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[信息] 终极电池"锂聚合电池"

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发表于 2007-9-7 13:49:11 | 显示全部楼层 |阅读模式

国外翻译文章---终极电池"锂聚合电池"

翻译: 张志炫 先生
感谢张先生的技术知识分享
以下是小弟买了一颗KWT 11.1V 2200mA锂聚电池使用之后感觉很不错,上网找到一些相关文章,特此翻译以享各位,由于时间关係先就前半段post出来
原始文章在http://www.rcgroups.com/links/index.php?id=4286
很精采的
以下小弟就献丑了,翻的很烂不吝指教底下是我有关Thunderpower" 5s4p电池的使用经验
这个组合让我十年的飞行经验有很大的改观,这是一个对模型爱好者来说绝对是一个全新的技术,正确安全的使用任何设备都是使用前必需的,但是对于锂聚合物电池的特性描述目前却是缺乏的,本文将尽量的描述相关的文章让准备使用的人有个参考
这次我们将Thunderpower 5s4p与传统镍镉及镍氢电池在不同的机型上做比较这样就可以很清楚的将两者的特性显现出来,
一个做为测试的机种是Robbe BAe-146 EDF客机这是一款大型的机种我用的是5s4p 8200mA电池组,另一机种是Kyosho喷火,是由Kelvin Ritchie製作与试飞的
这款喷火是由3s4p 及 2s4p串联所达到7800mA的电池作为动力源
这两款飞机各有不同的特性,都可以很好的作为测试电池性能的平台
我们就拿Kelvin Ritchie用5s4p 7800mA Thunder power测试他的中型喷火战机的结果来开始
1. Thunderpower 5s4p, 7800mA电池
2. Kyosho .40 Spitfire ARF
以下是Kelvin Ritchie的经验 :
我在2002年二月开始飞电动飞机时就有一个目标就是希望有一天能飞超级海军喷火式战机,我原先规划以400马达搭配8颗镍镉电池,后来我放弃了这样的搭配,最后我选择了Hacker B50 10L及5.2:1行星齿轮减速组驱动APC 14 x 10桨,动力源是16颗Panasonic 3000mah Ultra Metal 镍氢电池,电变使用的是Hacker Master 77 3P Opto,并使用收脚架,总重是6磅15oz输出为52A,在MWE展览时我第一次看到大型电动遥控飞机的飞行,而且是使用新开发的电池---锂聚合电池,我以前也听过这种电池,但是还没真正看过它的使用,这次终于有机会让我见识到它的威力,过去3000mA镍氢电池可以让我维持7分钟的飞行但是我都将它设定在5分钟的飞行时间,在一次我的朋友借给我一颗Thunderpower 5s4p 7800mA锂聚合电池的机会中,我将它用在喷火上,还好我的电池室装的下它于是我便将它应用上了
这颗电池组是由两组合成的,一颗是3s4p 另一颗是2s4p每组都有1950mA其中3s4p有12颗每三颗串联成一组共有四组并联组成一个大电池,2s4p也一样每二颗串联成一组共有四组并联组成一个大电池,每一颗电池可以充到4.2V所以五组电池可以型成21V,输出电流可以从45A到50A,充电方式可以分压充各别电池最大电压为5A,用了这颗组合电池后不仅我的飞行时间增加了,在重量上还减少了6 oz,第一次用它飞了8分钟,过去用镍氢电池我还未飞超过六分钟,在起飞前我测量过马达,电变及电池温度,在SEFF的气候是80s到90s,而8分钟的飞行让电池温度昇高到120度华氏,马达约150度,如果’若将飞行时间延常到10~12分钟则温度不变,但是时间超过15分钟则温度会明显昇高到140 度,说明书上警告不要把温度超过140度,这是电池的极限温度
经过正常的10~12分钟飞行后我可以用5A充电,当充电电压开始由21V降低时我可以拿开电池重新开始飞行而不必过份的等待,喷火的巡航飞行时只要1/2油门,而3/4油门就可以做垂直爬昇及大翻滚,锂聚合电池真的是很棒,我不必担心会耗光电力无法降落,它提供大型飞机更强更轻的动力源,充电也更迅速可以用1C充电,并且它保持电力的性能也很优异在飞行前一个星期充的电一个星期后仍然保持电压,唯一的缺点是成本太高,不过这会在将来改善
另一个例子是
1. Thunderpower 5s4p, 8200mA
2. Robbe BAe-146飞机
我拥有一架大型的Robbe BAe-146导风扇客机已经有四年了,这架飞机在1990年设计了,它用了四个EDF碳刷动力在它的75英吋机翼上,总重8.1磅它起动时就像真的飞机,我的客机最初用34 oz 16颗RC2400电池,在2002年夏天电池开始恶化,自此开始飞机就不能再飞了,后来才发现其中一颗电池已经开始漏液
, 在修复动力源的过程中我发现了一个新的动力源,一个5s4p 8200mA的电池居然只有27oz,这个重量比我原来的2400mA镍镉电池轻了7 oz但是电力却大了足足四倍,5s4p电池有16到17颗电池可以提供41A的连续输出而不须冷却,如果加上冷却可以连续输出达到49A(在140华氏下),5s4p可以提供最大电压达到60A
我想在我使用这个新产品之前我必须先做一些功课,1.我的AstroFlight 204D店变是否可以承受锂聚合电池60A的最大电压?,我的Schulze充电器是否可以安全的充这颗电池,在充电的过程中它的电压特性曲线是如何?
