Battery Breakthrough

At this years F3A aerobatic world championships held in Poland, history was made. For the first time in it's over 30 year existence, an electric powered model was competitive against the most powerful O.S. and Y.S. glow powered pattern airplanes in an FAI world championship format. At the start of the event, contestants and spectators alike were skeptical believing that competing with an electric model was more of a publicity stunt than a serious competition attempt. But after the first flight, all skeptics were silenced and by the end of the preliminary rounds, a 4^th place position transferring into the finals proved that an electric powered model had the right stuff to compete against the most powerful glow powered aircraft as flown by the best pilots in the world.

The technology that's made this all possible is also changing the face of electric modeling at local fields and indoor flying sights across the country. The latest technology Lithium Polymer batteries offer several times the capacity/ run time of previous generation Nickel Cadmium and Nickel Metal Hydride batteries with reduced weight and size. Plus the latest generation LiPo's (short for Lithium Polymer) have a low internal resistance so they're able to provide high amp draw for powering high performance and even large scale models.

Thunder Power is the current performance leader in LiPo batteries and Horizon is offering a variety of Thunder Power battery packs for most popular electric aircraft applications. Imagine flying a GWS Tiger Moth or FD stick for over an hour on a single charge. Or imagine an indoor 3-D model that you can hover in a small office for over 15 minutes. With LiPo batteries you no longer have to imagine, as this type of performance is now a reality.

Understanding LiPo's

Lipo's are very different than previous generations batteries and understanding how they work and especially how to charge them is the key to getting the best performance.

Series

Individual lithium Polymer cells have a nominal voltage of 3.7 volts. (vs. 1.2volts per cell for NiCd's) Cells are wired in series to give the following pack voltages:

1 cell =3.7 volts

2 cells in series =7.4 volts

3 cells in series =11.1 volts

Parallel

Unlike Nicads and NiMh's that self discharge when wired in parallel, LiPo cells can be hooked up, charged and discharged in parallel with no detrimental effect. Wiring two Lipo cells in parallel doubles the capacity (more run time) plus an import advantage of wiring in parallel is that each cell only sees half the total current.

3S 2P

A battery pack that has three cell in series (giving 11.1 volts) and 2 of these 3 cell pack are wired in parallel commonly is referred to as a 3S, 2P. (3 series, 2 parallel)

C Rating

Lipo cells are also commonly given a C or current rating. This is the maximum average recommended discharge current for the cell. For example the Thunder Power 1900mAh packs have a 6C rating. To determine the maximum recommended discharge rate multiply the capacity times the C rating. 1900mAh x 6C = 11,400. So the maximum recommended discharge rate would be 11,400ma or 11.4 amps. If your application has a higher amp draw remember that Lipo's can be wired in parallel and with 2 cells in parallel each cell sees half the total current. 3 cell in parallel, each cell see one third the current.

By wiring packs in a combination of series to get the voltage and parallel to achieve the capacity and individual cell current to an acceptable level lipo's can be used to power nearly every type and size of model.

Charging Lipo's

Charging Lipo's requires a very different charge method than other types of cells. It's imperative to us a charger designed specifically for Lipo batteries, and with most LiPo specific chargers it's necessary to correctly select the cell count (1 2 or 3 cells) manually. Fortunately several good chargers are available through FMA, Astro Flight plus many other companies including E-Flight and Thunder Power will soon be releasing inexpensive Lipo specific chargers within the upcoming months. These chargers give a constant current charge rate at 75% the cell capacity until the pack voltage reaches 3.6volts per cell. This charges the pack about 80% of total capacity. At this point the charger switches to a constant voltage charge rate of 3.6 volts per cell to top off the battery. Typical charge times are in the one and one half hour range to charge a fully depleted pack.

Serious Safety Issues

If Lipo's are improperly charged they can cause an explosive fireball. Our staff recently tested the effect of improperly charging lipo's and the results were dramatic! We cannot over emphasize the importance of using a charger specifically designed to charge Lipo batteries and to be positive that the manual cell count (if the charger has one) is correctly set for the specific battery being charged. If you us a good quality Lipo charger these batteries are totally safe.

