So, the Mellow Board looks really great except that (1) it’s not out yet, and (2) I can’t customize it (e.g., put it on 125mm trucks, for example). So I’m going the DIY route.
The idea is the following:
Get an Onan X2
Get some good hubs (I have Hummie Steel Hubs)
2 VESCs and a Switch (from DIYElectricSkateboards)
???
Profit!
So here’s the basic setup. Just flip the X2 over and remove a bunch of screws to get to the electronics. Don’t even mess about with the hubs.
This is the hard part. The board is in there pretty good. I actually gave up on the plastic wedges in favor of a mini crobar. Fortunately, it looks like I didn’t damage anything.
Now to somehow figure out how to get two VESCs in there…
Here’s the video. I think I fried my first VESC with a short, so I’ve only got one drive wheel right now. Waiting on a new VESC replacement with much anticipation!
maybe stick some lipos in as 10s2p will very likely not be enough power and you have little room. if you got 12s and 4mah or even 3mah and a high c rating things will really perform.
Oh whoops. I forgot to hit “publish” on the video. It’s up and running now.
The specs on the batteries are 4400mah, 159Wh. I’m only guessing as to the discharge rate (30A, maybe?), as I don’t know the precise cells, but I did pay extra for Samsung. The cells are strong enough to support the X2 (which actually has a good amount of power, it’s just the urethane is way too thin), but you can tell from the wiring that they don’t expect too much current flowing to the motors. I suppose I’ll give it a go when I get my replacement VESC. If it doesn’t work, I suppose I need to rebuild my 3 battery packs…
I’m actually not sure if I shorted the VESC or not. I saw the LEDs, connected the motors, then nothing. Not able to do R measurement on the motors, and the LEDs went off. When I looked, I noticed about half a mm of bare metal on my bullet connectors to the motors, so I assumed that caused it. Lessons learned.
I should also say that I don’t really need performance. I could be fine with lower top speed and less incline if that’ll work with my current battery setup.
What a transformation… I bet you paid a pretty penny for the X2. Did you ride it before taking it apart? If so how did it perform? I was talking to them a while ago and they wanted like $600 or something crazy (compared to their last model)
I’m happy to sell them if there’s interest. In fact, if Onan doesn’t plan to add more urethane, I sent them an inquiry on this. I have a spare X2 complete sitting around that I might be willing to sell too. Otherwise, I might look into tinkering with Urethane next.
As for my experience with the X2, I was actually pretty happy with it. There were two issues: (1) when you start and stop a lot in the space of a few minutes, it might jump skip the slow acceleration curve and (2) the urethane too thin. I think I could work around the first issue, but there’s nothing I can do about the latter. The roads around my neighborhood are pretty crummy, so I rode it around the block once and my numb legs told me it was a no go. That’s when I started taking it apart.
That being said, it was super awesome on smooth roads. It’s quiet as hell and didn’t seem to be lacking in the power department (unlike my Blink S), though I expect the new hubs will have more power if I can figure out how to deliver the necessary juice. The batteries snap in real nicely.
Do you think it could be possible to get the plastic battery holder and trucks from Onan and put really good hub motors and fit in as much cells with 2 vescs and all the other switches and stuff inside?
I’m using hummie’s Paris trucks right now, which seem superior so I don’t think I’ll go back to the Onan ones. In addition, the Onan trucks have some nonstandard elements, so they wouldn’t work for non-Onan hubs anyways. Also, one of the main reasons I’m doing this is to get a viable modular setup on 125mm trucks for one of my other builds (http://www.electric-skateboard.builders/t/mini-rover-22-carbon-fiber-125mm-trucks-hubs-12s1p-vesc-x/12851).
As for getting things to fit, I took a stab at that today. Dremeling some steel like an idiot and getting metal bits everywhere. I had to spend more time cleaning my station that the work itself. Here’s a pic:
I went ahead and took my damaged VESC to see how it’d fit. I’m pretty sure I can get two VESCs in there now, as long as heat isn’t too much of an issue.
Worst case scenario, I’d move my switch to the battery back itself, but I think that by hard-wiring some connections, I can get it all in there. One of the bulkiest items is the XT90 splitter.
As for the battery, I think I’m out of luck there. I see the following options:
Figure out how to get Hummie’s hubs working on 10s2p. Maybe reduced speed/incline, just swapping out batteries earlier when voltage sag kicks in, etc… Maybe there’s something I can do to get it to work. I’m after a solid commuter, not a racer.
Move to different hubs or a belt drive system. I’d rather not go belt if I don’t have to, but if it’s what’s needed for low-current viability, then so be it. Maybe get a geared hub, to allow for better performance at low current.
Build my own battery pack. I think I could probably fit 4 more cells into the existing pack, getting an 8s3p for added discharge. Or get higher end batteries or go lipo.
Use my second X2. Hot swap both battery backs for a 10s4p. I don’t really think this is viable because of space on my deck.
Some questions I wonder if any of you know the answer to:
Do you think any batteries would work in 2p for Hummie Hubs? Or do I definitely need to be in 3p or greater.
can the vesc or other esc be programed to have as much power at 8s as 12s? Can you up the amps to the point ohm’s law will allow…up to what the resistance will allow? (assuming the esc doesn’t overheat and the batteries can put the amps out). a bit less efficient in the esc and wiring but fine?
I suppose that, looking to Mellow’s 7s2p setup, the answer is that an 8s3p setup is likely. If heat’s an issue, then perhaps cooling could be the solution. I suppose it’s just a matter of the right configuration, the parts, and some experimentation. Time to get a spot welder, I suppose. I can then do a 10s2p vs. 8s3p comparison and measure my results. Maybe before then, I can measure just how bad the outcome of having 10A per motor is…
Interesting. On rough pavement, it was unusable for me. I prefer my old Blink Hub to the Onan X2, slower speed and everything. At least I could feel my legs afterwards.
Those were cuts of wood dipole which happened to measure just a hair over 26mm in diameter. Man, those batteries are HUGE. However, I don’t think the energy density is good enough to fit inside such a small pack.
I’m thinking I’ll build a few of the above, depending on what I can get, and also test them against the 10s3p’s I’ll be getting from the @JLabs group buy (thanks!).
As an aside, I took apart the hubs today. Here’s a peek:
It looks like my Onan X2’s come with only 11mm of rubber, which is perhaps why things are a bit bumpy for me. There’s some new rubber available, so I suppose I’ll try that out before I sell off my existing electronics (since it could turn out this could be the fix I need for my unit).