相关的测试
我买了一个3s1p 2100mA的锂聚合电池搭配我的无刷马达,这个实验是我打算万一失败了,这是一个我可以接受的最小损失
在此我需要买一个软体将我的Schulze充电器昇级以策安全
升级的费用很低晶片也很容易安装,市面上一些比较高级的充电器都可以用软体更新功能用来充锂聚合电池目前为止我找了电变的说明书发现还好它可以在这样的环境下安全操作,而锂聚合电池串连时每个电池正常的充电电压是3.75V,因此锂聚合电池不可以在低于3V下放电因为这种情况下电池的特性曲线会让它在3V下耗尽电量,并损坏电池.底下有两种方式可以保护你的电池第一个方式是将你的电子变速器更改晶片的程式,在危险电压时便自动关闭在我的2100mA 3s1p电池搭佩的是Castle Creations Phoenix 25无刷电变,我将程式设定在9V就自动断电,这样就可以保护串联的三颗电池(每颗3V * 3 = 9V)原先我使用的方法是估计每趟飞行的时间然后测量电池电压,将电池放电时间预估出来.经过几次2100mA电池飞行的经验,我第一次持续飞行5分钟, 第一次正常飞行五分钟后再回充500mA,第二次飞行10分钟后再回充1000mA第三次飞行15分钟后再回充1600mA经验告诉我还有500mA可以让我降落这时电池的电压也可以保持在3V以上用这种方式保护你的电池是最有效的,毕竟15分钟的飞行已经够了
接下来待续......................................
要获得高容量的电池用小容量的电池改装好吗?这个答桉是见仁见智,这完全要看你的需求及电池组装的技术,在这篇文章中我用小容量的电池去改装成大的电池是因为在我使用锂聚合电池时当时并没有足够让我参考的资讯去掌握这个新产品,我不想让这个实验花费太高因为大容量的电池价位远高于小容量电池,虽然如此我毕竟也将我的400无刷马达特性发挥到了极限,这是非常值得的事最后我决定买了5s4p的锂聚合电池,因为我已经可以掌握它的特性了,从订购到送达家门口共花了一个星期的时间,当我小心地打开包装时我可以确定这就是我梦寐以求的终极动力了这是一个用收缩模紧密包装20颗独立的小电池结构,有两条安全接头导线, 长度12.5英吋,2英吋宽,及1英吋厚,每5颗小电池串联,共有2050mA,整颗电池有4串这样的电池并联起来,所以是5s4p构成2050V*4= 8200mA,所以充电时是看成5cell,充电前必须确实的看完并了解说明,还好要将这种电池安装在飞机上并不难,我用魔鬼毡将它固定在我的Bae- 146.上,我使用的是标准的Deans Ultra Plug銲锡还不错这样的重量可以提供8200mA焊接时要小心不要把正负及弄溷了,如果不小心将电池短路了而造成电池高温,此时必须将电池迅速移往不易燃的区域等待15分钟已确定没有起火的危险,由于这个电池比传统的镍氢电池少了7oz所以在起飞前必须先确定一下重心是否改变了,
非常重要的一点是---锂聚合电池的cell计算是以串联数为准Thunder power出厂的电池标示它的串联数,我在我的Schulze充电器上设定5cell并将充电电压设定在1C也就是8.2A,但是我的机器最大安培数是 5.5A,当我检查好所有的设定之后我便放心的去充电了,有一点要注意的是再充电时千万不要离开现场也远离易燃物,最后我测试的结果是关油门的电压是 20V电源打开后电压会降下来但是都维持在稳定的水准,马力全开后电压降到17.4V电流也提升到45A五秒钟后缓慢上升到47A电压也都维持在 17.3V接下来我让它在平速下磨合10秒
Thunderpower 5s4p 7800mah & 8200mah
By Ed Putnam
Introduction
I'll be up front with you about my experience with Advanced Energy's "Thunderpower" 5s4p battery pack. This pack has transformed my electric flying experience into one that I only thought might be possible ten years from now! Before you purchase a Lithium Polymer pack based on first impressions, however, be advised this is new technology to most hobbyists. A dedicated safety mind set is required to handle these packs properly, and Lithium Polymer packs for hobby use, at this stage, are not for everyone. This review contains a lot of information with links to other much more comprehensive sources of information that will be only the first step for many to determine if they are ready for these batteries.
