All right: let's talk about batteries, remember this battery that we built here, it's capable of 300 amps, supposedly according to the cells specs uh. Well, we have an update. Remember we made a pcb board right to be able to well assemble it together right it just kind of helps assembling it uh and we printed it right and then we built it and then i made some changes. Uh, and so here is the board.

Now, with the changes, okay, so here is the original board um. I had all these little pads close together right, but, as you can see on this side, they were all separated and so the the copper on the the copper layer on the on the pcb um. Well, it was going gon na have to transfer all that power right all the energy and because these cells are rated at 300 uh amps um. Well, i didn't think this was gon na cut it right because it's a thin uh piece of copper and even if you did what i did here, see how i ended up putting a bunch of solder in there to be able to add some some thickness to That and so it could handle a bit more current right um.

I thought well that's completely unnecessary, because if you look at this side, then you can put the two tabs together and then once you're looking at it from the side here, you're like oh, i could move that one to here to the middle. I could move those two to the middle. I can move those two to the middle right and i'm like well yeah, why? Why are the am i putting separate right? So then we went and we changed the file and we moved those and put them together. Now here is the improved version of this uh board, and this is a 52 right, 14 s board and then on this one i just ordered the 20s, but the the the 14s is the same thing it just you know.

Has this or this moved up here right, so you just lose a few six cells or something like that right, um. So now what happens is that these are all the things are together and you see, and so now there is no copper on the board where it needs to carry all that current. Now it's just uh, i mean literally the the bus bars or yeah the terminals of the cells. Are i mean almost touching together right now, this big blob or of solder that is going to help connect them together right, and so, therefore, there needs to not be any current carrying on here.

So i got this. We put it together, here's a little bit of how that goes. Okay, so first things. First, you have to be very careful when you're dealing with these batteries cells because well they can put out a ton of power, and so, if you short them out, it's not just going to be some little spark.

It's going to be a big spark and it's going to melt things you're, going to probably ruin the board or ruin the cell through it right, you're, going to maybe burn yourself right, because it'll get hot, probably pretty quickly. So you have to be very careful and this board what it does it is that it requires you to will put the uh well put, but the cells right there right, i mean you're you're working with both tabs and and they're exposed to two of the tabs Are exposed of the new cell that you're doing right but see what i'm doing here? Okay, then i as soon as i can, then i just put the captain tape on there and so therefore uh that one you can no longer uh short right. So when you get the new cell, then you got ta figure out which one's positive, which is the negative. Then you got ta bend it because the positive is made out of aluminum or aluminium, as many of you guys might say, and then uh it just has another piece at the very end that has um.

Well, it has a uh, a spot welded, a piece of copper in there right and so that's how you are able to weld into it or solder into it. So once i measure right and then cut the tabs to that size, then i put them in there and then i just tape it and then i just start going and then i start trying to melt the solder into that those two uh tabs right that are Next to each other and then as soon as i'm done with that, it requires quite a bit of hit. As you can see the there uh. Sometimes i found it easy to use a second uh soldering iron right and you just put it in there.

But after a while it just got it got okay, it got easy by the time that i was doing loading up all the solder in there. Then it would flow and it was you know it was nice. It was nice and hot everything was hot right. Someone asked in the comments: how can i you know? How was i able to solder these without introducing heat into the cell? Well, that's impossible! You can melt solder without heat.

You can melt solder into the tab of the cell without introducing heat to it right now. How do i do it without introducing any extra heat or unnecessary heat? Well, just do it as fast as you can. That's the the only way that you can do it right. Uh, maybe using a secondary iron, sun and iron will help that, but you still have to melt that much solder into you see that that takes time you kind of have to heat up that area before the solder will start flowing, and so i think, there's no Shortcut here you just have to do it.

Take your time right, try to do it as fast as you can and then heat the whole thing, and as soon as you finish, then the whole thing just starts flowing like that right now, that's just a little bubble that was created there and then you just Have to go down the entire length of the board. Okay - and here is the final version here - is the original one right, the 52 volt. This is a 14 s and here's his bigger brother look at that. Now that is a 20s 20 cells, and i i'm currently charging it using my power supply here.

