My nanotech thread (other lipos, too) - RC Groups
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Mar 20, 2015, 07:09 PM
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Race Miata's Avatar

My nanotech thread (other lipos, too)

As has been covered in many threads here and in other forums, people have greatly different experience with nanotech lipos from HobbyKing and other lipos with nano-technology like the Wild Scorpion. Many people find them junk because they puff them in short time and find them have high IRs. I together with perhaps a few other people find the exact opposite. New nanotech lipos always have lower IRs then comparable C/capacity lipos without nanotechlogy when they are new and when used properly (right size for the application) they always maintain lower IRs than other lipos.

As I've mentioned in other threads, the key to nano-technology is to buy by size/weight not by capacity. Lipos with nanotechnology are often smaller and lighter than their counterpart of similar C/capacity/IR rating. Unfortunately, power handling capability is still highly reflected by the pack size and weight. Think of a high-wattage resistor for lipo discharge purpose. It doesn't matter of its low resistance but it still has to be physically big to dissipate the power.

For example, people normally fly 3S 1300mAh pack for the Blade 300X that I fly but I use 3S 1500mAh nanotech which weighs about the same as the stock E-Flite 3S 30C 1350mAh pack. I've put around 180 flights on my 1st batch of nanotech 1500 from September 2013 and they are still OK and I wouldn't say too high IRs as many people complain.

I recently bought some 6S 25C 3000mAh nanotech packs at spring sale for 20% off for my stretched Protos500 (470mm blades) which people normally fly 2600mAh packs. With my Turnigy (light blue) 20C 2650mAh packs I can already fly 4mins with moderate headspeed and get close to 3.80V resting voltage (much less than 80% discharge). I have tested to fly 4.5mins with a little less than 80% discharge. With the 3000 packs and more power available I'll be flying higher headspeed for 4mins and will still be a bit less than 80% discharge.

For reference, these are the weights of comparable lipos I fly with my stretched Protos:

nanotech 25C 3000                   427
light blue Turnigy 20C 2650         400
Voltz 35C 2600                      400
Thunder Power 70C 2250              395
Gens Ace 30C 2600                   385
Gens Ace 55C 2600                   450
Gravity 30C 3300                    520
Hyperion 25C 3300 on diet           548
Wild Scorpion 45C 3500              517
These 3000mAh packs came new with 21mOhm pack IR (i.e. 3.5 mOhm/cell) at storage voltage down to 17mOhm pack IR (i.e. <3.0 mOhm/cell) after 1 break-in flight which I took easy just flying lazy-8 in different orientations at normal headspeed for 4min10sec and came down with 3.92V resting voltage.

Since weather hasn't been cooperating, I did some controlled discharge cycles with the new packs using my charger's external discharge function at 7A (1 pack at a time) down to 25% of that (1.75A) at storage voltage. Each pack pulled around 1400mAh (from 4.18V charge). These are the 2nd discharges ever with each pack. At the end of the cycle (storage voltage), the packs warm up to 23C (from 18C room temp) and IR came down to 7-9mOhm per pack! That means cell IR is close to 1mOhm! That's not bad at all for 3000mAh cells.

Since I should have more capacity than I need for 4mins hard flying with these packs, my plan is to charge these packs to only 4.19V or even 4.18V and still have enough capacity to finish at around 3.80V. I'll use this thread to update the progress with these packs and any other nanotech packs I have. So far I have 50+ nanotech packs of different cell counts, sizes, ages, flights, etc. since 2011 and none of them has disappointed me thru the life yet and I expect these new packs to perform at least as good and last at least as long.
Last edited by Race Miata; Aug 15, 2015 at 01:53 PM.
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Mar 20, 2015, 11:39 PM
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Nice recording of data and a nice report.
Btw can i know where do you buy your wild scorpion lipos.
Mar 21, 2015, 12:24 AM
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Funny enough, the Wild Scorpion 6S 35C 3500 pack for my stretched Protos was a retired pack from my friend who didn't have a heli for that size lipo at the time. I put well over 100 flights in it over 13 months and it still performs as good if not better than my Thunder Power 6S 70C 2250.

I also have some other Wild Scorpion packs bought from my LHS.

The 3S 30C 2200 I used on my Trex 450DFC I got it from my friend. This is a good illustration of what not to do. This pack weighs about 170g while most other 2200 packs I fly my T450DFC with are around 200g. It's like flying a 1800pack with my T450DFC. This small and light WS pack didn't last. It didn't really puff but IR got high over time and pack got weak. If I were to buy WS for my T450DFC I would be looking at 2450 or even 2600 whichever hits 200g 1st.
Last edited by Race Miata; Mar 22, 2015 at 12:35 AM.
Mar 21, 2015, 08:43 PM
I have not tried nano techs but would have to agree with your findings. And anytime I could get away with being able to buy a higher capacity pack and still be at or really close to the same weight as a lower capacity pack I would use the opportunity anyway. And I'm glad that you point this out for when I do buy some nanos I'll pay attention to weight in my decision and hopefully the sizes are smaller for there capacities as well.
Mar 22, 2015, 12:47 AM
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Yeah, the advantage of the smaller/lighter nanotech lipos is that I can use bigger capacity pack without weight penalty. And the advantage of higher capacity pack is 3 folds.

