Anyway, what do we think… would we put a 4S pack of these on a quad?
@notveryprettyboy @Steviegeek
All in all, a man must always eventually walk his path alone. That means try it and if its good we might copy you 
Max current reported at end of flight last night was 25A (though I managed 33A last weekend)… Doubled for the change in current sensor calibration I did today, makes for 50A and 66A… But most of the time it’s well under that.
Ok… I’ll order a few, If nothing else it’s a good pack for the plane!
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Replacement arms arrived from Armattan and now it’s a 6" Badger…
Also the 21700 4200mAH cells arrived. Next to an 18650 for scale.
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BADGER
BADGER
BADGER
BADGER
Mushroom MUSHROOM
Snaaaaaake!
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A quick hover test in the back garden… It flies…
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Hehehe, I’ve not seen badger for years and that made me chuckle 
I’m not the only one to be trying these 21700 batteries.
I haven’t tried mine yet. The 1st flight with my 6" was with a LIPO and ended with the VTX GND wire coming loose and me losing signal. I had the 21700 4S1P pack with me but didn’t get to use it. I was hoping to try it tomorrow at Drone Circle… but, well, rain… (if I say “rain” enough it’ll go away, right?)
I’m looking at 26650’s for my new big plane
Not much choice in manufacturer/branding. Has anybody any experience with KEEPOWER ?
Cheers
Steve
A long time since I posted on here, but I thought I’d mention that with the 4S1P 21700 42Ah Molicell packs I made I have had between 9 and 12 minutes of cruising flight time.
They get barely warm at that and it is possible to do a bit of freestyle. Maybe more than I have been doing. I’ve been pretty careful.
I now have 3 of the packs made up:
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Soldered or welded?
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Soldered
Well it’s ridiculously tight, but with the addition of a 3d-printed 20mm to 30.5mm mount I designed, I’ve managed to get a HDZero 1W VTX into this build…
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Don’t know if anyone has even contemplated doing this, but I am planning on experimenting with dropping the smallest capacity Lipo of whatever cell size you are using into a quad power circuit via a relay, when using Li-ion. The idea being that in one of those oh shit moments when you really need power and have none, you can energise the relay circuit and enable an instant boost of power. I don’t know if it will work and I am nowhere near to that 4" LR build when I will do those experiments. In reality I want to know if I do it will it just explode mid air. 
I suspect without some sort of one way circuit/diode on the Li-ion it might overload them, but I am not an electronics engineer or battery specialist.
Basically the same as putting another battery in parallel. Well why not just do that. Run two lion batteries in parallel. A 6S2P battery.
The molicell 21700 molicell packs will then be able to kick out up to 90A without problems.
See the videos from this guy.
I had a think and for sure with mismatched packs you can potentially have really big issues. The higher voltage one will start charging the lower one. There will be no current limit. The result could be quite impressively exciting.
I think if you did it, you would have to put a diode on the Li-ion side to stop any current back charging it. the results of pushing current at a higher voltage back into a battery with a much lower max voltage may well be catastrophic. Might be worth an experiment in itself to confirm it.
The thing as I understand it, is Li-ion excels at giving power over a much longer period, but lacks punch. So ideal in our hobby if you want to fly for a long time, but not really change the throttle amount or push it very high. Where as a Lipo excels at giving lots of power (high discharge rate) very quickly, but isn’t so good at slowly dripping it out and is limited in how low you can push a cell before it goes off the proverbial cliff (and the drone falls out of the sky). It’s roughly 2.5v per cell, for a Li-ion and 2.9-3.0v for Lipos. So if by some stroke of bad luck you were caught in say a really strong downdraft and found you couldn’t utilise enough power to kill the descent you would crash (botgrinder had that issue in a video when he was doing acro with a Li-ion pack and a couple of times came very close to not pulling out of powerloops because the voltage wasn’t recovering fast enough).
So by sticking say a small 250-300mAh Lipo into the circuit, putting a relay connected to say an LED circuit, then binding it to a switch you would have an emergency source of high power, that could arrest a descent, or maybe give you the few seconds of power you need to land, or run a buzzer. I can think of a handful of reasons for having an emergency power source that can output lots of amps for a short duration on a LR cruiser. Whether it’s worth doing is probably down to the individual case. If you fly over land and never when it’s windy, it’s probably something you would never need. If you do flights over water, then maybe it might be worth considering.
Just doubling the pack into a xS2P pack might give you more time and possibly more power, but if using 18650’s, you’ve possibly now taken the weight up by around 200g. You now need to re-assess the motors, the ESC, etc.
Anyway, it’s just a crazy idea I mean to try for no reason other than trying it. One of those dumb things I thought up while running on a treadmill and contemplating things. 
GiantAntCowboy. He posts on another board I frequent. I’ve messaged/talked to him a few times about LR stuff and ideas.
His videos are pretty excellent. Well except the one where he was traipsing around in the ferns near mine workings in Cornwall, which I mentioned to him was unwise due to the number of uncapped shafts that can be found in said ferns.
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