How to Build a DIY 12S8P Molicell P42a Battery for BIG POWAH!!

[@stevemuzak8526]

This channel is a gold mine. I learn so much from you. Thank you!

[@RBEMotion]

Thanks so much! Means a lot.

[@dieselphiend]

Beautifully placed welds.

[@RBEMotion]

Thanks!

[@uhjyuff2095]

Hey man! Thank you for choosing a "SMART BMS" for this build because IF you were to show your viewers to change the "FUNCTION" setting in the app to be "STATIC BALANCE" instead of "CHARGE BALANCE" the BMS would do a fantastic job keeping the "CELL DIFFERENCE" low!

[@RBEMotion]

Of course! You bring up a good point, I don't typically like to show off the app because it's very confusing. "Technically" it can run on stock settings, but I do like to change a couple things around. I'll add a BMS setup video to my list to get to eventually. Thanks for the suggestion

[@justmehereUK]

man, this is a really slick video for what it is. Loving the lighting, sound and picture quality.

[@RBEMotion]

Thank you I appreciate that!

[@woomdawg]

Great video man. I love your style. Attention to detail and good strong fundamentals. Hat off to you.

[@RBEMotion]

Thanks for the nice compliments! I try my best to present as much detail and useful information as possible.

[@woomdawg]

@@RBEMotion I am a noob looking to build my first battery and ESK8.

[@dieselphiend]

I always have somewhat of a tough time getting the fishpaper on evenly. I've developed a special method, lol. Haven't built a pack in years, and got all these new cells laying around- guess I better start again.

[@RBEMotion]

Haha go for it mate! I usually roll the fishpaper around the cells to get it on

[@MikeBeard]

Awesome build dude!

[@RBEMotion]

Thank you! Turned out good imo, if I did it again it would be even cleaner. Believe it or not I built this before esk8con 😂😂😂

[@MikeBeard]

@@RBEMotion oh dang! Looking forward to seeing that 20s build 👌🏻

[@RBEMotion]

Ooh unfortunately since I built that for a client I had a stricter schedule and couldn't record it. Would have been cool to share though, but recording can make them take like twice as long

[@MikeBeard]

@@RBEMotion dang!

[@RBEMotion]

Haha sorry to disappoint! That one took AGES to begin with, couldn't imagine filming it too, one man show over here 😉

[@vigolivenca]

Hi, can you explain in the series connection the benefit of having the wires connecting the two nickel plates, when they are already touching? wouldn't just soldering the two plates do the same? Can the connecting plate handle has much current has the 3 wires? since for the current to flow true the wires it needs first to flow true the plates. How much current is that nickel plate rated for? Thanks for the detailed video

[@RBEMotion]

Hey there - thanks for watching. Basically, the nickel pressed against each other is not nearly reliable enough for an esk8 application due to the high vibration. Similarly, soldering the nickel together is possible, at least for the big brick parts, but for the enclosure crossing, the nickel wouldn't even be durable enough due to its low fatigue life. Better to just use cables. The connecting plate can handle less current than the cables by area - I think, but the attached ESC wouldn't have been able to pull that much anyway. Usually you want to build the battery to the capacity of the cells, but not always.

[@kurtcprins7956]

Great vid, trying to decide on a bms for my build.

[@RBEMotion]

Thanks! Are you looking for smart or a normal one?

[@eBoard3R]

⚡ 12S8P 😲 *Premium power* ⚡

[@RBEMotion]

Haha that's right! 40 miles of range of average riding with this baby on 8 inch kendas

[@zpepe]

Hey Rob once again great video! I'm speculating here but I assume the reason why the middle wire is longer than required (and harder to handle) is because it must match the length of outer ones. Otherwise of you made it shorter the current would take the shorter path and thus over load that middle wire?

[@RBEMotion]

Well, technically, no. I thought that it was going to make an aesthetically pleasing middle line, but it ended up not being as good as I had hoped. Electric current is always going to take the path of least resistance, but the difference in resitance at this scale is so small that I do not think the wire length will really matter at all.

[@redriot2173]

love the video, where do you buy your batteries? I keep finding them for around 25 per battery. or is that just the general price point for them? another thing, are there any alternatives for a spot welder? Am i safe to solder the nickel strips to the batteries?

