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Kokam 340SHC Cells - A Lithium Revolution!

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Old 07-10-2003, 12:24 AM
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Greg Covey
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Default Kokam 340SHC Cells - A Lithium Revolution!

Here is a picture of the new Kokam 340mAh SHC 2-cell pack. It can deliver an amazing 20C (20 times Capacity) current! That's 6amps for this little 0.8oz pack!

A 2-cell Lithium pack has equivalent voltage to a 7-cell NiCd pack. For comparison, let's parallel 2 of these packs together and compare it with a 7-cell, 600AE NiCd pack.

The 2s2p configuration of Kokam 340SHC weighs about 1.6oz, delivers 12amps current, and, has a 680mAh capacity.

A 7-cell, 600AE NiCd pack weighs about 5oz, delivers 12amps current, and, has a 600mAh capacity.

In summary, you can essentially replace your 600AE pack with two of the 2-cell Kokam 340SHC packs in parallel and drop almost 3.5 ounces from your parkflyer!

Click here for a larger image.
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Old 07-11-2003, 01:54 AM
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Default Kokam 340SHC Cells - A Lithium Revolution!

How much would that cost?
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Old 07-12-2003, 02:04 AM
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Default Kokam 340SHC Cells - A Lithium Revolution!

Found the price - $57
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Old 07-12-2003, 11:23 AM
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Default Kokam 340SHC Cells - A Lithium Revolution!

Sorry for the response delay. I'm vacationing down in South Beach, Miami and have limited use on a dial-up link.

You will soon see Kokam Lithium cells being sold at many different vendors. The latest vendor is Hobby Lobby but they don't sell the 340mAh cell yet. For that, you need to try either FMA Direct or Bishop Power Products.

I believe that you price is correct for 2 of the 2-cell 340SHC packs. As you can see, the price of dropping weight in your application, or increasing duration, does have a high cost at this time. I hope to see these prices drop in the future.
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Old 07-12-2003, 08:09 PM
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Default Kokam

The local hobby shop is trying to get me to try the E-tech, I believe that was the name of the packs that he carries. I am just starting in the E-flight stuff and didn't want to invest in new chargers and what have you. All I have seen on line is Kokam, has anyone tried the E-tech? If I am calling the pack by the wrong name I appologize.
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Old 07-12-2003, 09:09 PM
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Default Kokam 340SHC Cells - A Lithium Revolution!

Hi George,for good data on LI-POLY see www.lightflightrc.com


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Old 07-13-2003, 10:36 AM
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Default Kokam 340SHC Cells - A Lithium Revolution!

George,

The E-tec cells are very good cells also. Do not hesitate to buy them locally.

Another good source of information for both Kokam and E-tec lithium cells is Bishop Power Products.
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Old 07-14-2003, 03:00 AM
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Default Kokam 340SHC Cells - A Lithium Revolution!

There is short lithium polymer battery history for E-FLIGHT.

A)Type of Secondary(rechargerable) battery

lead acid battery.................40wh/kg not enough power for rc/2v
nicd .................50wh/kg enough power/1.2v
nimh ---------------50wh/kg enough power/1.2v
lithium ion ....... 120-140wh/kg not enough power/3.6v
lithium polymer(lipo).....150-200 wh/kg enough power/3.7v
special grade needed.

B)WHY lipo is getting popular

-high weight energy density
-better safety
-serial and pararell connection is possible
-high discharge rate is possible like nicd.

C)which was the first battery for e-flight

-nicd
-lithium ion;few people tried but not popular due to low discharge
rate
-lipo from 2002 at MAV competition by Florida university(won) with
kokam 145mah battery.They won 2003 too.

D)who are the lipo makers

-kokam(FMA DIRECT.COM)
-Etec
-Thunder power
-etc

E) What is the best battery for rc?

-Choose right battery for required motor according to the vendors
recommend capacity and discharge rate(so called c-rate)

F)what is the discharge rate=c-rate of

c-rate means discharge rate capacity/cell(personal
when the battery is capable to discharge 100% capacity(mah) within one hour continuous...say 1C,
190%(200) within 30 minute......2C
270% (300) 20 minute......3C
360% (400) 15 minute......4C
450% (500) 12 minute......5C
510% (600) 10 minute......6C
595% (700) 8.6minute......7C
640% (800) 7.5minute......8C
720% (900) 6.7minute......9C
800% (1000) 6 minute......10C
1600%(2000) 3 minute......20C

( )% MEANS IDEAL VALUE ONLY

G) What capacity lipo cell are avaiable

45mah/145/250/340/500/600/700/830/1020/1140/1200/1500/2000/2400/3300

H)what capacity lipo battery packs are avaiable

any serial/pararell connections are possible so that from 45mah-10000mah packs are avaiable

I) what voltage range are possible

average 3.7volt/7.4/11.1/14.8/18.5/22.2/25.9/29.6..........