This power supply goes all the way to 120 volts dc, and so this is an 81 82 volts. I think fully charged right. I don't know what the the upper voltage. I think this could go all the way to 4.2, just like all the other ones, so i'm charging it just to 80 volts and it's tapering down to 2.2.

There now here's the other, so here's the uh the board right in here are all the the blobs here. All the the uh solder blobs right there. So hopefully that's the only thing that are gon na carry all the current. Can they do 300 amps? I don't know, but here is the deal i don't even have a load that could do 300 amps like how do i test this right, uh, i'm looking at all my equipment, this two inverters that i have here can handle the 80 volts right um.

The thing is that these are two thousand plus two: that's only four thousand watts right, so you're, looking at like 55 amps, so we're gon na do the best we can tonight and we're just gon na load. It with 55 amps see how it handles 55 amps. At least that what is that that's one-sixth of the power right so because it's uh like 50 and uh yeah, that's like i don't know like one-sixth of the power that it's supposed to be able to do now. My my theory is that the board? No problem.

It's gon na it's not even gon na sweat. It right. The i think, what's gon na happen is those little terminals. I don't.

I don't think those terminals can do 300, but then again, why would a cell be um rated at you know, 50 c right. If it's 6.2 amp hours, 50 c literally, is well 300 amps. So can can that little i don't know, i don't know we'll see, but you know and then you're and then you're like well this chinese sal right. So you know chinese are known to sometimes fudge with the numbers you know just to make it look good or whatever that could be very possible here, and the only way to really find out is to do some tests right and the only thing is you're going To have to get creative, if you have any ideas of how i can load this properly right, because i'm yeah i'm kind of at a loss right now, so the other.

The one thing i was thinking is that maybe i can make a board the 10s. A few guys, a few of you guys, have asked for a 10s and i'm like come on. You know i'm giving you the 4s, the the one that is that i didn't drew, that's the one that people want, and so but here's the thing. Maybe i should draw it.

I should draw the 10s because then 10 s, then you can put it right here. Then i can. You could just solder that in there and now with the 10s, now you make it into a 30s right and that's 111 nominal volt uh battery pack, and i know what you're saying is what the hell is. That 111, like that's weird.

Well, that's my car and my car is an 80 kilowatt load, and so i can essentially build a 20s and then a 10s put it together. You know, and that's a 30s pack that i can put on my car - put a big connector and then try to see if this tiny little pack will drive my car. You know, i don't know it's only going to go a few miles. You know maybe two three miles or something before it dies, but it should be able to do it at full speed.

Well, not full speed, because my thing could pull like 700 amps, and this thing it's a it's a 300 amp uh pack. But let's just think about that right, uh! If this is a capable of doing 300 amps. So then we do. You know it's like we built another 20 and another 10 and a battery pack this size could push my bus at full speed at full power.

You know for five miles or something uh. I think it's less than that um. That is pretty amazing when it comes to this right. Of course that's if these can push 200 amps uh, we'll we'll have to see - and that's that's going to be an interesting uh project and test.

But you know the problem, the thing with those take a long time i got to build this, then i got to go in there. I got to put my car got, disconnect the other pack. You know what i mean like so just kind of to prove a point or whatever you know it's like uh yeah, i don't know, maybe we'll do it. Maybe we'll push to just just for fun right just to see what these things could do, but definitely i mean this could do a very powerful e-bike build this one, even bigger right, 72 volts.

This could do like an off-road bike or something could push quite a bit of power. Definitely could do 200 amps. You know no problem right, so let's actually look at that. It just reached 80 volts.

So oh here's. The other thing that i want to talk about is these connectors, so the original one i put the this connector here, because this had enough pins to do the 14s. But on this one here now it's a it's a 20s right, so you're, looking at how many pins well 20 122 pins right. 21.

21 pins. I think if it's a 20s uh, so i didn't have a thing and i didn't want to put in you know it's like. I wanted to keep this small and so what i ended up doing just doing these eight one, two, three, four, five, six, seven, eight! Yes, these eight pins and here's the thing that i did. I repeated the uh some the last pin right.

