E-Flight Power Sources Ask questions or read about power sources as they specifically relate to e-flight including Lithium-ion, Li-Poly, Nimh and Nicad battery packs.

Thunder Power or Kokam Li-Poly ????

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Old 11-03-2004, 06:08 PM
  #1
Robermonti
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Default Thunder Power or Kokam Li-Poly ????

Please say your preferences, experiences and reasons to choose Thunder Power or Kokam.

Thank you
Roberto Montiel
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Old 11-04-2004, 08:44 AM
  #2
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Default RE: Thunder Power or Kokam Li-Poly ????

I like the thunder power packs, they both are good packs though.
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Old 11-04-2004, 09:58 AM
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Default RE: Thunder Power or Kokam Li-Poly ????

It is almost an apples to oranges comparison. For example...

Kokam 11.1 v 2100 mah 20c
weight = 8.9 oz
size = L 108 mm W 63 mm H 16 mm
amp output up to 42 amps
cost about $104

Thunder Power 11.1v 2100 12c
weight = 4.5 oz
size = L 96 mm W 34 mm H 18 mm
amp output up to 26 amps
cost about $80

Kokam. more amp output, heavier, larger in size


Woodduck
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Old 11-04-2004, 10:24 AM
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Default RE: Thunder Power or Kokam Li-Poly ????

where is the best place (cheapest) to get Thunder Power batt?
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Old 11-04-2004, 12:50 PM
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Default RE: Thunder Power or Kokam Li-Poly ????

Almost everyone sells them at the same price, I have not found any real deals. For service and quick delivery I use allerc.com
Allerc also has polyquest which are very good.

Expect to pay about $75 to $80 for a 11.1v 2100 mah 3 cell Thunder Power
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Old 11-04-2004, 06:19 PM
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Default RE: Thunder Power or Kokam Li-Poly ????

What about the Poly Quest Li-Po??? [:-]
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Old 11-04-2004, 09:29 PM
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Default RE: Thunder Power or Kokam Li-Poly ????

I had never really looked over the Poly Quest specs. I have been using the Thunder Power 2100 at 4.5 oz and a cost of $79.
I think I will try the Poly Quest 2600 at 5.6 oz and a cost of $75 , more amps.
You can email info@allerc.com and David will answer your questions, he is a great guy to deal with. I have placed several orders with allerc and have never had a problem, 2 day shipment from Mesa AZ to St. Louis!!!
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Old 11-04-2004, 10:39 PM
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Default RE: Thunder Power or Kokam Li-Poly ????

Kokam and Polyquest do not hold their voltage up worth a hoot under there "advertised" C ratings. Thunderpower holds the voltage much better then kokam or polyquest and are rated accordingly.
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Old 11-05-2004, 06:17 AM
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Default RE: Thunder Power or Kokam Li-Poly ????

Thunder Power or Apogee packs are the choices IMHO, both have worked well for me. Two of the four Kokum 3 cell 1500 mAh packs that I used on my Pigi, last year, lost a cell after a dozen flights or so. They didn't hold up to the rated discharge which at the time was 10C.

Ken
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Old 11-05-2004, 01:21 PM
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Default RE: Thunder Power or Kokam Li-Poly ????

I just got my hands on a couple Thunder Power 2S 730 lipoly packs. The specs say they are good for 7-9 A continuous with burst to 13A.

This 2 cell pack is almost exactly the same weight as a Kokam 2 cell 340. Even Kokam packs that I took the PC board off, and re-soldered cells aren't much lighter than the 730 pack. I'm impressed with the 730 pack for my shocky. It holds over 10 minutes of juice and has a higher rating than the Kokam pack.

Actually, I'd rather have a lighter pack (ie 300 ish) but if I can't also have the amps, I'll go with the 730. I was overdriving my 340's and while I got my money's worth from them, all my 2 cell packs are "tired" and won't deliver the amps they did before. I have higher hopes for the TP 730's.

Maybe Kokam will have a newer generation "340" size in the works, but I don't know. This is last year's model.
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Old 11-05-2004, 01:42 PM
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Default RE: Thunder Power or Kokam Li-Poly ????

I have had a bad experience with Kokam's. I have two 1500 3 cell packs and after 35 flights they started loosing power and I started having shorter flights times. My local hobby shop said
that they were defective and to send them to FMA with the receipt. They gave me the run around and never did take care of it. Because of this and many other people having problems the hobby shop is dropping Kokam's and only selling Thunder Power's. It's amazing how much
better some company's customer service is over others. You would think that they would be
smarter about how they treat customers. In only a few seconds via websites like RCU the poor customer service that they provide can be brought to everyone's attention.
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Old 11-05-2004, 05:48 PM
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Default RE: Thunder Power or Kokam Li-Poly ????

