For some pilots, the idea of tuning a combustion engine is enough to keep them away from the flying field. Electric-powered aircraft provide these pilots a means to enjoy model aviation without the fuss of a “traditional” engine.
LiPo (Lithium-Polymer) batteries are a popular means for powering our electric models. When used properly, these batteries provide convenient, reliable, renewable, and relatively inexpensive power. As is the case when working with any power source, there are a few things that modelers need to know to stay safe and keep their batteries performing.
In this four-part series, we’ll teach you all about this popular power source.
Part 1: Understanding the Technology and Its Safe Use
Battery Types
General Battery Safety
Understanding the Labels
Memory
An Introduction to Charging and Storage
The Secret to Long Life
Disposal
Connecting It
Ultimate Low-Tech Tester
There are two items everyone entering electric flight has to deal with: batteries and connectors. On the surface, it’s simple, but it causes more confusion and questions than practically anything except motor designations. I will shed some light on these and I hope to clarify things. This is for the electric newbie who wishes to understand and make the right choices for his or her requirements.
Battery Types
Everyone is familiar with the batteries he or she uses around the house. Most are alkaline in AA, AAA, C, D, or 9-volt formats. Others are rechargeable Nickel Cadmium (Ni-Cd) or Nickel Metal Hydride (NiMH). In the dark ages of electric flight, we used Ni-Cd and NiMH batteries, but now the standard is Lithium-ion Polymer (LiPo) and that will be the focus here. These batteries are sometimes referred to as battery packs or simply packs.
There is another type of battery chemistry called a Lithium Iron Phosphate (LiFePO4) that some use for flight packs, but are more often found in receiver and transmitter packs. They are usually referred to as LiFe packs or A123 packs, referencing their makeup and brand name.
Each type has its advantages and disadvantages, but because LiPos are the de facto standard in electric flight, I’ll concentrate on them.
Safety First
Rumors abound about safety, or lack thereof, when using LiPo batteries. Much of that is leftover from the early days of LiPo packs and the lack of information available to the user at the time.
Incorrect chargers were used, incorrect voltage cutoffs were used, and they were being discharged at levels that the packs couldn’t support. As chemistries, protective circuits, and information improved, LiPo batteries have become a safe and suitable source of power. Here are a few simple rules for increasing your safety:
• Always store batteries in a fire-safe container.
• Always charge with an appropriate charger designed for LiPos.
• Always follow the manufacturer’s instructions for charging and discharging rates.
• Always size a pack according to its usage.
• Never overcharge.
• Never overdischarge.
• Never use a puffed pack.
• Never use a pack that has visible damage (dents, cracks, etc).
• Never charge a pack unattended.
• Never disassemble or reconfigure a damaged pack.
Most accidents involving LiPo packs are the result of not following one of these rules. Understand the charger you’re using and follow the manufacturer’s guidelines and they will serve you well. Charge safely.
Understanding the Labels
Labels contain plenty of information, but understanding them is often confusing. A few simple definitions will help you.
• 3S, 4S, etc.: Battery packs are composed of a number of cells in series and this number represents that. If the pack is listed as a 3S pack, then it has three individual cells connected in series within the pack, each with a nominal voltage of 3.7 volts. The pack’s total will then be listed as an 11.1-volt pack. A 4S pack would be 14.8 volts, etc. (four cells x 3.7 volts = 14.8)
• Capacity: The capacity rating of a LiPo battery tells its output potential, or how long you can take power from the battery at a given rate before it reaches the cutoff voltage, or is discharged. The faster you take power from the battery, the less time it will last.
Many times, our batteries’ capacities are listed in milliampere hours (mAh) instead of ampere-hours (Ah). This is merely a metric conversion to a smaller unit—1 ampere hour = 1,000 milliampere hours, so 2.2 Ah is 2,200 mAh.
• Discharge rating: “C” represents a measure of the rate at which a battery can be discharged relative to its maximum capacity. If the battery is discharged at a rate higher than the discharge rating, the battery may be damaged, or worse, could pose a safety hazard, like a fire.
If a battery’s discharge rating is 15C, it means that the most power that can be drawn from it at one time is equal to 15 times its capacity. Using the example of a battery which has a capacity of 2,200 mAh, this means that greatest flow of electricity you can safely get from the battery is 15 x 2,200 = 33,000 milliamperes (or 33 amperes).
