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Old Feb 07, 2012, 05:43 PM
keithy4129 is offline
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United States, NJ, Clayton
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Quote:
Originally Posted by everydayflyer View Post
Sorry but I have data to prove otherwise. I have charged other brands of Lipolys at 5C for over 300 cyles and discharged them at rather high rates as in 17C (less than 4 min) to greater than 90% depth of discharge and the capacity decrease was very minimal and the voltage under load did not demish.

The days of less than 3C charges are history IMO and 3 to 5C is my norm with some at 10 and even 12C.



Charles
Quote:
Originally Posted by everydayflyer View Post
So you have conducted controlled test such as charging a 40C at 1 or 1.5C and discharging it at say 25C to say 3.3 volts per cell for hundreds of cycles to determine how many cycles before it is reduced to less than 90% of original capacity and also charged one at 5C discharged same way and for the same number of cycles or same 10% capacity loss?

If such test have been conducted I would very much like to see the data. If you do not want it made public fine it can be emailed to me. Remember I was the one contacted by your Representative .

In case my statement on 5C charging is being questioned which it surely seems here is a linke to one of my test and I can supply addational ones.


Thunder Power Pro Power 45 tested

http://www.rcgroups.com/forums/showp...19&postcount=1

As some have a difficult time understanding graphs I will offer a short summary.

TPPP45 3S 2250 was charged at 11A (4.88C) and discharged at 40A (17.77C) that is a 3 min. discharge equal such as in an extremely hard 3D flight..

The first 40A discharge was used as a base point and during the life cycle testing the capacity delivered was compared to this fourth cycles test.

After 300 cycles the 3S Thunder Power Pro Power 45 still delivered 91.8% of the capacity obtained first time 40A (17.77c) discharge was completed.

Now some will be fast to point out that since the PP45 was rated for 45C I was only discharging it at just 39% of it Cont. Dsc. rating but the subject which seems to be in question here is charge rates effecting life not discharge rates .


How about in a real flight under normal(?) aerobatic loads) . This aircraft is normaly flown with a large LiPoly either a 4S 2600 plus or a 3S 3300 plus.

http://www.rcgroups.com/forums/attac...2&d=1250359146

I have some Poly No One LiPolys which I also tested. The vendor clearly stated not to be charged at more than 2C
as he was concerned how higher rates would effect cycle life.

I charged these ar 3 to 5C ,mostly at 5C and one I have flown the most is a 3S 3300 rated 30C from July of 2009 and it now has 198 discharges on it 114 bench cycles (test cycles) and 80 flights.




The math is very simple for me. One can purchase 6 LiPolys and 5 chargers so they can charge at 1 or 1.5C and have enough LiPolys to fly without having to spend a lot of time waiting of LiPolys or they can have 3 capable of 5C plus charging and 2 chargers and fly non stop.

Do not care to fly non stop then how about this two LiPolys ,one charger 5C charges and a flight every 13 minutes. all day long or until you get tired. Did it again yesterday. 2each. HK nanao tech LiPolys rated for 5C charging and 25C discharge. Two aircraft which use the same size LiPoly. I charged at 5C and flights were 5 min. down to 90% state of discharge or aprox. 12C discharge rate. Five minute flights and 13 minute charges plus time changing LiPolys, walking out to flight station, flying 5 min. landing picking up plane waling to pits, removing LiPloy walking over to charger wait 2 min. swap LiPolys and repeat. Seven flights ina very short time period . Note I had 4 more fully charged LiPolts with me but felt no dires to use them. Even I like a short break between flights.




I would rather have 3 LiPolys to manage than 6 and I do not believe most flyers are going to complain a great deal about only getting two or 300 flights from a LiPoly. By the time most flyers reach 200 cycles their LiPolys will be 3 years old and very outdated anyway. Most will damage thier LiPolys thru other means such as crash damage, lost in a filed,tree,river. Left connected to a ESC and drained to close to zero volts, droped on hard surface due to careless handling, deformed by using to much velcro , creased by wrinting on labels on them with a ball point pin using inexpensive inaccurate chargers / balancers and I could go on and on.


Now I imagine the good folks at Haiyin now wish theyhad never contacted me but be that as it may. As I have posted here numerious times over the years. I do not make these numbers up. My test equipment does not lie, I do not lie. If I test LiPolys I post the results be it good or bad.


I apologize for such a long post and perhaps a bit of subject but I am very tired of the old 1C charging myth in this day of 20-65C LiPolys and balancing chargers. 1C was fine when LiPolys were less than 10C discharge rated and there was no such thing as balancing. Anything less than 3C charging recomendations reminds of of the old better not have sex before you are married or you will get pregnate ,or do not look at photos of naked women or you will go blind or better not ....... .

Charles
+1 Its irritating to hear people say that "if you charge at 5c, the pack is not gonna last long" ..................soooo annoying.........just my two cents
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