My first build - questions

Hello guys,

My first post here - I have couple of questions regarding the build I’m finishing now. Thank you in advance for any help that you can provide.

I’ve been riding my V2+Boosted for several years and l love it. However, when joy riding on empty roads or beautiful paved bike paths I often feel like I want to accelerate faster, or go faster in general. So one year ago I decided to make my own DIY longboard. I’ve done the research, purchased majority of parts and then didn’t have any time to finish it :slight_smile: Now, a year later I decided to finish it and immediately made some changes (including changing to DT deck). It is supposed to be a performance build, so I was trying to get the best components available back then.

I’m a mechanical and nuclear engineer in nature, but during my studies and even now at my job, I’ve always struggled with the electrical part. So I have couple of questions mostly regarding the battery and BMS. I am using four high discharge hobby 3S LiPos (5000mAh, 50C) that I want to connect in series to create 12S battery pack.

  1. could you please double check my wiring diagram? Is it better to solder all the joints, or is using XT60 connectors fine?

  2. I don’t have BMS now and I will charge the LiPos separately for the initial testing, but eventually I want to install it and i would like to prepare all the wiring in advance. How do I connect the BMS (I want it bypassed for discharge) and charging connector?

  3. what BMS would you recommend me for 12S LiPos? (I prefer to have more flexibility in the BMS as I expect I will change the build in the future)

  4. antispark - what’s the purpose? I’ve seen it on several diagrams here, but missing on others. Is it necessary when I’m using focbox Unity? It seems to be almost impossible to buy XT60 antispark around here…

  5. since I will not be using the BMS now, what to do with the battery balance connectors? Leave them as is?

  6. I’m using Loaded Dervish Sama deck, 2x 6374 190kV motors, focbox Unity, but pretty terrible remote controller - I would like to buy a better one. What’s the current best remote? (I love the style of boosted remote - preferably something similar.)

  7. how much cooling does the focbox Unity need under extreme loads? I will be testing the board with some lunchbox enclosures, but I’m planning on designing and 3D-printing my own enclosure. I was planning to make some fancy air channels to help with the cooling.

PS: I know that I will probably rethink the build in the future, but for now this is what I want to try. I can send some pictures once i get home.

Here are some questions and answers for you.

  1. Do you really want to use lipos? I assume you must already have them?

  2. Connecting all those lipos to bms is possible, but a pain. Some people will argue that Lipos are designed for a seperate battery charger and that a dedicated li-ion pack with 18650 is more of a standard approach.

  3. Depending on whether you decide to use lipos, the bms question is pending.

  4. Dont need it on FOCBOX unity. But essentially it is a circuit design that prevents a large arking spark occurring when you connect the battery to your esc. Xt90 spark plug is probably the simplest way to integrate this into your power circuit. Not needed though with unity.

  5. You will need to balance the lipos during charging, maybe not every single charge, but at least every few charges. Leave them intact so they are functional with a lipo charger.

  6. Not to sure there are any boosted style clone remotes available. Maybe the vx1 is the closest:

  7. Unity probably wont need any extra cooling. Can easily monitor temps and adjsut cooling later.

Thank you! I already have the LiPos, so the path is set (for now). Is there any reading material regarding how to connect 4 Lipos in series to BMS? (I’m not a big fan of opening the batteries - these are Gens Ace batteries / not cheap / don’t see any easy way in).

  1. for some reason, XT90 antispark is nearly impossible to get around here (I tried several shops), even specialized shops that sell XT60/90 connectors don’t have the antispark. I was 80% sure that I don’t need it with Focbox, I’m glad you confirmed it.

  2. what are the favourite remotes these days? Any recommendations?

You can build add-on bms for your lipos for cheap. You won’t have to open any lipo and you won’t have to remove or cut any wires from lipos. You can use that bms as charge only bms only when charging your lipos out of enclosure, or you could put it in your enclosure and wire separate charging port and just balance charge your board and bypass discharge. Here is photo of simple add on bms for 2x 6s lipos in series:

In your case, you would have 4 balance connectors to connect all 4 lipos. If you want to use it in enclosure, add parallel xt90(or xt60, whichever you use) connector between bms and your lipos.

do you already have a focbox unity? also has some good remotes.

You got me here. How does that work? I was thinking about charging like this: I still would have to disconnect all the batteries, but it is definately faster than charging them one by one.

@tardyparty7 yeah, I already have the Unity, I have all the components with exception of BMS.

you can use parallel board like in that video, but you will still have to open enclosure and disconnect everything to charge. here is scheme for simple bms add on, which can stay permanently in enclosure. if you wire batteries like this, you will charge through charging port and bms, but discharge directly bypassing bms. also, when you plug your xt90s loop key out, board and voltage (or bat %) display will turn off, buy you will still be able to charge board through charging port. parts you will need: xt90 anti spark, few xt90 or xt60, wires, 12s bms (red daly from aliexpress is cheap and good), 12s (50.4v) charger, charging port of your choice, JST XH 2.54 4-pin connectors. I think that’s all.

I see, thank you for explaining it to me :wink: So basically the purpose of that loop key will be to disconnect the battery % display and VESC before charging (as I am using focbox Unity and I therefore don’t need the antispark function)? Not 100% sure which wire from the balance connector is which, but I guess I’ll figure that out once I get my hands on the BMS.

Thank you again!

oh sorry, didn’t count in unity. yes, you don’t need loop key since you have on/off button on unity