The discharge rating listed on the battery’s label is based on what the manufacturer believes the pack will handle during discharge without degrading the pack. These discharge ratings, sometimes mistakenly referred to as C ratings, can be optimistic and are best used as a guideline. Packs with higher discharge rates have lower internal resistance (IR), which is a good thing.
Many batteries with provide two discharge ratings such as 30C/60C. These represent the continuous and burst ratings.
The first number means that it will continuously support a 30C discharge, and for short bursts (typically less than 15 seconds) it should support 60C. This allows for spikes during rapid throttle changes, but shouldn’t be something you use regularly. If you need higher current levels, buy a higher capacity/rated pack.
• Internal Resistance: This represents the internal resistance of a cell or pack. Some chargers will test the IR for each cell within a pack during the charge cycle. As internal resistance increases, the battery efficiency decreases. So as a general rule, the lower the resistance the more punch a battery will provide. It’s nice to know, but not something to get hung up over as a beginner. As a rule, packs advertising a high discharge capacity will have a lower IR.
Battery pack labels are often the manufacturer’s attempt to put its product in the best light. A pack rated as a 65C pack and sporting small-gauge wires to the connectors won’t really handle that amount of current. Sometimes packs come with large-gauge wires, but they’re soldered to tiny tabs inside the pack, which negate the benefit of those monster wires. Shop carefully and use the best battery you can afford.
Memory
If you’re beginning to fly electric-powered aircraft and your only experience has been with Ni-Cd or NiMH packs, you’re probably wondering about memory effect. Older Ni-Cd and NiMH batteries suffered from an effect termed memory in which the way the battery had been discharged in the past would affect its performance in the future, even after being fully recharged. The good news is with LiPo and LiFe packs, there is no such concern.
Sizing Your Battery Pack
If you’re new to electric-powered models, you will probably follow the manufacturer’s recommendation for an appropriate pack for your aircraft. That’s what you should be doing.
As you expand your hangar, you may decide to add a bigger battery or need something that isn’t specified. You need to do enough research to get a feel for what type of current the setup will pull under full throttle and size your pack accordingly.
If your airplane requires a 3S setup using a typical 2,200 mAh pack and you change to a “hotter” motor—meaning one that is more powerful and will pull more current—you need to see if your current packs can handle it. If your current power system is pulling 20 amps with your 2,200 mAh 15C pack, but your next motor upgrade will pull 35 amps, that pack won’t be happy. Let’s look at why.
The 15C pack is technically capable of pulling 33 amps (2,200 mAh x 15 = 33,000 mAh or 33 amps), so your 20-amp requirement was well within its limits. Now looking at the new setup with the motor requiring 35 amps, you see that the pack is undersized, if only by a couple of amps. That’s enough to cause problems that can be costly in the long run.
I recommend buying a quality LiPo pack that is well beyond the projected requirements of the setup. Running a pack at its limit will guarantee a short life and wasted money. Pay attention to the label and notice if it gives two ratings such as 30C/60C. These represent the continuous and burst ratings as previously mentioned.
Charging and Storage
Always balance charge when you can. Balance charging evenly distributes the energy stored in the battery across the multiple cells inside. This will prolong your pack’s life and ensure better service from it. You can get away with fast charging at the field without balancing if your regular routine is balance charging at home.
There are debates about charging and storage levels, but the safe bet is to store batteries at something other than fully charged or fully discharged. Most good balancing chargers offer a storage mode that takes them to a level of approximately 3.8 volts per cell. The important thing is not to leave them fully charged or discharged for long periods of time.
The Secret to Long Life
The secret, at least for your batteries, is to charge to 4.1 volts per cell as opposed to the full 4.2 volts per cell, and never discharge them to full discharge level. Working your packs in between the two ends of the charge/discharge levels will greatly increase their lifespan.
Engineer/charger/ESC designer Doug Ingraham described it this way: “There are several things that cause degradation of lithium batteries. One is heat and for the purposes of RC modeling, this is most likely the one that causes the greatest degradation. The others have to do with the effects on the materials at both ends of the state of charge.
“The lithium ions are forced into the carbon material on the plates at both ends of the state of charge. This causes a breakdown in the material, and in future charge cycles less ions can be held causing degradation in capacity. It is mostly at the ends (full and empty) that this damage occurs so staying away from the ends even a little can help extend the life of the cells.”
