eMTB, 12s, Turnigy D5035-125KV, Turnigy SK8-ESC

Could anyone please sanity check this setup? I’d like to convert my MBS Core 94 mountain board. These are the components I’m considering (single drive):

The batteries would be wired both in series and parallel giving 12S2P, 13200mAh. I should get 132A constant discharge from that, which is more than enough for the motor and should be sufficient even if a second motor is added later (the Turnigy D5035-125KV takes 45A).

I should also get 586 Wh, which, as I understand, should provide ~25-30 km range on a MTB.

For the mount, I’m considering one for MBS from Idea that has 4.8:1 gear ratio. On MTB with 8 inch wheels that should give me 37 km/h of max speed (http://calc.esk8.it/#{“batt-type-lipo”:1,“batt-cells”:12,“motor-kv”:125,“system-efficiency”:85,“motor-pulley-teeth”:15,“wheel-pulley-teeth”:72,“wheel-size”:200}|).

Does this all sound correct?

This is my first build. I want to start with something on a low budget and upgrade later. Might add another drive and/or get a better ESC. Even though this is a MTB, I’m mostly going to take it on road. More about that here: http://www.electric-skateboard.builders/t/mtb-with-easy-to-add-remove-motor/49317/14

I’ll greatly appreciate any suggestions. I realize this may be too much on a low budget.

The Tunigy VESC doesn’t look too promising. It’s just too cheap for a VESC and i think i never heard of someone using it for a long time without any errors. You should at least get a regular 4.12 ESC, or even better a Focbox or similar design. Think about it this way - if this VESC fails after a while you lost 70 Bucks and have to buy another, better vesc for above 100 bucks anyways. You should just go for the better VESC in the first place.

The motor should be fine if you don’t have to climb any steep hills on you way, same goes for the batteries.

Maybe consider waiting a bit and saving up to get components that are already approved in the esk8 community. Like FocBox, SK3 Motors and Zippy Lipos.

Thanks. This is helpful. I don’t really need to save up. I just prefer not to spend too much on my first build. I want to make sure I will actually use and enjoy the eMTB before I pour a lot of money into it. On the other hand, I don’t want to buy shit either (even if it’s cheap).

I’ll take your advice regarding the ESC/VESC and avoid the Turnigy SK8-ESC.

I chose the motor because it’s sensored, which seems like a good feature. The Turnigy SK3 motors are about the same price, but with no sensors. They have more power, but 2 kW of the one I chose seems like plenty and it has very high KV so torque should be good. It may not be super fast, but I don’t mind that. I prefer not to kill myself anyway. :slight_smile:

Regarding the battery, what problems can I expect from buying these cheap ones? The Zippy are not that much more expensive and in fact, I could live with a little bit less of a range, so maybe I could get Zippys with less mAh for about the same price.

I recommend you to read another eMTB build threads. A motor is very small and that vesc will probably die on the first hill in MTB use. I recommend using car esc and 6s system if you want a budget build. But first, read a lot. However eMTB and budget really don’t belong in the same sentence.

I have actually read quite a lot already. The problem is my use case is quite a bit different from everybody else’s. People usually don’t build a MTB to take it on the road. I guess my config should actually be closer to what people use on skateboards.

The Motor isnt as small as you think, it’s just the stator size in the measurement instead of the rotor size you usually see. In the link it says 6376 i think.

Alienpowersystem sells the cheapest sensored 6374 motors that i know of, you might want to check those out. For on road use and not so many steep hills FOC would be enough, no sensors necessary. But it still feels nice on start up of course.

Low kv is related to more torque at the same amps compared to high kv. High kv motors can handle more amps but also need more amps for the same torque. Just to clarify.

The Problem with multistar batteries is that they are more of a 3C in the real world. Read that somewhere on endless sphere a while ago. They are only good for really low current applications so i would advise against them generally. Zippys are the mainstream Lipos from hobbyking and sufficient for most esk8 applications with regular motors, graphene would be high end for either really big low c packs or small high c packs.

Is the turnigy esc not sold out in the US?

From Hobbyking motor specs: Can Diameter C (mm) 62.50 Can Length D(mm) 54.80

It’s fine for a flat environment, but like Der6Finger said you should check out APS motors. Those are very popular and affordable. I would use 170kv 12s or 260kv 6s system. The last one is cheaper option.

Yes, it’s currently sold out. It might still be available later, no? Anyway, looks like people here don’t recommend it.

I’ve been waiting for it to come back for a little while, I contacted them and they didn’t know anything about new stock so it seems it may not

Multistar batteries are not known for good performance. So expect some voltage sag. Consider buying 30c+ batteries :wink:

This is exactly me 2 years ago :laughing: I think we have a similar story, i also started with landkiting and then wanted to convert my board to an e-mtb on a low budget. I’ve paid a lot for parts for selfmade motor mounts and chain drive but in the end it didn’t work and I lost a lot of time and money. I bought different vescs until I realized I need a proper one and run in FOC. I bought different motors and drivetrains, I spent so much money that I’m afraid to tell how much it was :rofl:, all started with a budget build…

Long story, what I mean is don’t try to cheap out because you WILL upgrade and loose all the money from the “cheap” parts which is very expensive. If you don’t cruise in wet dirt or very high grass a belt drive is fine, the mounts from @idea are nice. Also like @Der6FingerJo and @Grozniy mentioned, don’t buy these Multistar Batteries, go for Zippy’s or Graphene, they are much better.

