Lithium Polymer (AKA “LiPo”) batteries are a popular choice for long run times and high power. They have a shorter lifespan than the ordinary flashlight battery (NiCd/NiMH). They have a sensitive chemistry that can lead to a fire if it is punctured or misused (for example charging a swollen battery) and they need special care for charging, use and storage.
There are four main ratings to be aware of, which are printed on the battery.
- Voltage - the number followed by a "V"
- Cell count - the number followed by an "S" (the S stands for "series" which refers to how the cells are connected to each other so that their voltages are combined)
- Capacity - which is the number followed by mAh (milliamp hours)
- Discharge rate - which is the number followed by a "C" (The C stands for "capacity") - but the C Rating is simply a measure of how fast the battery can be discharged safely and without harming the battery. It is not necessarily true that a higher C rating means better performance.
Voltage directly influences the RPM of the motor - so the more voltage available, the faster the motor will go. This is why you might notice the motor slow down as the voltage drops from usage.
The battery should always be kept at its nominal voltage when not in use. This is also called resting, default or storage voltage - all interchangeable terms. Then, just before use, charge to maximum capacity. The battery should not sit longer than a day or two fully charged, or discharged after use.
Each cell inside a Lipo battery pack has a "nominal voltage" or default voltage of 3.7v. You get a total nominal voltage by multiplying 3.7v by the number of cells in a battery pack. For example:
- Home Original is a 3 cell battery - so the total nominal voltage is 11.1v (3 x 3.7v) It's easy to remember because that is the voltage printed on the label.
- Home Plus is a 4 cell battery - so the total nominal voltage is 14.8v (4 x 3.7) This is the voltage printed on the label of the Plus battery.
This bears repeating: The LiPo battery should be kept at the nominal voltage until you are ready to use it - and then just before use, charge it to capacity.
IMPORTANT! The nominal voltage is NOT the maximum capacity the battery can be charged to. Each internal cell also has a maximum voltage of 4.2v. So the maximum capacity is determined by multiplying 4.2v by the number of cells. For example:
- Home Original is a 3 cell battery - so the total maximum capacity is 12.6v (4.2v x 3)
- Home Plus is a 4 cell battery - so the total maximum capacity is 16.8v (4.2v x 4)
The usable voltage range for a standard LiPo battery cell is 3.2v to 4.2v. Any lower than 3.2v and the battery will be permanently damaged.
- Home Original minimum voltage is 9.6v
- Home Plus minimum voltage is 12.8v
Other factors affect longevity and performance such as cold and heat. Search this FAQ using key words to find more information on your LiPo battery.