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Other › Kokam 2000 mah 15C bad quality ( junk )
10-11-2005 09:47 PM  12 years agoPost 1
zrdcorp

rrApprentice

Caguas, PR

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Hi there,

After only 8 flights my kokam 15C started to swell. The top ( or bottom ?) cell swells really bad while the others stay OK, including the middle which I though was the one getting more strain.

I had to remove the red shrink wrap to measure the individual cell voltages, and noticed it swells when the cell is still 3.71 volts. The other ok cells are 3.76 volts.

This is no-load voltage.

Does anybody know if there is a warranty or some type of replacement from the manufacturer? It was rated at 15C (30 amps). The motor is rated at a maximum of 25 amps.

Or are all the Kokam batteries this bad??

Should I try to balance this thing? From other posts It seems it is too late...

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10-11-2005 10:06 PM  12 years agoPost 2
hpilotrc

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NY--->>Mooresville, NC USA 8/2005

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Kokam 2000's
I tried using that same battery on my TRex during the summer and ended up sending it back. The battery was much heavier than my TP2100's and I really could notice it when on my heli.

The cells shouldn't swell at all unless perhaps the battery is getting too hot by drawing excessive current. Maybe the pitch is too high and you are drawing alot of current.....but still the current is not continuous and it should not ruin a new battery.

I would send the battery back and see what they say. I would think it is defective and they would replace it.

You may want to think of going to a 4-cell pack which would lower the current. The Thunder Power Pro-lites may be a good choice since their batteries seem to be much lighter then the Kokams.

Michael

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10-12-2005 12:28 AM  12 years agoPost 3
dkshema

rrMaster

Cedar Rapids, IA

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Sixty flights on mine, inlcuding one bad crash on flight number five that actually bent the three cells about 30 degrees. I carefully straightened them out and watched them closely for the next few cycles. Still going strong.

The Lipos tend to swell if you abuse them.

Dave

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10-12-2005 12:56 AM  12 years agoPost 4
poletime

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vic Australia

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I bent mine just a few degrees from a crash but I havn't been game to straighten them. I'm only getting 8mins and they don't seem that powerful. Charger says it's put in 1600ma. Is that normal or should it read the full 2000ma?

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10-12-2005 01:11 AM  12 years agoPost 5
dkshema

rrMaster

Cedar Rapids, IA

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You'll never put back 2000, not even on a new pack.

One of the things you give up on LiPos when drawing large amps continuously is up to 20% of their capacity. Nothing comes for free.

Dave

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10-12-2005 01:57 AM  12 years agoPost 6
Orion_V

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Cliffside Park, NJ

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same thing here...had about 4 charges on mine and one of the cells swelled up. i sent it back..still waiting to see what happens.

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10-12-2005 02:04 AM  12 years agoPost 7
zrdcorp

rrApprentice

Caguas, PR

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Where should I send them?
Could you guys give me the address to send the pack?

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10-12-2005 04:48 AM  12 years agoPost 8
Coolpowered

rrKey Veteran

Youngstown, ohio

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Been using the kokam 2000 for a few months now with out any problems, there are also a bunch of other guys flying the kokams without any issues so far either, the tps we were using were running way to hot in the summer, thats why we changed over to the kokams, more power, run cooler, but about a minute shorter flying times compared to the tp's, I get 9 minutes of 3d or 14 minutes of hovering with the kokams compared to 10 and 15 with the tp;s2100mah.

YRCHA CLUB MEMBER

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10-12-2005 05:56 AM  12 years agoPost 9
drvcrash

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Whaleyville, MD

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cell is still 3.71 volts. The other ok cells are 3.76 volts.
Thats out of balance bad. should be no more than .02. Are you letting them cool for at least 30 minutes or more before chargin? Charging them hot will make them go out of balance quick. Also the first 3 or 4 cycles should be no more than 5-6c discharge.

I have over 15 of those packs and never a problem and im pretty hard on them. Ihad 2 be in a L shape after a crash and I just bend them back flat. I run mine over 30 amps alot and they never get above 130f. One year old pack has well over 150 cycles on it and I can still get 1400mah out of it and its still in balance. They are heavier but they are a good all around pack


I would try and balance it but normally once it puffs its pretty much done

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10-12-2005 05:57 AM  12 years agoPost 10
thunder21

rrApprentice

College Park, MD

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I've had a Kokam 2000 mAH 15C pack for over a year. It's had many dozens of cycles and it's still going strong. I never get more than about 1500 mAH out of it, regardless of the current draw. It is over an ounce heavier than most other packs with similar capacity so I'd expect that you'd notice your T-Rex is a little sluggish using it.

Kokam is distributed in the US by this company. I'd suggest calling and getting an RMA number before sending them in...

FMA Direct
5716A Industry Lane
Frederick, MD 21704

Sales: 800-343-2934
Technical Support: 301-668-4280
Marketing: 585-261-4120
Fax: (301) 668-7619

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10-12-2005 06:36 AM  12 years agoPost 11
lloyd

rrKey Veteran

Perth,Australia (South African)

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yip mines also swelled on only 10 flights with no dings or crashes....

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10-12-2005 07:57 AM  12 years agoPost 12
Mhw

rrApprentice

earth

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Kokams are still the best cells out there IMO. Never had a single problem, and one of mines pretty banged up, and still works fine. Have had over 100 charges on that same pack, and I havent seen any power drop. Same goes for the bigger 3200mag 20c cells, they are fantastic.

Every pack gets charged and discharged at the factory, and the cells are also matched thatway. The only kokam I have ever seen come back is a 1250mah 3s pack, and that was when the person thought it was a 2000mah pack, and charged it at 2 amps! Bad mistake.

Note, the old kokams like the 1500 8c packs are a complete different story......

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10-12-2005 01:57 PM  12 years agoPost 13
Signsurfer

rrNovice

Sunny Stockport

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Kokams are great batts.

If one cell swells it is either badly out of balance or a faulty cell. If all the cells swell then its been abused.

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10-12-2005 11:40 PM  12 years agoPost 14
dkshema

rrMaster

Cedar Rapids, IA

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As for who you send them back to...the most obvious answer is the fellow who sold it to you!

Dave

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