Posts: 4445
Joined: 5/24/2003 From: Rochester,
NY, USA Status: offline
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!
Posts: 4445
Joined: 5/24/2003 From: Rochester,
NY, USA Status: offline
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 [URL=http://www.hobby-lobby.com/kokam.htm]Hobby Lobby[/URL] 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.
Posts: 66
Joined: 6/26/2003 From: gainesville,
FL, USA Status: offline
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. George RAGBAG
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.
-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
Posts: 4445
Joined: 5/24/2003 From: Rochester,
NY, USA Status: offline
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!
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.
Posts: 4445
Joined: 5/24/2003 From: Rochester,
NY, USA Status: offline
It appears that [URL=http://www.b-p-p.com/KokamSHCpacks.htm]Bishop Power Products[/URL] 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!
Posts: 20
Joined: 3/29/2003 From: HereintheUS, USA Status: offline
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.
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
< Message edited by JJ HONG -- Aug 5 2003 3:52PM >
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Kokam 340SHC Cells - A Lithium Revolution! - 
