| RC LIPO BATTERY GUIDE: EXPLANATION, SAFETY, AND CARE
Without LiPo batteries, quadcopters and drones most likely would not exist.
Why?
Because no other battery offers as much power while supplying high quantities of present in so small of a plan. This means: longer flight times, far better maneuverability, and much faster flying. To put it simply, even more fun.
Nonetheless, there is a great deal of complication about what terms imply, just how to correctly bill lithium polymer batteries, as well as how to be secure when making use of batteries.
In this lipo battery overview, you'll obtain:
A comprehensive explanation of battery specs-- Nominal and also cut-off voltage, ability, C-rating, internal resistance as well as even more
Just how to enhance the life of your lipo battery
What to try to find in a lipo battery charger
How to utilize a lipo battery charger
Why equilibrium charging is essential
The difference between different types of battery connectors
Appropriate lipo battery safety and security as well as treatment
A glossary of common lipo battery terms
So, allow's start with battery requirements.
Battery Voltage
The first spec that many people take a look at when picking a battery is the voltage. As discussed in my article on electric motor Kv continuous, the rate of your motors is symmetrical to the voltage you provide to them so greater voltage batteries can turning electric motors quicker than reduced voltage batteries. The voltage of your battery will certainly identify the kind of ESC's and electric motors that you will need to use.
Lipo battery voltage is specified by the number of cells in collection. Each cell has a nominal voltage 3.7 V. Different battery business note their lipos in different methods however the majority of people often tend to describe their batteries as ONE, TWO, TWO, etc
The complying with voltage chart shows each battery classification and also the corresponding voltage.
1ST = 1 cell in collection x 3.7 V = 3.7 V.
TWO = 2 cells in series x 3.7 V = 7.4 V.
SIX = 3 cells in series x 3.7 V = 11.1 V.
4S = 4 cells in collection x 3.7 V = 14.8 V.
5S = 5 cells in series x 3.7 V = 18.5 V.
6S = 6 cells in collection x 3.7 V = 22.2 V
You may additionally see lipos that use a letter "P" to designate voltage. For instance, 2S1P or 2S2P. This is not as usual with quadcopter batteries however you might see it with LiPo's indicated for various other types of RC automobiles.
" P" means the number of cells in parallel. 2S1P means "2 cells in series and 1 cell in parallel." If a battery doesn't have a "P" then it is thought to be "1P." So 2S1P and TWO coincide point.
3S2P means "3 cells in series and also 2 cells in parallel." This battery would certainly have a total of 6 cells with 2 parallel teams of cells with 3 cells in series in each of those teams.
Maximum Voltage and Cut-off Voltage.
Take into consideration the 2 battery voltage curves in Figure 1. An "excellent" battery and an "actual" battery are shown. An ideal battery would certainly be capable of offering continuous voltage for the entire time it is releasing till it is totally released.
Actual batteries do not behave by doing this. Rather they begin at a higher voltage and afterwards their voltage will gradually lower as the battery is discharged.
So while an ideal battery might have a voltage of 3.7 V during the entire time it is releasing, an actual battery will begin at the optimum voltage of 4.2 V As it discharges, keep reducing.
How much will it reduce? If you let it, it will fully discharge to zero volts.
However:.
Battery makers normally suggest you do not discharge your battery listed below a particular minimum voltage. This minimum voltage is called the cut-off voltage. Several producers advise the cut-off voltage for lipos to be 3.0 Volts.
Almost talking, this means you ought to establish your voltage alarm to something greater than 3.0 V to make sure that you can securely land your quadcopter before it goes down below 3.0 V Lots of people set their alarm systems to 3.3 V.
Battery Capacity.
Battery ability is measured in Amp-hrs or milliamp-hrs. It gives you a sign of the complete energy that a battery can save. In general, the higher the ability, the longer your battery will last.
Using the gas container example, a high ability battery has a large gas container that allows it to store a lot of gas.
The very best method to understand the capability of lipos is to take into consideration exactly how it is measured. The general procedure is to take a battery as well as identify what continuous present triggers the lipo to go down listed below the battery cut-off voltage in exactly 1 hr.
The ability is after that simply that current times 1 hr.
So a 3000 mAh capacity battery will certainly go down from full voltage to the cut-off voltage in 1 hr if you discharge the battery at 3000 mA (3 Amps). 3 Amps x 1 hr = 3 Amp-hrs = 3000 mAh.
There is one essential thing you require to note ...
The ability of a battery reduces as the existing draw increases. This means that if your capacity is 3000 mAh for a constant 3 Amp present draw, after that your capability will certainly be less than 3000 mAh if you attract a continuous 6 Amps or a consistent 30 Amps.
I've seen a great deal of explanations of ability that do not tell you this. You will certainly usually see it created that if your battery's capability is 3000 mAh, then that indicates you can draw 3 Amps for 1 hr, 6 Amps for 30 minutes, or 30 Amps for 6 mins. As a whole this is not the instance.
In order to tell exactly how present impacts ability, you require to consider a lipo battery discharge contours. A lot of excellent battery datasheets will certainly show various discharge contours for various constant existing attracts.
This figure shows the discharge contour of a 1S, 1700 mAh, 35C battery (extra on what "35C" means later). Each line stands for a different constant current (42.5 A, 47.6 A, 51.0 A, and so on). This number shows us that for a provided cut off voltage the discharge ability reduces as the existing draw rises.
In this instance, for a cut off voltage of 3.0 V, the capability at 1.7 A (1C) is 1700 mAh and I would estimate the capability at 42.5 A (25 C) to be about 1630 mAh and the capability at 68.0 A (40 C) to be regarding 1460 mAh.
So the 2 crucial points to keep in mind about ability are:.
Capability tells you the quantity of current that the battery can providing for 1 hr.
If you discharge your battery at higher currents than that, your ability decreases.
( Note that Amp-hrs is not an action of power. Energy is measured in Watt-hrs. If you assume that the battery is releasing at constant voltage, you can calculate energy from that. Nevertheless, as we learned in the previous area, batteries do not release at constant voltage.). | | |
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