We haven't heard too much from Trent@MyGeekShow since he restructured his time late last year. He has however just uploaded a video outlining some exciting news.
These new professionally-built 4S packs are based on Panasonic's NCR18650GA Lithium-Ion cells which offer comparable energy density but with upwards of twice the power density as Panasonic's well known NCR18650B.
With the primary factor prohibiting use of Panasonic's NCR18650Bs in a broader range of unmanned aerial craft having been the relatively conservative power density (compatible only with the most efficient craft) as well as the limited availability of suitably sized and terminated packs, this new offering is a fantastic option for many smaller fixed-wing (AXN/Bixler/Wicked Wing XL) and mini-multirotor (<350 ships, not fpv racing) flyers who are chasing a bit of extra endurance.
The only problem I can see at this point is that they appear to be available exclusively via Amazon and shipping is not available to me here in the land down under. It is a shame too because I would love to grab half a dozen or so for my park flyer!
Comments
This is really great! We have been looking at these batteries for quite sometime now. We are currently using 16000 Mah 6S Gens Ace Tattu which gives us a flight time of about 2 hours on 1 kg payload. We think we can really pull this to over 3 hours with the NCR18650GAs easily. Trent, we would be interested in getting some of these batteries if we can work out shipping to India.
Pravin
@Rob. Yeah the EU warehouse still has some stock. But the popular sizes are all gone and has been so for a good while now. I ended up having to stockpile some 16ah batteries, just because you cannot get large packs at an acceptable price any other place.
I use the Odyssey batteries in my truck. ;)
@John, I'm starting to get concerned that the Multistar batteries are actually discontinued. They're widely out of stock now.
This line of discussion sent me digging through my archives for a few editorials I penned way back when.
Nice to see Trent back here. These batteries seem really interesting and are surely an improvement in ernergy density versus the multistar LiPos.
Last year I flew 1h15 on A 16" prop quad with a self assembled 4S7P battery made of 18650 cells. I stopped the flight at 13volts (I could have gone down to 12V or 2.5V per cell). Eventhough the pack was limited to a 1C amp draw, it delivered enough current for a gentle flight even in a bit of wind (but it would not be suited for aggressive flying).
With this 18650GA 10 amps continuous discharge, it becomes much more flexible to build higher amp capacity packs. So for example, you can build a 6S pack, 20 amps continuous (40 burst), 6800 mah for a weight of 576g ! To compare to the Multistar lipo 6S 5200mah weighing 627g (51g saving on weight for an extra 1600 mah !)
I will buy a few cells, make some packs and test them out. Thx for posting.
I would love to try some Panasonic's in my next ebike build, but the form factor is just not practical for the pack size I need. There are also some 20ah cells they make for car batteries, but they seriously need to come down in price.
The Multistar 6S 16ah LiPo packs on the other hand are a great fit. With 3 of them in series (making a 18S 16ah pack) the ~10C rating is more then enough. Got a couple of hundred charges on some of them so far, and looking good.
blah blah blah, i was disappointed in the real world by my testing.
double density at low discharge != double density at max C discharge.
don't miss guiding people, assble these betteries should never use soldering iron. they won't blow on your face, but you will destroy the fuse under the positive terminal cap.
Hi Rob
if I look at a turnigy 3S 5000mah 25C battery it states`Internal impedance can reach as low as 1.2mO compared to that of 3mO of a standard Lipoly.`
so ``In theory```if I short circuit the ends of the battery(not counting the wires) then 12volt/ 0.0012 = 10000Amps and if fully charged it will deplete in 5 x 3600as /10000 amps = 1.8secs. (editied due to formula mistake)
Now back to reality. The cables attached to the battery and the connectors all have a resistance that decreases these theoretical values as the wire resistances add to the battery internal resistance.
A Lipo in a dead short condition (dropped tool for example) can easily produce 500-1000amps. just as your truck battery can provide close to 5000amps on a dead short.
In normal use the wires will melt just as a fuse melts.
I use a metal box for charging my lipos and yes, I made a mistake and closed the box onto the cable from a lipo !!! this was not a good move and the cables vaporized in the few seconds it took to open the box .. The battery did not survive that mistake. High currents are very possible. :) But to have a lipo with a Rating of 150C is stretching things a bit. !!
Oh yeah, here we go. 120C is so last year! We're now up to 150C!
http://www.maxamps.com/proddetail.php?prod=Lipo-6500-74-Pack-T
So this battery can deliver 975 Amps. Right... sure it can.
I actually do have a battery that can deliver 1000Amps in my truck. It weighs 80lbs. ;)
Dwgsparky:
I think it used to be that C rating was the maximum discharge rating of the battery before damage occurs. However, I don't think that is necessarily the case anymore. It's sort of taken on a life of it's own, and all the marketing people are using it to say that their battery "goes up to 11".
It's not hard to find 5000mAH batteries with a 120C rating. That would mean the battery could deliver 600 Amps. I think we all know that there is no way that is possible. Maybe on a short circuit, for about 0.01 seconds, and then the wires would vaporize.
Not that I've ever done that... ;)
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