LiPo batteries and C rating — transcript

00:00:00.600 --> 00:00:04.257 LiPo batteries: what the numbers on the label are telling you.

00:00:05.400 --> 00:00:11.173 Every pack shows three key ratings: its voltage and cell count, its capacity,

00:00:11.173 --> 00:00:12.505 and its C rating.

00:00:12.855 --> 00:00:19.352 Each cell is 3.7 volts nominal. Four in series, 4S, gives 14.8 volts.

00:00:19.352 --> 00:00:23.435 Use the cell count your aircraft specifies.

00:00:23.785 --> 00:00:30.656 A full cell is 4.2 volts; never charge above it. Heavy load makes the voltage sag.

00:00:30.656 --> 00:00:34.547 Below 3 volts a cell, the damage is permanent.

00:00:34.897 --> 00:00:40.716 Capacity is in milliamp hours. A 5000 pack runs an hour at 5 amps,

00:00:40.716 --> 00:00:45.059 or 30 minutes at 10. Use no more than 80 percent.

00:00:45.897 --> 00:00:51.899 The C rating is a discharge rate: multiply it by the capacity.

00:00:51.899 --> 00:00:56.947 65 times 2250 gives about 146 amps of constant load.

00:00:57.897 --> 00:01:01.293 After each flight, check the charge level and look for swelling.

00:01:01.293 --> 00:01:02.913 Then charge on a LiPo charger.

00:01:04.897 --> 00:01:09.159 Balance charging keeps every cell level, so no single cell is overcharged.

00:01:09.159 --> 00:01:10.409 Charge at 1C or less.

00:01:14.897 --> 00:01:20.331 Quick check: 1000 milliamp hours at 20C. What's the maximum constant current?

00:01:20.697 --> 00:01:23.205 20,000 milliamps. That's 20 amps.