharge process, as the outer cells are
always cooled more effectively than the inner ones. The effect of this, combined with nor-
mal manufacturing tolerances, is that the state of charge of series-connected Lithium-
Polymer cells always tends to drift. After several discharge / charge cycles individual cells
inevitably exhibit differences in voltage.
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