Ah yes, the flex. And its a dropthrough. That is what I like about the Dervish. If I keep my components close enough to the trucks, I think I might get away with it.
If worst come to worse… You can always mount the trucks on the bottom and even add risers.
Today was battery day. Considering the fact that I want to use ‘fragile’ Lipo’s and the Dervish is quite flexy, I spent some time jumping up and down on the board in my garage this afternoon. 35mm thickness would be the absolute max and in that case I would need an enclosure capable of withstanding scraping the pavement when I max the board out, which I WILL do when carving, I’m not the lightest of riders. 25mm max would be ideal.
Voltage: I think going with 12S makes the most sense as the current will be lower and the resistive heat losses will be considerably less. With 12S, the 190kv motor, 90m wheels and a 15/36 reduction the calculated theoretical top speed would probably be too much for me but if I’m not mistaken the VESC will let me limit the motor RPM’s to a comfortable level. Am I right ?
So I went onto the Hobbyking battery selector and it turns out only 4 x 3S would allow me to keep the thickness under 25mm. At least 5000mAh should get me far enough. Theoretically a dual R-spec 6355-190 setup would be 4800W installed power. At 44,4V the corresponding max total current would be 108A but I’m guessing that would be peak so I think continuous discharge rate for the 5Ah Lipo’s should be in the 10 to 20C range, not higher. AND I can limit the battery current in the VESC anyway right ?
This query returns 5 options for the EU warehouse:
- Multistar High Capacity 3S 5200mAh Multi-Rotor Lipo Pack Cheap, light and compact. What’s not to like about these ? Only 10C but if I read @okp’s Vanguard thread correctly I could get away with these.
The next three are very similarly priced, have 25C rating and have more or less the same dimensions.
Finally there’s this one, which I don’t really see the advantage of using, its expensive but it can be charged ad 5C, which my chargers won’t do.
To conclude, I think I’ll risk ordering 4 of those cheap Multistars, unless any experienced users here on the forum have other recommendations ?
1 Like
I have used the Zippy flight max on all of my builds for over a year now, I have put over 500km on them and they are still going stong. the minimum I have used is 20C and there have been no issues so far. I think as long as you care for them properly they will be fine. lipos are great batteries just not idiot proof.
If I ever buy lipos again ill pay the premium and get the better ones, the zippy flightmax have let me down before.
That’s right @trbt555 . RPM limits on VESC work perfectly. I’m using this feature now as I get used to my build and don’t need to hit its top speed. This way I can test things without any worry. Remote signal drops? Enclosure falls off? Motor wire unattaches? NBD cuz I’m only going 12 MPH!
I made some progress today. This week I happened upon these lunchboxes which turned out to be perfect for my build. They’re flat (33mm), they have rubber seals and reliable latches and they’re quite strong. I temporarily mounted them on rubber bushings using M5 bolts through the deck. I drilled all holes slightly bigger to have some play to account for the board flex. I pushed a few times around the block and took a few descents carving, the mounting seems te be rock-solid.
I also made a cutout for the anti-spark loop key:
I’m currently waiting for my fuse to arrive, after which I’ll be able to mount & wire the batteries into the box. I did go for the Multistar batteries after all, we’ll have to see how they hold up once I get the motors & VESCS.
7 Likes
those boxes are perfect! great find… i remember my countless hours of searching for the perfect pre-made boxes… walking around shopping malls looking like a box zombie… i think you nailed it with these!
1 Like
those are some pretty nice boxes there. how are you going to wire it? battery in one box and VESC in the other? also are you going to remove each battery for charging?
Yes, batteries up front, VESCs towards the drive side. Because the lids are so easily removed, I’m keeping the batteries in the box, fixed with velcro. I already own two chargers so I’ll parallel charge 2 x 2 packs overnight.
1 Like
Today I put the power meter in the drive-side box. I like easy access so I didn’t mount it to the lid but mounted it to the bottom of the box on a riser to bring the display up to the right level. I wasn’t happy with the look of the display in the cutout so I transplanted the original bezel:
This week I’ll be receivng my fuse and then I’ll mount the boxes and wire them up. Then comes the countdown to the November batch of Vesc…
4 Likes
@trbt555 I ordered one of these lunch boxes as a replacement for my plastic screw-organizer enclosure that recently failed, thx for the inspiration! I made a flat spot on the bottom of my deck with epoxy. It also eliminates flex in that area (which you don’t want, but I prefer). Are you going to line the interior of the box with anything so that it doesn’t facilitate shorts? You mentioned some rubber bushings around the bolts but it also looks like there is a layer of black rubber\silicone between the deck and the boxes; is that a full sheet of rubber?
@treenutter No, I don’t have anything like silicone inbetween, it just looks that way in the picture.
I’m using plain rubber bushings with a metal washer in them like these:
Here is a potato-quality close-up of how the box is mounted:
No need to line the interior to prevent shorts, the boxes are plastic. I’ve found a way to avoid having M5 bolt threads protruding into the boxes too. I’ll post pictures of that later, I’m short on time at the moment.
2 Likes
I really like that design of the board, thumbs up.
The boxes are a good finding, but have the question if the dimensions “255 x 170 x 33” from the website are the inside of the box? Because than there will also 3 Multistar 5200mAh 4s Lipos fit and there is some space for the Vesc and the Turnigy wattmeter, so with an single motor one box is maybe enough.
I currently have 4 x 5200mAh 4S Multistars in one box and there is very little room left for much else:
2 Likes
Sure you have 4 x 4s? So that would be a 16s Lipo together?
I think you are using 4 x 3s. 
The 3s are 142 x 49 x 22 and the 4s 142x49x29.
@hexakopter Yes you’re right I wasn’t paying attention when I posted… I measured the boxes up for you. Inside dimensions are approx. 233x163x30mm.
Thanks a lot for measuring it. So the 29mm high 4s Lipos maybe also work when it is possible to put the XT60s between them.
I am very new to eSkateboards and you are there first person who will use a wattmeter. The idea is great and a wattmeter is also on the way to me. But on an electrical point of view I am not sure if it will work with the regen of the VESC. I am not sure if the current in the opposite direction will maybe destroy the wattmeter? I really don’t know. Do you or any other person has tested that?
When the consumed mA are not displayed correctly, because the energy going back in to the Lipos that would not be a problem for me, but when it will destroy something that would be bad.