15-Jul-2022, 10:33 AM (This post was last modified: 15-Jul-2022, 10:36 AM by Rob Axel.)
… Here is the back story… my wife is a Middle School Science teacher… she uses Tinyhawks (along with other RC stuff) in her classroom, yeah cool RIGHT!?. Anyway, the kids beat the tinyhawks to death, and they are limited to the classroom. Sometimes they get to fly in the halls or gym. The 1s flight times are a tough for the kids, she used Tellos at first, the brushes motors didn’t last long… I stick with the 1s platform due to the simplicity and “safety”… remember these are middle school kids.. and they WILL put a square peg into a round hole.. I have a box of TH FCs that got fried with batteries being plugged in wrong.. So I was on a mission on trying to increase the flight time.. I did the 550mh 1s lipos .. but I wanted more.. Then I saw the 18650 long distance build with 10-15 min flights, on a 1s 1860…A possibility, but first let’s solve the square peg round hole issue.. I KNOW that battery would get installed wrong and fry the fc..I solved this by printing the battery holder and a plug.. making it easier for charging and HOPEFULLY not get plugged in wrong.. Frame was easy eanough, followed the build specs, I used my eachine UZ65 components (2s rated).. the build was simple enough.. untill it came to the maiden… it would lift 1-2inches then brown out.. did some research.. the 18605s need to be HIGH Discharge.. so I ordered some (so I thought) and had the same result.. I’ve flown it on a 1s lipo.. flies fine.. Amy suggestions?
My first impression is that it may not be an issue with the build but rather the lion cells.
Im a smoker and tried vaping for over an year and chat with several fellow vapor’s, the common issue is there are several fake Molicel lions on the market. Even cells bought at some reputable vape stores have turned out to he fakes. Try googling for “Molicel fake” and you will see the drama.
I’ve seen various threads throughout forums about the 18650 drama. I went to a reputable store.. waiting for them to get back to me regarding what “exactly” I ordered.. I’ll keep post discoveries
Did more digging, yes.. I do believe you are correct. The cells I purchased are not counterfeit, but are “regular” 18650s not “high discharge” as I thought it was.. Bardwell “VTC” cells and I used it in my search .. I decided to just see if there was a “suggested” cell on the recon 3 RTF version of this quad… Yup sure enough there is.. Sony vtc6 (Murata)… the place I purchased mine doesn’t carry this.. Apparently, it is not readily available.. I only located one place.. and the cells are $14 each. So I’m 99% sure it is a battery issue. There is a vape / smoke shop on my way home.. gonna pop in and see if they have it..
Murata's seem to be readily available over here (in the UK). I tend to use LG HE2 18650's (Cheap) for the majority of stuff and Molicel INR18650 P28A for things that can benefit from 25A max discharge. Guessing that's what your drone needs.
Well apparently Sony / Murata vtc6 batteries are “suggested”(in other words REQUIRED) to fly this quad.
These “High Discharge” cells are not readily available.. I found very few suppliers, and mostly “out of stock”… priced between $9-15 when I did find them.. I called a bunch of vape shops, none carry them, even Batteries+, no luck… So, to anyone THINKING of this build.. source your VTC high discharge cells before you begin ..
15-Jul-2022, 06:00 PM (This post was last modified: 15-Jul-2022, 06:09 PM by Pathfinder075.)
If you were UK based I'd say try 18650.uk and see if they had them.
Unfortunately their is a worldwide battery shortage (apparently). Do you have the lift to modify to a 1S2P config?
Funnily enough the VTC5 should also work. It has better discharge than the VTC6.
Code:
Sony/Murata VTC6 - 18650 Battery
3000mAh - 15A Continuous Discharge - Flat Top
Brand: Sony/Murata Model: VTC6 (US18650VTC6) Size: 18650 Chemistry: NMC Nominal Capacity: 3000mAh Nominal Voltage: 3.6V Discharge: 15A Max Continuous or 30A Max Continuous with 80°C temperature cutoff) Positive: Flat Top Protected: NO Rechargeable: Yes Dimensions: 18.22mm x 64.80mm Weight: 46.8 g
Code:
Sony/ Murata VTC5A - 18650 Battery
2600mAh - 25A Continuous Discharge - Flat Top
Brand: Sony/Murata Model: VTC5A (US18650VTC5A) Size: 18650 Chemistry: NMC Nominal Capacity: 2600mAh Nominal Voltage: 3.6V Discharge: 25A Max Continuous (35A Max Continuous with a temperature limit of 80°C) Positive: Flat Top Protected: NO Rechargeable: Yes Dimensions: 18.22mm x 64.80mm Weight: 47.8 g
But then most batteries that have 20A discharge should work fine. The ones I found are as follows.
Code:
BAK N18650CNP Samsung 25R LG HE2 Molicel INR18650 P26A Sony/ Murata VTC5A Molicel INR18650 P28A
All of those have either 20A or 25A discharge. The VTC has a slightly better max discharge, until the temperature hits 80C, then I guess it either fails or explodes (or your drone falls out of the sky).
According to the supplier.. the Molicel 18650 IS a high discharge battery..but to be honest.. the price was $3.50 per cell.. so I HIGHLY DOUBT it’s performance is the greatest.. I have several whoop FCs.. I may just for Sh*ts and Giggles swap it out and see if the fc is the issue.. I may also direct wire the battery carrier.. to eliminate any plug questions
I wish i could get Molicel at that price, they are not cheap over here. P28's are about $13 each. I tend to use (Li-ion) for 4S2P packs for portable solar arrays. High discharge is useful, but I tend to prefer the $7-8/cell batteries.
15-Jul-2022, 07:07 PM (This post was last modified: 15-Jul-2022, 07:09 PM by BadRaven.)
Errrrr.............
the average weight of a 520-650mAh LiHv is 14 grammes.
The weight of a Li-on 18650 VTC6 is 47 grammes............ around 3.4 times higher. (A VTC5 is still 46 grammes) And of course, delivers less burst current.
No surprise the poor Tinyhawk struggles!!
I have both a Rekon3 and a NanoLR (3D printed by me)
I run them both on VTC5 and VTC6. Got four of each. The 5's are lower capacity and so obviously give less duration, but not a game stopper. Always get 20 minutes plus on the 6's.
I buy from 18650 ltd in UK.
Its difficult to help more when you do not know where someone is (not in profile, etc)
What are the rest of the specs of your build? Motor size/Kv? Prop? FC? VTX? What's the AUW?
The most important thing I've learned with these NLR builds is, while cute, using the 18650 cell holder is a major bottleneck in performance. The resistance is high, and they weigh a lot. You're much better off making your own 18650 "cell" by soldering an XT30 directly to the terminals.
Second, you'll probably need an external step-up voltage regulator to power the VTX. Li-ions sag much more than LiPos due to higher internal resistance, and you need to run them down to 3.0V in order to get anywhere near the stated capacity from the cells. Typical 1S FCs are not made to operate down this low.
With 3" biblades, I've found the Flywoo Robo 1202.5 11,500Kv motors to provide the best performance and efficiency. Deviating too far from this motor size/Kv will either draw too much current or not provide enough thrust to keep you in the air as the battery voltage drops.