My advice: buy 2x 6374 motors (Alien are fine or the sealed maytech which I use now but they are double in price) and when you are based in US get 2x B-boxes, you will never ever have to upgrade and start with a proper reliable running system, I would call this the REAL low budget build because that’s it, no upgrade needed.

BTW since I have my e-mtb I enjoy it so much that I didn’t kite for almost 2 years, the wind is in my thumb and controls if it’s gusty or just a little breeze :rofl:, it’s amazing.


@pat.speed HobbyKing just responded to my question and said “It could be out 4-6 weeks”. Just FYI. I’m no longer considering it as an option.

Thanks everyone for responses. You guys are super helpful.

@rich Love your wind control analogy. :smile: Does that also work for sending the kite and jumping? :slight_smile:

What you say makes sense to me. I’m rethinking this upgrade idea. I guess I’ll go with good quality parts, but I’ll stick with a single drive to keep the costs reasonable. Adding a second motor is then a straightforward upgrade and it’s adding rather than replacing.

Plus, 2x 6374 really seems like an overkill for on-road use. These motors are around 3 kW each so that’s 6 kW for a dual drive. In my student times (long long ago), I used to have an electric scooter with 1 kW motor. It ran on 32V lead acid batteries and it was heavy as hell – like 40 kg. I could still make over 30 km/h on flat road and it even climbed steep hills (not particularly fast, but it would get there, eventually). 3 kW ought to be enough for anybody. :wink:

Plus, my wife will kill me if I spend 1000 EUR+ on a mountain board. I’m still under suspended sentence after “investing” into my kiting gear.

BTW, I’m in Europe, so I guess it’s ESCape for me if @stewii can get enough so that there’s one for me.

Well… this knob is missing on the remote, have to talk to the manufacture :laughing:

If you buy 1x ESCape and 1x 6374 that would be perfect, you can always upgrade with the same parts without loosing money. Just one thing to consider. I would buy a motor mount where you don’t need a crossbar otherwise you would have to mount both motor mounts including crossbar even when you only use 1 Motor. The new aluminium mounts from Idea can be mounted as single mount, too :grin:.

And next year if you want more power you can invest another 250€ (ESCape & 6374) and have a full powered MTB (and probably less struggle with your wife :wink:)

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Use high wind (aka full throttle) and a ramp? You may be missing a soft landing feature then though. :slight_smile:

So, I’m taking everyone’s advice on the battery and considering 4x 8000mAh 3S1P 30C (https://hobbyking.com/en_us/zippy-flightmax-8000mah-3s1p-30c-lipo-pack-xt90.html) to connect in series. Now, I would greatly appreciate some advice on wiring and charging. I’d rather avoid using BMS for the battery pack. It seems complicated. I’m thinking of putting XT150 connectors on all batteries. That makes connecting in series very easy and I would be able to take it all apart for charging. Then use this guy (https://hobbyking.com/en_us/imax-b6-dc-charger-5a-50w-copy.html) together with 2x 3S to 6S BMS adapter (https://hobbyking.com/en_us/6s-battery-pack-balance-charge-adapter-lead.html) for charing. I would only be able to charge two batteries at the time, but I don’t mind. Making charging less of a hassle is a part of my upgrade plan.

For connecting the battery pack to the ESC, I would use anti-spark XT150 connectors (https://hobbyking.com/en_us/7mm-as150-anti-spark-self-insulating-gold-bullet-connector-2-pairs.html). Each of the two terminal batteries would get one so that I don’t need any adapter.

Does this sound like a good plan?

Looks good, but the charger only does 50W. Your pack is 355 Wh, so more than 7 Hours to charge it from zero to 100 with balancing. If you can life with 6 hours of a small fan going berserk in the corner of the room it’s fine, but i would recommend a ISDT Charger and a used server power supply for charging.

It’s kind of the same thing in terms of being “cheap” but not as severe as with the ESC. Your charging setup would be 20€ for the charger and somewhere between 10-20€ for the power supply. An ISDT Q6 would be around 50 bucks with a <20€ power supply. Or just get 2 Imax Chargers for the beginning and a 100W PSU.

@DanSkates is the expert for ramps, maybe he is thinking about a small kite for a softer landing when he builds a mega ramp :laughing:

Or 3x 4s Zippy’s or 2x 6s Turnigy Graphenes 8Ah :grin: About charging, this will be slow and annoying. I’m a fan of BMS and could help you with the wiring, it’s not really complicated You could get a 12s BMS for 25€ plus a charger between 12-25€ (2-4A) on aliexpress and you can charge the whole battery at once without taking it apart plus it is much faster. Can provide the links if needed.

XT150 is kind of overkill but why not. You could use XT90, 4mm bullets or 5.5mm bullets.

I also have a 6s HK 6A balance charger which needs about 10 hours for 12s8Ah (5 hours for each 6s). With BMS and 12s charger it takes 2 hours :sunglasses:

Don’t listen to @Der6FingerJo, he doesn’t like BMS :joy::rofl::laughing:

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Don’t listen to @rich, he hates clean and simple charging solutions :joy:

But truth be told, a BMS is still a valid way to go. Didn’t think of it because i don’t really trust them with Lipos. I have no bad experiences or anything, just nut my way of doing it. Especially since i already had a nice 500W ISDT Charger before building my first board.

If you want to dig into this i’m sure you could find a cheaper solution than an ISDT charger.