Hello I'm constructing my big Lithium-ion phosphate battery uh, 8 s 3p. Currently it's going to be 5p 5 cells in parallel. You can see the eight cells across the top there. so I need another uh row of these Pcbs? And then it occurred to me.

Um, how am I going to link the top PCB to the bottom? PCB Um now on my other battery, the one in the shed. perhaps we could go and have a look at that. it's that horrible drizzly rain today. So on this battery I linked the top board this is an 8s4p I'll link the top PCB to the bottom PCB with these links and this is only about 14 now 15 amp cable.

so I put two on there. but of course this links the end of the cells directly to the end of the other cells. Now on this new printed circuit board of course. I've got these spokes coming out from each cell into the copper area and every cell has these spokes.

So the idea is that the cells are fused into these back plane areas. so what? I can't do. and this was my original idea to make up little bridging pieces like this so you can see that spans the two cells and it would also span across like that. But the trouble is that links a cell end point to a cell end point thus completely breaching this fuse idea.

So what I really need to do is link the copper area and that's these two pads here with the copper area up here now I was concerned. Um, the one up here has an angle bracket in these two holes, so of course I can screw onto that. but this one has these two holes just arbitrarily on these plastic cell holders and I was thinking, oh no, I'm gonna have to uh I can use a a ring terminal here on this bolted one on the top, but I'm going to have to solder the end of this wire to this slotted hole on the bottom board because there's plastic behind there. But I Got incredibly lucky and this was pure luck.

This wasn't designed in any way behind this slotted hole. it's this little aperture here. this triangular aperture and actually the one below it is slightly smaller because this piece of plastic is no thicker for some reason. but this hole up here just happened to be, um, an okay size to take the head of a bolt.

now. I've actually put some nuts on there as well because um I've only got a limited number of short bolts I'm using the longer Bolt but that stack fits down in that hole absolutely perfectly by pure fluke and thus gives me, um, a nut and bolt point which I can anchor the top row to so that can be bolted onto there. Now on the other battery. I've got two wires coming across.

They weren't as thick as this wire. this is much thicker while it's 12. AWG mustn't short that across two lots of cells. uh 1280 WG So I think that's good for about what 40 amps? something like that.

So back to the shed because I need to get these sort of part batteries I made up because I want these boards with angle brackets on them I need more cells I need more cell holders. There's another earlier version here which had the Voltmeters on it. so I need to rob the holders and the cells to complete my 8s 5p battery. Yeah, this is annoying.

Look, these um, slide in from the inside and then you push them towards the outside. but this front set slide in from the inside so of course you can't put cells in and then get them on here. So I think what I'm going to have to do is populate this whole rear section with cells and then lift off all of this front section at the the extra cell holders on the top and then sort of put it all back in. Which means undoing all these nuts.

Yeah, that's a real pain, right? This is kind of it. I've got my one two, three, four, five rows, and eight columns. so eight s five. P Now I know all these bottom cells are fresh out of the box so they're all kind of harmonized.

but I seem to remember some of these upper cells I fully charged so they're not harmonized in with the bottom ones. One link like that's not gonna harm. but if I put more of those links in, it will redistribute currents. So what I might have to look at is doing a little bit of discharging of the top cells.

I'll measure voltages and and try and get them all harmonized. Um I'm a little bit short of nuts and washers I have to pop down to B and Q and get some more of their pick and mix nuts and washers. They didn't have a lot left in this four mil. but I have to go and scavenge.

What? I can. Um, but yeah, that's it for this video. My 8 S5p battery is essentially Uh built. That's the other side of it with the Uh four boards on this side.

Of course there are five because these are the that's the most negative. that's the most positive, but uh, and my interconnects on the top. There's one missing there. But I need to get some more of these um, uh, banana terminal posts Hello, I'm doing some more work on the big 768 watt hour battery.

Uh, it's eight in series. five in parallel and in particular I'm making more of these things which link the top Uh two cells to the bottom three. but before I put them on, I'm just checking to see how much current flows between these two nodes. So let's check the current between uh, these two which I can uh, put the wire on next and that's tiny.

That's just uh 15 milliamps. This is in the amp setting, so of course, uh, it's going through the 10 amp shunt so that's effectively now transferring energy from the top set to the bottom set and there's very little there. Let's try that the one on the left here because I could do that one instead. Yeah, that's got a little bit more current um 60 milliamps dropping to 50, but again, it's not going to stress either my made-up cable or the cells themselves to have 50 milliamps of transfer current.

so that's fine. I can just simply attach this piece of wire onto the battery now, so that's the latest piece of wire put on. I'll just tighten that a little bit. Um, I might set these closer to the boards when I build the final version, but uh, yeah, just make up another one of these now and put it there, then flip back around to the other side.

I think I need about five more of these now. So I've got a big bag of these uh, blue ring terminals I don't really need them for anything else, so I'll use them for this. Take the blue insulating sleeve off because I don't need that. I'll just use it as a bare ring terminal piece of this uh, 12 AWG wire with the ends stripped.

like so now this doesn't quite fit in there. Um, so I just need to slightly open that out and this battery welding jig has found another purpose in Uh, this. Spike I've had for many years and the tip broke off a few years ago. so it's not much use to make pin holes, but it is fine for shoving in here, jamming it in there, and just slightly opening.

uh, the end of this out. and then the next thing is to solder this in here. So just put a little bit of flux on there to get the solder to run and with a nice hot iron. If I'm going to boost this up to 400, let's start laying the solder in.

Try and get this ring terminal hot enough that the solder will start to flow. so just build up a ball of solder so that we get a better area spread of heat. Okay, that's starting to drop down in there now and the flux should help it. Uh, flow in between the copper strands of wire and the copper ring terminal.

Yeah, that's soldered rather nicely and then the heat shrink. I Didn't want to put heat shrink on this wire before soldering the ring terminal because this all just gets extremely hot and it would pre-shrink So I needed to find a piece and this seven mil is about right that fits over the end of the Ring terminal. It is a bit of a tight fit, but I can push that on there and push it past the ring terminal ready to be heat shrunk. These are in one of those little sets of heat shrink and their pre-cut length.

So I'm just cutting them in half because that's about right. Okay, slip that over the other end and get it under the hot air gun and once again, check the current that's uh, flowing from the top section to the bottom section. What's that? Oh, that's next to nothing. 15 milliamps? Okay, that's fine.

I can stick the wire on there. Uh, tighten that one up okay. washer and nut on the bottom if you can see that. Oh I don't think you can very well.

I'll tip it up a bit so mustn't tip this into my camera stand there because that's made of metal and I don't want to short anything out. so I'll tighten those up and that's another one of the interlinks. Done! Uh, that's it. Ready for this video Just Gonna Carry on making these wires more of the same until I finish the whole battery.

Cheerio!.