This review will provide an inside look at two distinctly different models using Thunderpower 5s4p packs, and of course the effect the Thunderpower packs had on the models. Both models started out on Nicads or Nimh's, so the LiPoly upgrade is easily compared to a known quantity. One test model is a Robbe BAe-146 EDF airliner. This is my big EDF that provided the "lift" for my measurements and review of the pre-made 5s4p 8200mah pack. The other model that contrasts this perspective is a Kyosho Spitfire .40 ARF built and flown by Kelvin Ritchie. This Spitfire uses a combination of 3s4p and a 2s4p, 7800mah packs wired in series to create a 5s4p, 7800mah pack. The two models are quite different and provide a good review of the applications this pack will readily adapt to.
To start this review off right, we will share Kelvin Ritchie's experiences with the Thunderpower 5s4p 7800mah battery pack in his mid sized Spitfire.
Thunderpower 5s4p, 7800mah Pack Kyosho .40 Spitfire ARF by Kelvin Ritchie
When I started flying electric powered RC model airplanes in February 2002, I had a goal that someday I would fly a model of the Supermarine Spitfire. I envisioned it would be a model powered by a speed 400 motor and 8 Nicad cells. I did reach my goal but instead of a Speed 400 Spitfire, I ended up converting a Kyosho 40 sized Spitfire ARF. I had done some research on Ezone and the Internet and found a couple of conversions had been completed with this model. Nothing ventured, nothing gained, so I proceeded with the project. After some research and asking for advice on a power plant I chose to power my Spitfire with a Hacker B50 10L, coupled to a 5.2:1 planetary gearbox driving an APC 14x10 propeller. The "fuel" was 16 Panasonic 3000mah Ultra Metal Nmih batteries. The motor was controlled with a Hacker Master 77 3P Opto controller. Along with a retractable landing gear the Spitfire weighed 6lbs 15oz AUW and drew 52amps static.
The Spitfire was finished just before the San Diego 2003 Mid Winter Electrics (MWE) in February and I decided to bring it to the event. If it didn't' fly I could at least display it. While at San Diego my Spitfire flew its first flight at the capable hands of Gary Wright.
It was at MWE I saw first hand demonstrations of large electric RC model airplanes flying on a new type of battery: the Lithium Polymer cell. I read about them on Ezone but had not witnessed any flights using them until MWE. It was unbelievable the power and duration these cells allowed.
The 3000mah Nmihs give my Spitfire about 7-minute safe flight duration but I always set my timer to 5 minutes and then proceeded to land just in case I needed to make several approaches.
My Spitfire managed to stay intact to take it to the Southeast Electric Flight Festival in June. Just before I was to leave, a friend of mine, David Shotwell, offered to lend me his Thunderpower 5s4p 7800mah lithium polymer pack to use in the Spitfire. The battery compartment was big enough and the plane balanced correctly so I took him up on the offer.