Several chargers offer a charge cutoff labeled “Long Life” or something similar and they stop the charge at 4.1 volts per cell. From Doug’s explanation, you can see that using the 4.1 volts keeps you off the top end and setting an ESC low-voltage cutoff above the traditional 3 volts per cell will keep you off the bottom end. Unless you’re a competitor trying to squeeze every last bit out of your flight, this will serve you well and save you money.
Disposal
When your batteries get to the point that they need to be disposed of, one of the simplest options is using a no-cost used rechargeable battery and cellphone collection program offered with a network of more than 34,000 collection sites throughout North America.
Call2Recycle accepts NiMH, Lithium Ion (Li-Ion), LiPo, and Ni-Cd batteries weighing up to 11 pounds. Simply visit the program’s website, www.call2recycle.org, and enter a ZIP code to find a collection center near you. If you don’t have Internet access, call (877) 273-2925.
Drop-off centers are located at corporate offices, healthcare facilities, manufacturers, military bases, and at major retailers such as The Home Depot, Lowe’s, Staples, and Best Buy.
Connecting It
The connectors you choose for your model are as important as any other piece of equipment. Connectors are designed for certain sizes or gauges of wire. As such, they are rated for specific maximum electrical throughput, just as wire is (as you learned in the terminology table). Like wires, if more electricity is put through a connector than it was designed for, resistance and heat will increase.
You can use the connector table to find out what type of connectors you have and what their capabilities are. There are many types of connectors available, and most beginner models come from the factory with some type of preinstalled connector. This connector may or may not match the battery you have. Adaptors are available for many types of connectors and existing connectors on models or batteries can even be completely replaced with a connector of your choice.
Many modelers with multiple airplanes try to keep the same type of connectors on all of their models and batteries for simplicity.
Ultimate Low-Tech Tester
Your hand is one of the best meters to gauge how your setup is doing. The magic temperature for a danger threshold is 140° on LiPo packs, and that is darn hot if you touch it. If your battery feels too warm, it probably is.
Heat is wasted energy and a sign of trouble. If your motor is too hot to touch, it’s probably over-propped. If the ESC is too hot to touch, it’s probably undersized, as is the battery if it’s hot. If your connectors are warm, they’re a choking point in the circuit, causing high resistance and lost efficiency.
Heat is a natural byproduct of our setups, but we need to size things accordingly to keep it at a minimum. A small, inexpensive IR temperature gun can be a valuable tool when troubleshooting.
Wrapping It Up
Don’t make your world more complicated than it has to be when trying electrics. Information abounds on the Internet, as do rumors and conjecture. “Experts,” and even experienced modelers, tend to load up newcomers with more information than they need to get started, and do it out of their exuberance for the hobby.
Do your homework, study the manufacturer’s information, and try to make the best decision you can. Don’t obsess over it! Most Plug-N-Play systems work well and are well matched. There’s plenty of time to venture out on your own.
Don’t overtest your batteries on the bench. That doesn’t replicate actual flight conditions.
Part 2: Transporting Your Batteries
FAA Security and Hazardous Materials Safety
How It Affects Us
Lithium batteries have been around for quite some time. They seem to be everywhere—in virtually all portable electronic devices such as cell phones, tablets, and laptops. Many of today’s electric-powered tools fit into this category as well.
You’ve probably read about or watched videos of LiPo batteries that caused fires because of damage or improper charging or incorrect use. These items can cause serious damage and injury if not handled using appropriate safety precautions.
Even some of the newest airliners have been equipped with these powerful batteries, some with not-so-good results! According to recent reports, in the Boeing 787 Dreamliner’s first year of service, at least four aircraft have suffered from electrical system problems stemming from its lithium-ion batteries.
The National Transportation Safety Board (NTSB) released a report on December 1, 2014, and assigned blame to several groups:
• GS Yuasa of Japan for battery manufacturing methods that could introduce defects not caught by inspection
• Boeing’s engineers who failed to consider and test for worst-case battery failures
• The FAA, which failed to recognize the potential hazard and did not require proper tests as part of its certification process
As a result, the FAA has directed the Transportation Security Administration (TSA) to look into the lithium battery situation and how they are being transported from the manufacturer to the importer, to the retailer, and then to the public. Once in the hands of the consumer, the TSA is looking into how these batteries continue to be transported as we travel with our electric-powered models onboard aircraft.
