LiPo batteries are very different from previous generation batteries and understanding how they work, and especially how to charge them, is the key to getting the best performance.
Series
Individual Lithium Polymer cells have a nominal voltage of 3.7 volts (vs. 1.2volts per cell for Ni-Cds or NiMHs). Cells are wired in series to give the following pack voltages:
1 cell = 3.7 volts
2 cells in series = 7.4 volts
3 cells in series = 11.1 volts
Series
Individual Lithium Polymer cells have a nominal voltage of 3.7 volts (vs. 1.2volts per cell for Ni-Cds or NiMHs). Cells are wired in series to give the following pack voltages:
1 cell = 3.7 volts
2 cells in series = 7.4 volts
3 cells in series = 11.1 volts
Parallel
Unlike Ni-Cd and Ni-MH batteries that self-discharge when wired in parallel, LiPo cells can be hooked up, charged and discharged in parallel with no detrimental effect. Wiring two LiPo cells in parallel doubles the capacity (more run time), plus an important advantage of wiring in parallel is that each cell only sees half the total current.
3S 2P
A battery pack that has three cells in series (giving 11.1 volts) and 2 of these 3-cell packs are wired in parallel is commonly referred to as a 3S, 2P (3 series, 2 parallel).
C Rating
LiPo cells are also commonly given a C or current rating. This is the maximum average recommended discharge current for the cell. For example, the VP2150/20C packs have a 20C rating. To determine the maximum recommended discharge rate multiply the capacity times the C rating. 2150mAh x 20C = 43,000. So the maximum recommended discharge rate would be 43,000mA or 43 amps. If your application has a higher amp draw, remember that LiPo cells can be wired in parallel, and with 2 cells in parallel each cell sees half the total current. With 3 cells in parallel, each cell see one third the current.
By wiring packs in a combination of series to get the voltage and parallel to achieve the capacity and individual cell current to an acceptable level, LiPo cells can be used to power nearly every type and size of model.
Charging
Charging LiPo batteries requires a very different charge method than other types of cells. It's imperative to use a charger designed specifically for LiPo batteries, and with most LiPo-specific chargers it's necessary to correctly select the cell count (1, 2 or 3 cells) manually.
3S 2P
A battery pack that has three cells in series (giving 11.1 volts) and 2 of these 3-cell packs are wired in parallel is commonly referred to as a 3S, 2P (3 series, 2 parallel).
C Rating
LiPo cells are also commonly given a C or current rating. This is the maximum average recommended discharge current for the cell. For example, the VP2150/20C packs have a 20C rating. To determine the maximum recommended discharge rate multiply the capacity times the C rating. 2150mAh x 20C = 43,000. So the maximum recommended discharge rate would be 43,000mA or 43 amps. If your application has a higher amp draw, remember that LiPo cells can be wired in parallel, and with 2 cells in parallel each cell sees half the total current. With 3 cells in parallel, each cell see one third the current.
By wiring packs in a combination of series to get the voltage and parallel to achieve the capacity and individual cell current to an acceptable level, LiPo cells can be used to power nearly every type and size of model.
Charging
Charging LiPo batteries requires a very different charge method than other types of cells. It's imperative to use a charger designed specifically for LiPo batteries, and with most LiPo-specific chargers it's necessary to correctly select the cell count (1, 2 or 3 cells) manually.