This battery pack is actually two Thunderpower packs; a 3s4p pack and a 2s4p pack. Each pack is comprised of several 1950mah cells. The 3s4p pack has 12 cells. Four cells are wired in parallel and three of these are then combined serially. The 2s4p pack is similar but with only two in series. Each cell can be charged to 4.2 volts safely for a maximum voltage of 21volts for 5 cells in series. The cells are paralleled to allow sustained current draw in the mid 30-amp range with bursts into the 45amp to 50-amp range and to increase capacity to 7800mah. The 2s4p pack is velcroed on to the larger 3s4p pack. Each pack has a separate lead. The two leads are connected to a serial connector that allows the packs and the ESC to be connected.
An Orbit V6 charger with version 6.2 firmware is used to charge these cells at a maximum charge rate of 5amps. All I had to do was to fully charge each pack separately and then connect them together with the serial cable and fly. Then I could charge the whole pack as one thereafter. With the Thunderpower 5s4p pack I not only increased my duration three fold but I was able to reduce the AUW of my Spitfire by almost 6 ounces.
The first few flights using the 5s4p pack where flown for only 8 minutes! I had never flow my Spitfire for more than 6 on the Nimh's. I did this to measure the motor, ESC and battery temperatures before exploring longer flight times. The weather at SEFF was in the upper 80s to low 90s. The 8-minute flights yielded battery temperatures at about the 120 degree F range and the motor was around the 150 degree F range with the ESC being a little cooler. The flight times were increased to 10-12 minutes. The temperatures seem to stay the same. It wasn't until the Spitfire flew longer than 15-minutes did I see a rise in temperature of the batteries: about 140 degrees F. I've read that the 140 degree range is about the upper safe limit before damage might occur which would result in reduced duration and life span of the cells.
After a typical 10-12 minute flight, I would recharge the batteries at 5 amps. When the amps on the charger started to drop to maintain the maximum voltage of 21 volts I would pull the batteries off the charger when the amps were between 3 amps and 2 amps. This seemed to give enough duration without having to wait excessively. I would usually be ready to fly again within an hour.
The Spitfire has a lot of power especially with this motor configuration. It normally flies at ½ throttle for cruising around in a scale-like fashion with some gentle climbs to going to ¾ throttle to do long vertical climbs or big loops.
Lithium Polymers are great. I don't have to worry about running out of battery power on landings anymore. They give the power needed to fly larger electric models and are lighter than the traditional cells. Charging is easier also, just set it for 1C and the charger does the rest. Lithium Polymer cells retain their voltage longer after a charge. If you charge them a week before you fly there is very little voltage drop during that period. The only disadvantage with Lithium Polymer packs is the cost but that should change in the near future.
My Spitfire is a different plane with the Lithium Polymer batteries.
Thunderpower 5s4p, 8200mah Robbe BAe-146 by Ed Putnam
I've owned and flown a big Robbe BAe-146, scale electric ducted fan airliner for nearly four years. Designed in the early 1990's, it uses adequately powered and simple, brushed EDF units in 4 pod locations on the 75 inch wings. It weighs in at 8.1 pounds now (8.5 prior to the conversion). To it's credit, it looks, flies and sounds like the real thing - an notable accomplishment by Robbe for such a big model considering when it was designed, the fact that is was a mass produced kit and how well it flies on a completely stock setup.
My airliner was originally powered by a thirty-four ounce, 16 cell RC2400 pack. During the summer of 2002, the pack had shown serious signs of deterioration, and as a result the model wasn't flown much. Upon further investigation, one of the cells had vented, so a repair was made to the pack. It helped a bit, but the end game had played out for the pack. The few times I flew it this early spring, the pack was having a hard time maintaining voltage and capacity even with careful battery maintenance using my Schulze isl 6-330d charger. Even venerable old Nicad packs have a service life, and my packs were a year beyond theirs.
I was looking into the new Lithium Polymer power threads on the discussion boards as a diversion while trying to decide what new battery pack had to be purchased to get the BAe-146 back into shape. Among the many brands available, Thunderpower had a few ready-made packs that were drop-in replacements for larger models operating with 10 and more cells. The pack that caught my attention was the 5s4p at 8200mah at 27 ounces. This was a full 7 ounces lighter than my original 2400mah Nicad pack with almost 4 times the capacity considering I never got more than 2100mah out of my 2400mah packs. The 5s4p is a 16 to 17 cell replacement good for 41 amps continuous with little or no cooling, and 49 amps continuous with excellent battery in flight cooling. For brief periods (assuming batteries stay below 140 degrees F), the 5s4p is capable of "bursts" up to 60 amps.
