NCR18650B - The Future of RC Aircraft Batteries? - Blogs

Richard Johnson December 23, 2015 at 10:21pm

Thanks.. Guess you missed the high volts at low currents, im thinking about grams as li-oin are 4x power density than li-po. Yes there are big bldc machines designed for 40 odd volts, but im not after a racer.

Its all good, seems we are in different ballparks, im not interested in asking questions as im capable of working it out for myself...........

regads.

Quadzimodo December 17, 2015 at 6:05am

This paradigm shift you suggest should occur is actually more of an evolution and it started long ago.

What has driven this evolution has nothing to do with Li-ion verses LiPo. In fact, if it has anything to do with advancements in chemical energy storage technology at all then the transition from NiCd (and to a far lesser extent Ni-MH) to LiPo is far more relevant.

You seem to be getting a bit muddled by comparing LiPo batteries optimised for peak power density against Li-ion batteries optimised for peak energy density. There are low rate LiPos and high rate Li-ions too! Just as there are prismatic Li-ions and cylindrical LiPos.

The virtues of higher voltage systems are well know. We already have sensors, ESCs and BLDC motors designed for upwards of 60V. Off the shelf parts for micro fpv racing systems are already rated at 5-6s (upwards of 30V). How much higher do you want to go? As you yourself acknowledge above, things start getting pretty hazardous once you start climbing much higher.

Anyway, with all that said... your most fundamental misconception in conceptualizing this particular problem is to be under the impression that adapting a given powertrain to a higher voltage will somehow miraculously overcome the limitations in power density of a given battery's chemistry.

My advice to you is to stop thinking about Volts, Amps and Amp Hours and start thinking about Grams, Watts and Watt Hours.

If you wish to discuss further in this thread, I suggest you start asking questions instead of making silly statements.

There are no silly questions here ;-)

Quadzimodo December 16, 2015 at 4:13am

Richard - Nice to meet you too mate.

Jump online and you will find 18650 cells that have anything up to 8800mAh printed on side of them. That doesn't mean that they can deliver 8800mAh though.

The proof is in the pudding, as Trent has demonstrated through his practical tests above.

See here for performance and characteristics of the NCR18650B. Now compare those figures with these for 18650 cells which claim 4000mAh, 5000mAh and 6000mAh. Notice the difference?

Save your money. Don't believe everything you read.

Quadzimodo December 15, 2015 at 11:12pm

"I have found 6ah 18650 cells that for the same 'c' rating will give 12A draw" - Really!?!

They must be from Panasonic's the new Li-uno (Lithium-Unobtanium) series.

ausdroid April 15, 2015 at 3:54pm

Thanks so much.

Riccardo parola April 12, 2015 at 10:32am

Not really,

I simply look at the cell's specs. I'm currently experimenting with e-fest because of higher discharge rate, I'm using them in non parallel on a small racer quad and the NCRs C rating is too low for it unless in parallel. Liking it more than li-po so far...

Same concept though, while the chemistry is "Li-Ion" (keep in mind by now there is quite a few different Li-Ion compositions out there, thanks to Vapers and electric cars for pushing development) the specs are much closer to those of Li-po, especially the max charge voltage.

There is starting to be some batteries out there that have even higher voltage rating and would require a special charger or custom firmware on a lipo charger to fully charge... see http://lygte-info.dk/review/batteries2012/Samsung%20ICR18650-28A%20...(Purple)%20UK.html

A couple of sites I feel helped me understand what little I do understand:

http://batteryuniversity.com/learn/

http://lygte-info.dk/review/batteries2012/Common18650IndividualTest...

ausdroid April 11, 2015 at 11:49pm

Thanks Riccardo. Can you point me to some literature on the subject?

Riccardo parola April 11, 2015 at 8:23am

Yes, use Lipo setting

ausdroid April 10, 2015 at 9:24pm

I have built a 4p6s 18650b pack. I have balance charged with an icharger 208b on the LiIo setting. The charger cuts out when the batteries are at 4.08 volts/cell and my battery checker confirms that the 6S pack is 100%.

However, the charging graph for the battery says that peak capacity is achieved at 4.2V per cell and that the majority of charge is achieved in that last 0.2V. Some suggest that you should use the LiPo setting to get them up to 4.2V.

Anyone got experience with this?

Quadzimodo April 5, 2015 at 7:11am

jadwin edison - The ESC does not dictate how much load will be placed on your battery. Think of the ESC as attenuation (or volume control) only.

You need to know what the peak and continuous power loads will be. That means calculating or testing your driveline (prop, battery and motor). Ecalc is an invaluable tool for helping to understand what is possible in this regard.

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