J)What kind of chargers are avaiable

kokam lipo 402/101.....
Triton
etc

lipo specific chargers are strongly recommended due to the safety reason.

K)what is the danger of lipo battery

-overcharging more than 4.2 volt per cell(swelling or fire)
-overdischarge more than 2.5 volt per cell(swelling)
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Old 07-14-2003, 07:19 PM
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Default Kokam 340SHC Cells - A Lithium Revolution!

Hi JJ,

Thanks for stopping by RC Universe so that we can all benefit from your wisdom on Lithium technology. We welcome you!

For those that do not know JJ Hong yet, he is the CEO of Kokam in Korea. He often shares his knowledge of battery technology with readers and sometimes gives us a look into the future by revealing recent important technology breakthroughs.

We welcome everyone to share their knowledge for all R/Cers to benefit!
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Old 08-04-2003, 12:48 PM
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Default Kokam 340SHC Cells - A Lithium Revolution!

If anyone has very basic questions on lithium ion or polymer battery,it will be my honor to answer within my experience and knowledge.please don't hesitate to know the new battery technology.
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Old 08-04-2003, 02:17 PM
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Default Kokam 340SHC Cells - A Lithium Revolution!

It appears that Bishop Power Products is making several pre-assembled packs that boast some impressive current delivery capability for Pylon racers and HLG gliders.

The 3s4p pack of Kokam 340SHC (Super High Current) cells provides the voltage of a 10-cell NiCd pack with a capacity of 1360mAh that can deliver current up to 27amps!

When you compare the weight of a 10-cell CP1300SCR NiCd pack at 11.5oz to the 3s4p pack of Kokam 340 cells at 3.75oz, you can see a huge drop in weight (7.75oz) for a similar capability!

Imagine dropping almost 1/2 pound from your R/C airplane!
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Old 08-04-2003, 10:32 PM
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Default Kokam 340SHC Cells - A Lithium Revolution!

And the difference in price of the two cells means you'll be spending about $11 for each of those ounces that you save. $110 for lipos - $35 for the cp1300s = $75 difference.
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Old 08-04-2003, 11:11 PM
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Default Kokam 340SHC Cells - A Lithium Revolution!

Those LiPo are expensive.... what can the plane do with that pack that it can't do with the NiMH pack?
bb
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Old 08-05-2003, 12:05 AM
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Default Kokam 340SHC Cells - A Lithium Revolution!

LiPlolys let a plane fly better because it is lighter, fly longer, and in some cases, fly stronger...
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Old 08-05-2003, 01:53 AM
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Default Kokam 340SHC Cells - A Lithium Revolution!

once you use lipo pack for your plane,then you will feel immediately why you change.I agree with you that lipo pack is expensive than nicd.gradually the price shall be cheaper.It is a matter of sales volume.in my experience no one came back to nicd after using lipo.There should be a real reason.
longer powerful flight,3 times
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Old 08-05-2003, 09:37 AM
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Default Kokam 340SHC Cells - A Lithium Revolution!

Hi

the 340mah cell is very close to "my goal" to be able to swich to li-po, and only gain the weight loss...

I don´t need 1 hour flight, I only need a lighter plane hehe


JJ,

is there larger SHC cells on their way?

I would love to see a 1500SCH, thinking a 2s3p would replace a 10cell 2600HR nimh battery. 1/4 of the weight and still the same power output.
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Old 08-05-2003, 03:02 PM
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Default Kokam 340SHC Cells - A Lithium Revolution!

I have a subject to make 3A SHD cell for somebody.
I don't want to be blamed by our auditor for too much investment.
2A by 20C rate=40A testing machines.I ordered already.
let me try and give me some time.
Today someone visited me and asked about 20C rate 340SHD cell whether it is true or not.340mah could draw 7A ?
yes,you already knew.
3A X 20c=60A draw.burst 90A. viagra battry?
Let's try. Thanks
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Old 08-05-2003, 03:26 PM
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Default Kokam 340SHC Cells - A Lithium Revolution!

