I'd be concerned about buying a $1,300 battery-powered skateboard without the ability to replace the battery.
I'm not exactly sure how much it costs them to produce the battery, but it looks like single cells of similar LiFePO4 batteries are about $20/ea. With 12 of them, that's $240. Add maybe $50 for the BMS and $10 for the enclosure, and the whole battery pack is maybe $300?
It'd be a shame to have to replace an entire $1,300 skateboard after a few years when your battery capacity is reduced, when all you needed was a $300 battery pack. Hopefully "non-swappable" means something besides "non-replaceable".
I can't speak for them, but I'm one of the beta testers and am under the impression you'll be able to send in the board for battery replacement when it finally dies. It's just not user serviceable at all.
Alright, so what life time can one expect as a customer? And economically speaking, how expensive will a battery swap be?
The whole reason I'm asking is this 20 year old skateboard I have down the hallway, which is working flawlessly with every single component easily swappable :-/
They are using A123 (or rather B456 now) cells. You can tell this pretty easily by doing a google image search for "a123 cylindrical cells" and comparing the pictures in the blog post.
Also, a cool thing about skateboard is how components (board, grip, truck wheels) get swapped out as the wear out. Each component gets to live out its entire useful life (and then sometimes gets a second life as a spare). The transition between one skateboard and another can be completely gradual. One piece at a time until nothing is left.
User serviceable is a part of the culture. It would be nice if that could survive.
BMS PCB has high current input rings and a blade connector for balancing (like removable laptop batteries).
Bottom of case has screw lugs going up through high current input rings in PCB. Battery has ring terminals that are crimped & soldered to high current wires. The battery is in a protective casing that holds mating balance connector and injection molded features keep the high current ring lugs in place.
Battery drops into board, high current rings go over lugs and balance connector engages.
Rigid plastic goes over the top of all this (bottom when in riding position) with silicone seal around the perimeter. High current lugs go through the cover. Special ratcheting thumb screws tighten down the cover using the battery lugs as a mechanical connection while also pressing the ring connectors into the BMS PCB. Conductive grease on the PCB helps keep out water.
Battery would be 100% rigid, no dangling wires. Installation is two lugs, drops in, can be done by hand. Battery should come with a protective pouch or have integrated flip-over cover so it can be dropped in a messenger bag etc.
Solves I think all the issues, including avoiding costly or underperforming connectors, environmental sealing, ease of use, and the expensive BMS does not need to be attached.
I emailed them something to this effect, since they asked for input, though it sounds like they've purchased battery packs already.
Plus they may have considered this, it sounds good but I know production high current battery stuff is really tricky, I've looked at the area quite a bit.
It sounds like their decision was justified, but it's too bad they settled on a non-removable battery pack. It would be nice to carry a spare battery with you if you were planning a longer ride.
My thoughts exactly. I wouldn't mind carrying a spare in my backpack for longer rides with friends or SO on weekends. In this state, the board is limited to be a commuting tool for me.
For the days I don't feel like riding a motorbike, I guess I'll keep using my regular $100 skateboard + train combo.
I hadn't heard of this, but it is very interesting to me. I couldn't skate to save my life, but for my capstone course, in our brainstorming sessions I had the idea of doing an all terrain electric powered board on wheels.
My initial intent was actually for carrying stuff for me. The idea came one of the many days that I was carrying a huge laundry bag to the laundry store a couple of blocks away. If only I had something I could just place the bag on top of with wheels. Then I thought it could also carry my backpack to school everyday, groceries, etc. Maybe I could tie a surfboard-like leash to it, and it would have a sensor attached that upon pulling it would know which direction to follow me on. The possibilities for my laziness are endless! Anyways, we ended up going with another idea, probably for the best, since the kinda board I was thinking off was probably out of the scope and time we had for the course.
Looking forward to how this goes. Best of luck to all involved.
Longboarding isn't like skateboarding very much. I never skated before but earlier this year I bought a $60 longboard of Craigslist and used it to get to work. It was a bit weird at first but I got there about 25% faster than walking. On the way back it felt pretty OK and next day it felt natural. I skated every day where it was dry outside since. It's exhilarating.
If there was one thing about it that had a learning curve then it was pushing. Knowing where to put the food and how to evenly push off takes some getting used to but that's not even something you have to do with the boosted board.
It's weird that skateboards became popular and longboards took much longer to go mainstream. Skateboards are roughly like BMX trick bikes, cool but limited use and hard to learn, longboards are the road bike equivalents.
You mean shortboards. Longboards and shortboards are both types of skateboards - despite what some overzealous shortboarders will tell you. Hey at least you're not a fruit booter (I kid! I kid!)
I wonder why they used cylindrical battery cells. It looks like the battery pack on this skateboard could have been a lot smaller if they had used rectangular cells.
Since they're low volume, off-the-shelf availability is bound to be an important factor. I've only seen LiFePO4 cells in either soft pouch packages or hard cylindrical packages, and in this case the choice seems obvious.
