Can I DIY the BEST Li-Ion Battery in FPV? 

I've made quite a few packs, and learned some technique the hard way. I strongly recommend adding more structural support. Add rigid plastic, and have the wires go back over the cells instead of out of them. Rigid plastic helps in a crash. Wires going back over the cells gives an anchor point other than the soldering connection. Look at the donor cell and copy.

For 21700 cells use AWG 18 wires to connect. Much easier than those strips. The isolation on the wire helps to prevent shorting the cells via the plus pole on top. Before making packs you should give the cells an extra shrink wrap. If the cells have play to one another and manage to rub the isolation off , your pack will short circuit. Please when DIY LI Ion packs, give extra isolation between the cells and make sure they are sticking well to one another so that they cant rub the isolation off. For the XT60 power cable AWG 16 wire would have been enough. The maximum amp draw is rated 45A anyway. Much lighter and more easy to solder Excelent choice on the p45b cells. Best you can get.

I find it a ton easier to do the soldering by switching from my normal iron tip (BC2) to a larger tip (D4). The bigger tip carries more heat so even with large wires / braid it bonds solder much faster and there's less risk of overheating the cells. Your pack seems to test great though so it doesn't seem necessary, but it does make it easier to build.

That was an awful long time with the iron on the cell. Heat transfer must have been pretty immense. Bigger hotter tip for cell work is key. It's almost guaranteed those cells were overheated during assembly.

Takes a lot of courage to post a soldering video in a community full of know it all's lol Thanks for the test.

Thanks Chris! Your videos are an incredible resource for the hobby. I've been wanting to try this myself

man to much time with the iron touching the cell. I think it´s a big mistake, just user a bigger iron with more termal inertia to solder the cells. With mine in less than a second I can solder 1mm copper strips.

Brilliant test Chris. Thanks for another interesting, informative, entertaining video. Happy flying amigo. Cheers 🍻.

Awesome Chris thanks for this!

THANK YOU for confirming, I've been arguing these points for a long time! I have always soldered my Li-ion packs and I push them incredibly hard, (often well beyond their rated values), but when I land my packs are always just barely warm. Meanwhile folks with "retail li-ion packs" (which are spot welded) often complain about extremely hot packs, those burn marks, & horrible voltage sag. I have never found those to be issues with my DIY packs and have always argued the use thin high resistance nickel strips is the likely cause... Cheers!

You really should spot-weld those cells, because of the danger of overheating them by soldering.

5:30 how long can you keep the iron on the cell before they start loosing performance ?

Thank you so much.I am just curious is there any way to charge this battery setting without parallel cabling ? And if there is , how should I set the charger?

Very cool. From a lot of these comments it seems like we could use a video comparing the nickel strips to the braid -- maybe a before and after of upgrading the auline pack? Nice work, as usual very informative.

effectively delivered as always Chris, thanks for the demo.

I would like to see a revisit of this pack to show handmade packs age comparably to bought ones too. In 6 months to a year?

The 6 welding points on the nickel strips doesn’t seem to cause problems, the strips are too thin for the current, just put more layers. The copper you use is better to get the power thru, but that can not be good to keep 400C for so much time. I suggest to also tin the copper, keep it hot until it touches the cell, and keep something ready to remove the heat, like copper bread from the frezzer. Did you know that tin solder has about 6 times the resistance of copper? So, the solder surface in contact with the battery terminal must be 6 time the section of the copper. For 10mm^2 copper = 60mm^2 solder Nickel strip, or nickel coated steel strips are not the best conductors either they must be oversized to pass the current without getting hot. But there goes your energy density, more copper, nickel, tin, lead, steel, less density. The conductivity of alumin(i)um is almost the same as copper, but much lighter, there could be varying results to solder it :-) Aluminium oxyde is the problem, to tin the aluminium it must be done without oxygen. If the surface is covert by common engine oil, oxydation doesn’t occur, scrach the surface with 80 grid under oil, while tinning keep under oil. Once tinned, degrease and solder. Using flux, there was no trouble for me to solder 16mm2 copper clad aluminium from starter cables into Anderson 50Amp connectors. Maybe worth to try, Well all that could make good fire, so be ready for it, don’t count on plastic to protect against short circuits, when things get hot or cold, a little hard landing, and flames ... :-D Cheers

