DIY for long distance offroad

DIY Builds
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Hi everyone, I recently borrowed some exway atlas. And now here I am, I really need to build my own. Actually two, my girlfriend wants one too.

I would like your advice on whether it is fine like this, or what you would do differently.

My idea is that it can ride on a variety of terrain, mostly cycle paths in our forests, where there is gravel, asphalt and only beaten paths. I live in the EU in the Czech Republic, we have quite hilly roads here. And now the hard part, 80km range (about 50miles). I am 80kg (170-180lbs) and I would like to ride about 25-40km/h (16-25miles per hour). So I need solid performance and a battery.

Here is my proposed build.

DECK: MBS Comp 95 Silver Hex
TRUCKS: 2x MBS Matrix III CNC Truck System 12 x 420mm Black
: 8x MBS MATRIX III TRUCK/DECK SCREW 25mm
WHEELS:
HUB: 4x Disk MBS RockStar II
TUBE: 4x MBS Inner Tube
TIRE: 4x MBS T3 Tyre
BEARINGS: MBS Bearings 12mm*28mm (8pcs)
MOUNTS:
2x MBS MOTOR MOUNT ARM
2x MBS MOTOR MOUNT CLAMP M3
PULLEYs:
ENGINE: 2x Flipsky motor pulley 15T D-shape
WHEEL: 2x MBS Wheel Pulley - HTD 5M - 72T
: 10x MBS PULLEY SCREW - M4 x 60mm (RSII, RS Pro, RS Pro II)

FOR 682$
_____________________________________________________________________

MOTORS: 2x Flipsky BLDC Belt Motor Battle Hardened 6384 140KV 4000W
REMOTE: Flipsky Screen Remote VX2
VESC: 2x Flipsky 75100 Pro With Aluminum PCB Based on VESC
: Dual ESC Can Bus Connector Compatible with VESC
: Bluetooth Module 2.4G Wireless Based upon the nrf51_vesc project ESC: For VESC6 / VESC75
BMS: LLT 14S smart BMS with Bluetooth function UART communication 20A
CELLS: 14S9P = 126x EVE INR21700-50E 5000mAh - 15A
CHARGER: LLT Li Ion 14s 58.8V - 5A

FOR 800$
______________________________________________________________________

I’m most unsure about the control unit - VESC, whether it’s worth paying extra for something better (MakerX Go-FOC D100S), but it’s a lot more expensive. Then I don’t know about the BMS, I assume it’s better to bypass and use the BMS only for charging, but I don’t know much about recuperation, so that it’s safe to brake. If you set the Battery Current Max Regen in VESC: -20 A and it will be fine and it will brake safely and sufficiently.

And then the cells, I don’t know whether to use some 5000mAh 15A max (10A continuous) at 14S9P, that’s 50V*90A=4500W, or go to 4000mAh 40A (25A continuous), I don’t really know how much I need to get the maximum (peak) available amperage output from the battery.

I’ll use EVE, BAK or TenPower from nkon.nl, they’re around 2€ each.

Of course I know that I will need to buy some fishpaper, nickel strips, copper cables and probably some fuses and more.

Thank you very much in advance for your valuable advice and if anyone has something that would be useful for my build and you are near the Czech Republic, I will be happy to take it on for a reasonable price.

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50E has no place in esk8, please choose a better cell

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I think to realistically get that range you need a battery that’s a bit bigger, riding and setup makes a huge difference for efficiency so it’s hard to tell. You might find it’s quite a long ride on an esk8 and you would stop and charge anyway.

Using 20S motor controllers on 14S is a little bit inefficient, on 14S 2800 watts they make about as much heat as they would with 20S 4000 watts. Could you switch to 12S11P which would let you use 12S VESCs like a DV4S? It would be much more reliable and compact than Flipsky.

I second using more powerful cells, you often get more energy overall from a strong high current 4.5Ah cell than a weak 5Ah one that has more voltage sag.
You probably know already but you will need to have a spot welder and be able to solder.
The battery builders club here on the forum is great for best practices and how exactly to do things.