Let’s first take a look at the FAA’s policies for transportation of lithium-based batteries. The following is an excerpt from the FAA’s Security and Hazardous Materials Safety website:
FAA Security and Hazardous Materials Safety
Our Specialists implement the Hazardous Materials Compliance and Enforcement program by conducting shipper assessments and inspections. The Joint Office’s goal is to “Prevent fatalities resulting from improperly shipped hazardous materials in the United States and on U.S. Air carriers abroad.” To accomplish this, the Hazardous Materials Branch is working more efficiently and collaborating with the shipper industry. The Hazardous Materials Branch targets its compliance and enforcement efforts by identifying those areas that create the greatest dangers for airplanes.
We also conduct Outreach to educate the various air operators, shippers and the public regarding the safe transportation of hazardous materials by air. The FAA Office of Security and Hazardous Materials Safety (ASH) wants to ensure that the public and industry are better informed and have designed our outreach efforts to accomplish this goal.
FAA’s Office of Hazardous Materials Safety strives to increase safety in air transportation by preventing hazardous materials accidents and incidents aboard aircraft. Over 100 special agents dedicated to enforcement and educational outreach, ensure compliance with U.S. Department of Transportation (DOT) regulations.
Hazardous materials (a.k.a dangerous goods) sent using commercial transportation must comply with Hazardous Materials Regulations, 49 CFR Parts 171-179. These regulations apply to those who offer, accept, or carry hazardous materials to, from, within, and across the United States.
FAA’s special agents conduct inspections and investigations of those who
• Offer hazardous materials for air transportation (the shippers)
• Accept and transport the hazardous materials (the air carriers)
• Compliance and Enforcement
Agencies that handle hazardous materials shipments for shippers or carriers, such as freight forwarders and repair stations, are subject to the Hazardous Materials Regulations and FAA inspection. Because these regulations apply to the aircraft cabin as well as the cargo hold, passengers and their baggage are also subject to these rules and FAA jurisdiction.
FAA Special Agents inspect U.S.-registered air carriers (certificate holders) for compliance with FAA hazardous materials training requirements found in 14 CFR Part 121 and Part 135. Air carriers in the U.S. cannot carry hazardous materials as cargo until they have an FAA-approved hazardous materials training program. The FAA principal operations inspector assigned to the carrier coordinates this approval.
How It Affects Us
Obviously, packing up the car and driving is a good way to avoid any hassles, but for other transportation modes, taking proper precautions and ensuring that the packs are properly stored is a must. Transporting lithium batteries must be done by a certified carrier that has been trained on packaging requirements for these batteries. As a result, all packages will have a label marking them as hazardous materials and noting that there are lithium batteries inside.
But what about jumping on an airline with your favorite model as a carry-on? Are you traveling to an international location as part of an AMA competition team to attend and participate in an international event or World Championship? Perhaps you are just visiting friends and want to fly your model while you’re there. There are some new rules and requirements that are now in place by the TSA and the FAA that we must now abide by.
AMA spoke with Michael D. Givens of the FAA Hazardous Materials Division. Michael provided information about transporting our model batteries. These batteries can be a carry-on item brought with you on the aircraft. These rules are specific to Lithium-ion batteries (rechargeable lithium, lithium polymer, LiPo, secondary lithium).
Passengers may carry all consumer-sized lithium-ion batteries (no more than 8 grams of equivalent lithium content or 100 watt-hours [Wh] per battery). This size covers AA, AAA, cell phone, PDA, camera, camcorder, handheld game, tablet, and standard laptop computer batteries, as well as our model batteries.
The Wh rating is marked on newer lithium-ion batteries. Passengers can also bring two larger lithium-ion batteries (more than 8 and less than 25 grams of equivalent lithium content per battery or roughly 100 to 300 Wh per battery) in their carry-on. This size covers the largest aftermarket extended-life laptop batteries and most lithium-ion batteries for professional-grade audio/visual equipment and our larger model aircraft battery packs. Most lithium-ion batteries are less than this.
The bottom line is that you can carry multiple lithium batteries with you as a carry-on on an airplane. There is no limit to the number of batteries (100 Wh or less), as long the FAA believes that the amount you are carrying is “reasonable” and not for resale. However, you are limited to two batteries between 100 and 300 Wh rating.
Recently, an AMA employee was at the airport and watched several AMA members go through the TSA inspection carrying lithium batteries as a carry-on and there were no issues. The packs were in a separate bag, and it went through the x-ray machine with no questions.
