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Old 12-26-2003, 04:33 PM   #1
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Lossing a small fortune with lithium poly

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Help! On two occasions, I have had my Kokam lithium poly batteries swell for now apparent reason. Here are some details:

1/ My charger is Orbit microlader v6. I use the lithium ion setting at 1A for a 1500mah High discharge (6C) 2 cell pack. The voltage reading on the charger during charging is 8.4V.

2/ The plane I use it in is a EPS 350C D6.6:1 with a 1080 propeller

This swelling is noticed most during discharge. It is my understanding that this battery should be able to withstand a 12A discharge.

What is swelling a sign of? Charging errors? Discharging errors?

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Old 01-04-2004, 06:32 PM   #2
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swelling is usually a sign of incorrect charging...its doubtful your EPS motor is pulling more than 9 amps ...have you upgraded to the latest version of Orbit software? there have been issues with that charger with the previous version of software and Lipoly's.\...we have also heard of the orbit not recognizing the 2 cell pack if your trying to top up a pack that is almost full...the charger sometimes see's this pack as a discharged 3 cell pack and proceeds to attemp to charge it as such..

Usually a lipoly charger starts to reduce amperage input as it reaches 8.4V
if your charger is staying at 8.4v have you watched the Mah input...does it increase or decrease..?

are you using a programable Voltage adjustable ESC such as the Castle Creations Pixie?...If not perhaps you might be depleating the cells beyond there recomended voltage cutoff...or may have done some damage previously...?

We have sold tons of lipoly Kokam HD packs and I personally fly them in my T3D Wild Beast with no issues...I have not heard of one customer complaining about swelling packs so far...

We are also charging the 1500 Kokams at 1.5C no problems!! as per the recomendation

Are you positive that you purchased the HD packs? or the older 4C Kokams..

just a few ideas

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Old 01-04-2004, 06:51 PM   #3
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kokam lipoly

I'm not sure who informed you of the 12 amp discharge but here is the spec we recieve as a dealer..

suggested charge rate

1.5C so... 2250 MAH in your case with the 1500 packs

6C -8C discharge rate so 9 AMPs on a 1500MAH pack

we have tested the 350 motor and with proper wiring and the 10/8 gws prop it draws approx 8.3-9.6 amps

if you are using JST connectors and cheap wire...you can lose up to an amp or more from what we have tested..

I personally reccomend to my customers that they use Ultra Deans and silicon wire... for battery connections and a direct solder connection to the GWS motor from the ESC.. and it seems to work very well...the packs hold up very well and provide excellent flight duration...I top up my packs once or twice in an evening of flying...and we are there for 4 hours...I only take 2 packs.. I beleave you should get about 15-20 min of good performance out of these packs with your combination..
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Old 02-20-2004, 09:55 PM   #4
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This comes from the Thunder Power web site.

Do not use Orbit charger with 6.1 firmware (use 6.2 firmware or higher)

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Old 02-21-2004, 07:19 AM   #5
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Another thing to check is se how much voltage is in the cell they should be all really close. Maybe the cells aren't balanced and one has more chare in it then the other so you may be running one to low i voltage when you discharge them. If that the case take the pack apart and charge the cells separate to get them back i sink
What do you mean , I can land upside down
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Old 03-28-2004, 07:53 PM   #6
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OK, here's a wierd death of a LiPo Cell in a 1500 3s1p HD Kokam pack. Flew my GWS Flying Pizza which I believe comes with the 100 motor (Weak version of a 280?) several times last week, charged them all Friday night removed them from the charger when done (I have 3, charger is Hobbico Quick Field Charger MKII) didn't fly Saturday went to fly today and 1 cell in 1 pack ballooned. Well I unsoldered that cell, and flew the pack as a 2S1P worked fine but why would that one cell balloon 24 to 30 hours after its off the charger????
Salutations from the Pacific North WET!

S.P.A.D.s, Fibreglas & Balsa EDF's, Foamies, Brushless powered and nitro balsa planes, they're all in my hanger, just don't explain what it all means to the mrs, eh?
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