Just connect VESC power leads onto the battery and set braking current based on what you want riding, with that size battery you won’t need more braking current than it can easily take.

Do you have a strong understanding of the difference between motor current and battery current settings? It’s really important and newcomers often don’t understand it

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If you get Rockstars, you’re locking yourself into the 8in (and smaller) tire standard. I suggest getting 5-stars, which work for the 8in (and smaller) tire standard as well as the 9in (and larger) tire standard. Gives you the freedom to try 9in tires later if you want.

I’ve had several bad experiences with MBS tires, and I’ve heard about a lot more bad experiences from other people. They are soft rubber, they wear down quickly, they puncture very easily, they dont grip soft terrain well.

Strongly suggest you get a different tire. Be sure to look for something with a hard rubber compound (both for tire longevity and puncture resistance) and something with deep/aggressive tread. There’s lots of “off-road” tires which have really whimpy tread depth when brand new, which quickly become slicks after they’re worn down.

Personally, I wouldn’t want to ride more than a few miles off-road on anything smaller than 9in tires, both for comfort and for grip. But that’s up to you. If you use a wheel like 5-stars then you can start on 8in and have the freedom to try 9in later.

Dont buy D-shape pulleys. Dont buy D-shape motors. It’s a really bad idea.

You’re locking yourself into d-shape pulleys forever, meaning you can never use any of the esk8 gear drives if you decide to upgrade. Pretty much all DIY esk8 drivetrains are built for an 8mm motor shaft with a keyway. Get that, and you’ll have tons of options for the future.

Also, 15:72 is a pretty steep ratio for belt drive. Having a high ratio for off-roading is good, because you’ll want the torque. But a 15t pulley is quite small for that much torque. You’re likely going to have issues with belt skip over that small pulley. This is why gear drives are better for off-road in my opinion, because you can have a very high ratio without the risk of belt skip.

These are a great choice (dont let yourself get upsold to reacher motors just because they’re shiny lol). Just make sure you get them with 8mm shafts with keyway (like discussed above.

Flipsky VESCs have a really bad reputation around here. Maybe they would be fine if you’re running them well under their rated specs, but maybe they wont. And also, no one is ever satisfied running under spec :grin:

I’d suggest MakerX instead.

Like @glyphiks mentioned, these cells are probably a bad choice for esk8, especially off-road esk8. Before building a battery, you need to learn about the difference between a cell’s rated energy delivery and it’s real-world energy delivery under load.

Those 5000mAh cells probably deliver less than 4000mAh under moderate load, and will experience a LOT of voltage sag (which you feel as whimpy power on your board when you punch the throttle). You need to look for a cell which can deliver a lot or energy at high load. The Molicel P42A is a classic choice around here, but there’s lots of newer and better options.

Google “battery mooch” and start reading. He does some of the best independent cell testing and data publishing I’ve ever seen. If you want to learn about how different cells will work at different loads, he’s your guy.

Also, as mentioned elsewhere, you’re probably going to need a much bigger battery. Off-road riding really eats up battery like nothing else. To get 50 miles of pure off road riding you’re gonna need a massive battery. And that massive battery is going to make your board heavy and awkward off road. Just FYI.

It sounds like you’ve got a lot more reading to do! But that’s a good thing. The more learning you do on the front-end, the better your boards will turn out on the back end :ok_hand: Good luck!

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Curious if you know something I don’t.

I’ve run 6” NOVAs and BKBs in my rockstar II hubs, they’re great. Best hub out there, imo. Durable and light. (Tho, I rarely ride off-road)

Everything else you said is based tho. @Lysergic, @BenjaminF is the closest thing to an authority figure we’ve got :grin:

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Can confirm, running 6 inch NOVAs on Rockstar II’s right now.

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I thought so, I’ll take one of these:
EVE INR21700-40P 4000mAh - 50A
BAK N21700CGP 4000mah - 40A
Tenpower INR21700-40TG 4000mAh - 35A
will depend on availability. Thank you!

Yeah, but i rlly want to have big battery and have the opportunity to drive a lot without recharging.

