The new Thunder Power RC TP-535C Lithium Polymer Battery Charger li-po charger (also known as TP535C or TP-535) combines the value of the TP-425C charger with new features previously found only in top-of-the-line lithium polymer chargers like the TP-1010C. These features include a data port to connect to a Thunder Power balancer (such as the TP-205V or TP-210V), and higher charge rates (3000mA and 3500mA).

Able to charge 1 to 5 cells, the TP-535C charger has a 45 Watt maximum power output, and requires a 12V input capable of 5A. Also newly released, the Thunder Power TP-1205P Power Supply is perfect for powering the 535 charger. The 1205P outputs 12V and can supply a current of 5 Amps. The TP-535C charger and TP-1205P power supply are also available as a combo, for more savings.

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Choosing the right Electronic Speed Controller (ESC) for your radio control electric aircraft can be made quite simple. ESCs are available with many different features, limits, and price ranges. Sorting through the list of ESCs can be done by identifying what you need, and eliminating the rest.

The general procedure is to narrow the list down to ESCs that will get the job done, and then make your final selection based on price and preference. First, select ESCs based on their most fundamental features.

Brushed or Brushless?
R/C speed controllers are separated by the type of motor they work with, either brushed or brushless. If your motor has two wires, it is brushed, and you need a brushed speed control. If it has three wires, it is brushless motor, and you require a brushless speed control. An exception to these rules are ESCs that can work with both types of motor, however this feature is not commonly available. Castle Creations and Hacker Brushless are two manufacturers of brushless motors and ESCs.

Current Rating
An ESC will have a power limit. To handle more power, the ESC needs to be larger, heavier, and is more expensive. It’s important to know the peak current your motor is going to pull at full throttle. This determines the current rating you should look for in an ESC. Always choose an ESC with a current rating that is higher than what you need. If the motor is going to pull 12A, a 25A-rated ESC is a much better choice than a 10A-rated one. The 10A ESC will probably overheat and cook, even if you only fly at half throttle. ESCs are relatively light and maintain great resale value, so this is one item in your power system where skimping isn’t worth while.

Choosing the correct type and identifying the minimum current rating are the two big steps. The next choices depend on your preferences. Here are some of the features and limits that can affect your selection.

Voltage Rating
All ESCs have voltage limits. Some even have more than one! What is your battery voltage? Choose an ESC that is designed to work with an equal or higher voltage. Some ESCs are designed for low voltages (below 13V), some for medium voltages (below 25V), and some for high voltages (above 25V). You shouldn’t connect a high voltage battery to a low voltage ESC, but it is also wasteful to use a high voltage ESC with a low voltage battery. The second voltage rating that some ESCs have is based on their Battery Eliminator Circuit (BEC). For an ESC to provide power to your receiver and servos, it has to drop battery voltage down to 5V. This becomes difficult once battery voltage is above 13V, so usually a separate receiver battery or voltage regulator is required. Consider what is going to be powering your receiver and servos.

Low Voltage Cutoff (LVC)
To protect your lithium polymer battery pack from being discharged too much, most ESCs can shut down when they sense battery voltage has become too low. This is almost always a useful feature, as it can save your li poly battery from being permanently damaged.

Price
ESCs with the same current and voltage rating can vary in price. Investigate this large market, and put prices on the features that you want.

Programmability
Some ESCs simply work out of the bag, like a servo. Others can be fine-tuned and set up with exotic throttle profiles. The most advanced can be configured via a computer program and cable.

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Finding the brushless motor that is the best choice for your plane or helicopter can seem to be a daunting task due to the large number that are available. There are a few important considerations you should keep in mind when choosing. This article will help you identify these issues so you can spend more time flying and less time trying to find that “perfect” motor.

Ultimately, you want to swing a certain size prop at a certain RPM. In fact, the freedom you have in choosing propeller size and operating RPM can lead to huge performance gains over comparable glow motors used in many remote control airplanes. Prop and RPM selection determines how much power you need, it is important to choose a motor that is almost at its limits when running at that power level. A motor that is too small will overheat and ruin itself, a motor that is too large will be a detriment to performance, due to the added weight.

Translating propellor size and RPM into power requires some help. This help can come from a computer-based prop simulator, such as the Slough RC Model Club Prop Power, Thrust and Efficiency Calculations web site by Rod Badcock. You can also find data posted by someone who has done what you are trying to do; find out what prop they used, what RPM it spun, and how much power was used.