So it goes one through six, no one through eight and then eight also is on this pin right here, and so it starts eight through uh, fifteen and then fifteen again it's on this one and it goes and why would you want to do double, pin right Wise eight over here and over here and then 15s over here and over here too well, because that allows you to use these little things to check the uh. You know there we go. You just connect it in there. Look at that! It's not perfectly balanced.

I guess uh, i just grabbed these cells, random, they're, new right so and then let's see this thing, does it right and so now, if you, if i had three of these, i don't. I only have two. But if i have three of this, i could put on all three connected into this battery pack right here and i would be able to visually see exactly what every single one of the 20 cells is at um right and so the only way we can do That is, of course, if we disconnect another, because i don't have three of them, but but you could do that right now, of course, these the main reason for that is uh. You know, maybe you want to do a bms and you put the bms on the side here, connect the you know the negative through the bms and then all these leads are going to go into the bms.

So you make a little connector sort of like this and then you put it in there and then now you go right. Um, maybe i don't know maybe that's kind of weird because it kind of sticks out, but this kind of sticks out. It's just a thing that i try there. You don't have to use that one you could put uh well, you kind of do need some kind of connector in there right, but there are choices.

This is a very popular um pitch right of connector right here, so they come in all kinds of size like you can even put one in here with little screw terminals and stuff right. But of course i don't know if you want to do that again. These this is our. This is a risky battery right.

This can, if you short any of this out. Obviously, if you short these, these little uh traces are so small that they will, they will burn they're almost like a fuse right, um, maybe in the future iterations i'll, put those bigger so that the bms can balance at you know one or two or three amps Or something like that, so anyways, the voltage is up there. The cells are about four volts, already right, um, let's connect our four kilowatt load and then see how it does see how it handles 55 amps right, the best that we can do tonight. Okay, so here is our test again just our battery.

You know 72 volts right at 80 right now, then we have this to measure the current. Then these are connected in parallel right. They can do up to 90 volts so and then i'm just gon na plug in 240 volts on these ones in here. So i know it's a thin wire, but you know four kilowatt and uh 220 volts, it's just like 18 amps or something so this this thing will be able to carry it.

We're not going to do run this test very long. So let's do this. Let's plug in the first one and see what it does so here we go. It recognizes that 80 volts and 206 volts and the grid.

Oh, that's weird! Oh 33! There we go so it does doing 33 amps. So if we do the second one, it'll do six all right: it's doing 69, almost 70 amps, let's put the thermal camera and see how the batteries do. Oh by the way, here's the cells uh there's some sagging at 70 amps. I don't know about these batteries.

Oh look at that. Oh, oh, this battery is warm. This ain't, no 50 c cells. Okay, those those those cells are, are a bit warm look they're almost.

You know: they're 30. Almost you know: they're gon na get at 40 right now and they're sagging 3.5 they're sagging, half a volt with only 71 amps, but what's 71 amps six, this is 10. So this is like 12c, oh, no! Okay, so one cell already dropped number three! Okay! Let's take this okay, so number three where's number three, this one one, two three yeah this pack is it's warm at 12 12 c's, and you see that number three cell number three okay, so that is actually warmer than all young's yeah. Look at that and the difference two point: oh it's 2.9, so yeah it just literally just dropped off all right all right.

So what happened here? Well, it turns out our little battery packs here. Are i mean if 50c, that's the you know, that's the that's! The peak like burst rating, obviously right um. This is not the continuous rating of the cell, the continuous rating it's somewhere around 10 to 12 c, like we loaded on with 12c right 70 amps right on a 6.2, and this is continuous. It ran for.

I don't know like 10 minutes or something um until the battery ran out until the battery just completely died, and then that one, you know number three, i'm thinking that maybe there's something wrong with it. But to tell the truth, i didn't balance this. I just built it and then i charged it a little bit and then i'd loaded them up right, and so now we caught it. It didn't go down too far.

Uh it stopped. We stopped right around three volts right and so then i just put a bit of charge in there and then uh. Now it recover right. So we'll have to balance this put through this through a one balance, um cycle and then it'll be fine.

