IT JUST KEEPS GOING…
What’s a Lipo battery?
A Lipo Battery or lithium polymer battery is a rechargeable battery of lithium-ion technology using a polymer electrolyte instead of a liquid one. These lipo batteries provide a higher specific energy than other battery types. It is a newer type of battery now used in many consumer electronics devices. They have been gaining in popularity in the radio control industry over the last few years, and are now the most popular choice for anyone looking for long run times and high power.
For more and more people, they do. In fact, there is nothing to fear from LiPo batteries, so long as you follow the rules and treat the batteries with the respect they deserve.
This guide mainly introduces the basic Lipo battery knowledge, Parameters, maintenance and safety.
Lipo battery parameters introduction
We can see there are some parameters on this Lipo battery, they are Battery Capacity, Battery Voltage, Cell Configuration and Discharge Rate.
A battery is constructed from rectangular cells which are connected together to form the battery. A cell which can be considered a battery in itself, holds a nominal voltage of 3.7V. By connecting more of these in series, the voltage can increase to 7.4V for a 2 cell battery, 14.8V for a 4 cell battery and so on. By connecting more batteries in parallel the capacity can be increased. Often you will see numbers like 3S2P, which mean the battery as 4 cells (4S) connected in series, and there are 2 cell sets connected in parallel (2P) , giving a total number of 6 individual sells in the battery. So the number of cells is what defines the voltage of the battery. Having a higher voltage means the battery can provide more power to drive bigger motors, however more power does not necessarily mean the battery will provide energy for longer, that is defined by the battery capacity.
A LiPo cell has a nominal voltage of 3.7V, and a lipo cell = 1 cell = 1S = 3.7V. For the 14.8V battery above, that means that there are four cells in series (which means the voltage gets added together). This is sometimes why you will hear people talk about a “4S” battery pack – it means that there are 4 cells in Series. So a four-cell (4S) pack is 14.8V, a three-cell (3S) pack is 11.1V, and so on.3.7V battery = 1 cell x 3.7V= 1S battery
7.4V battery = 2 cells x 3.7V= 2S battery
11.1V battery = 3 cells x 3.7V= 3S battery
14.8V battery = 4 cells x 3.7V= 4S battery
18.5V battery = 5 cells x 3.7V= 5S battery
22.2 V battery = 6 cells x 3.7V= 6S battery
29.6 V battery = 8 cells x 3.7V= 8S battery
37.0V battery = 10 cells x 3.7V= 10S battery
44.4V battery = 12 cells x 3.7V= 12S battery
The voltage of a Lipo battery pack is essentially going to determine how fast your vehicle is going to go. Voltage directly influences the RPM of the electric motor (brushless motors are rated by kV, which means ‘RPM per Volt’). So if you have a brushless motor with a rating of 3,500kV, that motor will spin 3,500 RPM for every volt you apply to it. On a 2S LiPo battery, that motor will spin around 25,900 RPM. On a 3S, it will spin a whopping 38,850 RPM. So the more voltage you have, the faster you’re going to go.
When you select lipo battery, you need to know your motor of rc model, Voltage has an impact on motor, and motor influence the speed. The higher voltage is, the higher power(P) of the motor is, and here is the formula:
“P” is power, “U” is voltage, “I” is current. As you know, the voltage influence the power of the motor of battery, and the power has an impact on the RPM of the motor, that means speed. So in some racing, pilots need the batteries are of high voltage to meet the needs of their rc model to get a high burst.
The mAh means the capacity of the lipo battery. Capacity is used to measure how much power a battery can hold and the unit of capacity is milliamp hours (mAh), which means 1300mAh can be put on the battery to discharge it in one hour. Milliamp also can be converted to amps(A), here is the conversion:
1300mAh=1.3 Amp Hour(1Ah)
Generally, capacity can determines how long you can run before you have to recharge. A larger capacity pack may give you longer usage times but being heavier it will adversely affect performance. Typical mAh for RCs range from 2500mAh to 9000mAh.
Discharge Rate (“C” Rating) is simply how fast a battery can be discharged safely. In the RC LiPo battery world it is called the “C” rating. A battery with a discharging rate of 50C, that means you could safely draw it at the 50 times more than the capacity of the pack, a 80C pack = 80 times more, a 100C pack = 100C times more.