[@RBEMotion]

25? What currency? That sounds insane. Most common sites are Liion Wholesale, Bulk Battery, NKON, or 18650Batterystore There are no good alternatives to spot welding. Soldering to cells is a huge no-no, it damages the cells.

[@JohnTravert-id3em]

Hello 👋 . Dites qu’elle spot welder utilisé vous ? Pour la construction d’une batterie 12s8p dans un enclos EboardPeru Kaly , j’aimerais utiliser les meme plaque de niquel que vous , c’est du 0.20mm ? Merci beaucoup

[@RBEMotion]

Yes it is 0.2mm thick! Best of luck with your build

[@vendetta8ma]

I have few questions about this cells. If u look to molicel data sheet each cell can provide 40 A. If u build 12s8p it does mean that, this confiquration can give 8*40=320 A. Is it truth??? Nickel wire that u used can afford this current? and with which experimental methods u can confirm it? than u!

[@RBEMotion]

Molicel P42a are still, in April 2023, the best cell we use in esk8 in terms of value to performance. However, they are not as the spec sheet says. If you read very carefully, you'll see that that rating is a temperature limited rating. It is NOT a safe rating to use them at, all the time, especially when you have potentially hundred(s) of cells packed into a closed space. In terms of cell ratings, the best place to look is Battery Mooch. He's the most reliable source of information because he TESTS every single cell he receives and gives them "official" current ratings. For P42a, he rates them at 30, and I will ALWAYS set my ESC's to be within that rating of 30a per cell. So, for example, this 8p pack from me is rated for 240a. However, I know what this board is doing, and since it's a single ESC board, I know the max it would ever have drawn from it is around 160a with one of the better escs on the market. That being said, I built it with 3x 12awg wire per series section, which should be capable of transferring something like 70a each without getting too hot. So, it is built to spec no problem. Does that all make sense?

[@TheDarkstar826]

my dude! On 32:19, what heatshrink size did you used!? I need it asap! Thanks

[@RBEMotion]

250mm wide clear stuff, found it on Amazon

[@TheDarkstar826]

@@RBEMotion thanks.

[@coleyuhas7891]

Great video! A few things I’m wondering is if 2 wires of 10 gauge would work since that’s what I have. I was also wondering if I could use the soldering wire that comes with my soldering iron. I plan on building a 12s3p board and plan on using one of those pre cut sheets to parallel the 3 batteries, do parallel connections need less metal?

[@RBEMotion]

Thank you! Two 10 AWG would be plenty, it's just more annoying to solder. How much wire came with your iron? I personally use unleaded solder but many people swear by the Kester 63/37 wire. For 12s3p, you could even get away with 2x 12 AWG if you wanted. If you use precut sheets, you would want to get ones that are designed for 3P instead of 8P. For a small pack like yours, yes, they would be okay with less metal.

[@coleyuhas7891]

RB E-Motion gotcha yes I got the 3p style! Maybe I’ll order up some 12 gauge

[@giannisskoun]

Very clean build! I had a question regarding parallel cell fusing. I'm working on a project requiring high capacity - high amps (10kWh, 30-40kW peaks) and I've stumbled upon industry standards being that parallel cells must be fused (also Formula Student rules seem to want that). This is in case of a short circuit within the cell, the energy of the rest of the cells does not get dumped into the failing one causing a thermal runaway event. But in DIY builds this is never the case, what's your take on this? Unfortunately I haven't been able to find good info on the matter.

[@RBEMotion]

Ah, you have stumbled onto a big debate topic lol... Yeah it's a very complicated question to answer that I'm probably not fully qualified to give an opinion on. Someone named Battery Mooch gave a pretty good explanation against it on the Esk8 forum a while back (can't find the post). In my opinion, in an esk8 pack scenario with relatively small P groups (4 to 10p) versus a car or Formula E, where you might have 20-100p groups, there is a big difference. If a cell in an esk8 pack hits thermal runaway, I seriously doubt that cell level fusing will make any difference in a pack. To add to that, our packs are jammed in a very tight enclosure with almost no airflow. At the end of the day I just don't think it would help that much, and you're screwed with or without it if a cell decides to go that bad. One way to help avoid that is to have a smart BMS so you can monitor battery health through the balance of the cells. Generally a well balanced pack of quality cells will not encounter issues that could cause a cell to go into thermal runaway. Anyways, again, don't take my word for sole truth but this is kind of my opinion on it.