Before I could jump on the opportunity to lighten up the load and increase the duration by a previously unthinkable amount, I had to do my homework. Would the original AstroFlight 204D brushed speed controller work with Lithium Polymer batteries? Could my Schulze charger in fact safely charge the new packs, too? How would I charge the packs, and what about all the potential pit falls along the way? Was I personally ready and able to approach the new technology with the required safety mindset?
Early Testing
As a test project, I went ahead and purchased a single, pre-made 3s1p 2100mah Lithium Polymer pack to try out on my single motor brushless models. This, I reasoned, was to get used to the new technology on a smaller, less expensive setup in case I made a costly mistake.
As it turned out, I needed to purchase a software upgrade for my Schulze charger in order to charge the packs safely. The upgrade cost was minimal, and the new chip was easily installed. Of note, most quality chargers that claim to charge Lithium Polymer batteries now have upgraded software. Be sure to check with the manufacturer to see if any upgrades are available prior to charging, and verify the software revision if you buy a new charger. On a good note however, it appeared my electronic speed controllers (ESC) would be able to safely operate with Lithium Polymer power. This does require some thought, however.
Lithium Polymer batteries have a nominal charge of 3.75 volts per cell in series. It is essential that Lithium Polymer batteries do not de-charge below 3 volts per cell. The discharge behavior of these cells is that they will be depleted in capacity when they are below 3 volts, and any further discharge can and will damage the cells. For this reason, there are two ways that flyers can choose from to protect their batteries while flying.
One way to protect from over-discharge is to use a programmable ESC and to program the ESC to cut off the voltage to the motor via the battery eliminator circuit at the appropriate voltage. In the smaller 2100mah 3s1p case, I was using a Castle Creations Phoenix 25 sensorless, brushless controller. I programmed the controller to BEC "auto cut off" at 9.0 volts, a perfect setting for a 3s pack.
A more cautious method, and the one I primarily use now, is to time a few flights and measure the capacity after the flight by topping off the battery. Over a few flights with my 3s1p 2100 pack, I logged the flight time and approximate power levels used. Example: Flight 1, moderate aggressive power use, 5 minute duration, 500mah put back into pack after charge. Flight 2, moderate aggressive power use, 10 minute duration, 1000mah charged back into battery. Flight 3, same power use, 15 minute duration, 1600mah charged back into the pack. I came to a happy medium with 15 minutes of flying time, knowing that I had approximately 500mah left in the pack after landing. By knowing that the battery voltage limit of 3 volts is directly linked to the capacity left in the pack with Lithium Polymer batteries, capacity control via established time limits can protect your battery packs. Besides, 15 minutes is a lot of flight time. I generally I land a minute or two before the 15 minute self imposed limit, out of choice.
On to the 5s4p
Is a smaller LiPoly pack a better way to get into the bigger LiPoly packs? Not necessarily, but this is a personal decision that must be made based on experience, comfort level, and one's own self assessment. It is necessary, however, to have solid battery charging discipline established with Nicad or Nimh batteries, as well as a quality charger specifically capable of charging current generation Lithium Polymer batteries. I purchased the smaller LiPoly pack because I was getting into LiPoly packs before a lot of specific information was easily found. I didn't want to make an expensive mistake. Besides, I wanted to supercharge and lighten up my brushless speed 400 scale and sport models. It was a great excuse at the time, anyway!
When I finally did feel ready to buy the 5s4p pack, I was now ready and able to make the transition into the big time with LiPoly. The pack took a week to make it to my doorstep. I looked over the pack very carefully to discover exactly what I was getting into.
The 5s4p 8200 pack compared to a 3s1p 2100 pack.
