Hoping to built a fast ESK8 with no problem climbing hills

Like @Namasaki said, if you need a lot of current ( which you will need for those hills ), Li-Ions are not an option ( you don’t want to pull more than 10A per cell even if they are rated for 20A ). Well, they might be an option, but you would have to do like 10S8P pack which would be HUUUGE. It’s just so much easier with LiPos for those high-power builds thanks to their small internal resistance and shape. You just have to be more careful working with them and properly balance-charge them.

1 Like

Thanks @Namasaki and @IDVert3X will bear those things in mind. Though I want something easy to charge and carry around. How much power does a motor take in though? I’ve read some people say that motors don’t even take up to 30A unless really inclined hills. Maybe I’m understanding things wrong here. :sweat_smile: Sorry.

Depends on your weight, hill grade, wind, speed… You can calculate how much power you need using complex physics formulas, but to keep things simple: it can draw much more than 30A climbing steep hills. Prob. max. power you will EVER need is ~3kW ( really steep hill, 95kg rider, high wind resistance … dont ask me how I calculated it ), which is about 70A at 12S. LiPo can do that without any problems, 4P Li-Ion will have terrible voltage sag and heat up fairly quickly. But that is really the worst case scenario. Most of the time, you should be under 15A on flats. I cant really provide you with exact number coz there are so many factors… Also, I have never built an eskate before, I’m planning my build for early 2017 when VESC 6 and other cool stuff will be out. I have just got quite some experience with electrical engineering, high-current devices, batteries, electric motors in general and so on.

If you want something easy to charge, just use BMS with balancing.

I see. Really nice input man! Thought of stalling my built too, but these things just excite me too much. Anyway, probably need to do a little more reading on LiPo now. Haha. Really appreciate the help. Thanks!

1 Like

If you really want high performance going up hill. Consider building a dual beltdrive system with 6355 190kv motors and a 10s Lipo battery system similar to the build I did with 300a continuous capability Voltage sag on 12% grade is only 1volt That’s with a 188lb rider.

1 Like
1 Like

Quick question, will the vesc limit the battery discharge up to 50A? Because the specs say up to 240A for a few seconds or 50A continous. However some battery packs have a 40A fuse like the space cell and 80A like the Epower. Just trying to understand :sweat_smile:. Like if using a Lipo will give you more power, will it damage the vesc?

VESC pulls as much current as it needs, but you can limit it of course to something like 40A per VESC. If you use two of them, the load ( and so current ) will spread between them. Just don’t overload it ( you should not be able to fry it with two motors and correct configuration tho ). Battery pack rated for 50A is just NOT ENOUGH. You don’t want to pull more than 1/2 of the current battery is rated for. That’s why enertion puts 40A fuse on their “80A rated” battery pack. They know it’s real limits and rate it for 40A, enough for most people. For hill climbing? Not really. Just get something that can deliver 150A+ continous current, then you should be totally safe. Most LiPos can do that without any problem.

Multistar batteries are not a good option from experience. I use one for my high-power LED project which draws about 30A from 5.2Ah battery rated for 52A continous. It gets hot fairly quickly and voltage sag a lot. I would say it’s more like 4-5C than claimed 10C.

2 Likes

I agree with everything that @IDVert3X has said. That is why after some trial and error, I have ended up using Lipos 5000mah 60c. At 10s I’m pulling less than 10% of my battery’s continuous current capability.

1 Like

Thanks guys for the intel. It was really helpful! now i just have to find the right lipos. How much range do you get with a 5000mah anyway @Namasaki ?

Actual mileage can depend on many factors but for a ball park idea I usually got around 12 miles with 12s/5000mah/25c on a dual belt drive. I haven’t had a chance to do a full range test yet with my 10s/5000/60c battery. But the other day I went 7 miles on flat ground with some wind and still had 80% battery left. I have found that higher C ratings can have a very positive effect on range. Simply because of reduced voltage sag.

So guys, I’ve just ask Enertion about the space cell. They said that the 40A fuse could be exchange to a higher Amp fuse. But only if it repeatedly blows (indicating you probably need more power right?). So, I think I can get more juice if needed in the future if I choose to purchase it. On the other hand, I’ve been doing some research on lipos. I was wondering if it’ll be alright for me who lacks the technical background and knowledge ( I’m a medical student :sweat_smile: ). I mean, I’ve read some threads (correct me if I’m wrong) that there are a few techniques for soldering certain apparatus. Something thats needed to connect the BMS right? Just a little paranoid here. Haha.

Connecting a BMS to Lipos is easy and I could walk you through it.

Your lipo set up looks really cool man. Are you still using the same setup? Any chance I can see your housing for the electronics? :grin:

Would really appreciate the help. Thanks to you guys I think I have a clear idea on what to and not to buy now. Will keep you posted if i need help with a Lipo setup. Too bad esk8 isn’t a thing in my country yet, still have to bare in mind the shipping costs :confused:

Trust me, space cell is not a good option for hill climbing board. There is a reason why it has 40A fuse. And you don’t want to draw more current through these cells. If you want to go with Li-Ion, go with 6P or even better 8P ( gonna be huge ). Otherwise there is still a LiPo.

1 Like

Thanks @IDVert3X. Been exploring some vendors. Should this be okay? Will it have significant difference from a 10s?

I don’t know this product, but if the numbers are real, aka it’s really a 25C pack ( 250A max ), it should be fine. 8S vs 10S? Not a big deal. I’m personally going to stick with 8S as well. 190kv 16/36 97mm should give me ~ 40kmh^-1

Those are some big wheels you got there bro. Haha. How much would you limit your power on your vesc? And how about heating? Will this cause the motor to heat up a lot?

Roads are terrible where I live, pavements are sometimes even worse… I would use 107mm flywheels if they were available at a reasonable price. I’m going dual motor and because I live in really hilly area, I’m going to limit each VESC to 40A. If you do the math, it’s ~ 1200W per motor for total power of 2400W or ~ 3hp. Probably never gonna use that much power as I’m pretty light person, but why not. VESC can handle it, motor can handle it, batteries can handle it, no reason to limit it.

And about heating? I don’t think this is going to be an issue with dual-motor even on really steep hills. Same goes for the VESC.

1 Like