Your list of potential motors should now only contain motors that can comfortably (but not ‘in their sleep’) put out the power you need. Now you’ll have to make decisions on the other things: battery voltage and capacity, direct drive or geared, outrunner or inrunner, and kV.

The easiest choice is whether to use direct drive or a gear box, so make that one first. If you want to turn high RPM (greater than 10,000 RPM) you’ll probably want a direct drive inrunner. For lower RPM, you can run an outrunner in direct drive or an inrunner through a gearbox. The outrunner is simpler and quieter, but the inrunner in a gearbox can be more adjustable and slightly more efficient. In some cases, the outrunner can be quite a bit cheaper. Each has its advantages, so consider them both.

At this point you know what RPM your motor needs to turn. It is either the same as you want the prop to turn(direct drive), or at a ratio faster than the prop when using a gearbox. Motor RPM is going to determine your specific motor and battery choice, by the following approximate formula (assuming lithium polymer batteries).

Motor RPM = 0.8 x 3.5V x Series Cell Count x Motor kV Rating

You need to select the right motor and battery combination that will satisfy the motor RPM formula. You can do it with a low kV motor and a high series cell count battery, or vice versa.

Lithium polymer battery packs, such as the ones made by Thunder Power, are ideal for use with brushless motors in radio controlled airplanes and helicopters due to their low weight and high capacity compared to NiMH and NiCd packs. Along with a brushless motor and battery, you will also need a brushless speed control (ESC) with an amp rating equal to or greater than the peak current drawn by your motor.

Make your choice, order the parts, put them together, and test it with an Eagle Tree watt meter. You want to make sure that you are near the RPM and power levels you were aiming for. Remember, though, the most important test is how it performs in the air. Fly it, and fine tune with prop selection. Hopefully this article has brought you close enough that a motor or battery change isn’t required.

In the event you require an upgrade, Draganfly Innovations Inc. is your best choice for Hacker Brushless Controllers and Motors, Castle Creations Brushless Controllers, APC Landing Products electric RC airplane propellers, Eagle Tree flight data e-loggers and Thunder Power RC Lipo Battery Packs.

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Lithium polymer batteries are expensive. How you handle yours will have a big effect on how long they last. Therefore, it is worth taking the time to learn about proper charging procedures.

Lets say you just finished using your lithium polymer battery. It can be charged again without delay, as long as it isn’t hot. If it is hot, you will need to wait until it has cooled down; preferably to below 35° Celsius (95° Fahrenheit).

Your battery isn’t hot, so let the charging begin. The first steps are to power up your charger and connect your battery charge cable to the charger. You should plug in the charge cable before connecting it to the battery, because charge cables usually terminate in exposed bullet / banana connectors, which are easy to short to each other directly or via anything metal (i.e. the charger). Now you can connect the battery to the charger via the charge cable.

It’s time to set the charger’s settings. Whatever the input method, there are two important settings: charge voltage and current. The correct voltage setting is determined by the lithium polymer battery you are charging. Most batteries say their nominal voltage, with the common ones being 7.4V and 11.1V. This number is calculated as

Correct Voltage Setting = 3.7V * Number of Cells in Series

On small to medium sized lithium polymer batteries, the number of cells in series is simply the number of cells in the battery. However, on large batteries, some of the cells are wired in parallel and as such do not contribute to the correct voltage setting. The standard for writing the number of cells in series is Xs. For a small battery, like the Thunder Power Pro Lite 3s 1320mAh, we see that X=3. For this battery, correct voltage setting = 3.7V * 3 = 11.1 V.

Correct voltage setting now determined, all that remains is current setting. Current setting is largely up to the user. The most common and always correct setting is:

Standard Current Setting = Battery Capacity / 1h

Continuing with the above example, the battery capacity is 1320mAh. Therefore, standard current setting = 1320mAh / 1h = 1320mA = 1.32A. This is known as a 1C charge, because C is defined as 1 / 1h.

Some like to charge slower than 1C to be gentle with their batteries. However, there is no scientific evidence of slower charging leading to longer battery life. There are also a few chargers that charge faster than 1C to save time, such as the Thunder Power 1010C. These chargers are usually very specific about when this fast charging is safe; please follow the instructions and warnings they come with.

With those two settings set, you are ready to start the charge. Once the charging process has started, the charger takes care of everything. It will end the charge when the battery is full, at which time you can use it again. There is no need to wait between the end of a charge and the start of a discharge.