The pack revealed itself to be one block of shrink-wrapped base cells with two safety-capped leads. The pack consisted of 20 individual base cells. The pack measured 12.5 inches long, just less than 2 inches wide and 1 inch thick. The base cells are 2050mah LiPoly cells, wired appropriately. The cells are attached in a series of 5 in a row, making up the voltage of the pack. 4 identical rows of this "5 series" stick are glued on top of each other, constituting the 4 units in parallel. This is how the pack gets its name of 5s4p. It works out to be five in series, 4 in parallel. Of note as explained in just a moment, a 5s4p pack is charged as a 5 cell pack. Read your charger instructions, the Thunderpower pack instructions and the rest of this review prior to charging your pack. This review does not replace your instruction manuals, so be sure you are fully educated prior to charging.
Fortunately the mounting of the battery pack in the model was easy. I used two heavy-duty Velcro strap attachment locations mounted to the fuselage of my Bae-146. Two small strips of Velcro were also mounted to the 5s4p where the Velcro straps from the fuselage would attach to the battery. A small strip of Velcro was also glued to the battery mount floor on the fuselage and a corresponding bit of Velcro is located on the battery pack as a third attachment point for the battery mount.
The battery bay inside the fuselage with velcro mounts
The 5s4p mounted in the bay
The total weight came out at 27.1 ounces with a standard Deans Ultra Plug soldered to the 5s4p. Not bad for 16 -17 cells worth of voltage and 8200mah!! Care must be taken during soldering of the battery connector to ensure that no accidental touching of the positive and negative wire leads occurs. This would make a short circuit, and sparks or smoldering wire insulation may result since the packs are shipped from the factory with some charge. The real problem is that once a short occurs in a LiPoly pack, it must be carefully monitored in a non-flammable area for at least 15 minutes to ensure the pack does not show signs of damage (puffing up) or fire. Skip this step entirely, please, by ensuring that you keep the wire leads covered in the protective sheath (as shipped) until that particular lead gets soldered to the connector. Also, shrink wrap the first lead solder joint after the solder joint is complete, before taking the second wire's protective sheath off for soldering (to protect against this risk).
As mounted in the model, the 5s4p took off 7 ounces of weight yet no CG difficulties were encountered since the battery mount location was so close to the actual CG. Additionally, the shape change of the LiPoly pack as compared to the Nicad pack alleviated any CG shift. Please be sure to check your CG before flying when converting to the lighter batteries! In your model, it could make a big difference depending on the layout. A monitored top-off of the battery was completed to ensure the full 8200mah would be available for the first round of testing.
View from above in wing saddle area
IMPORTANT: To charge any LiPoly pack, one is concerned with how many cells are in series for "cell count" input into any applicable charger menu. It plainly states the cell count for charging purposes on the label of all new Thunderpower Packs, too, for clarity. Read your charger instructions, the Thunderpower pack instructions and the rest of this review prior to charging your pack. Again, this review does not replace your instruction manuals. If something is different in your manuals, your manuals are the ultimate authority. However, it would be a good idea to call the vendor if a question exists, to be sure you have the correct understanding. For my first charge on the 5s4p, I entered "5 cells" into my Schulze isl 6-330d charger, set the amperage to 1C (that would be 8.2 amps, but 5.5 is the maximum I can get on my charger so that is what I went with). After a thorough check of proper input data into the charger, I commenced with the charge.
I charged on top of concrete (away from anything flammable) and proceeded to do some long needed housekeeping work to my fleet of models. I had an excuse to do this sort of thing now, as I needed to stay near by to keep an eye on my charging pack in case anything was to go wrong.
The reason LiPoly packs need to be monitored and kept away from flammable material while charging is because of a few readily identified reasons. For one, chargers can still be set up incorrectly. If a higher cell count is incorrectly selected on some chargers, the resulting over charge voltage can cause possible problems such as cell venting and pack fires. Secondly, if there is undetected damage to one of the cells or an unforeseen large cell imbalance (due to damage), some base cells can short out causing a cell vent and even a fire if the battery is left to charge.
The Schulze chargers now have a new chipset they provide as a free upgrade that is said to prevent an incorrectly selected cell count. Several other charger manufacturers have released very good, quality chargers onto the market recently too. I believe charging hazards will decrease as hobbyists and the industry gain more experience. It's no mystery that millions of people all over the world use LiPoly cells every day with excellent safety records. Applications like Laptop computers and cell phones are good examples. However, we are "fast charging" these cells without the benefit of built in cell phone or lap top computer safety devices. We cannot blindly assume the associated "plug and play" safety environment exists with our rapid charge hobby cells. In fact, it doesn't, so pay attention.
