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Old Mar 03, 2012, 10:32 AM
Southern Pride
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Data
HK Turnegy nano tech 25C 3S 850

Same size and weight as the HAIYIN 20C 3S 800 which I tested earlier.
SAme issue with power leads also but worse on this nano. Haiyin has 18 gage leads and this nano has 20 gage. Both came with JST / parkflyer connectors which I replaced with Deans Ultras.

Added: Standard warning that these discharges greatly exceed the recomended 80% discharge level. Once again I often push the limits during testing as I know good and well that many will likewise over discharge their in everyday use.

Thaaat 11.7A should be 11.7C . I hate typo on graphs and they are to much bother to correct when the error should be easy enough to spot.
Charles
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Last edited by everydayflyer; Mar 03, 2012 at 11:05 AM.
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Old Mar 03, 2012, 10:43 AM
Southern Pride
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Turnegy nt 25C 850 and HAIYIN 20C 800 compared

Here is a direct comparison of these two.


Charles
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Old Mar 03, 2012, 11:01 AM
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Wow, the Turnigy flat out destroy the Haiyin, assuming pack voltages and temperatures were identical at start of testing.

I surmise that you see a dramatic performance difference between these two?

Mark
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Old Mar 03, 2012, 12:11 PM
Southern Pride
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Close enough Mark. I use a FMA PowerLab set to Accurate Charge when testing LiPoys which means a CV termination of C/20 thus all cells are at 4.2 to 4.206 when connected to CBA . Room temp varies from 72 to 80 depending on the time of year but then ambient varies out doors at flying sites a lot more than that.

Initial charges for testing are always at or very close to 1C these were at 1A .

IRs for nano after 5 discharges were 9.5 / 9.5 / 9.5 at 3.7 per cell 71F and 400 mA charge rate. Now at 3.81V per cell and 72F they are 12.6 / 12.6 / 13.0.

Do not ask me to explain why IRs drift during a charge as indicated by a PL8 but they do. I know Wayne has stated that state of charge does not effect IRs.

All the years I obtained IR by discharging at two different levels I used fully charged batteries / cells.
Quote:
I surmise that you see a dramatic performance difference between these two?
Next trip to the field I will stick this one in my Mini Gremlin and find out. I may even do a ststic check here at the house if I can find a 9V battery for my tach as it died one me last trip to the field.



Charles
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Last edited by everydayflyer; Mar 03, 2012 at 12:18 PM.
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Old Mar 03, 2012, 12:18 PM
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Thanks for the update Charles.

The going theory as to why IR can drift during charging is due to I2R heating effects from charge current. At 1C or slower charging, these effects should be very small unless the pack is just plain garbage. This is one of the reasons why I personally prefer either Wayne's meter or an iCharger to measure IR, with the main reason being speed and convenience (I'm very impatient, and sometimes lazy).

Pretty darn good packs there. Hope they will last a while and they'll be a winner.

Mark
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Old Mar 03, 2012, 12:24 PM
Southern Pride
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But any heating due to charging should drop the IR not increase it and at 1/2C in a room at 73F there is not going to be any measurable heating to speak of.

If they last is the key. I know many could care less. These were around $6.50 each and most likely would be happy with 20 flights or so per LiPoly. Used in a foamie that spends its' nights stuck in a tree,lost in a field of corn, gets smashed into the ground every few minutes etc.being very inexpensive to purchase means a lot to a great many.

Charles
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Old Mar 03, 2012, 12:50 PM
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I need to pay closer attention when I read...

In this particular case, my guess is that the difference in your IR readings is due to temperature coefficient and the pack was warmer during the 3.7v post-discharge measurement. Either that or it's an odd artifact from the FMA measurement technique. My guess is temperature. Would be interesting to see back-to-back FMA and iCharger readings at various charge states. Sadly, I cannot do this as I do not own an FMA charger.

Mark
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Old Mar 03, 2012, 02:51 PM
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Quote:
Originally Posted by everydayflyer View Post
But any heating due to charging should drop the IR not increase it and at 1/2C in a room at 73F there is not going to be any measurable heating to speak of.

Charles
Charles, (and Mark)
I'm not sure that this is true; genuinely don't know. I believe that the charging process is endothermic but is probably a direct function of current. We also have the I2R heating effect which is exothermic. Being a square law the latter will obviously become dominant as current increases. Therefore at low current it may well be overall endothermic and at higher currents it will become exothermic.O
I know I have stated that IR is Independant of state of charge but have recently measured some of the latest lipos which show fully charged IRs about 5 - 10% lower than the value at storage charge. Not a big difference but consistent.

You have probably seen this plot I did trying to quantify it and I thought that the slight fall in the charging plot was due to heating. When the IR continued falling in the very low current discharge plot I reduced the current even further and it stopped. That tended to confirm my belief that it was just heating but now I am not so sure as the lipos I have measured at full charge and at storage charge were just soaked at a constant temperature for some hours.
It could be that some lipos vary SLIGHTLY with state of charge and some do not dependant on different chemistry ??


http://static.rcgroups.net/forums/at...ge%20State.jpg

Wayne.
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Old Mar 10, 2012, 01:41 PM
Southern Pride
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This HK Turnegy nano tech 25C 3S 850 only has 5 bench cycles and 3 flights on it so to soon to form any life cycle opinions as yet but it sure makes my Minin Gremlin streak across the sky. Five minutes of fairly hard flying and it is still going strong whereas the Haiyin is screaming for mercery and demanding I land at 5 minutes flown the same way.

Charles
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