With the 3s4p pack of 340s you have 1360ma. With the cp1300s you have 1300ma. Could you explain how you get a "longer powerful flight,3 times". You may get a little extra flight time from the lighter weight, but not 3 times longer.

And when you lose 7 oz of weight from in front of the CG, you will have a tough time getting most planes to balance. You may even have to add some of that weight back to the nose in the form of lead.
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Old 08-05-2003, 07:09 PM
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Default Kokam 340SHC Cells - A Lithium Revolution!

One of the big advantages of Lithium power is its high-density energy storage. This advantage can be used for reducing weight or increasing flight duration. Often, you can get both together.

My example above was simply one way to drastically reduce weight of a plane, a pylon racer for example, and maintain an equivalent capacity and current delivery capability.

Many glow pilots think in terms of adding lead weight to maintain balance. Typically, e-flight enthusiasts just move the battery pack around to maintain CG because it is often the component with the most weight. Some plane designs make this easy while others make it more challenging.

For another example, check out my Wipa Firecat page.

When compared to a 10-cell, CP1700 NiCd pack, my 3s4p pack of Kokam 1200HC Lithium Polymer cells held their voltage slightly better than the NiCd cells. I measured 36amps at a "whooping" 8300 RPMs using an APC 11x7 e-prop. If this wasn't enough benefit, I also almost tripled my flight duration over the CP1700 pack. (4800mAh / 1700mAh = 2.8). Finally, my RTF weight dropped by 5oz.

You truly can get both increased flight time and reduced weight using Lithium Polymer technology!
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Old 08-05-2003, 08:24 PM
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Default Kokam 340SHC Cells - A Lithium Revolution!

Who all makes LiPo cells?
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Old 08-06-2003, 12:50 PM
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Default Kokam 340SHC Cells - A Lithium Revolution!

There are 3 major manufacturers of LiPo cells for R/C; E-tec, Kokam, and ThunderPower.

Each manufacturer has multiple distributors and vendors.

Look at places like these:

FMA Direct
Bishop Power Products
Hobby Lobby
Flight Energy
Esprit Model
All E RC

and many others...
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Old 08-08-2003, 02:21 AM
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Default The economy of Li Pos

Yes, LiPo cells cost more than Ni Cds. Glow engines cost more than rubber bands too, but, thank goodness most modelers accepted engines in models because the improvement in performance was obvious. So it is with Li Pos. If you use LIPOCALC at www.fmadirect.com , you can design for the most economical pack and, if you choose, set up a pack that lets you do what it takes several packs of NiCds or Ni Mh to do. I think Heyward Macdonalds experience with his Herr Starlite tells it best: The Starlite with a pack of seven 350 mah Ni MH brought no enjoyment at all and weighed 8 ounces. It barely flew and wiped out the carbon fiber LG on eachlanding. Replacing the Ni MH pack with a 2S1P pack of KOK 340HSC dropped the weight of the airplane by 40% and made it a joy to fly. It is like anything in life: you can stick with what you have if you are willing to make the sacrifice.
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Old 08-08-2003, 11:50 AM
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Default Kokam 340SHC Cells - A Lithium Revolution!

Quote:
Originally posted by buzybee
Who all makes LiPo cells?
bb
There are not a large number of Li Po manufacturers. JJ mentions three who are actually distributors of Li Pos. In a recent survey by a major commercial & industrial manufacturer in the US, 12 such manufacturers were identified world wide. The applications involved demand 100s of millions of cells per year. The qualified list has been reduced to four who are considered capable and have the chemistry required to produce the power density required. Kokam Engineering Co. , Ltd is one of the four found acceptable. Kokam holds many patents regarding the chemistry and mechanical assembly of the unique package for Li Po cells.

Kokam is located in Korea. JJ Hong is the founder. JJ has advanced degrees in Chemistry and is an astute businessman. The Kokam factory turns out 10s of million of cells yearly in a highly automated factory. Required QC , safety, and support for the above mentioned manufacturer are very much more stringent than for RC.

Kokam USA is located in Maryland and is the exclusive agent for Kokam in North and South America. Kokam USA has arranged for independent test of Kokam cells going into inventory with a number of distributors, including FMA Direct. Kokam USA and FMA Direct are divisions of FMA, Inc. You may read the history of FMA at our web site at www.fmadirect.com Presently, a great deal of effort is devoted to the US OEM market for Li Po cells and packs. Kokam developed the factory assembly needed to produce RC packs during the past year.

