LiPo safety — transcript

00:00:00.400 --> 00:00:05.416 LiPo safety: voltage maths, storage, transport and damaged packs.

00:00:06.400 --> 00:00:12.899 Quick recap: a cell is 3.7 volts nominal, 4.2 full, and 3 minimum.

00:00:12.899 --> 00:00:21.048 Energy is volts times amp hours: 22.2 volts at 5 amp hours is about 111 watt hours,

00:00:21.048 --> 00:00:23.667 before losses and reserve.

00:00:24.017 --> 00:00:28.428 Now the exam favourite. The minimum is 3 volts per cell,

00:00:28.428 --> 00:00:34.155 so multiply by the cell count: a 4S pack's minimum is 12 volts, a 6S, 18.

00:00:34.155 --> 00:00:40.500 Course notes put a warning at about 3.3 volts a cell. On a 4S, that's 13.2 volts.

00:00:41.017 --> 00:00:47.377 In flight, work it the other way: divide by the cell count. A 4S pack showing 13.

00:00:47.377 --> 00:00:53.503 5 volts is about 3.37 volts a cell. That's close to the warning. Time to land.

00:00:53.853 --> 00:00:59.418 Quick check. Your 6S pack reads 19.2 volts. What's that per cell?

00:00:59.953 --> 00:01:03.898 3.2 volts a cell. Below the warning. Land now.

00:01:04.353 --> 00:01:08.690 Charge on a LiPo charger with balancing, in a fireproof bag or container,

00:01:08.690 --> 00:01:13.496 and never leave it unattended. If the pack is hot from flying, let it cool first.

00:01:17.353 --> 00:01:22.327 Storing it for more than a few days? Bring it to about 3.8 volts a cell,

00:01:22.327 --> 00:01:26.142 the storage voltage. Many chargers have a storage mode.

00:01:26.142 --> 00:01:30.911 Smart batteries discharge to storage on their own after sitting idle.

00:01:31.353 --> 00:01:35.267 Flying to a job? LiPos go in your carry-on, never in checked baggage,

00:01:35.267 --> 00:01:37.336 with the terminals taped or covered.

00:01:40.353 --> 00:01:43.970 Capacity limits apply, and they change. Know your packs' watt hours,

00:01:43.970 --> 00:01:48.478 and check CASA's current dangerous-goods guidance and your airline before you travel.

00:01:50.353 --> 00:01:56.336 Last job of the day, and a pack comes out puffed. One more flight? No.

00:01:58.353 --> 00:02:02.673 Swelling, heat, a dented or punctured case, damaged leads,

00:02:02.673 --> 00:02:07.360 or cells that won't stay balanced: that pack is out of service.

00:02:07.360 --> 00:02:13.217 Never charge or fly a puffed battery. Quarantine it, record it, and replace it.

00:02:14.353 --> 00:02:15.936 Log each pack's cycles.

00:02:15.936 --> 00:02:20.553 Course notes retire a pack below 80 percent of its original capacity,

00:02:20.553 --> 00:02:25.038 and worn-out or damaged packs go to an approved recycling facility.

00:02:25.388 --> 00:02:30.717 Recap: divide by the cells, store at about 3.8, carry them on board,

00:02:30.717 --> 00:02:32.493 and quarantine damage.

00:02:32.843 --> 00:02:38.093 Final check. A pack is slightly puffed, but the job's nearly done. What do you do?

00:02:39.843 --> 00:02:43.840 Quarantine it, record it, and replace it. Damage isn't negotiable.