Haha yeh, I always massively research / overthink / overplan / overengineer any project I work on. This is why I usually end up spending more than I need to, and taking longer than I should, but usually I do end up with a pretty decent end result so it’s not all bad
The area I live in is actually very flat in general. From my window there is a single hill, and it’s a landmark because for miles around it it’s all flat land. But then I also live near a place called cheddar gorge, which is an area with flat land, followed by a long sweeping/winding somewhat steep climb, followed by more flat land.
However much more common will be riding over short grassy areas like parks, as there’s a lot of those around.
So, going back to the original question, but assuming the use of Li-Ion for the moment - Would I be better off with S or P for the ‘light terrain’ use? Assume I can only fit 40 cells on my little board, so it would be 8s5p vs 10s4p.
I -believe- the 8s5p gets me more consistent power/torque on the hills/terrain, as well as less potential braking issues, while the 10s would get me a higher top speed… and that’s all?
What @venom121212 said. Get the 10s4p and motors with 170-190kV 1:4 gearing and 7-8“ wheels and you will have a great all terrain board with nice torque, good brakes, average range and good speed.
1:4 gearing is where I’m going (15/60T), and I was looking at the Maytech 170kv motors. I was also recommended the cheap motors from Dickyho, but I’m currently waiting to hear back from him about whether he has access to a sealed motor. May be overkill but it seems for around here sealed motors might be less likely to get damaged. (I suppose I could come up with some kind of motor shroud though to protect from grit/sand etc…)
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However one great side effect of todays discussion is that it is now decided that 4p will work for me. Which means I can start looking into and prototyping 4p battery enclosures.
So as far as VESC’s go, was the best bet to pick up two 4.12’s from ebay or similar?
Also for BMS, is the Dickyho waterproof BMS any good? Or is it required to get a Bestech for safety?
I have the sealed maytechs 6374 and they hold up pretty strong so far. If you decide to go that way, keep in mind they are a bit longer than usual 6374.
Regarding vesc, well you on a budget, so I think it’s clear for you that you can’t get everything you want.
If you get a Flipsky 4.12 or similar you will be limited to 35A max per vesc. After that they get hot pretty fast. Adding a heat sink can add some amps on top, but also add some extra moneys.
Next step would be a Flipsky 4.20 plus. Should be good for 10s without cut outs. After that you could go up Flipsky dual 6.6 or focbox, focbox unity, but that might be out of your budget.
Focbox Unity current price isn’t that bad, unfortunately it also doesn’t exist and probably won’t exist for several months.
Flipsky Dual would be my next bet potentially. But again you’re right it’s not too cheap.
Correct me if I’m wrong though (which I very well might be), but isn’t the VESC amp max based on battery amps discharge, and not the motor amps? And as the peak discharge of my pack would be 76A, then 35A per VESC ends up being about right? Not much headroom, but I’d probably find a heatsink version.
Your conclusion is right. The rating is based on the bat amps, not the motor amps. That’s why I said a hw 4.12 based vesc wouldn’t be that bad if you on a budget and anyhow don’t plan to hit it too hard. But well it’s never bad to run things somewhere in the middle of there capabilities than on the top or low limit. Oversizing in this case isn‘t that bad.
@shaman is working on a improved version of the hw 4.12 for a good price which could be an alternative for you as well.
But here is also the BUT that it’s just in progress and beta testing will start only in one two weeks.
Yeh I already read through the cheap FOCer thread last night haha. Was promising, but I’d like to be working on this now and hopefully be able to ride it over the summer months, and it’s looking like that won’t be ready until much later in the year unfortunately.
Dispite what some say lithium ion 18650 cells are nearly always safer. Nearly all have a current interupt device (CID), thermal fuse (PTC) and safety pressure vent on each cell! In fact if i understand the spec sheet correctly, you can short circuit a Samsung 30q, and it wont go bang. Within 20secs its current and voltage will drop to nil and its peak temp will only reach 100c.I dont think the same can be said for most Lipos. You can also individually cell fuse them, though theres debate on the benefits of doing so.
