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Alj

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About Alj

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  • Location
    Seattle area
  • EUC
    KS-18XL

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  1. The current will depend on the energy stored (i e capacitance), and film capacitors will have much smaller value meaning they will take much less current. the particular issue here is a combination of 1. Improper capacitor location. Electrolytic caps do not like high temperatures (no more than 100C) and they should not be mounted on top of hot components, such as MOSFETs here 2. Cheap capacitor brand (low quality) 3. Need to specifically pick capacitor with low ESR for high current applications. Also why would it be such a big current there flowing through the caps? If you just short charged cap it will not explode like this. Most likely the problem is overheating due to suboptimal PCB design and poor heat dissipation.
  2. Yes that naturally should be proportional... Capacitance depends on foil surface which defines max current. But series resistance, overall quality and ambient temperature are all factor into it as well. I never save on a good cap brand (elna, nichicon) because budget brands not so much cheaper but quality is usually "just enough so they buy", they just don't last very long, esp if you put it on top of piping hot MOSFET. Good example is budged LED light bulbs, which suppose to last longer than incandescent ones but they don't because they soon lose electrolytic cap which goes bad due to poor quality and hot temp. Also actual ripple current will depend on a capacitor value. I e the bigger the value the bigger current there will be and also the bigger current cap can take, so its not like "put bigger cap and problem solved". it is rather "put better cap with lower ESR into cool location" thing.
  3. From what it looks, a cap exploded. Some "KKJ" unknown brand. So whoever has those wheels, replace that "KKJ" junk to something more trustworthy (like Nichicon - https://www.mouser.com/ProductDetail/Nichicon/UCY2C561MHD?qs=%2Fha2pyFadujuHIr5Yj8HTZAEG6x9RB%2FLXUas5hyoen4%3D ). Also capacitors should never be placed on top of MOSFETs like this, the max temperature for good caps is only 105C and they start to age quickly when operating in hot places. Kingsong did a great job installing those caps facing away from the board on KS18L (and they are also 4x the capacitance value there).
  4. (not my video) https://www.youtube.com/watch?v=DFavoAFEcDw To save time fast forward to 42:00 then to 59:30
  5. The thing is that combination of not charging to 100% and discharging too low has a risk of one element getting out of balance and receiving negative charge (that happens when you drain battery low when this element is already discharged but other elements in series still have some charge left). Negative charge destroys lithium cell (creates a short circuit due to copper migration), and the full battery capacity is only as good as the capacity of worst element in it. The recipe for healthy battery is always charging to 100% and let it continue to charge for some time after it is already fully charged (to balance out elements) and to not discharge it past 20% at least to decrease risk of negative charge.
  6. Absolutely agree on 1 condition: Each EUC riding soldier should get a standard issue of colorful juggling balls. That will significantly disorient potential enemy to submission.
  7. I'd argue that it is easier to learn than a bicycle, also it is arguable that popularity will be beneficial.... It takes only 1 picture of crying child with broken arm on facebook for this to become prohibited almost everywhere or extremely regulated...... But nevertheless if you want to make it popular, make an official competition sport out of it. But right now i enjoy it being a niche thing. It is not regulated (because of small numbers) and people did not get annoyed by it yet and you pretty much get thumbs up from everyone you pass.
  8. How was battery been used during that 1 year? Did you always charged it to 100%? How many times did you let it to discharge past 20%?
  9. In Seattle shared trails have 15mph speed limit which is usually posted everywhere. I don't know about NY though, but even if it is not posted, bicycles normally do not go as fast as EUC. Lets assume this kid is not being used as shield but he is on a bike.... which does not change situation much.... he goes about 5 mph (and completely allowed to do so) and 35mph speed difference is enough to kill someone in the event of collision (especially kid)..... That said, i agree that some parents are somewhat reckless, Partially because pedestrians have right of way even on the road in USA and they have a bad habit to just step on the pavement and never look around for the cars knowing cars will all stop anyway (I was very surprised about that when I migrated here many years ago).. and partially because parenting is hard, and total 24/7 control of your kids wears you out pretty fast.. also there are many people living in USA which have completely different culture origin (including myself) that have different idea about cost of human life. However 1) It is absolutely pointless to try to fix everyone around us to our liking (and in a moment change the culture and everyone's habits) and kids are not guilty if their parents are idiots. 2) this is not a parenting forum :-) We only have control over what WE do.
  10. Well! Apparently bicycle trail etiquette in Europe is not that much different of the US one. But i just realized that you have to ride a bicycle for some time to be accustomed to it, if one just got introduced to bicycle trail with the purchase of EUC, he/she doesn't know much about how things should be done there... Stepping away from the topic for a sec - FYI: AVAS feature of "EUC World" android app completely solves "pedestrian spookiness" issue you mentioned.
  11. In US this is called "harassment" (look up legal therm). It is illegal even if short guy thinks he protects the law.
  12. If 2 pedestrians collide with each other it will not cause problem. Unless one side of the party decides to make a projectile out of himself by mounting on top of some motorized device. That essentially means that vehicles are weapons. A source of danger. And person who handles weapons has always elevated responsibility. If someone will run into them in EUC that will cause problem for both sides. Yes idiot pedestrian may die but EUC rider will have to live for the rest of their live with the fact that he murdered a person (need to remember that all the time). But I see where you coming from, if pedestrians break the law then why should we care about not speeding around them? THats not how it works in real life, pedestrians represent least danger for everyone and they are not assumed to have any knowledge of walking next to speeding EUCs, some of them have never seen EUC in their life. The only thing you can expect from them is to not jump in front of the car on a roadway or do very stupid things like crossing highway. I know in some EU countries (I never been in Denmark but at least in Netherlands) bicycles have right of way against pedestrians, but it is never the case in USA. The pedestrian can be an idiot, but (sorry for disappointment), you still cannot kill them, and people usually do as much as honk and pass slowly, politely and carefully, that's how things are at least where i live, and we are culturally very far from that changing any time soon.
  13. I missed context then. I've seen worse places than NY in that department. Moscow for example. Yes, being aggressive on the road is pretty normal in NY, but pedestrian walks and road have pretty clear separation. People can normally walk fine without expecting their kid to collide with fast moving EUC rider. This is where i would focus my rage and anyone who defends that kind of stuff is out of their mind.
  14. I've been in NY twice, walked through the Central park with the kid. I do not remember being surrounded with a-holed and dickheads. People were cool and nice. No one have passed my kid in close distance going 30mph. If they did I'd probably remember that because i'd kick their ass (if I would be able to catch on). So i refuse to believe that being an a-hole is normal for NY. Very interesting city! Loved it! So I believe one can be a dickhead in any state or any country, it does not depend on particularly being in NY. The same goes for reasonable and nice people, which constitute majority of population everywhere including NY. Just an opinion.
  15. Yep lost a zero there. For electric circuits final price is usually 5x of BOM. But battery pack has very few things besides just cells. The point is it does not have to cost 6000 to be good quality wheel, there is plenty of margin to make a good wheel for the same money as we pay.
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