Since we are using these cells in hobby applications with greater stress on the cells, we are pushing the envelope of technology. That's why it's mandatory to monitor the charge and always a good idea to be near by with an appropriate class fire extinguisher and thick heat resistant gloves handy just in case. Also, if a charger were to fail in some way, any sign of pack bulging or smoking would necessitate a quick removal from charging and monitoring in a non-flammable area. I can't identify how likely or rapidly a LiPoly pack fire can result from misuse or internal damage, however it seems that during a charging fire (as recounted by some on Ezone threads), a number of minutes with some sort of warning sign (cell puffing, venting, smoking) has elapsed before a pack fire resulted.
My flying buddies and I have never had a difficulty with LiPoly packs, but some have. It's essential to have a safety mind set with any new technology and understand the risks so that they can be minimized.
Read up on LiPoly cells on the Battery and Chargers forum pages here at the Ezone as the first step to purchasing your LiPoly pack. Note the "sticky" thread on the top discussing basics of "do's and don'ts" in Lithium Polymer batteries, among the many other related threads.
Finally, testing!
The first test was not a test flight, but rather a wattmeter test. Using my Astro Super Whatt Meter, I checked the initial power up of the model. Initial numbers were surprising. The voltage was higher than I expected. Throttle-off voltage was just over 20 volts! After powering up, the voltage decreased but remained stable and predictable. At full power, the voltage was 17.4 and the amp draw stood at 45 amps initially and then crept up to approximately 47 amps after 5 seconds, with voltage staying right at 17.3. I never conduct full power, static testing for more than about 10 seconds at a time to ensure the least amount of wear and tear occurs. A static test is good for initial numbers via wattmeter, but the value of such a test diminishes rapidly with the lack of cooling and unrealistically high workload the power system goes though in such a test. In flight, the ducted fan units (as in this case) and prop in other cases will "unload" in the air, reducing amp draw by a slight amount as well as providing cooling airflow to the motor and batteries. Wattmeter numbers showed just over 800 watts of power flowing to the EDF units. The previous Nicad system was a 700 plus watt power setup. The new, lighter, higher duration system appeared to promise additional power. The tests were looking promising so far!
The Astro 204D brushed Opto speed controller had absolutely no difficulties with the Lithium Polymer batteries (why should it?). However it is not a BEC equipped controller because of the opto coupling combined with the high voltage of the system. Hence, the flight timing method (covered earlier) was to be used to establish a safe flight time for the BAe-146 and the 5s4p combination.
At the flying field, things continued to look good for the new battery pack tests. The weather was perfect and the wind had yet to come up. It was now or never! So, taxiing into position, I slowly added throttle to establish forward movement, then crept up to full power. The BAe-146 smartly began to pick up speed and sounded stable. A few seconds later a smooth rotation to climb attitude was established. I observed a higher performance climb rate with the 5s4p as compared to the RC-2400's. I turned for the downwind leg and noticed I kept throttling back to keep the climb rate in check. Before, with the Nicad packs, I needed full power until nearly half way through the downwind leg to maintain altitude and accelerate.
During normal maneuvering I found power response crisp, and ability to return to full power was never in doubt. During extended full-power runs, the battery always delivered consistent power and displayed better power under similar throttle settings than the Nicads. Additionally, I found the LiPoly pack to never sag in power like previous RC2400mah Nicads did, under continuous operation. Overall, the performance of the Thunderpower 5s4p was superior in all aspects to the RC2400 Nicad pack.
Photo by James Frolik
After a number of test flights, I established that a 10 minute flight was a perfect match for this airframe and the battery pack, as well as the flight routine. I have flow 15 minute flights, but on a transport type model, 10 minutes is just fine. One important aspect of any LiPoly conversion is to make sure your components are ready for the extra flight time. I checked the controller, the 4 individual motors and the batteries during the shorter test flights leading up to the eventual 10 and 15 minute flights. At all times the motors, controller and battery demonstrated cool running performance.
Photo by James Frolik
If your model does not have adequate motor, speed controller and battery cooling, then those items are certainly on the "to do" list for your conversion. Most Nicad/Nimh powered models have been designed for 3 to 8 minutes of flying. Excessive heat can build up in the system above these time frames if extra cooling of components is not considered.