It looks like the general consensus is Thunder Power, I agree, they have a larger selection of mah , are generally smaller and priced reasonably, very reliable!!
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Old 11-05-2004, 11:03 PM
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Default RE: Thunder Power or Kokam Li-Poly ????

I have tried all of these as well as the new Tanic packs( with plugs for each cell!) For price, highest discharge , and weight savings , go for Apogee. Compared to Kokum, I see almost 15% more performance. The packs seem rock solid. However this has only been my experience.
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Old 12-05-2004, 03:26 PM
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Default RE: Thunder Power or Kokam Li-Poly ????

I have a couple of Thunder Power 2-cell packs and they are great!! I get mine from Hobby Lobby because they have always been more than willing to help me with any problems I might encounter. Not that I have had any problems with my li-polys, but if I did I know they would help me.
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Old 12-05-2004, 05:19 PM
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Default RE: Thunder Power or Kokam Li-Poly ????

aPOGGES ARE THE SHIZZNET, i HAVE 2 OF THE 830 3SP in my Shocky and love em....1050's are on the way
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Old 12-05-2004, 08:43 PM
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Default RE: Thunder Power or Kokam Li-Poly ????

Try Aeromicro. They have most brands and sizes and great service. Frre shipping over $100. too.
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Old 12-10-2004, 02:35 PM
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Default RE: Thunder Power or Kokam Li-Poly ????

I have tried most brands of lipolys out there, And have abused all of them by drawing too many amps, overheating, and overdischarging cells. From my experience, Apogee packs are by far the best, with PolyQuest a close second, and believe it or not e-techs held up pretty well under my abuse and are cheap comparatively. I don't want to fly worrying about whether or not I should land because my cells might be low, but I have paid dearly for it by throwing away expensive packs. I cannot say I have been very impressed with thunder power packs. They are over-rated in my opinion, and don't hold up to the advertised discharge rate. I have also noticed a high variability in two brand new 860 TP packs, with one not being worth the bag it came in. I personally will not buy another TP pack. The Kokam 340 are hot cells, and get my approval. The Kokam 1500HD is over-rated(toasted one of these with 20 flights on a brushed 370 geared 6.6:1 with 12-6 gws drawing no more than 7.5 amps). This of course is all IMO, and I realize others have had very different experiences. But I hope this wordy post helps someone!
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Old 12-10-2004, 04:33 PM
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Default RE: Thunder Power or Kokam Li-Poly ????

I would like to add a few thoughts into this thread based on my experience with Lithium cells.

For the most part, Lithium is Lithium. The assumption here is that we are all discussing Lithium Polymer and not Lithium Ion technology.

Notice that the packs from various manufacturers are all different sizes and weights. This is an external characteristic that can be very important when choosing a pack. For example, on my Fliton ICON 312, I had no choice at the time to use a Kokam cell so I choose a ThunderPower cell because it fit my fuselage and my power system needs.

You should be aware that Kokam and ThunderPower both rate their pack capacity differently. This makes it more confusing for most of us unless we remove the emotional connection that we often get with our hobby choices. Kokam rates their capacity at the continuous current rating and ThunderPower rates the capacity at a lower current. Nothing is wrong with either, you just get different results.

I always try to use a Lithium pack where my full throttle current is equal to or less than the packs rated discharge rate. The higher the pack's discharge rate, the more effective capacity you will obtain.

To further add to the confusion, we have manufacturers providing "new generation" cells that may look to improve upon the older cell but are merely repackaged for more current delivery or capacity or both. Again, nothing wrong here since we see this with every product from paper towels to potato chips.

Finally, on my other Flinton plane, the Flubber, my initial Kokam 3-cell 1500 pack fit and worked great with a geared Razor motor. When I upgraded to a more powerful Lehner motor, the "new generation" Kokam (15C) 2AH pack was a perfect fit (and color).

As you know, I could go on with many other examples. The ThunderPower 3s2p 4200mAh pack reminds me of my old Zagi NiCd packs and is a great fit in many of my planes. Soon, the newest Kokam 3.2AH (20C) cells will likely eclipse many of my favorites when it arrives as a unitized pack with taps for true cell balancing. Lithium safety issues will be a part of our e-flight history. My conclusion is that I love all my Lithium packs when they are a good fit for the application.
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Old 12-10-2004, 08:21 PM
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Default RE: Thunder Power or Kokam Li-Poly ????