First, for the same C rating, a bigger capacity pack means higher current/power capability which means for the same load application there's less stress on the bigger capacity pack. Second, with extra capacity I don't need to charge to 4.20V and I don't need to fly till it's down to 20% capacity left. These two should help longevity. By how much, I'll hopefully see results from these nanotech 3000 packs. Third, I always charge my lipos at 2C. So for the same amount (mAh) that I need to put back, a bigger capacity pack means I can charge at higher current yet still maintain my normal charge rate of 2C and that means shorter charge sessions without extra stress on the lipos!
Last edited by Race Miata; Mar 22, 2015 at 01:39 AM.
Mar 22, 2015, 01:25 AM
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Put 4 flights in each pack today (3 recharges, 1.5C, 1.6C, 2C, all to 4.18V which I'll keep doing from now on). I progressively flew the packs harder towards my normal flying style. By the end of the day I flew the nanotechs like I normally do my Turnigy 20C 2650 packs. Each pack got down to 3.80-3.81V. I just finished charging them for tomorrow morning and put back around 1500mAh to 4.18V. I'll eventually run higher HS and fly harder (not as hard as my WS 45C 3500 pack though) to draw more capacity. But yes, that means I've been under-using my Turnigy 2650mAh packs' capacity.
Last edited by Race Miata; Mar 22, 2015 at 02:55 AM.
Mar 24, 2015, 09:23 PM
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At 13 flight each...

Have been flying almost daily the last few days and I've been recharging at least once each flying day so I've already put in 13 flights each pack so far. I accidentally dropped one pack on concrete pavement from about 2ft high and cracked the heatshrink at a corner. Looks like the cells are not damaged base on the consistent IRs with the other pack. Talking about IRs, since I'll seldom use controlled discharge with the charger and then measure IRs right afterwards like I did in the beginning, the packs won't be in that particular condition to result in 1mOhm/cell that often. I'll most likely often be measuring IRs once I get home after flying, at about 3.80V, in room temp around 18-23 deg C. Today, they measure about 18mOhm per pack, or 3mOhm per cell, which is similar to when they have just been broken-in 10 flights ago. IRs didn't get lower after break-in as I wished they would but in reality the 3mOhm per cell after broken-in was not bad to start with, and are quite lower than my favorite strong packs already: Thunder Power 70C 2250 and Wild Scorpion 45C 3500.
Mar 27, 2015, 12:43 AM
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At 17 flights each pack still 18mOhm pack IR...

Did 4 more cycles today. I was planning to hold on til 25 flights for the next update but today I decided to record some flight video which I haven't done for some time so I thought might as well post the video and do an update.

Right after each recharge (warm 19degC day, lipos not shielded from the sun), pack IR got down to 3mOhm which is 1/3 of that of my Turnigy 20C 2650 from Sept 2014 with about 70 flights. More realistic IR numbers I took after I got home with the discharged packs are still around 18mOhm per pack. No sign of puffing at all, but then my Turnigy 20C packs from Sept shows no sign of puffing either. Not sure if you can see in the pic, the rightmost Turnigy 20C pack for comparison is a little puffed. This retired pack is from January 2014 with probably 140+ flights with lots of abuse pushing it to 60degC in the summer.

Here's the recorded flight, 4 mins moderate flying (not exactly my normal style and sorry for the repetitive moves as I was testing out the governor/cyclic aggression re-tuning by comparing different "banks"), pack temp 38degC, 3.80V (using fast charge to 4.18V).
My Stretched Protos Re-Tuning Governor/Cyclic Agressiveness (4 min 46 sec)
Mar 31, 2015, 05:08 AM
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After 28 flights, pack IRs ~19mOhm...

Looks like I need to re-tune governor settings. I cranked up all pre-comps so much it's like constantly flying higher than desired headspeed and that means pulling more capacity with not just these nanotechs but all my other packs as well. Ambient temp gets up to high teens (deg C) these days (looks like well into spring) and I check lipo temp after each flight and it peaks around body temp. To act as control for testing, my Turnigy 20C 2650 packs are used to fly the same settings/HS as my Nanotechs. The 20C packs consistently show at least 3 times IRs of the Nanotechs. While tuning governor settings or doing certain maneuvers, if the 20C packs start to bog the motor then I know I don't want to push too much further. The 20C packs consistently run 10degC higher temp than the Nanotechs.