Although there are new regulations in place, there are no real issues with carrying batteries with you, as long as you are not bringing extremely large packs. I recommend that you check your packs and find out if you have any that are between 100 Wh and 300 Wh and be prepared to limit yourself to only two of these when you go to the airport.
If you are going out of the country or plan to take more than two of these larger packs, you will need to send them to your final destination by cargo aircraft or surface means.[dingbat]
—Tony Stillman
[email protected]
Sources
FAA
www.FAA.gov
FAA’s Office of Security & Hazardous Materials Safety www.faa.gov/about/office_org/headquarters_offices/ash
FAA’s Office of Hazardous Materials Safety
www.faa.gov/about/office_org/headquarters_offices/ash/ash_programs/hazmat
NTSB
www.ntsb.gov
Part 3: Charging Your Batteries
Chargers
Input Power
Output Power
Single and Multiport Chargers
Balancing
Connectors
Read the Instructions
Storage Charge
Charge Rate
Safely Charging Batteries
Safely charging and storing LiPo batteries is an important requirement of electric-powered flight. LiPo batteries rose to popularity with their ability to provide longer flight times with less weight as compared to the NiMh and Ni-Cd batteries they have largely replaced.
The saying “with great power comes great responsibility” would be a fitting description when describing LiPo batteries, but understanding the basics of this battery technology and having a working understanding of your charger will go a long way.
Chargers
It should come as no surprise that if you are going to use LiPo batteries to power your electric aircraft, then a charger designed to charge LiPo batteries is required. Although some RTF aircraft come with basic chargers, we are going to focus on stand-alone chargers that offer more flexibility, and functionality.
When it comes time to purchase your first charger, or possibly a replacement charger, there are many things to consider such as input power, output power (in watts), capability to charge single or multiple battery packs at the same time, number of cells supported, balancing, and computer connectivity (for tracking and updates).
Selecting a charger with an LCD screen is also a good idea so that you can easy and accurately change charging parameters and monitor the charge cycle and the voltage of individual cells.
Input Power
Chargers receive power from alternating current (AC), direct current (DC), or have the option to use either one. An AC charger has a built-in power supply allowing it to be plugged into a wall socket, making it handy to charge batteries anywhere there is an available outlet.
DC power comes by either plugging the charger into a power supply or by connecting it to a battery. This is convenient for charging at the field or at events when electrical outlets are unavailable.
Output Power
Chargers are typically rated in watts. Watts are calculated by multiplying the voltage and the amps. A fully charged 2,200 mAh 3S LiPo battery would have a voltage of 12.6. Charging at 1C, it would draw roughly 28 watts of power (12.6 volts x 2.2 amps = 27.72 watts). As you might expect, charging at a higher C rating will increase the required wattage needed from the charger.
Single and Multiport Chargers
Multiport chargers allow two or more batteries to be connected to the charger and simultaneously charged. The only drawback is that the separate ports on the charger split the available wattage, so a four-port charger might only support 50 watts per channel versus 200 watts that might be supported on a single charger.
The Graupner Polaron is a two-port charger with each port supporting 400 watts. This DC charger can be purchased with a matching power supply. Its form factor doesn’t take up much space on the bench.
The Hitec X1 Touch AC/DC charger is a 55-watt touch screen charger that is capable of charging one- to six-cell LiPo batteries.
Balancing
Balance charging LiPo batteries is essential to getting the most from your batteries by ensuring that the voltage of each individual cell in a pack is equal. Balancing helps prevent single cells from being overcharged or discharged, which can damage the cell and has the potential to cause a fire.
The balancing process will typically discharge the higher-voltage cells to match the lower-voltage cells during the charging process. Balancing can also be done with stand-alone products such as the Astro Flight Blinky LiPo Battery Balancer.
LiPo batteries composed of two cells or more could utilize one of four balancing connectors: XH, EH, HP/PQ, and TP. Some chargers include one or more balancing boards and some have all four on one board. If your charger doesn’t have the balancing connector to match your batteries, you can probably purchase one.
The Hitec universal balancing board, supplied with the X1 Touch, supports all four types of balancing plugs. Other chargers might come with up to four smaller boards.
Depending on the different connectors on your batteries, you may want a charge lead that can support several, such as the one pictured, as opposed to a separate charge lead for each connector.
The XH balance connector has become the most common connector found on batteries in the US. E-flite and ElectriFly are examples of brands that use this plug.
