This depends on what you are using the battery for. If you race competitively you will certainly want a higher “70C+” rated battery. If you are a casual racer or just backyard bashing you will be fine with a 50C rated battery. We do not recommend using lower than a “30C” rated battery pack as voltage drops may cause radio glitches. If you are using 4S packs in a 1/8th scale buggy or Truggy we recommend using at least 70C rated packs or higher as these types of vehicles draw very high amounts of current.
The “C” rating is a number that battery manufacturers use to rate the maximum amp draw a pack will withstand. It has been reported to me that the parameters for establishing this rate are as follows. The manufacturer measures the highest amp rate at which a battery will yield 80% of the stated capacity of the pack. So let’s say for a 5000 mah 50C pack, it would yield at least 4000 mah of capacity when discharged at 250 amps from a fully charged state to a cutoff of 3.0 volts. It says nothing of what damage was caused to the pack after this test, or that the test was done by direct connection to the cells and not through the power wires and plug. So take from this what you want. The only conclusion that can be legitimately be drawn from the “C” rating is that the higher the “C” rating within a particular brand the better the performance will be. The “C” rating of a pack is probably the most ambiguous measure performance that I have ever seen. Hopefully, in the future, a “real world” measure of performance can be established. “VDUL” (Voltage Drop Under Load) and “IR” Internal Resistance are the two biggest factors relating to performance. Since the resistance of the cells is so dramatically affected by increased temps, this measurement is also subject to manipulation.
Some companies really inflate this rating so it is important to understand that the “C”rating is quite subjective. Also remember that buying a lower “C” rated battery and running it in a high current draw application such as 1/8th scale cars will overstress the battery and cause the pack to “swell”.
The “S” stands for the number of cells in the pack. A 2S pack is a 2 cell pack and is rated at 7.4 volts. A 3S pack is 11.1 volts, 4S 14.8 volts and so on. Basically, each cell in a pack is 3.7 volts.
It means that the pack is made up of 4 cells total. 2 cells are wired in series and 2 cells are wired in parallel.
The “rated voltage is a number used by the battery industry to rate the median (50% charged) voltage of a battery cell. When fully charged each cell in a Lipo pack will reach 4.2 volts. The lowest voltage you should ever discharge your lipo packs to is 3.0 volts per cell (6.0 volts for a 2S pack). I highly recommend a minimum voltage cutoff of 3.4 volts per cell.
This is the “balance plug” and is inserted into the output balance port of the battery charger. It allows the charger to adjust the current so that each cell in the pack reaches the same (4.2) voltage at the completion of the charge cycle. Make sure the balance ports match the balance plug on the battery pack as their are a few different types of balance plugs. The most common is an XH plug and is found on most brands of Lipo chargers. Adapter for different types of balance plugs are available and many chargers come with different balance adapters.
Nothing. The balance plug is only used for balancing during charging or discharging
After you are done using your Lipo battery make sure you unplug the battery from the car! Leaving a Lipo battery plugged into the speed control (even with the switch off) for extended periods of time can cause the voltage to drop too low causing permanent damage to the pack. Make a habit out of removing the pack from the vehicle and putting the pack into a lipo bag. Just put it in a cool dry place. If you don’t plan on running the pack for a month or longer charge or discharge the pack as necessary to get the pack to 3.8 volts per cell. For example, a 2S pack should be at 7.6 volts. This is referred to as a “storage charge”. A trick for extending the life of Lipo packs is to place the pack in a plastic storage bag and put it in the Refrigerator. Allow them to return to room temperature before charging them. Never ever leave a Lipo in a hot car! Although Lipo’s are designed for a maximum temperature of 140 degrees F, a temperature of 100 degrees F for an extended period of time (<24hrs) can cause “puffing” and will cause permanent damage to the pack. The cooler is always better.