Lipo do's and Don'ts

Do- Only use a charger that is specifically designed to charge Lipo batteries. Using other types of chargers can cause an extreme fire hazard!

Do- Lipo's don't develop memory or voltage depression characteristics like nicd's. Do charge them without the worry of cycling or discharging them.

Do- store lipo's at least partially charged. Lipo's will maintain their performance levels over time even during non use much better than nicd's and there's no need to cycle them.

Don't- Use any type of charger that is not specifically designed to charge Lipo batteries. Using non Lipo specific chargers can cause an extreme fire hazard!

Don't- Fully discharge your Lipo battery pack. Most speed controller have a voltage cut off that will prevent over discharging the battery. Discharging a Lipo beyond it's critical minimum voltage will cause damage to the battery.

Don't- if you have a crash and the battery is damaged don't put the battery in your car or house immediately after a crash. It's possible that a chemical reaction can take place in the damaged battery that could cause a fire. Put the battery in a safe place for a least one hour.

Thunder Power is offering several pack sizes and configurations for most common applications. More pack sizes and configurations will be added as the need exists.

730mAh 7.4volt (2S)

Application- GWS Slow Flyers, 280 powered aircraft

Size- 50mmx 34mmx 9.5mm

Weight- 1.1oz

Current rating- 6C

730mAh 11.1 volts (3S)

Applications- GWS IPS power systems, indoor 3-D models, small brush-less

Size- 50mmx 34mm x 14mm

Weight- 1.6oz.

Current rating- 6C

860mAh 7.4 volts (2S)

Applications- GWS Slow flyers, IPS and 100C power systems,

Size- 62mmx 34mm x 9mm

Weight- 1.3oz.

Current rating- 5C

860mAh 11.1 volts (3S)

Applications- GWS IPS power systems, indoor 3-D models, small brush-less

Size- 62mmx 34mm x 14mm

Weight- 1.9oz.

Current rating- 5C

1320mAh 7.4 volts (2S)

Applications- GWS 100, 300 and 350 series power systems, Speed 280 motors small brush-less hacker B-20, Astro 010/020 systems

Size- 64mmx 34mm x 13mm

Weight- 1.95oz.

Current rating- 6C

1320mAh 11.1 volts (3S)

Applications- GWS 100, 300 and 350 series power systems, Speed 370 motors small brush-less hacker B-20, Astro 010/020 systems, Indoor electric helicopters, Larger Indoor 3-D models, small outdoor park flyers.

Size- 64mmx 34mm x 20mm

Weight- 2.85oz.

Current rating- 6C

1900mAh 7.4 volts (2S)

Applications- GWS 300, 350 and 400 series power systems, Speed 370, 380 and 400 motors, small brush-less hacker B-20, Astro 010/020 systems, GWS outdoor park flyers.

Size- 68mmx 45mm x 12mm

Weight- 2.75oz.

Current rating- 6C

1900mAh 11.1 volts (3S)

Applications- Hacker B-20, Tribute 3-D, Astro 010/020 systems, Larger Indoor 3-D models, 3-D outdoor park flyers.

Size- 68mmx 45mm x 20mm

Weight- 4.0oz.

Current rating- 6C

2100mAh 7.2 volts (2S)

Applications- speed 400, Speed 380, Speed 480, GWS park flyers, Hacker B-20, Zagi 400, Astro 010/020 systems, Larger Indoor 3-D models

Size- 96mmx 34mm x 14mm

Weight- 3.0oz.

Current rating- 6C

2100mAh 11.1 volts (3S)

Applications- primarily brush less motor systems like Hacker B-20, Astro 010/020 systems.

Size- 96mmx 34mm x 20mm

Weight- 4.6oz.

Current rating- 6C

Thank you,

Lori Schwartz

Account Base Manager

Phone: 800-535-5551

Email: lschwartzDELETE@horizonhobby.com