Elysian | Subsonic Century 40 | 11S5P Samsung 40T | Xenith v1

reyder · February 22, 2021, 4:02am

Ok, here we go, my first build thread. I don’t even know how to start… so basicly building DIY board been on my head for quite some time but lack of time never allowed me to do that, until now. Why Century 40? I really like idea of a low deck so Century 40 was one of the obvious choices. Getting Evo is close to impossible here in EU. Currently I’m gathering all the parts that will be necessary for my build and I will probably start building it in next month or two.

PARTS:

Deck Subsonic Century 40 (in transit) → Painting and varnishing will be made. Still looking for an inspiration.
ESC BKB Xenith (in transit) → Obvious choice I guess ? I have been also thinking of MakerX DV6 but decided to go with Xenith.
Enclosure eBoosted SS (arrived) → It’s pricy, yes, but damn it looks good. Thanks @eBoosted
BMS FlexiBMS (arrived) → It is tiny and developed by our guy @SimosMCmuffin. I think it will fit nicely.

…and here where my struggle begins. The battery. I’m not really sure what’s the best choice regarding battery cells. I will be building it on my own. I just struggle with choosing cells. Let me explain what I want this board to be. I want it to hit that 50 km/h. I’m usually not gonna ride that fast but I don’t want someone to beat my board with some prebuiltd What is more important for me:

Capacity
Acceleration

In that order. Here are my current cell options:

Samsung INR21700-40T 4000mAh - 35A €5.15 → I can fit 12S5P or 12S4P. I know that amount of power with both of this option will be more that enough but I’m more worried about range in 4P configuration. 0.691 vs 0.864 kWh
Samsung INR21700-50E 4900mAh - 9.8A €3.76 → Insane amount of range but only ~-50A peak. Probably not enough ?
Samsung INR18650-30Q 3000mAh - 15A €3,79 → 0.648 kWh, 75A peak. That’s the cheapest option and I like it because of it. I’m only worried about the range and power…
Sanyo NCR2070C 20700 3500mAh - 30A €3.99 → Seems like a great deal ? 0.756 kWh
Sanyo NCR20700B 20700 4250mAh - 15A €5,80 → Too pricey and not worth probably ?

I know there are a lot of pro builders on this forum so any help, advice will be much appreciated

Regarding rest of the parts. I still need to make a decision. Informations, advises, suggestions are more that welcome. Still need to pick trucks, tires, gears, motors…

I’m from EU so if anyone want to advice something regarding parts, please take that into consideration.

THE BUILD:

--> 22-02-2021 <--

Here is (for now) empty enslosure. Looks good even without the deck

This is currently WIP transformer for battery build. Still need to work on that but it is a beast (the left one ofc).

Halbj613 · February 22, 2021, 9:32am

where are you seeing those prices as they seem extemely high
you can get 30q cells as low as 2.50 euro
also look into the molicel p42a as it has capacity plus quite a nice amount of power

also remember prebuilts are mostly running off 20-40 amp batteries so you really dont need much to shred past them. last thing is… is the enclosure double or single stack?

eBoosted · February 22, 2021, 4:47pm

Get the Molicel P42, the enclosure has been perfectly designed for 21700 12s4p.

ProfoundMagician · February 22, 2021, 5:11pm

^^

If your going 21700 40t or p42a are the best options imo

rusins · February 22, 2021, 5:12pm

Where did you buy the Century? I see Evos in the EU all the time, but not any subsonic boards…

Speed will depend solely on gearing, for the battery just optimize for capacity and power (maybe cost). Molicel P42a is the way to go, you can get them from Fogstar, they have a vendor thread on the forum.

Without knowing what wheels you want, it’s hard to give any truck recommendations. Boardnanics trucks will probably be the cheapest quality trucks though, nexusboards stocks them.

reyder · February 23, 2021, 2:06am

I cannot find Molicel cells anywhere in europe and if I find one the price is insane. Samsung/Sanyo are only options here.

Actually I found INR21700-40T for 4$. This is probably the closest match to Molicel P42 and a good value. I will try to squeeze 12S5P. I have seen people do that on that enclosure but we will see.

@Halbj613 It’s SS. I have never seen these cells for 2.5 euro. 3.11 is the lowest price I have seen some time ago. I suspect that everything in EU is ~19% more expensive

@eBoosted I will probably go with INR21700-40T. No Molicel in reasonable price around me.

@rusins You are right. You cannot find Century 40 in EU. I can recomend 2 options for getting one:

Buy it from someone in US, used.
Try to buy it directly from Subsonic. (Yes I know taxes but nothing we can do here) There is a special section One of a Kind Longboards on their website. You can get Century with 50$ off there. You just need to snipe one.