Kokam USA continues to develop a compendium of useful tools to promote the safe and effective use of Li Pos in RC. After you open the web site, click on Support and scroll to Applications Notes where you will find the Li Po Applications Note. This l applications note is meant to address general use of Li Pos.
An applications note and user application gallery are in preparation designed specifically for RC.

The objective for the RC App Note is to present answers to Frequently Asked Questions (FAQ), including incorporation of information to be presented in forums such as this. While these forums are very useful, the information does drift off the bottom of the column and the same question arises again when a newcomer enters. The gallery will make current information that stays in place available to all comers.

One FAQ seen in the forums is to know what battery pack to use in a given model. MOTOCALC and ELECROCALC were developed to assist with that task for Ni cd and Ni MH. Only now, these tools are being modified to add Li Po. FMA Direct has a tool that helps greatly to select the Li Po pack of your choice. On the home page, click on Store/Kokam Batteries/LIPOCALC. LIPOCALC has within it, a HELP section to show you how to use it to calculate and do the trade off of weight, endurance, cost, etc in order to fit your unique need.

FMA Direct promotes Li Po as a System. As Li Po cells were introduced by Kokam USA in 2002, there were impediments that limited their use to the most persistent electric fliers. Not many chargers were avaiable. There were no speed controllers available that could match the cut off needed to protect against undervoltage. It was a challenge to assemble the packs using individual cells with the fragile tabs that are a normal part of Li po cells. For engine powered models, a single cell at 3.7 V under load is too low a voltage but a 2S pack at 7.4V is too high. So the voltage regulator to provide 5 to 6V for the radio was developed. All these items are described in the Store section of the web site.

Our use of Li Pos for RC imposes some unique specs on the cells. That is, the power can not be cut off as a means of safety and protection while flying. Your radio has to have power to continue to operate even after the motor is shut down. In OEM applications, e.g., in a PDA, Li Ion cells (Of which Li Po is a subset) are required to have protective devices called a Protective Circuit Module (not to be confused with PCM radios).

The PCM protects the cell from three operating conditions: 1) Undervoltage. If voltage is permitted to drop below 2.5V per cell, the cell may not accept recharge 2) Overvoltage during charge. This is the only problem encountered thus far in RC operation in that one must use a charger designed specifically for Li Po. The charger required is actually simpler than a peak detection fast charger for Ni Cd or Ni MH packs; it is just that it is different. All Kokam distributors have available chargers suitable for Li Pos. The user must, as for any battery, accept responsibility for safe charging. This is a subject covered almost daily in the forums.
3) Overload during discharge is handled by design of the pack to match current required and by using a fuze as one should for any pack.

No matter what chemistry, the high energy density cells we use for RC must be treated with great respect. As you see in JJs post above, Li Po cells have the highest energy density by a large margin with current cells running around 170 to 200 WH/Kg. The advice iterated often is to treat all RC batteries as you would a small stick of dynamite.

Later!
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Old 08-08-2003, 01:12 PM
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Default Kokam 340SHC Cells - A Lithium Revolution!

I've seen some posts on LiPo fires. What precautions should be taken? What should a person be careful about? What are the danger signals that something bad is about to happen? Do the batteries come with a "how to use, what to do and not to do" information?
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Old 08-08-2003, 01:49 PM
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Default Kokam 340SHC Cells - A Lithium Revolution!

All good questions.

Yes, the batteries do come with safety instructions.

Lithium Ion initially got a bad rap for safety and the newer Lithium Polymer (Li-Po) technology, although safer, still has some safety issues.

For the most part, over-charging is the biggest safety issue. This can be done using chargers that try to auto-detect the cell count and get it wrong. It can also be done by human error in simply selecting the wrong jumper setting for cell count.

I prefer to use chargers that require the user to set the cell count (voltage) and current using hard jumpers. Several manufacturers are working on electronic safety means using tiny modules.

An example of a safety issue is charging a 2-cell pack with your charger set to 3 cells. When the cell voltage gets past it full capacity, it will start to puff up and look bloated before starting on fire. Some gases are also sprayed out before hand.

Charging on a cement floor or ceramic tile is a good practice. Never leave a lithium pack unattended while charging.

I have never had a problem from single cell 145mAh packs to 20 cell, 7.5AH packs...but I respect the potential for hazzard and use a little common sense.
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