Greg, I have always respected you, and your commitment to the electric portion of our hobby.
Thanks.
Hot Tip, try the Apogee line..if you still have anything small in the way of foamys to run it in...
NO BS..compared to my Etec, Kok's and TP, the Apogee's rock.
I found mine at
www.parkflyermotors.com
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Old 12-11-2004, 11:53 AM
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Default RE: Thunder Power or Kokam Li-Poly ????

The problem with the manufacturers using different discharge currents to rate their cells capacity is that a hobbyist cannot make an informed decision. They should all rate their cells capacity at the maximum continuous discharge rate. This would prevent a hobbyist like myself from being dissappointed after buying a 1000mah cell rated at 8c cont discharge and drawing 8 amps and getting 4 minutes flight time instead of 7. I prefer Apogee and Polyquest batteries not because I think they have a special chemistry, but because from my experience The advertised capacity and discharge rating represent real-world information that I can rely on. This is why I have been following this thread to find out if other rc'ers have found advertised ratings to be true. Not until I hear it from a fellow hobbyist will I believe the advertised rating on ThunderPower or Kokam cells. For all I know they are all made in the same factory in Korea with a different label applied as they roll out the door! But please, give me useful data I can rely on when I choose a cell. Until then, Apogee and Polyquest will keep my business!
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Old 12-11-2004, 12:58 PM
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Default RE: Thunder Power or Kokam Li-Poly ????

Thanks, Mike. I've been wanting to try the Apogee line ever since I saw a pack that included taps for monitoring each cell. There are so many new products in the hobby now that you just don't have time to "play" with them all. I dream of being retired so I can devote even more time for R/C fun!

rhoon,

Yes, I agree. Unfortunitly, the manufacturers seem to do it purposely. Perhaps not so much as a point to confuse us but rather to show their product in the best light.

As for the advertised rating, I believe that Kokam USA is the only brand that publishes graphs and also has them rated by third party professionals like Red Scholefield and Steve Neu. Let me know if you ever run across a discharge curve for other brands.

Below is my new 4-cell Kokam 3.2AH (20C) pack that weighs 12.8oz. It is shown with a 3.0AH NiMH pack for size comparison. Note that the new cell width is the same as a sub-C cell length. The 4-cell Lithium pack has a voltage equal to about 14 cells NiMH which weighs about 26oz or twice the weight of the Kokam pack.

A 3-cell Kokam 3.2AH pack would have a similar size and weight to a 6-cell sub-C pack but with the voltage of a 10-cell NiMH pack. Note that discharge curves are posted in the sticky thread at the top of this forum.
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Old 12-12-2004, 12:17 PM
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Default RE: Thunder Power or Kokam Li-Poly ????

Greg, I agree that kokam does publish discharge curves for some of their cells, but their published curves do not match those of the independent testers you mention. For example, if you compare the discharge curve for the Kokam 3200 at the top of this thread to Steve Neu's in QuietFlyer magazine January 2005 they are noticeably different. In Steve Neu's test at 20c discharge the voltage drops well below 3 volts initially, and then drops again at 2500mah which is well below the rated 3200mah capacity of the cell. Kokam's curve at 20c discharge does not drop below 3 volts until past 3000mah. Also in the same article by Steve Neu Kokam's 1250 15c discharge cell is curved and the voltage drops below 3 volts at 700mah or only %60 of its rated capacity! Kokam certainly is not rating their cells any more honestly than the next manufacturer. Thank you for your expert contribution to this site Greg. Robin Hoon
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Old 12-16-2004, 04:01 PM
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Default RE: Thunder Power or Kokam Li-Poly ????

I have been very happy with Thunder Power packs, ranging from 860's to 2100's. Good performance and capacity (based on run-time and mAh required to re-charge) is realistic. Lately have been buying them from Troy at Bishop Power Products B-P-P.com because he has the best prices and good service. Recently placed a big order and got an even better deal!

Mike
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Old 12-16-2004, 04:51 PM
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Default RE: Thunder Power or Kokam Li-Poly ????

wee!

compared the new kokam 360 to TP 480 both packs brand new.

B20 22s 4:1 9x3.8

Astros large wattmeter.

TP 12.3A about 110watts 9volts 26C 31.53grams

K 13.2A about 130watts 9.7votls 34C 35.32grams

they both provided this high output for 5sek before voltage started to drop. throttling down and gave it half speed or so for 10sek then full power agan, and they did deliver full power again! so thumbs up for these cells!!!

kokam weighs 8% more, but deliver 8% more power... but 33% less capacity.

both cells are brilliant for extreme indoor 3D, and kokam has the edge on power!.

will flight test them soon
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