I want to put AT tires on it. I have been thinking about 200mm from here: TIRES

Minimadness · February 23, 2021, 2:09am

I would wait until around half of march, battery vendors expect to have P42A stock around that time.

rusins · February 23, 2021, 2:11am

Regarding Molicel P42a: I paid ~4.4€ per cell after shipping, and a friend of mine paid 5.72€ per cell after shipping and now UK import taxes. If you found 40T for 4$ (3.30€) a piece – damn! Share with the rest of us

reyder · February 23, 2021, 11:49pm

@Minimadness I would probably do that but INR21700-40T is too good of an opportunity to miss out. I will probably replace battery with something more powerful in the future.

@rusins He turned out to be a local supplier from my city. Lucky me. He is also sending to other EU countries. It seems that those cells are brand new, unwelded from battery packs, 0 cycles. He’s been selling variety of cell types from years and he’s got trustworthy reputation on a forum where I found him. You can check out endless-sphere.com.

reyder · June 29, 2021, 10:27pm

Ok, time for update. I’ve been putting off for quite some time but finally I can share with you my bumpy road while building this deck.

The build is done (almost). I still have a few small issues that need to be addressed but first things first.

I will share multiple posts for each part od the board.

Battery

I got 80 Samsung 40T cells. I bought them at a really good price, brand new. My plan was to build 12S5P battery. I believe in speed and power.

So I started with assembling P groups. Cells in P groups are glued using silicon and wrapped in fishpaper. I also extended fishpaper on the positive side so I can bend it to protect +/-. All connections are made using 0.2mm pure nickel and 0.15mm in a few places but mostly 0.2mm.

Here is a my first struggle. Spot welding 0.2mm is not that easy. Spot welding 0.2mm nickel strips to each other is even harder. I bought 2 microwave transformers 900W for it but it is not enough. I tried to connect it in parallel and in series but both scenarios failed. I had around 3V when connected in series with really thicc and short wire. In parallel my voltage was probably too low because of only 1,5 wrap around transformers cores. Yea… so that was a failed project but I will try to make it work at some point. Anyway, I ended up using mini spot welder from China with Lipo after modification (originally they break easily). To my surprise welds were really good. It makes good welds to cells but not nickel with nickel. Here is picture of it:

Can I recommend it ? As a backup, sure. For 0.15mm, single 5000mAh 3S1P 100C peak is perfect. For 0.2mm, double it.

Here you can see few pictures of P groups. I added 2 layers of fishpaper and kapton tape where potential short negative/positive can happen, just to make sure. I also smoothen all sharp edges ofc. at the end.

I made 10 of them because that’s all I can fit in my enclosure. The other 2 are made from pair of twos. Connecting it all together was a nightmare. Here is picture of them in enclosure:

What was worrying the shit out of me was short between negative side of 2packs and positive side of the large one, as you can see at the picture. I tried to fit some solid separation between them but I had no space. This battery is tight fit, really tight! Here is what I’ve done. I put 2 layers of fishpaper beetwen them and shit ton of silicone. I’m not taking any chances.

I forgot to mention when I tried to fit all packs in enclosure with fishpaper I realized that there is no space for anything else. I though I will be able to fit VESC somewhere but those mm adds up quickly and I ended up ditching one P group… so it is 11S5P with a blasting power of 0.8 kWh.

More about my journey with battery will come soon. I need to find time to write it.

reyder · August 24, 2021, 2:50pm

It’s been a few weeks. I have been riding this board for a while now but unfortunately I crashed 4 weeks ago. Nothing serious, few scratches a lot of blood. Head is fine I was wearing helmet, no helmet - ground impact. After 1 week I was able to ride again. Although my feet still hurts.

The bad news is. I broke my front Matrix truck. Yes, imagine that… Here is picture:

So what actually happened, right ? I’m not sure… but here are my thoughts. During a ride I think I felt that one of the motor is losing power and I was losing control. I started slowing down I though that I was still in control but I hit the ground pretty quick. It was matter of 1 or 2 seconds.

I’m using bullet connectors for my motors and I think that one side disconnected during ride. I was worried about this before that ride (I was doing maintenance) but I forgot to check it. My connection between motor and ESC does not have a lot of ‘free wire’. I think that lesson learned: don’t use bullet connectors.

I never showed you completed build:

More posts about this build coming soon I hope. I’m looking for new trucks with mounting btw I don’t really like chamber trucks for long street rides, hard to turn the board at low speed at any degrees. They are stable af though.