Regarding IRs, I don't know if there's something wrong with my Reaktor 300W charger but the IR readings are jumpy. I mean once I leave the main and balance leads hooked up I'll then get say 21mOhm the 1st try and right afterwards the next try may read 17mOhm and then 19mOhm, etc. However, I did confirm with my HobbyKing X charger that the cell IRs read about 3mOhm (except cell #1 which is always way off on this X charger). As I mentioned above, my Turnigy 20C 2650 packs (from Sept 2014) still consistently read at least 3x IRs then these nanotechs 25C 3000s. I'll dig deeper with the Reaktor's jumpy IR reading issue.
Mar 31, 2015, 10:30 AM

setup request for protos..

Can anyone offer some setup input for a protos 500? I just bought an empty kit, and trying to use what I have on hand, which for now is an Ice Light 75a Castle ESC.

basically a tabula-rasa protos 500.. I have an ESC for it, but Need motor, tail and cyclic servos + pinion.

Is the stock 880kv the right motor?, or is there a better choice out there? also, I'll need to buy some lipos since I dont have any 6s 2600 or 3000 on hand..
Mar 31, 2015, 11:44 AM
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Forgot to mention that I'm putting back about 1500-1600mAh per charge. Still far from the 80% rule and even by charging to 4.18V I still get at least 3.80V resting voltage after flight. With the Reaktor charger during balance charge mode, the cell voltages are so balanced the charger never drops back charging current to balance them (distinctive iCharger software behavior where you see cell voltage display flashing and input current dropping).
Mar 31, 2015, 12:09 PM
Thank you Race!!

Originally Posted by Race Miata
Apr 07, 2015, 12:58 AM
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At 50 flights, pack IR 9-10mOhm (new measuring condition with new better balance lead "squid", equivalent to 18-19mOhm old measuring condition)...

Soon after my last update I realized the reason for jumpy IR readings from my Reaktor 300W charger. Firstly the iCharger software just adds individual cell IR together to report the pack IR. With a +/- 0.5mOhm tolerance for each cell IR, the pack IR for a 6S pack accumulates tolerance to +/- 3mOhm which doesn't sound a lot for my other packs with pack IRs above 20. These Nanotech 3000 packs have single-digit pack IR so +/- 3mOhm tolerance is a big percentage. Secondly, my favorite balance board seems to be wearing out. I can wiggle the leads/plugs and the individual cell voltage reading on the charger may vary a bit. I changed out the board for a balance lead "squid" plus my home-made 2-pack parallel charge leads. No more varying individual cell voltage display on the charger when I wiggle the plugs/leads. IR reading is now consistently at 9-10mOhm per pack (i.e. 1.5mOhm per cell), same condition at 19C room for at least 2 hours after a flying day (3.80-3.81V), while the old board would still show an average of 18-19mOhm pack IR. From now on I'll be reporting IRs using this balance squid. Hopefully, this squid will last much longer.

So, at 50 flight mark, the nanotechs still show no sign of puffing, weakened performance or increased IRs. I was going to make a flight video pushing the packs a bit but my cyclic felt weird so I pretty much used this flight for diagnostics and to test out my tamed-down governor settings. Read more in the Youtube page description.

My Stretched Protos Long-Term Test with Nanotech 25C 3000 (4 min 40 sec)
Apr 17, 2015, 12:53 PM
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After 75 flights, pack IR 10-11mOhm...

The pack IR numbers are impressive especially compare to those of my Thunder Power 70C 2250 and Wild Scorpion 45C 3500 which are at least twice as much. I always wonder if these IR numbers accurately reflect their actual performance so I decided to run my "insane mode" (i.e. FBL bank settings specifically tuned for my Thunder Power 70C pack) despite my fear of possibly puffing my nanotech which luckily hasn't happened yet. Battery still came down lower than body temp (less than 20degC over ambient) running insane mode. Turns out the performance difference is noticeable but not far behind. With full-collective prio-pogo's, Thunder Power 70C is noticeably faster (lighter) and stronger (higher terminal speed). Don't get me wrong the nanotech still performs very well for a 25C battery.

My Reaktor still doesn't need to hold charging current in order to balance cells throughout the entire charging session with 2 packs in parallel. The cells are that well balanced after 75 flights each pack. Even with single pack balance-charge mode the Reaktor only needs to drop current for a very short moment to balance the cells. I'll post the logview graph later. As always with my good condition nanotech packs, CV phase takes very little time (3mins or less) to get down to 1/5th of 2C starting current.

Here's what the packs look like after 75 flights each. No sign of puffing.

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