Connectors
Beyond the balancing connector, most batteries have a primary connection used to connect the battery to your aircraft and to the charger. This consists of a positive and negative wire with a connector that is usually preinstalled on the battery when purchased. Some batteries come without a connector, allowing the end user choose the connector. (To learn more about connectors, see page 33 of the July 2015 issue of Model Aviation.)
Bullet connectors with one positive and one negative lead are used to connect the charge lead to the charger. On the other end could be a pair of bare wires (requiring that a connector be installed), a preinstalled connector, or multiple connectors.
Read the Instructions
Before using a charger or charging a battery for the first time, thoroughly read the instructions. On a charger with an LCD screen, take time to navigate the menus and learn how to change the charge setting. If the charger includes a USB connection, check online or with the manufacturer to see if there are any firmware or software updates. If so, follow the manufacturer’s instructions and update the charger.
Visually inspect the charger to ensure that all of the leads, connectors, fans, etc. are serviceable and working.
Thunder Power provides the following instructions before installing a connector or charging a battery for the first time:
1. Make a visual inspection of the pack. Check for any damaged leads, connectors, broken or cracked shrink covering, puffiness, or other irregularities.
2. Before installing or changing the connector, check the pack’s voltage using a digital voltmeter (not your charger). All new packs ship at approximately 3.8 volts to 3.9 volts per cell. For example: A 2S pack should read approximately 7.60 volts to 7.8 volts; a 3S pack should read approximately 11.40 volts to 11.7 volts.
3. If you find any damage to the pack or leads, or the voltage is significantly less for your pack than specified, do not attempt to charge or use the battery. Contact Thunder Power [or your battery’s manufacturer] directly as soon as possible.
Storage Charge
If storing a LiPo battery longer than one week, batteries should be stored at 3.8 to 3.9 volts per cell (approximately 50% charged). Storing a LiPo battery fully charged can affect its capacity loss over time. A LiPo battery charged to 4.2 volts per cell and then left on the shelf at room temperature will lose roughly 20% of its capacity in two or three years. Store the same battery at the optimum storage voltage and put it in the refrigerator and it will take approximately 10 years to lose 20% of its capacity.
Many chargers on the market today have a built-in storage charge/discharge function. Chose this option, input the battery parameters, and let the charger do all of the work!
Charge Rate
To get the most from your batteries, manufacturers recommend charging at 1C, even if the battery states it can be charged at 3C or even 5C. Charging at a higher rate throughout the life of a battery will affect the number of cycles you are able to get from the battery.
Think of your charge rate as similar to shipping a package. To get your package faster than standard shipping has a cost associated with it—namely money. The same goes for your batteries. Charging them at higher than 1C will allow the charge process to complete faster; however, it is at the cost of reducing the number of cycles that the battery will provide throughout its serviceable life.
Safely Charging Batteries
The two most common instances of having a LiPo battery vent or catch fire is arguably during the charging process or resulting from a crash. In the case of charging the battery, you can further protect yourself by never charging batteries unattended, charging batteries in an isolated area away from flammable materials, and using some type of device or container that will encompass the flames if a battery were to vent.
Commercially available products include the LiPo Sack, LiPo Bunker, an ammunition can, or concrete blocks. Any device that you use should contain the flames while allowing the gases to vent. In the case of the ammunition can, you can drill small holes in the top to allow venting. If the LiPo is unable to vent, it could cause an explosion.
It is important to have a nearby smoke detector, sand, and fire extinguisher. The detector will alert you if a pack begins to vent. The sand should be used to extinguish a LiPo fire and the extinguisher is to put out any other material that might ignite because of the fire. Household fire extinguishers are not rated for use on a LiPo fire. Class D fire extinguishers can be used for a LiPo battery fire, but they are costly.
Designed by Mark Wood, the LipoSack was released in 2006 as a means to charge, store, and transport LiPo batteries.
Conclusion
Advancements in LiPo batteries have made it possible to power aircraft from ultra-micro-size to Giant Scale models. Having a basic understanding of the batteries and the chargers used will go a long way toward ensuring the safe use of LiPo technology so you can benefit from lighter batteries and longer flight times.
I want to thank David Buxton, Tony Stillman, Thunder Power RC, and Hitec USA for their assistance with this article.