Yeah, it is probably better to go 12S11P and use DV4s, but i dont understand the parametes, it is saying continuous and max. So is there some adjustable MAX value that it allows high current for, say, 10s? Just for peak situations?

I I wouldn’t call it strong knowledge.

bemf_voltage =motor_rpm / motor_kv

  • so bemg_voltage is voltage generated by a rotating motor

pwm_effective_voltage = duty_cycle_%_bldc * battery_voltage

  • pwm_effective_voltage is the % of battery voltage what is actually trying to push motor.
    duty_cycle_%_bldc is part of time in % when the voltage is on - like 0,5(50%) * 50V = 25V

winding_resistance_ohms = (foc_resistance_detection_one_phase_milliohms / 1000) * 2
some kind of resistance between points A and B but here is it Motor Resistance: 0.05Ohm??

motor_current = (pwm_effective_voltage - bemf_voltage) / winding_resistance_ohms

battery_current = (pwm_effective_voltage * motor_current) / battery_voltage

so that all mean that current is the force what is pusning me forward and voltage is just speed xd.

Okey, I am going to change them right now for 5-stars.

Yeah, I didn’t like the grip when I saw them, but I couldn’t find any other ones in any of the online stores I want to order from, I’ll try looking. Thanks.

Okay, I didn’t think of that. I wanted the D-shape because it looks more durable, or rather, the pulley will stay on the D even if the key falls out. But it’s a very good argument, I’ll change it to an 8mm round axle.

I’ll try to find a bigger pulley, but I’ll have to adjust the gear ratio and KV of the motors. I’d like to stay belt drive, I know it’s not ideal but it’s the cheapest solution for now.

Yeah I already seen, that guy is cellgod.

It’s not actually offroad, it’s cycle paths, mostly pretty nice asphalt (not smooth asphalt) but there are parts where there’s gravel or dirt and roots. So I want it to be off-road in the sense that I don’t have to change direction when the terrain changes, not that I’ll always be riding off-road.

But really thank you very much for your advice, I really appreciate it guys!

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He meant that you lock in 8" as the maximum. With 5-stars you can also run 9". Either can run smaller.

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I believe you can use the “Max” numbers for maker-x VESCs

At a certain speed and force you could be drawing 15 amps from the battery and putting 180 into the motors. Amps is torque, volts are speed, watts are power.

So if you are moving at 50% of your top speed you are putting half of battery voltage through into the motors and twice the current. While at 20% of your top speed you could be drawing 10 amps from the battery and 50 amps into the motor.

Motor amps are max force / low end torque battery amps are max power / top end torque, a lot of people don’t understand that motor amps and battery amps are quite independent and you don’t need to match them up.

If possible watch Nkon for a while, prices change and deals come and go. Look for “(battery name) batterymooch” to get data on the cells, he does amazing work like measuring total energy output at different power outputs across every cell. Even if cells are rated the same there is often a decent difference.
I have sent Battery Mooch EVE 40P and Tenpower 40TG for testing in the past, pretty sure 40P were a good bit better.

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Something to consider too; You might get more of your money’s worth if you build a slightly smaller battery, but spending ~$300 on a fast charger (ex. roger charger) with EV hookup.

In my experience, once I get to 1500~2000Wh of riding, I want to take a 30min break anyway to relax, eat, etc.
With a fast charger, plugging in during that stop can “effectively” increase the size of your battery pretty significantly. Plus your board would be lighter, which is a plus.

Then again, most of my long range rides are on roads that have pretty good access to electricity.

8" Novas might be satisfactory for you, they’re great tires. or 200mm kendas if you’re on a budget. They’re both fantastic on cyclepaths, especially NOVAs.

Getting a more “street” tire will improve your ride quality and energy efficiency when not on dirt

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Novas are great but shipping to Europe is super expensive unfortunately.

On a budget I’d probably go with these 200x50 CST for 9$ each + free shipping. 15$ each with tubes. And pretty decent.

https://www.aliexpress.com/item/1005008830782068.html

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Does it not tell you “one per customer” ?
I can’t order bc of that.