There are two ways of increasing the safety of your charges. One is to use a balancer, such as the Thunder Power 205V or 210V. The balancer will fight cell imbalance, and provide some a warning if the cells are dangerously imbalanced. The other is to place your battery somewhere nonflammable. Ask yourself, if this battery ignites, will anything nearby ignite as well? Leaving the battery on a wood counter or in a wood airplane is more risky than isolating it on a bare cement floor.

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As of December 6th 2006, Thunder Power produces 16 different cells, both in their Pro Lite and eXtreme series batteries, to meet the widely varying needs of R/C modellers. Whether you fly radio control airplanes, drive rc cars, or boats, there’s a Thunder Power cell for you. This article will help you choose between them.

Thunder Power’s 350mAh Pro Lite 18C cell is their smallest. Offered only in 2s (22g) and 3s (33g) packs, this cell is meant for the smallest indoor airplanes. Common all-up-weights for a 350mAh-powered airplane are 3-6oz. These packs are available with a JST connector or with bare leads. A balance connector is not available, so max charge rate is 1C.

The Thunder Power 480mAh Pro Lite 15C cell is just a little larger. Offered only in 2s (23g) and 3s (34g) packs, this cell is meant for small indoor airplanes. Common all-up-weights for a 480mAh-powered airplane are 5-8oz. These packs are available with a JST connector or with bare leads. A balance connector is not available, so max charge rate is 1C.

Thunder Power’s 730mAh Pro Lite 13C cell bridges the gap between indoor and outdoor airplanes. It’s small enough for an indoor plane, but large enough for an outdoor plane. Common all-up-weights for a 730mAh-powered airplane are 7-13oz. It comes in 2s (34g) and 3s (49g) packs, and is available with a JST or with bare leads. A balance connector is not available, so max charge rate is 1C.

Thunder Power’s 910mAh Pro Lite 16C cell is for small outdoor airplanes weighing 9-15oz. It is available in 2s (46g) and 3s (65g) packs, and with a JST or bare leads. A balance connector is standard, so max charge rate is 3C.

The Thunder Power 1320mAh Pro Lite 13C cell can fuel a lot of very fun 10-20oz airplanes. The two 1320mAh packs are 2s (58g) and 3s (85g). A balance connector is standard, so max charge rate is 3C.

Thunder Power’s 2000mAh Pro Lite was released in early 2005. When it came out its performance eclipsed the competition. It had lithium polymer’s incredible energy density and revolutionary power density. It also premiered a second revolution: the balance connector. To this day, no one – not even Thunder Power – has been able to better it. More recent batteries do offer considerably better power density (higher voltages under higher loads), but that is at the expense of energy density (they weigh more for the same capacity). The 2000mAh Pro Lite cell remains the best choice for any model that has to run longer than 15 minutes, and a very competitive cell for 12-15 minute run times. Because of its performance, Thunder Power uses it in a huge range of packs, from 2s1p 2000mAh to 5s4p 8000mAh and 10s2p 4000mAh.

Some of us have seen electric aircraft with stunning performance. Key to this performance is a high C rating and high power density. Thunder Power’s take on this is the Pro Lite 2100mAh cell. Rated at 24C burst, this battery attracts attention from the glow crowd. It is available in 2s, 3s, 4s, and 5s; and in 1p (2100mAh) and 2p (4200mAh). A balance connector is standard, so 3C charging is available.

Thunder Power has developed a cell specifically for the T-Rex 450. It is the eXtreme Series 2070mAh, in 3s form. This cell unlocks the extreme performance possible with a T-Rex, and will do it over a long cycle life (the T-Rex is known for killing other cells faster than usual). The 2070mAh eXtreme Series cell is available in 2s, 3s, 4s, and 5s, all with a balance connector and 3C charge rates.

Thunder Power’s eXtreme Series cells – 2200mAh, 3300mAh, 3400mAh, 3800mAh, 3850mAh, 4500mAh, 4600mAh, and 5000mAh - are all about power. With 22-25C continuous and 50C burst ratings, these cells seriously perform in the most demanding applications, like electric ducted fans and 3D helicopters. eXtreme Series cells are available in 3s, 4s, and 5s packs, all with a balance connector and 3C charge rates. A few special 2s or 2p packs are available, too.

Packs with higher capacities than the above cells are made by combining 2 or more cells in parallel.

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Lithium polymer batteries have made R/C flying more fun. The performance they offer is revolutionary and remarkable. But, they are susceptible to damage and need to be treated carefully. One important device that protects and maintains your lithium polymer battery is the balancer. Let’s examine how that is.