Sources
LiPo Battery Basics (Part 1)
www.ModelAviation.com/lipo1
LiPo Battery Basics (Part 2)
www.ModelAviation.com/lipo2
Tony Stillman
(765) 287-1256, ext. 230
[email protected]
Thunder Power RC
(702) 228-8883
www.thunderpowerrc.com
Hitec USA
(858) 748-6948
http://hitecrcd.com
Part 4: Storing and Disposing of Your Batteries
Discharging for Storage
Protecting Connectors
Storage Environment
Battery Disposal
Battery storage: If storing a LiPo battery longer than one week, batteries should be stored at 3.8 to 3.9 volts per cell (approximately 50% charged). Storing a fully charged LiPo battery can affect its capacity loss over time. Many chargers on the market today have a built-in storage charge/discharge function. Select this option on the charger, input the battery parameters, and let the charger do all of the work!
According to Thunder Power RC, the optimum temperature to store batteries is between 40° and 70° and they should not be exposed to direct sunlight for an extended period of time. It is also a good idea to cover the connectors or ensure that multiple connectors cannot come in contact with one another and possibly cause a short. Caps can be purchased to cover many popular connectors.
Batteries should be stored at 3.8 to 3.9 volts per cell—approximately 50% charged. The optimum temperature to store batteries is between 40° and 70° and out of direct sunlight.
Image
Caps can be purchased to fit and cover many popular connectors and prevent a short.
Commercially available products that can be used to store your batteries include items such as the LiPoSack, the LiPo Battery Bunker, or even an ammunition can. If you are using an ammunition can, you can remove part of the seal or drill small holes in the top to allow for venting in the event of a LiPo battery discharge or fire.
Many products, such as the LipoSack, can be used to safely charge and store your batteries.
Recycle It
If your LiPo batteries have reached the point where they have lost 20% or more of their capacity, or have puffed, it’s time to say your goodbyes and recycle them.
Call2Recycle, a battery collection program that has accumulated more than 5.7 million pounds of rechargeable batteries, will recycle your NiMH, Lithium Ion (Li-Ion), LiPo, and Ni-Cd batteries weighing up to 11 pounds (New York’s weight limit is 25 pounds) for free. There are approximately 30,000 participating public collection sites across the US and Canada.
The collection sites are conveniently located at retail stores, small businesses, and municipalities. In Indiana, where AMA Headquarters is located, drop-off sites include Sears, Lowe’s, Best Buy, Ace Hardware, Staples, Home Depot, Office Max, HobbyTown USA, Office Depot, and solid waste districts.
Finding a drop-off center located near you is simple. All you need to do is visit www.call2recycle.org and type in your ZIP code. This action opens a map showing the closest drop-off locations. If you don’t have Internet access, you can call (877) 273-2925 in the US or Canada.
Call2Recycle provides free battery collection at many popular retailers. Drop-off locations can be found on the organization’s website. Best of all, the batteries are recycled.
There is a collection box for the batteries at each drop-off site. All batteries intended to be recycled must be individually bagged to ensure that the terminals cannot touch. Puffed battery packs can also be recycled as long as the structural integrity has been maintained, they are bagged, and the terminals are protected.
You may be wondering why you should recycle your aircraft’s batteries when it’s more convenient to throw them in the trash. Before you toss them, you should know that some states have passed laws making it illegal to dispose of certain types of rechargeable batteries and cellular phones in the regular trash. New York, North Carolina, New Mexico, and California have such laws in place. You can find more information on each state through the Call2Recycle website.
After the batteries are collected, the chemicals in them are used to make new ones. The cadmium in Ni-Cd batteries can be used as a stiffening agent in materials such as cement, and the nickel is used in stainless steel products.
In its more than 20 years of existence, Call2Recycle has diverted millions of pounds of rechargeable batteries from landfills. In 2014 alone, 12 million pounds of batteries were recycled instead of being tossed into landfills. In California, more than 1 million pounds of batteries were recycled, and collections in Canada climbed to an all-time high of 4.4 million pounds.
Call2Recycle is funded by major product and battery manufacturers that want to ensure that the batteries and cellphones they sell are recycled.
Call2Recycle does not accept single-use/disposable or automotive batteries. A detailed list of what batteries can be accepted is found on the Call2Recycle website.
—Jay Smith
[email protected]
—Rachelle Haughn
[email protected]
Sources:
Call2Recycle
(877) 723-1297
www.call2recycle.org
“LiPo Battery Basics” (Part 1)
www.ModelAviation.com/lipo1
“LiPo Battery Basics” (Part 2)
www.ModelAviation.com/lipo2
“LiPo Battery Basics” (Part 3)
www.ModelAviation.com/lipo3