Looking for advice on battery configuration

I’m trying to decide on the best battery configuration for my first build…

Parts List:

  • Molicel 2170 P42A (X 50)
  • BLDC Belt Motor 6354 190KV 2450W (X 2)
  • FLIPSKY Dual Mini FSESC6.7 Pro 140A

I chose the P42A because they are quite energy dense (4.2 Ah / 70g ), relatively cheap, and low impedance. My original plan for the motor was to go with a single 190 kv 6374; however, I believe two 190 kv motors will serve me much better since I live in a very hilly area and weigh about 90kg. Instead of one 6374, I opted for two 6354 which should be compatible with my salvaged trucks and mounts :crossed_fingers:. For the esc, I wanted a high end vesc capable of reaching the full potential of the 6354s. The 6.7 Pro should be overkill since it’s capable of delivering 140A continuously and the motors take a maximum draw of 65 A each. The 6.7 pro inputs up to 60v (they recommend up to a 12s), so I have a few battery configuration options.

  • 10s5p
  • 11s4p
  • 12s4p

or I could even do two battery packs of

  • 11s2p
  • 12s2p

My goal with this build is to get up and down steep hills all day long (relatively) safely, so I want to choose the best configuration option with this goal in mind. Obviously, more batteries in parallel would be better for an all day riding experience, but if you guys believe I need the 12 in series to take advantage of the two 6354s, then the 12s4p or 12s2p * 2 may be the better option.

This is my first build, so I’m still learning. I do have a background with electronics; however, there’s still a lot to learn building these things and I can admit I may have gotten some things wrong or purchased wrong parts (honestly I already know I have with the drive train). Anyway, thanks a ton for any advice you can give me.

Edit: grammar

12s4p is your best option, unless you’re doing a small board type build, then a 12s2p is best. The esc is a hit and miss. I would get a makerx dv6 or a stormcore 60D and call it a day right there.

Talking about battery configuration and all these things, before talking about helmets, decks, and enclosures, is a recipe to have a really difficult time finishing your build.

My suggestion is to heed order of operations. Don’t choose anything else until you’ve chosen your deck and enclosure. Because you need to know if it will even fit. Enclosures are much more difficult than you think, and you need to know if flexibility will be something you design for, or not. So go in a certain order, along the whole way making sure you choose things that are compatible with each other.

  1. helmet
  2. deck + enclosure (flex?)
  3. battery (flex?)
  4. ESC(s)
  5. drivetrain & trucks & motor mount
  6. wheels
  7. motors
  8. {everything else}
  9. remote
  10. aesthetics: grip, colors, lights

Leaving enclosures until last as an afterthought is a surefire way to end up in a less-than-ideal position.

@LeonCamero Thanks a ton for the reply, can you explain to me why the 12s4p would be better? Is it just standard for the motors or vesc? Thanks.

Its basically getting more out of your system. You can go 10s for a balanced board. But if you’re making a small board, a 12s2p would benefit that.

@b264 Also thanks for the reply. I can see that your very experienced on this form and with electric longboards. I’m glad your first concern is safety. Electronic longboards are obviously not the safest hobbies/sport/mode of transportation in the world, thus we should strive to make them as safe as possible with proper pads, helmets, and technique. I’m not a physician, kinesiologist, or any other practice that’s qualified to recommend a helmet for any application whatsoever, but I think there’s some obvious concerns I can mention. Should the helmet be full faced with jaw protection? What should the mass of the helmet be (too heavy may increase the chance of a neck injury)? What is the certification of the helmet? With these concerns in mind, I think the best solution would be a light-weight, full-faced, longboard-specific, approved-by-a-physician helmet, but TBH those are kind of expensive. Instead, I will be going for an approved hard-shell brain-bucket helmet, that I have been using for years whilst flying downhill on conventional longboards. I will, however, start slow with my DIY electronic longboard. When I feel the need for speed (which is inventible), I will purchase a better helmet. While we’re on the topic of safety equipment, we should really be taking about pads. Knee pads, elbow pads, and wrist guards or sliding gloves. They are imperative to not getting hurt while going fast on a longboard. My 20+ years riding skateboards and longboards can definitely vouch for this. The saving-grace technique is when you get speed wobbles, keep low and transfer the momentum in horizontal direction using the pads to catch the fall and slowing down by creating friction with the pads. There’s other situations where pads can not help. In those situations it comes down to rider discretion and not being an idiot.

On the topic of boards, I am using a great board that I have a lot of experience on and trust at high speeds. It is an extremely ridged board with 2 layers of fiberglass. The board is a Prism HindSight Cop Caller. It’s made a hell of a freeride board and will hopefully make a decent electronic board. The enclosure I will make out of fiberglass. I am choosing fiberglass since it is an incredibly strong material and I know how to work with it. I can also bond the enclosure and bolt inserts (for the lid) directly to the board. It should be incredibly strong and impact resistant. Furthermore, since I am making the battery myself, I can design it’s spacers such that they can also mount with bolt inserts directly to the board. Mounting the battery directly to the board will be an additional layer of protection since there will be a gap between the enclosure lid and longboard (thinking impacts here, e.g. tree roots and other deformations in the pavement). I am not going into details about how I am manufacturing this enclosure (materials, quantities, gauges, techniques) here, since that would be a several page essay I don’t feel like writing down. Maybe if manufacturing this enclosure goes well and it proves to be a good enclosure, I will make a video or guide on how I made it. I will mention that safety should take precedence here. Some of these enclosures available on the market are just ridiculous vessels for lithium ion batteries a few inches of the ground at high speeds (think catastrophic failures i.e. punctured battery). Ultimately, I am going the DIY fiberglass route with the enclosure because there’s no board/enclosure that I like at a specific price point. Please do share any advice/wisdom you have on this topic.