With properly scuffed pads, good flux and high heat you should be in and out of there with the iron in 2-3 seconds MAX from a room temperature cell. You're applying heat for way too long. This is exactly why people keep whining about soldering being bad for LiIon packs. High heat and short heat times will get the job done without harming the cells and provide a much better connection than spot welding. Work on tinning one cell pad at a time, giving each cell time to cool before coming back to the opposite side and then again to make the actual wire connections. Your cells wont even get warm if you do it right, you'll have better connections than spot welding and you'll have better current flow than the typical thin nickel strips.

The Molicel P30B 18650 are also great for smaller drones such as the 4" Flywoo long range.

Was thinking about this but wasn't sure how it would go. great video thanks for showing.

Great video Chris, thank you

Hello Chris, what I see is that the join between the strips cause a problem not the welding on the batteries? My I be wrong but could you think about it? I think that soldering with to less heat and heating iron with to less thermalcapitiy couldt cause bigger problems than welding?

Nice work 😊

I regularly make packs with the P45B/P28B, 4S/6S-1P/2P, great cells! my first attempt at soldering was a fail and destroyed a cell, now I use a copper/nickel sandwich (0.15mm cu + 0.1mm ni) and spotweld. The strips are also really easy to solder leads to. Great video Chris!

Hey, My analog FPV setup has decent range, but sometimes the video in my googles starts to randomly drift to the right and gets black/white sometimes. After a few seconds my Skyzone Sky04X beep once and the video signal is perfectly finde again. This happens super randomly, completley independent on how far the drone is away from me... Also don´t think its a overheating issue... Any tips on what to do? I need the video signal to be reliable, since i´ll use it for a fpv-job!

If you wanted to keep doing this I recommend looking into kWeld and getting strips of nickel and copper. You need to use much higher welding capabilities than anything on Amazon can supply (something around 1000-1500 amps for copper-nickel). I build mine with 0.15mm nickel and 0.15mm copper strips (nickel being the top that is used to weld the copper) with the same batteries you used. Much cleaner than soldering and slightly easier IMO to make. I can easily push the battery more without overheating risks associated with just nickel strips.

One more case for testing ESR of the cells and total pack, specially if you compare packs. But its like beating a dead horse.

My main mx chaser rig I use 4s 21700 molicel and get a good 12-18mins from my 4" apex builds . And there plenty of current to get 140km/h and even can freestyle it fairly hard too . Been the best performing setup for this application

I want to mention why Chris chose to solder instead of spot weld since the comments seem to be negating what he said at 17:25 , though I also want to clarify that there are better practices for spot welding than the 'Gold Line' packs use. This soldered braid will have a lower resistance and allow for a greater current potential (higher amps) than the single strip of what looks like 8mm wide (prob 1.2mm) nickel strip. It's unfortunate that Auline isn't using a thicker strip or at least doubling up the strips for a 2.4mm thick strip, which would likely keep them from charing their fish paper insulator (lmao). As for the heat applied to the cell when soldering the negative side, it would be totally fine if flux and a 100w iron with a larger tip was used. Overall still a great video, Chris. Good work brother 🤙

He should have mentioned that the cells all need to be balanced before you start. Also showing a safe way to remove leads from the donor pack would be helpful because it’s easy for people to cause problems. Also a discussion of how hot you can get each cell during soldering would be wise.

Thanks Chris, looking forward to making my own li-ion packs now 😎 Oh Chris i can only find Molicell P42A's locally instead of the 42B's, would the 42A's still be ok?

To make everything easier and also give a much better connection, this is the right project where you should use external soldering flux! You first put soldering flux on both ends sides of the copper braids and then presolder the ends of the braids. After that step, you do the same with the cells like you did, but the soldering tin will make a much smoother connection to the cells. Now that you have presoldered all parts you solder all parts together and the soldering tin, which has soaked deep into the copper braids thanks to use of the external flux, will make a connection with as much surface as possible. Ah: And don't forget to preheat every part to solder before finally soldering the two parts together.