One surprise was that the 5s4p pack was barely warm after the typical 10-minute flight. It sure seemed it was not being worked too hard! LiPoly packs are, however, designed to run cooler than Nicads and Nimhs. The maximum temperature recommended for LiPoly packs is 140 degrees C, so they may fool you as to their relatively cool temperatures after a flight but remember they aren't designed to get hot. Make sure you have cooling inlets, and more importantly, exit vents for the vent air to leave the model. I was lucky with the BAe-146. The model has the best inlet and exit ducting I've ever seen designed into a kit aircraft. Additionally, the EDF units naturally allow the motors to remain cool, even in extended run times.
For 10 minutes of varied flying, the 5s4p 8200 typically took back about 4500mah after topping off. A significant number of touch and go landings can be had as well as several fly bys and higher altitude cruising passes in 10 minutes. For multiple flights in one day, a simple 40 minute partial charge at 1C would have brought the pack back to 6600mah. Since no memory effects result from partial charges or discharges with LiPoly packs, a partial re-charge is a viable option to continue flying for a number of charges before the majority of the pack would be used after the 3rd successive flight (in this example). I've been able to take the pack out of the model right after flying and almost immediately charge up for a quick top off because of the very cool temperatures of the pack, after flight.
In comparison, the Nicad RC2400 pack could fly the aircraft for only approximately 3.5 to 4 minutes (and that's pushing it) before a mandatory approach to landing needed to be made. After landing, the pack was very hot and needed to be cooled with a cooling fan for approximately 20 minutes. After cooling, it was then charged for 35 minutes or so, then cooled again for another few minutes. It seemed to be a whole lot of battery prep for such a short flight.
The extra flight time provided by the LiPoly pack turned out to be extremely liberating! After takeoff I used to have only a couple minutes to enjoy the full power and maneuverability of the Bae-146 under Nicad power. Now, after 9 and even 10 minutes, it is still flying as strong as it did right after takeoff. One additional value of the LiPoly battery pack to me is the lack of battery memory and low capacity loss over time of disuse. I can charge my packs a week prior to flying and the pack is still fully charged when it's needed. As soon as the model is set up, the pack goes in to fly. No topping off for the first flight, no battery maintenance to solve bad memory effects.
A very interesting scenario presented itself after several flights on the 5s4p. It seemed to me that I was flying the Bae-146 much more throttled back than I was before, for similar performance. I really don't think it is all due to the 5 percent lighter total weight. It seems that the Thunderpower pack keeps it's voltage under load very well, maintaining efficiency and allowing more partial throttle flight for better performance than Nicad power. In addition to the 8200mah of capacity, the batteries allow more efficient use of this very large capacity of power!
If there was only one regret with the model before, it was the flight time. Now there are no regrets, no excuses - just a lot of fun and enjoyment. The Thunderpower 5s4p has transformed this model into one that is twice as valuable, to me, as the one it was before.
Photo by James Frolik
Conclusion
Advanced Energy has produced a line of very capable LiPoly battery packs with their Thunderpower brand. This pack is well suited for all types of models in the 16 cell count arena and under 50 amps. From Aerobatic models, to scale fighters, to airliners and 3D aircraft: the 5s4p is a very capable power source.
There is a learning curve to deal with, however. I would be remiss to not mention in the conclusion, again, that a safety mind set is important, and that this new technology is not for everyone, yet. It is important for users to educate themselves and approach any new technology with respect, a desire to learn and good judgment. LiPoly cells are indeed different than Nicad and Nimh cells. If they weren't, we wouldn't be talking about 15 minute flights on large war birds and ducted fan models.
In the end, I feel comfortable with my personal decision in choosing the Thunderpower 5s4p for my most valuable model. It has transformed my flying experience and I look forward to any new product from Advanced Energy as a result.
Authors note
Advanced Energy has very recently decided to introduce the Thunderpower 8000mah packs as a continuing upgrade to the large pack line of products. The 8000mah shares the light weight qualities of the 7800mah packs and the higher power and capacity of the 8000mah packs. Since the upgraded cells are so close to the 7800mah and 8200mah specifications, the company has decided to go with the 8000mah for all future packs of this size. For the purposes of this review, the new 8000mah pack is nearly identical in performance to the 8200mah yet as light as the 7800mah.

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