Having ridden an electric skateboard a fair amount, I am excited for Boosted's play. They seem to have good solutions to two of my main gripes, which are weight (crucial for turning on the spot) and weight distribution (most boards have the battery pack in the middle where it gets in the way if you want to climb a curb). The battery pack still looks bulky, though.
One thing I am missing is the ability to disengage the electric motor from the wheels - as it is, you can't just free roll on the board if you want to save power or the battery is depleted; the motor is engaged to the wheels at all times. I guess it is a difficult problem since no boards seem to be able to do this.
(By the way, I used to ride five-six kilometers through downtown Copenhagen to work, charge at the office and do the same trip back at the end of the day.)
Is the board waterproof with this design? If it rains, can I still use it? Most electric boards I've found are not water proof and it's going to suck dragging a 15 pound lode stone when it starts raining.
A light splash won't hurt, but rain, puddles, and long rides over wet pavement will probably damage it. Wet roads will also be dangerous with the slick longboard tires and will corrode the bearings and other mechanical parts on the skateboard.
Why does nobody create an electric board that is waterproof with grippy wheels? I know it's possible if waterproof cameras and waterproof electric motors exist.
grippy wheels are tricky. You can't use urethane, but instead need to use rubber, which is a lot less efficient (heavier and slows you down too much as it takes too much effort to push with the deformation/heat loss). What you can do is buy grippier wheels and swap them onto your board (get maybe a 78 hardness compound) and get wider or bigger wheels too. Easy to swap out.
Regarding waterproof batteries, I agree entirely.
Instead of a remote control with buttons to control the speed/braking of the board...
What if it had a pressure pad on top so that it would accelerate when you put more weight on the front [1], and brake when you put weight on the rear. How would that control scheme compare (after getting used to it)?
[1] - The opposite arrangement wouldn't work, because it would create a feedback loop that'd drop you out of control. As you put more weight back, it accelerates, shifting your weight more back, accelerating even harder.
Zboards do this. In practice, I found the pressure pads extremely clunky. They were very sensitive to foot positioning, and rather all or nothing on the acceleration.
That would probably not work, since braking puts all your weight to the front of the board (which would then make it accelerate). Remote controls works very well in my experience.
A123 cells. 70A continuous, 120A burst, will stay at 3.4V until really tired. The bottom, with the array of holes, and the dead on power delivery numbers both give it away.
The batteries sound impressive. But I think statement
"...the battery needs to deliver thousands of watts of electrical power"
should read "hundreds of watts" -- the watt has a unit of J(oules)/s. Thousands of watts then refers to thousands of Joules per second. They later clarify actual power output as being a sustained 230W (or 384W for a 10sec burst).
That was the power rating for a single cell - the pack has lots of cells in it.
If you take hobby remote control cars as an example, I just bought an average lithium powered one that can do 45A at 11.7v, or roughly 500w to drive a <5lb toy car (very quickly). A 12lb skateboard and a 180lb rider will need several thousand watts peak I would imagine, at least.
Ahh -- makes sense. I haven't played much with RCs or batteries in general and typically think of power in terms of cycling. 1.3kW sustained for a skateboard is rather impressive. I'm comfortable doing 20 minutes at ~310W on the bike (more like 1.24kW once you account for cycling being roughly 25% energy efficient) and it's enough wattage to get you moving pretty fast.
Yeah 310 watts for 20 min on the bike is impressive, but accelerating at 310 watts isn't terribly so. Also remember that you've got gears to achieve better acceleration but that the electric motor has none.
If you're sprinting or accelerating hard you could easily be putting down 800-1000 watts or more.
Gears are only required because human muscles only work efficiently at pedal RPM. In cars, they're only required because the engine is only efficient at certian RPM.
Electric motors have a far greater range of RPM at which they can deliver a sufficient power.
A motor that delivers 700W attached to any gearbox will deliver 700W after the gearbox (minus losses). The difference is that shaft will rotate at different speeds and with a different number of Newton / Metres. A slow shaft attached to a 700W motor (at full power) will have more torque than a fast one.
It sounds like you're saying "Electric motors are less dependent on gearing because torque goes up as shaft RPM drops, so you still get 700W of usable power at the output shaft regardless."
If that's what you're saying, you're making several false assumptions and your statement is incorrect (because electric motors DO have a medium high RPM range where they are much more efficient than when near stall). Although it is true that (for some but not all types) of motors the stall torque is very high, that uptick in torque does not and cannot rise high/fast enough to balance the loss of work output caused by choosing a gearing that results in a slow motor shaft RPM. Recall that work is force over distance. A completely stalled motor is doing no work yet consuming prodigious amounts of power (which all goes to waste heat). In order to produce "700W of mechanical power into the gear train", a motor in a stall or very near stall would have to produce infinite torque, which is clearly impossible. Furthermore even if you consider, not a stalled motor shaft, but one turning below optimal RPM, you don't always get twice the torque when you halve the speed, you get maybe a fraction of that. So there's still a power/efficiency curve. Finally, a motor that is turning at an RPM significantly slower than its optimal rate is usually drawing much more power than it will for the same input voltage if running at higher RPM, so looking just at motor RPM vs torque at the shaft as a measure of output power ignores the important fact that you're putting a lot more electrical energy into the motor to get that output.