My friend is making his own Li-Ion packs from these 21700 cells for his long-range drone all the time. But he uses a contact welder to weld the metal strips to the cells. Good thing about it is that you can choose the best cells for the pack and also you can customize the pack shape and size exactly according to your needs and the drone...Also you can make 2P, 4P packs if you want, scale it as you wish...

It's cool and very useful that you showed a burned isolation layer after some load tests on another battery pack. Thanks

I really appreciate your content. Is this video just in a lower frame rate or is something wrong on my end?

UpgradeEnergy uses these Molicell 21700's in their DarkLithium long range packs. They have a robot spot welder and decades experience building batteries! I used them to make my Stay High Fueld Charging Pack that's 6S 15Ah (6S3P 21700) Copper bars FTW 💪

I made my own battery’s years ago and still running strong , I was told soldering was bad but a big iron fast heat has always worked maybe not for a first prodject. But even on the demo the battery can take a lot , but as said there are lots of off the shelf items as a option.

You can also use welding and copper in conjunction, welding for the speed and not overheating the cells and the nickel stips are easy to solder the copper to either braid or wire to increase current capacity.

nice!!

Great video, but: Bigger tip, hotter tip, flux, pre-tinning and you’ll get a better result holding the solder there for 2 seconds

Thanks for making this video. I liked the comparison of the braid vs the nickle strip with respect to resistance. It would be interesting to see what happens if you change the nickle strips to braid...

I always thought long periods of heat was a complete no no with these cells?. Please tell me if I'm wrong

I wish he would have measured the thickness of the nickel stripping. It's probably something like .15mm thick, which would limit it's ampacity to roughly 14 ampere. 10mm x .3mm would do almost double that. Nickel stripping can also be doubled though it's not ideal. What is ideal, is copper stripping but it takes specialized welding equipment. The kapton tape is a good alternative to ring gaskets but if you have a choice, ring gaskets are ideal.

Wow really keeping the soldering ion on that for quite a long time think I would just use some silicone wire to join if soldering less chance of a short and possibly some flux would speed things up.

I've been harvesting the lion cells from disposable vapes. 550mah, 1500mah, tested with high volt charge. They're pukka.

Maybe we can double spot weld another set of strips on top of original nickel strips to improve the current flow? What do you think?

I use solder AG soldering acid. You can solder lots quicker with it.

I did it with molicell's too, 4S got me like 15min's of flight

With the P45B in a 4s pack, I'm getting 18' flight time easily with my 6''.

Molicell p50b is out soon its 5000mah 50amp continuous discharge 60amp burst

Also Maxamps makes custom 21700 packs. I want to try a 6S4P 21700 20aH pack. Big jump in maH vs the weight jump

all my packs are soldered no issue. that said Ive made p42a, p45B, 40T and more... the 45B isnt worth the cost for an extra 300mah compared to the 42B and similar discharge curve unless Chris has tested both and found any major discharge discrencies. if you are gonna solder i have vids on my channel BUT fatter tip, max that iron at 450c (or more) and I use 12ga silicone wire and all is good in the world!

This video is comparing apple to orange. The latest Molicel P45B VS other older Li-Ion cell at different MAH. Better to compare DIY P45B VS manufatured P45B at the same cell count (4S, 6S, etc)

i know everyone doesnt like soldering to liion cells, but its really not that bad, personally i pop them in and out of the freezer while working on them so it doesnt get them nearly as hot overall, its also important to note that once connected in series, you have "cans" that are positivly charged and you really should have used flux, like proper flux, also also, the 18650 molicells actually have more energy density if you do the math based on specs, id love to see you test the 2 molicell 18650's

Molicel batteries are hard to beat,been using them in vapes for years and still going strong, Fogstar is the best place to buy them if you're in the UK 👍

Ok so cells werent damaged 😅.. For 1P i def use P45B for a 2P or more id prob switch to 50S. I have a 4P 18650 i want try 4P 21700 if drone can fly the pack U were running 20aH & 22.5aH draw 5C. Damn no wonder when i run 6S1P on the 8" the pack gets warm and i try to stay light on throttle 15aH average i think

Under the Goldline battery wrap, it should have the MFG of the cells printed right on them. I'm willing to bet they just re-wrapped a Lishen or Molicel would be my guess.

why didnt you spot weld the cells?

