Part 1 (cont'd) "What do the technical ratings on the label mean?

Here is a way to understand it.

An analogy with Mark's car.

**Analogy:**

The battery we are using is a **3S, 11.1 volt, 20C continuous, 40C burst rating, Charge at 1C Max charge 3C.**

Mark loves his car. Comparing Lipo batteries and their quirks to Mark’s car.

Picture the following:

- Mark’s car has 3 cylinders (3S)

- 3 gas tanks on top of the trunk, each holds 22.00 litres of fuel (Amp- capacity)

- One tank is connected to a fuel injector of one cylinder. 3 Cylinders, 3 tanks

- The tanks are full of fuel.

- The fuel line diameter is a percentage of the tank/battery capacity (C rating) let’s say 2% for 20C, 4% for 40C

- The Electronic Speed Control (ESC) is the accelerator.

Here are the definitions:

**Voltage**: 11.1 Volts, 3S- three cylinders are operating at the same time. You get the output of 3 cylinders for as long as the gas lasts. All three fuel tanks draw down fuel at the same time. All three cylinders work together for the same length of time.

**C rating**- The fuel line is 2% (20C) the diameter of the tank but it is way more than the engine needs to run full blast. Even if we double the diameter of fuel line, the engine only consumes it at a rate it needs to give full performance. Note: if your Apprentice flies for 10 minutes it is only drawing down the battery at 6C. (solve for “X” 60/X=10, therefore “X = 6).

**Charging**: To make this analogy work, we can only refill the tanks through the fuel line which is 2% of the diameter of the tank. If we fill it at an easy rate for 1 hour (Charge at 1C). No problem. We can speed it up it up to 3 C for 20 minutes but it requires a lot of pressure. Greater than 3C it blows.... because it will.

Another way to look at it. If Esso’s self serve stations used a fill hose that is 3 (C) times the diameter of the current hose do you think we would have problems? They probably established a long time ago that the current diameter is perfect (1C). An Indy car gets refuelled in 5 seconds. Probably 90C and yes, very dangerous.

**Balancing**- What happens if two tanks of the 22 litre tanks are empty but one still has 2 litres in it. A full charge would force 22 litres into all tanks. The two empty tanks will be fine and full. The 3rd tank will blow because you are forcing 24 litres into a 22 litre tank. No go, she will blow.

Two ways of balancing:

**balance charging**- the charger reads all 3 tanks and finds out two are empty and one has 2 litres in it. It puts two litres in each of the two empty tanks and it is now balanced and can safely accept the rest of the equal charge of 20 litres per tank so that all 3 tanks now have 22 litres.

**External balancing**- The electronic balancer plugs into the small white balancing plug. It reads all 3 tanks and finds out two are empty and one still has 2 litres. It empties the one tank that still has 2 litres in it and then the whole thing can safely be charged.

**Flight time.** If Mark wants to drive further, he just uses larger gas tanks- instead of a 22 later tank (2200 mah) he can install a 44 later tank (4400 mah. lipo) and get twice the run time at the same power setting. The car’s performance will be the roughly the same but it will weigh more and the tanks have to physically fit on the car.

Example- A 2650 mah battery will run 20% longer than this 2200 Mah battery (2650/2200). It will not make the plane go faster.

**Testing:** when I test a plane in my shop and the plane uses 3 or 4 cells, for safety sake I use a 2S battery (2 tanks of gas). Only 2 of the cylinders will work but I just need to test whether it is spinning the correct way, to make sure the servos work, the functions are not reversed and to program the throws on the transmitter. Purely a safety thing.

This also shows that if you plug in a 4S battery into a 3S ESC and motor, things “just ain’t fittin”. The indication is usually the white smoke of surrender.

Frank