You brought up a lot of things to consider, so I am not going to cover the full build. That should probably go in a different thread anyway. Hopefully I have addressed some of the points you brought up. Thanks again for the reply.

Edit: clarity ( :grimacing:I read my post again; thankfully I’m not a professional writer)

Yeah I’m not either, and for legal CYA reasons I have to say: ignore all my advice at all times.

But I personally hate full face helmets and I don’t like my vision restricted and they are a motherfucker to get on and off of the dome.

A relatively cheap but very comfortable, lightweight, and pleasant helmet IMHO is the “S-one Retro Lifer”.

I don’t ever use pads. Ever. I don’t even own pads.

Great!!! Fiberglass is probably the BEST material to use for these. Don’t use carbon fiber.

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This is a very bad idea if it’s your first battery. You are very likely to end up with an unsafe battery that cost more than just buying a professional one. (read: professional, not one from a youtuber)

I strongly prefer to mount the battery in the enclosure. Mounting it to the deck is a band-aid for having a terrible enclosure, especially one made of ABS. If you will have a handmade fiberglass enclosure, then I would mount the battery in there. And use butyl rope/tape to seal it to the deck or to a rubber sheet lid.

I agree, but I do have to start somewhere with building larger batteries as I have plans for other projects that are going to be battery based and will most likely have to be custom due to space requirements. I do want to say I’m not going into this blind, but this will be my first 12S battery (i have built smaller lower voltage batteries). I am experienced with soldering and confident soldering 10 awg onto nickel strips. I have rehearsed this. I have bought the correct tools i.e. a good spot welder. I tested and practiced spot welding using some older batteries. I also chose high quality wires and nickel strips. I spec’d both to exceeded the max current they should experience. I tested both and they preformed as expected. The batteries themselves have come from an authorized supplier. I tested each one and they all had the same voltage ± 0.1 V. I plan on using insulated rings on the positive end of each battery. For the parallel connections, I am using custom PLA battery spacers, secured with friction, then wrapping each with fish paper and taped together with Kapton tape. The whole battery will be wrapped with heat shrink to protect against shorts and moisture.

Honestly, I think the budget batteries off Amazon or somewhere random would be pretty sketchy. In fact, I’m guessing there’s a lot of manufactures that are not trust worthy and produce questionable batteries with cheap materials. I am sure my battery will be at least somewhat more reliable than their batteries since I sourced all my materials from reliable sources. I am choosing to build my own since the task is at my skill level, the battery would be higher quality than budget batteries off the internet, it could meet the space requirements, and it would give me the experience creating custom batteries.

I do agree with you, a professional battery made by someone who manufactures batteries for eskates would be amazing, but I am taking a risk anyway. I fully acknowledge this is dangerous and I should take precautions.

Still curious, would you go 12s or 10s?

Thanks

@diy3 10S is just fine.

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Can someone steer me to a source for 2x 6S 12Kmah lipos that fit a Trampa monster box, besides Hobby King which can’t ship from EU to US?

If you have plans to build many batteries, then DIY and buying the tools and spending LOTS of time reading is definitely groovy.

IMHO it’s a huge mistake to try to DIY one battery for a vehicle. It’s almost always going to be better to buy it.

When the quantity increases to “many” then the situation changes.

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lightly sand the nickel right where the solder will hit it

Heat shrink does NOT do a good job of protecting against shorts due to abrasion caused by heavy vibrations. For that, fishpaper is much better.

This is where heat shrink can help a lot, combined with (neutral cure) silicone or another kind of sealant.

kelvin-milli-atto-hours? That’s an interesting measurement? Do you know what it’s measuring?

I suggest using the proper units, which is probably 12Ah or 12000mAh

MAH = mega·amp·henries
mah = milli·atto·hours
mAh = milli·amp·hours
Ah = amp·hours
kmAh = kilo·milli·amp·hours = amp·hours (maybe you meant this?)
KmAh = kelvin·milli·amp·hours = ??
Kmah = kelvin·milli·atto·hours = ??
KMAH = kelvin·mega·amp·henries = ??

Haha, what friendly help you are in this community;

12Kmah = 12,000mah, sorry I didn’t capitalize the “A” for you and offended your sense of battery vocabulary.

Beyond total scrap and rebuilds of Trampa boards, I’ve been building drones since 2010 (only fixed wing back then)…yes, back in the day when you had to solder all of your connections between the controller, ESCs, motors and lipos. I probably have triple the hours you have working with electronics such as these, including lipos…not that anyone should ever consider that bragging rights, maybe you do.

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