I managed to WELD the tips of my metal tweezers together when I was building my Li-Ion packs. I wasn’t being careful enough and must have created a short circuit. Learn from my stupid mistake! Also, don’t use fully charged packs during the build.

My trick to dont suffer from bad batteries anymore worked the best. I quit fpv.

These are sold out everywhere... is this normal?

You can buy stick on insulator rings, better than kapton tape I reckon

just when everybody seems to settle on spot welding because of possible heat damage to the cells, here comes one and sends them back to the roots - to soldering. Dang...

Thanks a bunch for the tutorial, Chris! 😊 I've made a few of those... But I definitely going to get a spot welder for it. Sequr has a pretty cheap one. Anyway, stay safe there with your family! 🖖😊

Only issue is we need to unpack and unsolder the whole thing every time to charge those 21700! Just kidding. How do you charge them? Just started learning about building batteries

Samsung have a 50S cell tat is more capacity, but slightly less discharge rate.

this is fine! 🔥 🙃😉😂

What’s going on with the shutter speed on this vid? This hurts my brain.

I recommend always, to discharge all the individual cells before making packs. Than I use a dremel with a wheel and shortly clean the cell top's before soldering, than use a C4soldering Tip or even bigger and quickly Pre-Tin all the cells, (5 seconds solder time). Then you can solder the wires,or I use copper strips. (also 5 seconds) during soldering add some additional tin. (normally no need for extra flux) (5 seconds max) . the soldered PACKS have lower IR than the spot welded packs and are better suited for high current applications.

COMPARE WITH UPGRADE ENERGY DARK LITHIUM V2 MOLICEL 21700 😮

Chris com on bruh you are cooking this cell's ...

Why not use typical wire? Is this really lower resistance?

Why not sony vtc6 ?

Those cells look like they test great, thanks for those results Chris! If anyone is looking to spot weld nickel strips to make a pack and is looking for clarity on the size of strip and how to arrange them I found this video useful. ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-wdZ_Ca_sAZE.htmlsi=HRH6x8kpTCWSnT1B

Was this meant to rage bait?? For someone who “sticks to the science” in FPV this is piss pour work… not trying to hate but damn. Do I need to make a video on how to do this better and safer?

oh man. so much contention over soldering the cells. Lithium cells are ALWAYS DANGEROUS. nickel or copper with solder, both are not without issues. Use nickel if you are most people because it is most common and well documented, I prefer copper and solder for many reasons, but higher fail rates using nickel has always been my experience.

Come on man, buy some 21mm (or 18mm if using 18650's) isolator rings at least if youre going to make a video. Also, standard silicon insulated wire is much easier to use... soldering is fine if its done quickly but its taking you way too long with that braided cable.

Good video, but I think the nickel stripes a better solution. Obviously those are charred cause they are either too too thin or their width is not enough. There are bigger, thicker nickel stripes that can support 45A. I even made some of my batteries with two nickel stripes one on top of each other. Anyway - their big advantage is that they add a significant structural rigidity of the pack. This can't be done with flexible braided stripes. The cables are flexible, the tape in between is soft... everything is flexible. Whilst the nickel stripes make the pack solid.

Just use thicker and wider nickel and spot weld that.

Bro at leastuse alot of flux and it will be much easier and much faster on binding to the cell, also less damage on the cell

Are these cells the same as Sony VTC5D?

All the people complaining about soldering the cells have been watching to much RU-vid

my selfe made battery packs have more Wh/g. the cell has 12,45Wh at 5C. I use 3850mah (rated) 52g cells out of the „DJI Mini 3 Pro Intelligent Flight Battery Plus“. C rating is lower than yours.

