So I finally bought everything I need for my Ranger 2400 RC plane. And I am thinking of perhaps also buying li-ion batteries so I can get a better range / flight time than my small (2x 3000 mah) li-pos.
I live in Romania so EU shipping is needed on all suggestions.
First of all, anyone knows of li-ion packs? I found this: ZOHD LIONPACK 10000mAh 4S Li-ion Battery (XT60) | HobbyRC UK (and a 5000 mah version) but I’d like some opinions on whether it is worth the extra money or I should just DIY a li-ion battery pack myself (I have done research on how to do that, and I also have a friend who has a spot welder and has done the soldering on my last Ardupilot plane)
I cannot seem to find 5000 mah cells that are not pre-order, out of stock, or from a questionable source or quite high prices. Can anyone help? I don’t want to accidentally buy fake cells. Anyone knows of other good suppliers? And if someone tells me of their experience with a supplier that would be useful.
Side notes on my plane: Do I have to reconfigure Ardupilot for it to work with li-ion cells?
Also I got an airspeed sensor. Should I get it on the plane on first flight, or should it wait until after I get the tuning working? I think it could help get the tune to work better if I install it correctly first flight so that I can maintain a more consistent cruise speed while tuning.
What is your current draw? Peak during takeoff and typical during cruising?
I recently made 4S1P pack out of Samsung INR21700-50S cells that are 5000mAh and supply 25A (45A if you monitor temperature and reduce power before it overheats).
Regarding speed sensor do a quick flight with it installed doing few gentle circles to check and if applicable correct the calibration. In that flight you can also check the minimum (stall+20%) and maximum speed.
So the thing is, even though I purchased all the parts last week, none of them have arrived yet. Im watching the tracking though. It seems like the plane and the ELRS rx/tx should arrive in about a week. The flight computer, airspeed sensor, everything else I need to make this thing fly with Ardupilot may be taking some more time than that.
Shipping to RO is also… slightly weird. I’ve experienced occasional delays of up to a week, altho mayby that was just me. Slow shipping is the main reason why I am already looking at li-ions despite having not even received the plane yet. To be clear, I do have some li-pos. They are 3000mah, so I think I would wire two in parallel if I cannot get a good li-ion pack to work.
How would you go about monitoring temperature? I thought I’d just do some ground tests and find at what throttle do the batteries maintain a safe temperature.
Thanks for the suggestion for the airspeed sensor. I think I might do that on the maiden flight if everything seems stable after autotuning.
I think I might end up using the 45 amp molicell if you say that cell looks OK. Because I plan to always fly 4s2p / 4s3p (I wonder - 4s4p? Has anyone done that to a Ranger? Don’t know if anything beyond 15000 mah would result in more flight time though) I think that I should end up with only 20A draw per cell max - the Ranger’s stock ESC is 40A.
That’s the cells I used, I will give you a opinion after a test flight as I haven’t had a chance to fly with my pack yet.
I would do the first flights with LiPo to get current requirements unless the plane manufacturer specifies those. As to temperature monitoring Ardupilot supports I2C temperature sensors though if you exceed 25A only during takeoff I wouldn’t bother unless you plan on doing a lot of consecutive takeoffs.
I have soldered my pack as I don’t have (proper) spot welding equipment. It isn’t recommend because it puts more heat than is recommend into the battery but it works and for high currents might be a necessity as home spot welders aren’t really capable of welding strips suitable for 25A.
I mentioned 2 different cells - some Samsung inr21700 50s and molicells inr21700-P45B. Which are you referring to? Unless anyone has anything bad to say about the Samsung ones I think I want to go for higher capacity. Because I will be always be flying with 4s2p (or 4s3p) I don’t think there will be any problems with amps even during takeoff.
“current requirements” - what do you mean by that? Like how many amps the plane needs to cruise, etc? Sorry, I don’t particularly understand this that much. Do you mean amps? I usually get the manufacturer-reccomended li-po battery, or something slightly bigger (in terms of mah) with similar weight and a better amp rating. Please don’t judge me for not knowing 100% everything, because otherwise I would not need to be here.
Since the ESC cannot use more than 40A, and I will be flying with a 4s2p / 4s3p (if 4s1p, I might as well just put in my li-pos and get better results) that seems to mean a max ~20A per cell which these cells can handle. (I did some googling, some people tested these cells)
I assume the things holding the cells together are 3D printed? Good idea. Ive got my own 3D printer so I think ill do the same - was planning to use glue gun cells together.
EDIT: If you don’t mind my asking, what will you be putting that pack into? or is it general purpose?
He didn’t show takeoff but in cruise he doesn’t exceed 3A and oscillates about 1-2A most of the time though if he is using a SiK telemetry radio powered from pixhawk I wouldn’t be surprised if ~6A were lost in measurement error (power module uses the same wires for current ground and current measurement reference which means that voltage drop across power module wires affects current measurements), even with true current consumption of ~8-9A in cruise unless takeoff draw is extremely high the plane would likely work with cheaper INR21700-50E in 2P or 3P configuration that can supply ~9.6A continuously.
Yes, spacers and caps are 3D printed, spacers are optimized for one wall thickness.
It is for my AtomRC Swordfish that I use as an experimental test platform (currently will be testing LD2450 and LD2411S human presence sensors aka 24GHz radar rangefinders)
I’m not entirely sure what that means. My FC will be Matek H743 wing v3. I will be running telemetry via mavlink-rc on ELRS. So am I at risk of running into same issue? I don’t think so but am not sure.
I think I will go with the -50S because it gives me some higher margins of error with the current. Might mean less temperature, and I think it might also means it will have less voltage sag so I can use more of the battery’s capacity. Also those packs could be used for other planes in the future.