The only way in which your comment makes any sense would be to talk only about torque and say that for most types of motors, if the motor has enough torque to turn the drivetrain at operating RPM then it will almost certain have enough torque to start the drivetrain from a dead stop. So the motor doesn't necessarily need changeable gear ratios in order to get going if you ignore or amortize the energy wasted getting up to most efficient operating speed.
I need to spend as much time writing articles about the tech behind GridSpy as Boosted boards write about their tech.
Not only is it fascinating, it's great branding and marketing collateral. I wasn't sure I wanted a boosted board when they ran their KickStarter but I sure am ready to buy now.
That was an awesome write-up. Incidentally, these guys have designed the ultimate BattleBot battery pack. Send the enclosure specs to a Ti shop to get a Titanium holder made and we're talking serious durability. Almost perfect sweet spot of power capacity too.
Very sexy build photos!! I asked on their post, but I'll ask here too: "How about LiFePO4 batteries instead?" They're slightly lower energy density, but much safer that LiPoly. It's the type of batteries we preferred for big robots...
I think you didn't read too closely - that's what they chose.
>Cells
After realizing the inherent risks in some lithium chemistries and finding it difficult to source low volumes of high-power cells, we decided to use a different lithium-ion chemistry known as lithium iron phosphate (LFP or LiFePO4).
I love the effort that Porsche is putting into their engines, but wouldn't it be better to cut costs and bring the price down to compete with Hyundai? :)
Not hating on the zboard, they're just different markets.
I'm surprised & impressed by the power goals. That board, at "thousands of watts", delivers at least 3hp peak. I've ridden old heavy motorcycles with less.
Yeah, electric is really amazing for high power stuff, I'm realizing. It's hard to do, but the simplicity in the end of battery + motor with just electronics doing the rest means we can get some pretty amazing form factors out of electric things.
Since I was young I have dreamed of a "boosted" snowboard, with a snowmobile-like tread that came down the middle and would accelerate me in slow areas. The weight and noise of an internal combustion engine would have been prohibitive, but clearly we're getting to the point where electric isn't so bad.
If I'm doing snowboard runs all day though, I want to show up with a handful of battery packs and run through a few in a day.
The same would be fun with Boosted. Not being able to replace it means I can't buy a handful of batteries and take them somewhere for a day of uninterrupted riding up and down my favorite hills.
Charge dead packs in the car while you ride and with a few packs you can manage a continuous day of fun. That's not possible with non-removable batteries, and customers willing to pay for all that are good customers to have and indulge.
If I have a fully charged board and 5 friends, I feel like "OMG look at how cool my $1300 board is" is going to turn into "oh it died, sorry guys, more fun tomorrow".
I think that even if people don't buy the spare battery, knowing it's an option will help them feel more comfortable with the $1300 purchase. If the current range falls just short of what you need, an inability to simply buy a second battery to keep in your pack is going to be pretty upsetting. And always being able to keep one topped off at home means that after your commute you can still go out and enjoy your board.
An electric snowboard would probably be less compelling. Batteries do not like freezing cold temperatures, and a little 2-stroke could fit in a very small weight profile.
In a downhill situation, you could always do some regenerative braking to recharge the battery! No fiddling with extra packs, or futzing with battery electrodes with big gloves on...
An electric kicker on a snowboard would be great, since it would be easy to keep up with skiers on long traverses. On the other hand, the extra weight is terrible - expensive snowboards use exotic composites to be lighter, and ounces matter when they're out on the ends of your feet.
If RC Monster trucks can have replaceable battery packs, I imagine board vibration more than moisture has to be pretty severe to warrant permanent connections.
Sounds right, 9v batteries aren't about current, never were. They are about voltage, that's even why they have the voltage in the name unlike basically every other kind of battery. Inside though, they're just coin cells in rolls. Cells are 1.5v each, so you need a stack of them to get to 9v. You wouldn't expect a stack of coin cells to put out a lot of current would you?
I think a lot of people think voltage means power, so the 9 volt battery probably sounds much more powerful than a 1.5v AA, but they don't realize the 9v has a bunch of smaller cells and the internal resistance is a lot higher, reducing the current output capabilities. I had a guy tell me one time I should hop up the strength of my walking robot by replacing my 6 AA cells with a 9v. :)
I know you're joking, but keep in mind that the metallic object that "polevaulted" into the Model S battery pack did so with ~25 tons of force. On this board, you're just going to get thrown off.
I'm not exactly sure how much it costs them to produce the battery, but it looks like single cells of similar LiFePO4 batteries are about $20/ea. With 12 of them, that's $240. Add maybe $50 for the BMS and $10 for the enclosure, and the whole battery pack is maybe $300?
It'd be a shame to have to replace an entire $1,300 skateboard after a few years when your battery capacity is reduced, when all you needed was a $300 battery pack. Hopefully "non-swappable" means something besides "non-replaceable".