Chris, please do not solder the cells.. this will damage the internal separator between the electrodes inside the cell. The separator melts at around 130C, specially a problem on the anode. Spot welding!!! I am sure you'll not hear the end of it...

yes . and then u find out that in a parralel version the cells are not balanced and u blow the pack before u can say: i sure hope i dont burn my house down. and soldering is mweee ,, better to use a contact welder to zap the cells together , after uve made sure their at te same voltages of course,, and when soldering ,, make sure u can OSHIT the cell somewhere where is not indoors. if u smell sweet ,, stop and out the cell .. better to throw a cell then to throw your house..

I had to downvote this video because it's not safe to solder Li-Ion. Spot welders are readily available and inexpensive these days. Sorry 😢

Прогрів непогано оловом)))

Aluminium tabs ? Soldering?

I expected much better from this video... the construction of that pack is far from ideal/safe. good isolation is lacking, and soldering introduces a lot of heat causing potential damage and a shorter lifespan/performance from the pack. If there were a note saying that "this pack was made for the purposes of testing, please do research on good pack building methods/practice before making your own" I wouldn't mind it but a lot of people look up to you for your knowledge, and going straight into the wrong ways of making a well performing and safe pack shows some oversight (not trying to praise the pre made batteries either, they have their fair share of shortcomings)

No, you can't diy the best li-ion pack, just a humble one ;) Don't want to sound banal, but next time please use welding strips and a spot welder. This way you can make much durable pack without risking overheating the cells. And also with much less added weight.

Way too long with the iron on the battery. I use 5 seconds as my max and yes with a more powerful, hotter iron with a larger tip. I also dont like how that braid is so close to the negative area of the battery hiding any solder blobs that could be close. You need to be able to see that you have not created something that might short.

I love your videos, but this is a bit dangerous. Never have a hot tip on the battery for long. Also the top of the liion is positive but it's extremely close to the negative parts. A copper braid could stray onto the negative bit. Look for Kweld and nickel strips. Also loom for the Samsung 50A 21700 batteries. Way better than molicell for power.

lol - nice tape job - don't you know they make specific "stickies" that protect the positive terminal??

I wouldn't feel comfortable holding a 400°C soldering iron to a LiIon cell for that long. In the video it looked like 20 seconds which I have been told will definitely have a negative effect on the cathode. I would always aim for 5 seconds max. and if that cannot be accomplished with the soldering iron I would try to find a soldering tip with a larger surface.

Hillarious all those cry babies Done right this is 100% safe Most people just don’t prepare the pole’s correctly with solder acid or a dremel

You should actually use a 2 pin spot welder with 1-2mm copper strips. There's no need to use braid in this pack at all, the copper strips will create structural integrity of the new battery pack and you don't be adding 400°C of heat onto to + end of those cells which contain a fuse inside of them. That fuse by its nature is the most delicate part of the cells and the most vulnerable to temperature (they short out "thermally"because high heat usually means high current) so you risk changing the cells thermal point cut out either making it weaker (not so bad but will kill you battery back faster) or potentially create a stronger thermal cut off (this is bad as the cells may output more current than what they are rated for and lead to thermal run away =>fire => explosion) The fact that this happens on a regular basis with lithium ion cells in electric vehicles, means that it's not uncommon ot rare for the thermal fuse to not do it's job? Drone batteries have no smarts inside of them with thermal sensors or a micro controller cut out chip or anything like that, the throttling is basically the user on the sticks and listening to the voice over on their radio transmitter(receiver). So the chances of you screwing things up and having a molten fire ball in the sky is considerable high! Get a nice little 2 pin spot welded with a foot petal on it 👍 It makes scaring sound using it because it puts both positive and negative of a separate power source to cause the fusing of the metal strip to the top of the ends of the cells but it doesn't this for less than ½ second so it is not long enough to raise temperature in any way

I don't like you soldering the cells. It is a big safety risk and no one should imitate that.

🙀😅

It seems soldering and DIY is not your strong side, Chris 😂😂

Damn. Better title: how to kill any liion cell. Chris I have expected better from you unless this is a 1st of April video accidently released too early.