[@giannisskoun]

@@RBEMotion Thanks a lot for the reply, subscribing for the quality content! Thankfully I'll have space, so I might go for 30P modules, use spacers, and connect them in series afterward. Some airflow may also reduce dangerous temperatures and help me avoid the grueling task of fusing.

[@RBEMotion]

You're welcome! Thanks for the sub, lots of content on the horizon. Your stuff sounds like a lot of fun!

[@htx_rc4256]

Price wise is it cheaper to build a battery or buy one pre made? Im wanting to build a 12s6p pack and for just the batteries is about $360. Or should I just run lipos?

[@RBEMotion]

Hey there, thanks for watching. That's kind of a complicated question to answer, but the very short answer, is if you only need a single battery, it's going to be cheaper, easier, and safer to just buy one from a reputable builder. If you are only building a single battery, you will need to purchase: Nickel, a welder, a power source for the welder, fishpaper, fishpaper rings, cable, bms, etc. It adds up really fast. If you really want to learn how to do it, of course, I would recommend going on that journey, but if you just need a battery, probably just buy one. If you have some of those things, maybe it won't be so bad, but the truth is, cheaping out in the wrong places is a good way to have a battery fire, early failure, or other issues. As for the vs. lipos question, of course that is an option. However, the difference in range between a 12s6p and lipos is enormous. You would need to run a ton of lipos to get an equivalent range. I started with lipos back in 2017 and they were fine for a while but only got me like 8 miles of range. Hopefully this answers your question well enough, let me know if you need anything else.

[@htx_rc4256]

@@RBEMotion understandable. I do plan on getting just a single battery for myself for my daily work commute. Its only a 4 mile run going round so I wouldn’t need insane amounts of run time. But what I do want is plenty of power, thats why I At least want 12s. I can get some 6s packs that are 10000 mah each and run a set up thats 12s2p to equate 20000mah which id say is sufficient. But im not there yet to make a decision. What would a 12s5p or 12s6p run if you were to build it? Or any builder you recommend. To get something like that. Thanks!

[@RBEMotion]

Yeah Lipos may be the way for you if your commute is that short. And you can just charge them with a balance charger. As for the battery quote, all batteries I build are on a case by case basis, cost varies depending on complexity, so I can't give you numbers off the top of my head without the full details. There should be a link to the builders in our community in the description, but otherwise, Marios board garage, Skyart Power, and some others.

[@thomaslapham2372]

Hey I am building a 12S8P battery and I was wondering what BMS you used

[@RBEMotion]

I used a 12s LLT smart bms for this build

[@thomaslapham2372]

What charge port did you use? I can't find it online

[@RBEMotion]

We chatted on Instagram but for the people here, it's called an SP-13. I tried it out for this build and it worked well. Nowadays I tend to prefer the SF-12 though.

[@sammyjankis9567]

I'm a total newb, but whats port C- on the BMS for? I thought it was for the charging port and P- is bypassed or for lights?

[@RBEMotion]

Can totally be a little confusing! If you check out the diagram shown in the video you can see what it's used for. On this particular one I used B- for battery negative, then, the charge negative went into P- For lights you could either run them straight off the battery, or you could use the discharge path through the C one. Typically running them off the batttery is easier though and not all BMS have a C

[@sammyjankis9567]

@@RBEMotion it is. Thanks!

[@morozband]

Great video! You said that you dislike fish paper. What's your other alternative to it? Thanks a lot!

[@RBEMotion]

I don't recall saying I dislike fishpaper. It's essential for all packs, imo. It's the best insulator at a cheapish price

[@morozband]

@@RBEMotion sorry i misunderstood

[@RBEMotion]

@@morozband No problem man! Sometimes I do like to use some kapton tape for less abrasion resistant areas, like covering exposed nickel, so the user can't touch it. I'd always recommend fishpaper for high abrasion areas though.

