Lipo Batteries
Just like a li-ion battery, when we talk about a lipo battery, we talk about a battery composed of lipo cells, for the same reason. A single lipo cell won't move you anywhere, you need several of them.
LiPo batteries are the cheapest and easiest to use in an electric skate build. They are manufactured in large number as they are used in multiple products, keeping the price low and competitive. They also are plug-and-play (or almost), you can easily find batteries with XT60 or XT90 plugs.
They are fragile though. Each cell is a little pouch that can easily be pierced with a pointy object like a nail. If not protected properly, they can be damaged by external elements and caught on fire. Also, overcharging them can make them explode. Over discharge also damages them, not dangerously, they will just hold less power and/or turn bad.
If not stored properly (meaning stored while being fully charged or stored in a hot place), the cells can get over inflated and at this point, you'd better discharge them safely and throw them away.
They will last only for 200-300 charge cycles, although it depends on the battery quality and how you treat them.
When looking to a LiPo battery, you have to check for its characteristics: the voltage (volts), the capacity (mAh), the number of cells (1S, 2S, 3S, 4S…) and the C rating.
The voltage of a LiPo cell goes up and down during charge and discharge. A LiPo cell nominal voltage is 3.7 volts. The minimum voltage for a LiPo cell is 3.0V but it’s not recommended to get them that low, you should try to keep them to 3.4V or 3.3V minimum. A fully charged LiPo cell is 4.2V.
Battery | Nominal V | Full charge | Minimum V | Recommended min. V |
---|---|---|---|---|
1S Lipo Battery | 3.7V | 4.2V | 3.0V | 3.3V |
2S Lipo Battery | 7.4V | 8.4V | 6.0V | 6.6V |
3S Lipo Battery | 11.1V | 12.6V | 9.0V | 9.9V |
4S Lipo Battery | 14.8V | 16.8V | 12.0V | 13.2V |
5S Lipo Battery | 18.5V | 21V | 15.0V | 16.5V |
6S Lipo Battery | 22.2V | 25.2V | 18.0V | 19.8V |
7S Lipo Battery | 25.9V | 29.4V | 21.0V | 23.1V |
8S Lipo Battery | 29.6V | 33.6V | 24.0V | 26.4V |
9S Lipo Battery | 33.3V | 37.8V | 27.0V | 29.7V |
10S Lipo Battery | 37.0V | 42.0V | 30.0V | 33.0V |
11S Lipo Battery | 40.7V | 46.2V | 33.0V | 36.3V |
12S Lipo Battery | 44.4V | 50.4V | 36.0V | 39.6V |
The C rating is the battery output capacity. A
3000mAh (or 3Ah) 20C rated battery means that its output is 20×3 = 60A.
Usually, manufacturers will indicate the general output capacity of the
battery, plus its peak output capacity (output available for a few
seconds). The C ratings are almost always over-rated. A 50C
battery is often 35-40C in reality. This is especially true with cheap
batteries and the gap can even be larger.
The capacity means how much energy you can store in the battery, often stated in mAh (milli amp hours) or Ah. The more you can store, the bigger (in size) the battery is. Of course, having a big capacity battery means that your esk8 will have a long range, and the output will be better.
Recommended reads: nice introduction about LiPo batteries, and a detailed use of LiPo for an esk8 build.