Sometime, you would be required to get a battery of high discharging rate, usually in a race. So the higher “C” rating means your thing can get a higher burst in a moment. So, you know, why so many hobbyists attach such a great importance into the high discharge rate. But the disadvantage of the high “C” rating is it may get heavier and affect performance. It may e more expensive than the lower one.
Soldering battery connectors can be a real pain, so it is a good idea to try find a battery connector that you like, and stick to it. That allows you to swap batteries easily. Common connectors include Deans or Tplug, XT60, XT90, EC3, IC5, Traxxax plug and QS8 connectors.
“It’s not easy at all to solder, it’s tricky to get it right, dangerous if you do something wrong like short the battery, you can damage the battery or ESC, this happens to even the experienced solderers. Seek assistance from shop owners and groups, especially if you’re new to it.” EVO RC Top Tip
How to maintain the Lipo battery?
- Always check the battery before charging for any type of damage. Check the battery packaging, wires and connectors for defects, which may cause a short circuit and eventual battery failure.
- Make sure you are using charge leads which are compatible with the battery connectors.
- Always monitor the charging process.
- Only use charger designed for the battery type. Do not use an NIMH/ NICD/ LIFE charger. If the charger can support different battery types. Be absolutely sure to select the Lithium polymer (Lipo) mode on the charger.
- Always charge Batteries in an open area away from flammable materials, liquids and surfaces.
- Never charge Batteries inside of the model.
- Never charge Batteries that are hot to the touch (above 100° F). DO NOT handle Batteries until they are cool.
- Always set the charger to the proper cell count and/or voltage listed on Batteries’ labels.
- Always set the charger to the amp charge rate as listed on Batteries’ labels.
- Never overcharge Batteries beyond the capacity listed on Batteries’ labels.
- Use suitable and good quality chargers.
- Never discharge Batteries at amperage rates higher than specified on Batteries’ labels.
- Never discharge Batteries to voltage below which they are rated.
- Never discharge Batteries to a level below 3V per cell under load
- Never leave battery unattended during the discharging process.
- In case of emergency, discontinue the process immediately, disconnect the battery, place it in a safe area outside of any building or vehicle and away from any combustible materials. A battery can still ignite even after one hour.
- Check the conditions of the battery before using it
- Stop using it if user found the cells are not balanced or cells are puffing or weeping.
“If your lipo shows signs of burnt material or has started swelling up, don’t risk it, dispose of it and get a new one, always!” EVO RC Top Tip
Lipo Battery Storage
- Do not directly connect the terminals with metal objects. This will short-circuit Batteries, resulting in heat and electrical discharge.
- Never storage Batteries to extreme temperatures or direct sunlight. The battery should be stored within -10℃ ~ 45℃ range environmental condition.
- If the battery has to be stored for a long time (Over 3 months), the environmental condition should be:
- Temperature: 23±5℃
- Humidity: 65±20%RH
- The voltage for a long time storage should be 3.6V~3.9V range per cell
- Always disconnect Batteries when not in use and store Batteries in a non-conductive and fireproof container, lipo bags.
- Never alter, puncture or impact Batteries or related components.
“Always keep your batteries in a LIPO bag, ALWAYS !”
EVO RC Top Tip
Lipo Battery Charger
Chargers are getting smarter and they can detect the condition of each cell inside the battery pack, such as the voltage. It is convenient to know the battery performance and charging status.
Lipo battery storage works, we all know that lipo battery cannot be stored in full charge, it needs to be controlled in the range of 3.6~3.9V, and the smart charger can help you to adjust the voltage of the battery to a specific storage voltage value.
EVO RC Recommended Chargers. Local RC shops have in stock:
HOW TO SPOT BATTERY Damage
Watch out for the signs, swelling, puffing up, signs of burn, strange smells, when in doubt always ask for advice.
Instructions For Disposal By Users
This product must not be disposed of with other waste. Instead, it is your responsibility to dispose batteries responsibly by contacting Wasteserv.
Batteries are classified as Hazardous Waste, dispose of them by hand at the bring in sites below, do not throw them in any bin!