[@KhataarFelMataar]

Hi I have a question, why wouldn't you for example use XT60 connections between parallel packs? That way they are easy to disassemble if you ever need to replace a faulty pack, or even upgrade a pack.. Haven't seen any build doing this.. Is there a negative side to this? Too much resistance in the connectors? What are you thoughts? 😊

[@RBEMotion]

Well there are a number of reasons to NOT do it. First of all, it's probably 3x the amount of work to solder that crazy number of connectors. Second, it introduces a ton of failure points where connectors could come unplugger, have soldering defects, or get shorted. Third - it's really just unnecessary unless you're specifically trying to create a fully modular pack, for example, if you wanted to be able to fly with it. I have a friend that has done something like this and it's pretty cool, but I would only do it if the need was there.

[@thomaslapham2372]

What kind of controller do you recommend for a build like this

[@RBEMotion]

Nowadays, I always recommend MakerX. They have some of the best value Vesc's out there. Second choice for me is still gonna be Stormcores from Lacroix.

[@thomaslapham2372]

@@RBEMotion What model of MakerX? There is so much to choose from

[@RBEMotion]

@@thomaslapham2372 DV6 and DV6 pro are both great options, the D60/75/100 series is newer but less community testing

[@vesc007]

Can you make a tutorial on wiring front headlights to run off the battery?

[@RBEMotion]

That's a good idea, but unfortunately the solution is much more complicated than you might think. What kind of headlights, what voltage do they run at, etc, will make a difference on what the setup ends up looking like. I am working on my own headlights that I plan to eventually offer and I'm testing different setups.

[@coreyblack1261]

How are three 12 awg copper wires for the series connection enough for 200 amps continuous? When I look at charts they say 12 awg is rated for around 25 amps. For the positive end of the battery it seems you'd need 1/0 gauge wire to handle an output of 180 amps? What am I missing?

[@RBEMotion]

This is a complicated question with a lot of nuance in the answer. Most of the charts online are spec-ed for housing code, that is, usually solid core wire with PVC or PTFE coating. On top of that, many of the ratings on those charts are rated for up to 300ft of cable, running for an infinite amount of time. In this application, we are almost completely opposite of the ratings on those charts. We have thick silicone covered wire (when using the quality stuff) that is able to take much higher internal wire temperatures than the other materials. Additionally, the length of our cables is very short, making the resistance MUCH lower. With lower resistance and higher heat tolerance, you can push the cables much further. On top of all of that, with our speed controllers, unless you're doing an efoil, you are almost never pushing that high of a number continuously. To be truly continuous, it needs to be more than a few seconds, and with most of the DIY boards reaching 30mph in under 5 seconds, peak current draw is more of a pulsed thing than a continuous thing. All of these things come together to make a chart that most of us battery builders use on esk8news, that has higher current ratings, taking into account some of these things. Hopefully that answers your question, sorry for the late reply haha

[@coreyblack1261]

@@RBEMotion I appreciate the time you took to write such a nuanced answer. I have the good silicone wires. Just having soldering issues with the 10 gauge. Hopefully the beefy new soldering iron I ordered will make the difference. You think a Weller sp175 will work well? Thanks for the nice tutorials, I basically just copied you

[@RBEMotion]

@@coreyblack1261Of course. Best of luck! 10 awg can be tough sometimes but its definitely doable

[@thomaslapham2372]

Where did you get your battery enclosure from

[@RBEMotion]

This enlclosure was a legit Flux AT1 enclosure, from the company themselves.

[@thomaslapham2372]

@@RBEMotion Do you know where I would get this enclosure or something similar because I have scoured the internet and I cant find any more Flux AT1 enclosures available

[@RBEMotion]

@@thomaslapham2372 Oof. Yeah that's gonna be tough. You might try Facebook or the Esk8News forum, but other than that, it's gonna be hard to find now I think. The AT2 is pretty good tho!

[@thomaslapham2372]

@@RBEMotion Shoot yeah I looked on both without any luck. I think I'm going to have to design my own. Do you still have the battery enclosure? Would I be able to get measurements from you to replicate it

[@thomaslapham2372]

Or I could buy the enclosure off of you lol