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Old Jun 22, 2005, 08:16 AM
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Help me with this math:

A 3S pack would need to be charged at over 55.5v to ignite (3 X 18.5v)

As the cutoff on a Lipo charger is 4.2v per cell that is equal to a 13 cell pack.

As there is no charger (that I know of) that can do a 13 cell pack that would make these Kokam cells as a pratcical matter flame proof while charging.

And God knows I hate to say anything good about Kokam.

Brad
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Old Jun 22, 2005, 08:23 AM
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Quote:
Originally Posted by bjpaul
Help me with this math:

A 3S pack would need to be charged at over 55.5v to ignite (3 X 18.5v)

As the cutoff on a Lipo charger is 4.2v per cell that is equal to a 13 cell pack.

As there is no charger (that I know of) that can do a 13 cell pack that would make these Kokam cells as a pratcical matter flame proof while charging.

And God knows I hate to say anything good about Kokam.

Brad
I agree Brad . If someone trys to use their 40 cell NiCad charger to charge a 2cell LiPoly pack they deserve what ever happens. Careless users should take up bird watching or some other safer(?) hobby.


Charles
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Old Jun 22, 2005, 09:23 AM
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Charles, please re-read my previous message. I stated my agreement with what you said and was not questioning you at all. My questions were all in the context of a general discussion where many people are participating. But you make a good point about posting those questions on the Kokam forum and getting a response directly from the vendor.
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Old Jun 22, 2005, 09:29 AM
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Quote:
Originally Posted by Dave Hederich
Charles, please re-read my previous message. I stated my agreement with what you said and was not questioning you at all. My questions were all in the context of a general discussion where many people are participating. But you make a good point about posting those questions on the Kokam forum and getting a response directly from the vendor.
No problem Dave, this role reversal just seems more than a little strange.
What relly seems strange to me is that electroman's post is months old and it took this long to get an active thread started on this issue.

Charles
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Old Jun 22, 2005, 09:44 AM
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why? he's in the business of promoting his product, and therefore is automatically suspect in terms of strict adherence to the truth.

Sales technique can vary from 'ours is as good as anyones, if not better, do what tests you like' to 'ours is way better than everybodies, and they (independent testers) all have a vested interest in putting us down (because we refused to pay them or whatever sounds right at the time in the cuustomers ears)'..

Life has taught me that one simply cannot tell: A salesman may be honest or not. The only valid way to find out is by as much independent verification as possible.

When independent verification shows up disrepanciues, often the response is a deafening silence..
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Old Jun 22, 2005, 10:44 AM
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Honesty? My lipo suit works great!

Keeps me nice and warm.
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Old Jun 22, 2005, 01:44 PM
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Charles, the older I get the stranger life seems. I've been thinking about asking for more details on that 18.5V issue and just hadn't gotten around to it. I've now started a thread in the Kokam vendor forum.
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Old Jun 22, 2005, 01:48 PM
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Just so you don't have to search like I did

http://www.rcgroups.com/forums/showthread.php?t=385376
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Old Jun 22, 2005, 02:14 PM
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Wow, here are some "Kokam" wonder product:

LIPOCH2S10-BP
ORDERS JUNE 2005
Balance Pro 2s 10A LiPo Charger
10 Amp cell balancing charger for use with new FMA Balance Pro 2s (7.4V) LiPo aircraft packs
Size: 135.9mmLx92.7mmWx47mmT
Weight: 352 grams
Power Source: 11 to 15VDC 10A Power Source
Applications: Charges 2s Balance Pro lithium polymer battery pack
Features: Charge balancing design assures optimum charging for each cell in the Balance Pro 2s pack; fast charge capability brings packs to 90% of capacity in as little as 20 minutes. $119.95


That's right a 3C charge rate!!!!!

BPKOK3200-20C-2S2P
ORDERS JUNE 2005
Balance Pro 3200 R/C Aircraft Pack
3200 mAh 2p2s (6400 mAh, 7.4V) lithium polymer battery pack for R/C aircraft
Size: 130mmH x 45mmW x 46mmT
Weight: 430 grams
Ratings: 20C / 90%
Power Source: NA
Outputs: 7.4V Nominal, 6400 mAh, supports up to 128A continuous current
Applications: Electric R/C Aircraft
Features: 7.4V at high continuous current; Safe Charge Connector for use with FMA's Balance Pro 2s charger permits up to 3C charge rate (90% capacity in 20 minutes) $285.95

Brad
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Old Jun 22, 2005, 02:31 PM
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How does this compare to a Triton or Astro, that is to the 90% charge level?
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Old Jun 22, 2005, 02:58 PM
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Quote:
Originally Posted by bjpaul
Wow, here are some "Kokam" wonder product:

snip...
fast charge capability brings packs to 90% of capacity in as little as 20 minutes.

....snip

Brad

That's probably only if the pack still contained 60% charge prior to starting the fast charge

I thought you couldn't charge Lipos at above a 1C rate?
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Old Jun 22, 2005, 03:00 PM
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I read about those high charge rate lipo chargers and batts too and was curious. I'd like to see someone else test out a 3C charge rate a few hundred times before I tried it!!!
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Old Jun 22, 2005, 03:07 PM
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There is a Thread here where I did some Beta testing on a High Discharge rate / High Charge rate LiPoly that Thunder Power is working on.
I felt that the results were very good.
Charles
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Old Jun 22, 2005, 03:10 PM
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Hey Charles, since you and electroman are such good buddies, why don't you see if he will let you "test" these new "Balance Pro" products on your CBA?

I would hope that FMA would want a good independent tester to confirm these claims.

Brad
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Old Jun 22, 2005, 03:25 PM
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Quote:
Originally Posted by bjpaul
Hey Charles, since you and electroman are such good buddies, why don't you see if he will let you "test" these new "Balance Pro" products on your CBA?

I would hope that FMA would want a good independent tester to confirm these claims.

Brad
Electroman has imformed me in the past that I was not performing my testing incorrectly and even offered to explain proper testing procedures if I would PM him. When I asked why the same testing procedures worked fine with all other brands of LiPoly which I tested he refused to reply. I read later in the Kokam Forum a statementt by him that amateur testing of a few LiPolys cells had no value.What makes you feel that his feeling have changed?


Charles
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