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Oh nvm it does. You could try buying 1 piece 4 times, that should work I think. Or use this link: https://www.aliexpress.com/item/1005005107789485.html
But it’s 20$ for a tire+tube pair here. Also check amazon maybe they have it cheaper. Search term is cst tire 200x50

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Sorry, I should have been more clear. What I meant was:

“If you get Rockstars, you’re locking yourself into the 8in (and smaller) tire standard. I suggest getting 5-stars, which work for the 8in (and smaller) tire standard as well as the 9in (and larger) tire standard.”

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AliExpress is honestly the best place to find tires, particularly if you just care about price.

Ordering tires from AliExpress is always a gamble, because you never know what you’re actually going to receive. The way that tire molds get copied/resold/recycled/etc in china means that you can be looking at five tires that all look exactly the same (tread pattern, markings, branding, etc) but which are made by 5 different factories, with 5 different rubber compounds, and 5 different levels of quality.

Still, it’s probably the best we’ve got (especially internationally) and you’ll have a good experience more often than a bad one. It helps to order directly from links that other people have ordered from.

Check out the pneumatic tire compendium thread

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So I edited it a bit.

DECK: MBS Comp 95 Silver Hex
TRUCKS: 2x MBS Matrix III CNC Truck System 12 x 420mm Black
: 8x MBS MATRIX III TRUCK/DECK SCREW 25mm
WHEELS:
HUB: 4x Disk MBS FiveStar Hub
TUBE: ATBShop Mountainboard Inner Tube9 inch 250x50 Standard
TIRE: Trampa 9 inch Mud Plugger Tyre
BEARINGS: MBS Bearings 12mm*28mm (8pcs)
MOUNTS: 2x MBS MOTOR MOUNT ARM
: 2x MBS MOTOR MOUNT CLAMP M3
PULLEYs:
ENGINE: 2x Flipsky motor pulley 16T 8mm round shape (I’ll have bigger pulleys made)
WHEEL: 2x MBS Wheel Pulley - HTD 5M - 72T
: 10x MBS PULLEY SCREW - M4 x 65mm (Fivestar)

MOTORS: 2x Flipsky BLDC Belt Motor Battle Hardened 6384 140KV 4000W
REMOTE: Flipsky Screen Remote VX2
VESC: MakerX Go-FOC DV4s
:MakerX Bluetooth Module suitable for all series of VESC
BMS: LLT SP15S045-12S Li ion 100A
CELLS: 12s11p Tenpower INR21700-40TG 4000mAh - 35A
CHARGER: LLT Li Ion 14s 58.8V - 5A

1488$ with shipping

SPOTWELDER: kWeld kWeld – complete kit | keenlab 12V 90Ah car battery

Do you know the length of the belts? 475mm?

Please check it before I order it xd

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I use 460mm belts with 16t-72t pulleys on matrix 2s, 8 inchers, and idea mounts.

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One way to estimate belt length is to use a measurement tape.

Any reason why you choose those cells? I’m not too familiar with those. (Molicel P42a is popular).

Make sure you change your charger to 12s if you’re planning on using a 12s pack.

Any reason why you chose Dv4s instead of Dv6s?

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BMS’s are usually wired only for charging, so it cannot cut off your brakes. And actually a BMS cutoff could also blow up your ESC, so it’s better to run bypassed discharge. For charging only, the 100A BMS is very overkill. I’d definitely spec the BMS to accept a fast charger though because it really helps on long trips, but not 100A… Maybe a 50A BMS is reasonable, then I’d be comfortable charging up to maybe 40A, which is about what I trust the cells to take anyways (monitor temperature on Bluetooth though for that especially first time, and stop maybe 65C if it hits that).

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It might be worth the wait of the preorder to get EVE 40P instead of Tenpower 40TG, at 2.3kW for example the 40P will deliver 12.6% more energy which would be an extra approx 8km and they’re a little cheaper.

It will take you longer than you might think to actually get everything together and assembled and ready. I won’t tell you how long it took me but if you order the cells now they are unfortunately probably not going to be the last thing you need to ride.