So there you go, we got five if you multiply 70 times 72 right, 70, amps times 72 volts. Well, that's five kilowatt this battery right here was able to do five kilowatt uh continuous. Now, that's no 50c right, there's no 20 kilowatts, supposedly, but um yeah! This is this: is the burst rating, i'm sure if you load it right, an acceleration or something going uphill or something maybe it'll it'll give you 50c right, but even that i don't know, i doubt it right. Uh, like i said those little bus bars those yeah.

Those those will handle 70 amps, they won't handle 300 amps, like i said, i'm dead short, maybe right for a few seconds. It'll do 50c continuous. There. You go so we're going to put this information on our website right, because our website was kind of these cells.

There was not a lot of info on them, and so we just put what it was on the label here right and you know, i've been super busy. Now i'm getting around to testing this and making some of these little boards to be able to make these useful and stuff there you go solid. You know. 12C uh continues packs we'll put that on the description there, so that people will know what they're buying and then we'll put this video up there so that we can see that test right, a lot of the stuff a lot of times.

This is the only way to find out. You just have to test this stuff right, because you can't trust those labels, because you know who knows i mean it's like it's like the amplifiers from the 90s right. You know 20. 000 watts.

You know for a little thing: a little amplifier uh yeah manufacturers are known to fudge the numbers and you know be a little optimistic with the numbers and stuff. But there you go uh. We will uh move on tomorrow. We're doing another thing: we're building another high power battery now the headways we do know that they put out quite a bit of power.

Now. Will these be able to handle all the power that the headways do well just stay tuned tune in back tomorrow or the next day. I don't know whenever i can get to the thing and then uh we're gon na be putting that battery pack together uh. Oh, i'm also going to have trouble loading that i only have a 2000 watt inverter.

I'm gon na need some other 12-volt inverter uh, we'll figure it out, we'll figure it out there. You go. Thank you for watching these videos. We'll see you guys on the next video right, bye,.


15 thoughts on “The true continuous rating of the 300a cells – diy”
  1. Avataaar/Circle Created with python_avatars Andrei Calciu says:

    That soldering iron is great, but inadequate for this job. You may want to invest in a soldering station and some chisel tips that have more mass. That will allow you to put enough heat, fast enough to melt the solder without sending too much heat into the battery.

  2. Avataaar/Circle Created with python_avatars Bill Jacobs says:

    Hey, we used water heater heating elements. Take your DMM and go to Lowe's or whatever so you can figure out ac as listed or pure dc load. Hardly ever needed to submerge them in water. obw… don't use salt water 🙂

  3. Avataaar/Circle Created with python_avatars jayzo_sayers says:

    I've noticed you're using XT60 connectors with non-standard pinouts there, two positives/two negatives. It might be worth looking at the modular Anderson Powerpole connectors. Being modular, you can pick two red housings to denote they are both positives, or two black for two negatives. I'm worried about potential risk to accidentally connecting the wrong cable to it and causing a short/worse. Andersons are also genderless, so no needing two different genders for a cable, either.

    You can also "key" connectors (rotate one or both 90 degrees) so you can't accidentally plug a standard cable with single positive and negative into the double-positive/double-negative connection for a little extra safety. The PP180s can handle 180A per individual conductor so two positives + two negatives will handle 300A easy. (Plus they make a lovely satisfying click when they connect and disconnect)

  4. Avataaar/Circle Created with python_avatars Ron Safranic says:

    I like it but would like a 24V and a 48V Version using series parallel connections. Older APC Smart UPS"s can be had for cheap and I believe 2 24V packs would fit into it and provide a very good solution to the Home Lab crowd! I currently use 2 18650 packs to do this and can keep my whole Lab running for about 4 hours. (Warning! if you do this increase the cooling of the UPS as it cannot run for an extended length of time without over heating!

  5. Avataaar/Circle Created with python_avatars Gerald Koth says:

    I am going to guess that the 300 amps is a momentary discharge and continuous discharge is much lower. If you try it in your car, mount the battery outside on some sort of standoff arm and have a fire extinguisher handy. I think it may catch fire most likely from any wiring and perhaps from cell overheating if the wires last.