Lithium polymer batteries are damaged by:

• Mechanical deformation
• High temperature (above 60degC / 140degF)
• High voltage (above 4.2V/cell)
• Deep discharge (below 3.0V/cell in use, 3.3V/cell recovered, or 3.7V/cell storage)
• Rapid discharge (shorting cells or using above recommend discharge rates)

Of these, high voltage is the most difficult to control. Batteries made of lithium polymer cells wired in series will naturally, with time and cycles, become imbalanced. That is, each cell will be at a slightly different voltage.

This leads to high voltage while charging, as the charger can only read the average cell voltage. The charger will bring the pack to an average of 4.2V / cell, but one or more cells are above 4.2V / cell. Slight imbalance is always present -even in a battery that is new and balanced by the factory - and does no harm, but large imbalance does harm and is prevented by a balancer.

A balancer connects to a battery via cell taps. Cell taps are small wires soldered onto each cell’s tabs. The balancer thus has direct access to every cell, allowing it to adjust individual cell voltages by dissipating the energy as heat, or re-routing it to cells of lower voltage.

The tangible benefits of this include:

• Stronger performance throughout the battery’s life
• Longer battery life (more cycles)
• Ability to eliminate one cause of cell combustion, namely cell over voltage while charging due to imbalance

Though every brand and model of cell balancer works a little different, the general procedure for their use is: Connect the balancer to the battery before charging, charge, and remove balancer when charge is complete. Regarding frequency of use, a balancer can be used with every charge, though this isn’t necessary if the battery is in good condition. Most users feel the extra effort of using a balancer with every charge is worth the added safety features.

Examples of good commercially available balancers are the 205V and 210V from Thunder Power.

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Lithium Batteries are found in many modern electronic devices, such as laptops and cell phones. They are significantly lighter than NiMH or NiCD batteries, and have higher capacity for the same size. Over the last five years they have worked their way into the hobby market, for use in electric RC helicopters, boats, cars, and particularly rc model airplanes. Their light weight and high capacity make them ideal for long flight times, while also providing more power.

Voltage, Cell Count And C Rating:
The nominal voltage of each cell is 3.7V, but can go down to 3.3V during discharge, and up to 4.2V when fully charged. A battery pack is usually composed of two or more cells put together in series for increased voltage, or in parallel for increased capacity. The C rating denotes how quickly a battery can be discharged (a rating of 1C continuous would mean that a 2000mAh battery should not be discharged any faster than 2000mA or 2A, which would take one hour). A 2000mAh pack rated at 12C continuous would be able to discharge at 12 times its capacity (12 x 2000mA = 24000mA or 24A) at which rate it would discharge in 1/12th of an hour. If you know how much continuous current you will be drawing and the capacity of the pack you want to use, you can easily determince what C rating you require. If you are drawing 5A from a 1320mAh pack, just take the current and divide by the capacity: 5A = 5000mA, 5000mA / 1320mAh = 3.8C. Using a pack with a higher C rating than you require will leave some headroom, and extend the life of your battery. Batteries are also given a C rating in terms of burst, which is how quickly the battery is able to discharge for a short period. A burst rating of 20C would mean a 2000mAh battery could supply 20 x 2000mA = 40000mA or 40A for a few seconds at a time.

Naming Conventions:
Lithium Batteries are also know as LiPo, Li-Po, LiPoly, or Li-Poly. The pack configuration is denoted by the number of cells in series and the number of cells in parallel. A 3s2p pack would have three cells in series, and 2 cells in parallel, using a total of 3×2=6 cells. A 4000mAh 3s2p pack would have a capacity of 4000mAh, and a voltage of 11.1V (3 x 3.7V). It would internally consist of six 3.7V 2000mAh cells. The cells would be doubled up (the 2p part of 3s2p) to get 4000mAh, and there would be three in series (the 3s part of 3s2p) to get 3 x 3.7V = 11.1V.

Which Battery Is Best For Me?:
To select a battery, you first need to know what voltage you require and how much current you will be drawing continuously. If you have a motor that works with 11.1V, you would need a 3 cell battery. If you need to draw 20A, and you would like to have a 10 minute (1/6th of an hour = 6C) flight, you would need a battery with 20A / 6 = 3.3A = 3300mAh. This means you would need a 3s 3300mAh battery with a C rating of 6 or higher.

Safety Precautions:
Never charge a lithium battery if it is below 3.0V per cell, puffed up, or damaged. Always place on a fire-proof surface when charging. Only use chargers designed to work with Lithium Polymer batteries. Never leave your battery unattended while charging.

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