Yes, the fact that a capacitor can deliver all of its power instantly could result in some pretty spectacular welding in the event of a crash.
But I would assume a module like this would have a last resort fuse. Other than that maybe there isn’t a difference between them and LiIon packs.
Hmmm if it really is a capacitor and requires discharge to 0V to reach its rated capacity that will pose some pretty big issues.
The biggest one is that even if you find a way to maintain total watts with an ESC that can run to low volts or a boost converter system, the bus current will become enormous as voltage decreases in order to maintain watts.
So the most obvious answer to me if capacitor based batteries become the new norm is using super high voltage ESC’s but stay with normal kv motors, so the ESC will start off with a super low duty cycle and as battery volts decrease the duty cycle will increase until it no longer can.
Maybe we’ll end up with huge IGBT ESC’s just to make use of better batteries, and esk8’s will become lethal to work on in the chase for better performance 
Nope.
(Random google image)
Not quite. Imagine a battery that you’ve used with terrible voltage sag, where anything less then 50% charge in unusable.
Capacitors are even worse.
Powering anything off their output directly is very, very hard because of how varied the voltage output is- whatever you’re powering need to work across the entire range to use the stored energy
I didn’t watch anything😂
But it would totally make sense.
I’d wager that having power electronics integrated into the capacitor “battery” (to boost the output voltage to be constant as the battery drains) is required for them to make any kind of sense
Power electronics add mass, complexity, inefficiency, and cost compared to a chemical battery. (Much, much, much more complicated then a BMS)
Not to mention the engineering challenges of powering a motor controller (more complicated then a simple resistive load) and to be bidirectional(regenerative braking). Probably doable from an engineering standpoint, but adds more cost and complexity.
Ha! True. Would love to see a crash test.
screeeech
crash
bzzBANG
Not sure this is something a fuse could protect against. If a crash caused physical damage to the battery (ex. dented a cell), shorts the two capacitor plates. The high current density This forms plasma, which is even more conductive.
In human timescales, the pack instantly discharges all the energy (this is colloquially called an explosion).
Lithium ion batteries store their energy chemically. The chemicals can only do their chemistry so fast. An internal short causes a bad day, but only because the cells heats up and catches fire. This takes time, so is more “bonfire” then “explosion”
Similar problem to high pressure hydrogen fuel cell based transportation.
I’ve played around with capacitors a bunch.
Made a 400V 10mF bank from salvaged capacitors.
Used it to start a couple bonfires.
Being shorted in the video is max charge. Energy storage of 0.8kJ, or about 0.22Wh
At least 1000x time less less energy then you need to store for a practical EV.
Wolfram alpha makes my point;
The more I think about it, the less capacitor based PEV’s makes sense😂
Very curious what cap tech they’re teasing
One thing I noted from the video that @Battery_Mooch posted was that they are able to change the peak voltage of the cell. So in the case of the video it was charging to 4.2v but that was solely for the demonstration.
So in theory each cell could be a much higher voltage and the pack in Series could accumulate that leading to more usable capacity?
Say for instance (pulling numbers out of my ass) you could make each cell 42v, so an 18S would be 756v so even at 10% that’s 75 volts. If you could get 1A out of that it’s enough to limp for a little while.
Yes, you are correct, though I did find a comparison of Lead Acid v LiIon that demonstrates what I was getting at.
Granted of course that Lead Acids are shit batteries.
I’m choosing cells for 1s20p future onewheel build. (swappable battery)
Right now Nkon has Reliance RS50, Tenpower 50XG, Ampace JP50.
I heard some tabless cells had self discharge problems, was it only for EVE?
All these tabless battery companies seem pretty new to me. And there’s very little data on actual PEV performance of production cells. I know that Begode is planning to use RS50 in their wheels.
So I’m leaning towards RS50 (lighter) or 50XG (gonna be cheaper cause I don’t have to buy 50 of them).
Well for now I only have the motor, foot sensor and BMS. So it would probably take a few months till I get to the battery. Should I wait for 6ah cells like RS60?
ANY cell will have those issues with the lower grade ones.
It wasn’t an EVE issue, every model number of cell we can buy has huge numbers of low grade examples of it being sold. I tested multiple red and green-wrapped 50PL’s and they only lost about 0.001V/week, astoundingly slow self-discharge.
Make sure you buy from known trusted vendors who will tell you their return policy for fast self-discharging cells (and what the “leakage rate” has to be for a return).
No matter what is coming out and when you shouldn’t buy cells until you need them. Otherwise they are just sitting around, slowly losing performance (time-based “calendar aging”).
Thanks!
My source is Nkon (+forwarding, so no returns possible).
Yea makes sense, I bought molicels p45b, and then sat on them for a whole year till I had the time and energy to build the new skateboard last month. If I waited to get the battery last, I’d get some 5ah tabless instead.
Is it a bad idea?
Original XR had 324 Wh. 20s1p 5Ah is 360wh. And I want to make a second swappable pack.
So it’s like twice the range of original XR. And I want to get the weight <=12kg.
And this is how I’m thinking to implement swapping:
No just a comment on the typo, 20s1p is very different than 20p1s 
Haha, I didn’t even notice.