  6. Avataaar/Circle Created with python_avatars Jacques Schiltz says:

    I wonder if it was possible to overlap the tabs of the cells over one-another on a bare copper patch on the pcb and spot-weld them in place onto the pcb itself… I once had a battery pack in my hands were the tabs were laser-welded to thick copper bus-bars. Clean af but costly to make…

  7. Avataaar/Circle Created with python_avatars vic garbutt says:

    I am wondering what its "true" power rating. At 30 amps, will it do THAT without overheating with the max capacity yielded. So what is the actual maximum WHrs at What current level is a "cool" (continuous) operating range. 30 amps? 40?, 20?

  8. Avataaar/Circle Created with python_avatars Chris W says:

    Need to build your own load bank. The resistors would be a bit expensive, but you already have the wire to join them all up. Just need a couple large switches to add/remove banks (and never swtich under load.. lol.).

  9. Avataaar/Circle Created with python_avatars Jarrod Sinclair says:

    Using some brush on flux would make it flow better. At least that's what I have seen when soldering on larger lugs or pcb traces requiring more heat. Sometimes the flux core just doesn't have enough

  10. Avataaar/Circle Created with python_avatars Hola! Raphael Krug says:

    Hey Jehu, have you thought of making the tab hole wider so the tabs go through it already touching? I bet this would mean, that you need less solder and therefore less heat goes into the cells?

  11. Avataaar/Circle Created with python_avatars Creation Factory says:

    Nice board. For applications where the battery needs to be exposed to vibrations, I would prefer to use a more robust connector for the balance port. Like a Dupont connector with locking for example.

  12. Avataaar/Circle Created with python_avatars xmtxx2 says:

    Thanks for the update jehu, those cells are very specific, but sounds awesome.

    Remember guys, those are not vanilla batteries. They are made for very high burst (like a spot welder), or for a high load over a few minutes.
    They are not made for range or longevity. They are rated for a low amount of cycles (in the hundreds, compared to more than a thousand for a classic 18650).
    The main use I see for them, in a vehicle, is for a dragster.
    Otherwise you better go for the classic cylindrical 1-3C discharge rate cells (18650 or 21k cells). It will be cheaper and you'll have better energy density.

  13. Avataaar/Circle Created with python_avatars Ketansa Art says:

    We should make a contraption box for charging this battery pack. Make a box that is ventilated with in/out fans on opposite side. Then please lets apply this pack practically in an e-bike, and show us the performance. Like – capacity test, temperature monitoring while using it, etc

  14. Avataaar/Circle Created with python_avatars catch22frubert says:

    None of these PCBs or the way they are being connected can handle the 200 and 300 amp loads at all. You aren't considering that a 1/4 inch x 1 inch piece of soldier will raise the resistance by a lot, and resistance equals heat. It isn't meant to handle that kind of current transfer. That's why the pack is getting hot, and that's why the voltage losses are so high across the pack. If those connections were made with a piece of solid copper able to handle those kinds of amp loads, and the whole battery tab was touching that copper and each other, it would make a massive difference in how the pack took the load and how much heat was generated and how much voltage drop there was across the pack. This is why education is so important and why actual electrical engineers should be designing high discharge battery packs, or at least someone who considers the most basic electrical principles, like ohms law, should be making high discharge battery packs. It's all good when people don't know what they are doing and they only need 10 or 20 amps from the battery pack. That's a lot less dangerous than trying to build a pack with cells that output 50c and hundreds of amps at almost a hundred volts DC. If it's not designed properly with very low resistance materials, resistance will be high and cause way too much heat, and it's gonna cause a lithium fire eventually. Please, at least consider ohms law and resistance, and how much copper is needed to safely conduct 300 amps of current and consider how much of the battery tabs are in contact with each other to carry that kind of current. Those cells were manufactured with those big tabs for a reason. It's so they can make a lot of contact with a big piece of copper and have minimum resistance.

  15. Avataaar/Circle Created with python_avatars Jimmie Dean says:

    All manufacturers over rate. They have to.
    To Compete with other ridiculous manufacturer claims. There is no standard.
    Just like the treadwear rating on tires.
    They can be anything the manufacturer claims.
    Or amplifier RMS. Chains weakest link.
    Big wires. Small cell links.
    And those cells would have be twice that size. To pull that. Unless you are trying to grow, pouches of dendrites.

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