Also the advantage of running higher voltage is less current draw, my average current average is only 15a (Battery) on my mountainboard with 12s. Everything runs cooler. I think the consensus here is to stick to 10s max though.
I should add that when you put them in series and the voltage is over 30v the CID can arc when activated and the PTC destroyed if activated, im guessing this is why tesla fuse there cells. This research doesn’t seem to come up in forums.
A quick and dirty mockup of the space I have to work with. It’s… tight. I mean too tight obviously, as it doesn’t fit. The actual board is wider than that enclosure though, so I may just have to make my own enclosure that really gets to the edge of the board.
I know this was a while back, but since then I’ve gotten a bunch of my plans in place, and am at the point where I need to actually order some cells!
You’re right that 30Q and VTC5a are basically the same price now. Probably going to be fitting a 10s4p pack to my board. So would there be any benefit going for the VTC5a cells? I know I lose a little range, but don’t I also gain better braking and discharge? Though there’s only so much braking I could use before I get thrown off the board, so if the 30Q is already more than adequate at 4p then I guess I’ll go for them.
For an all terrain like you plan the 30q should be fine. With vtc5a you might have a bit less voltage sag, means you could still blast when you below 40% battery, but that’s just what I would expect from the specs I can get out of both cells. I don’t have a 30q pack, so unfortunately I can’t really compair real life performance.
And don’t worry about braking. You will have good brakes with either of them.
Further 3D modelling of cover designs. Though the NESE modules seem to be pretty strong by themselves, so I’m mostly aiming for splashproof and deflecting stones.
I may remove those spring-mounting loops for the nese, and instead mount the boxes using something like these.
Looks nice! What is the flap kind of thing? BTW, if you make the edges of the outer enclosure that thin, it’s going to chip.
BTW, In addition to the spring mounts, I have added 4P NESE style boxes that you requested to the thingiverse “thing”. There are 2 kinds of boxes: 1. It’s a single piece 4P+4P mount that is totally flat 2. Just a 4P mount with an incline end so that you can glue them together to make a 4P+4P box that better conforms to the curve of the deck.
They both utilize the vibration proofing standoffs. Couple of pics of each:
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2:
The flap covering the drop-through? I hadn’t gotten around to finishing the holes, but the idea was that it would be part decorative, part truck-riser, and part securing for the enclosure as it would have 4x bolts running through it.
It would mean that that section of enclosure could only be removed if the trucks were also unbolted, but I was going to try and design things so that the battery modules could be removed from the open end if needed, so that section of enclosure wouldn’t ever -need- to be removed.
Also trying to figure out how I want to bolt the stuff to the deck. I don’t want to have bolts going straight into the wood, as if I ever need to remove and replace components it might weaken the inserts and split the wood. Not sure. Was thinking of having permanently bolted-in mounting brackets, and then having the batteries etc bolted to those brackets. Might be unnecessary though. Also considering using the rubber vibration mounts, or just thick rubber washers.
Oh and the edge goes thin because it looks nice in the graphic haha. I may round it off a little so it doesn’t end up as a razor-thin edge.
Ahh awesome, I will take a look. However I notice the central piece is solid… but doesnt that need to be a continuous bar on the first pack in the series? (not describing it well, but here’s a picture)
The ‘8p’ bar at the bottom. I guess it can be done with a wire going around the pack though.
VESC - Probably going to get one of the newly updated Flipsky 4.20 Duals. Seems they’re (meant) to have fixed any capacitor issues now. The 6.6 would be better, but probably hugely unecessary for my needs, and not worth the extra $100. (or at least this is my thinking, by all means someone chime in with an alternative, especially if it’s cheaper!)
Remote - I want to have a fancy one, with the LED screen and all. Considering making myself a Firefly Nano. But in the short term, I should probably get a pre-made one so that I at least have something reliable for testing with. All the usual options though, I’m struggling to find for sale in the UK (at least under the names given on this site). Closest options are things like the Flipsky one for $50. Any thoughts/suggestions?
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