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Keith

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Keith last won the day on September 8 2016

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About Keith

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    Veteran Member
  • Birthday 10/07/1955

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  • Gender
    Male
  • Location
    Surrey, UK
  • Interests
    Radio Control aircraft, photography, Malta.

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  1. B & F****** Q

    😂🤣😅😀 Unfortunately, I don’t think B&Q intend selling them. Ironically just downstairs below the B&Q store I worked in is a large Maplins. They sold the full range of Airwheels. Maplins have just failed and gone into receivership - I’m sure these two things are just a coincidence 😀.
  2. B & F****** Q

    I’m certain @Hunka Hunka Burning Love Will do it for pics of your sister 😜. I still think finding a whole group of personable young riders confident enough to do one legged “superman” poses in the U.K., where take up of EUC’s has been so low that people still think Hoverboards are cool, was a tall order. Some did seem more wobbly than others though so, perhaps, there were a couple of experienced riders who spent a few days training the rest - and the trainers did the “clever stuff? B&Q often use their own people in their adverts ( I’ve giggled at a number of my colleagues on TV. ) but it seems unlikely these were staff. I got filmed meeting Ian Duncan Smith (https://en.m.wikipedia.org/wiki/Iain_Duncan_Smith) when he was Work & Pensions Secretary as an example of B&Q getting older people back into work - I’m still praying that doesn’t get shown anywhere as I can’t stand the man and had to work REAL hard at my smile!
  3. KS14D performance on hills

    @Sobaka, welcome to the forum. The very reason I got my KS-14C (which is chunkier than the 14D and not as powerful) was so it was easy to carry on transport and store at work. I found it fitted a small locker at work perfectly and was no trouble to carry on trains, subways or buses. Unfortunately London U.K. isn’t well known for its steep hills (the biggest hill within 50 miles is less than 700ft!) so I’ll let someone whose had more ups and downs than I give a better answer.
  4. B & F****** Q

    I wondered that as well - they all seemed to ride well, considering how few other riders I’ve ever seen. I have a feeling Speedyfeet might have supplied them? BTW @Paddylaz, I worked for B&Q for several years in one of their flagship stores and rode to work on my KS-14C. On several occasions as I was leaving - pushing it along of course - managers asked me to demonstrate riding it in the store (after we were closed). I wonder if I’m responsible? Personally, I think the advert is brilliant, anything that gets these into the public consciousness as a good thing is a step in the right direction IMHO.
  5. If I had a pound (or dollar) for every time this has been said.......... An EUC CANNOT SLOW ITSELF DOWN - that is fundamentally the problem with any self balancing vehicle. If you lean forward it HAS to either accelerate or faceplant you, they are the ONLY OPTIONS. The only way it can TRY to slow YOU down is tiltback or beeping. It is the failure to understand this that seems to be behind people’s surprise when things go wrong, if you understand this you know that suitable protective gear is a must. I would be damn surprised if electric bikes do not also get sudden power failures or overheat on steep hills, the difference with any vehicle that isn’t self balancing is that you just coast to a halt.
  6. Advice on first wheel

    Don’t forget emergency braking as well - start gently and then try to brake harder, preferably with a well padded backside just in case 😜. I found out the hard way I didn’t know how to stop quickly when a car turned fast on to a drive right in front of me without indicating. Falling flat on my backside certainly stopped me quick enough and my leash prevented the wheel hitting the car with possibly awkward insurance issues afterwards! BTW your route around Cissbury Ring brought back memories, my parents retired (as one does) to Vale Walk, just across the A24 and I flew from Shoreham for many years.
  7. 16S Battery Level Variance

    Just to be pedantic here, your capacity hasn’t dropped your voltage has. As @Chriull has said, the voltage dropping under load, and of course proportionally to load, is a direct product of the total internal resistance in the power train. On top of this batteries do chemically recovery a little when left to rest for a time. The problem, or at least the symptom, that you are seeing is that voltage is being used to indicate capacity and, as you can now see it is a fairly crude measure. since voltage drop due to capacity use isn’t as linear as one would hope and also varies with load (i.e. how much current is drawn) it is fairly pointless to put a percentage figure on it. It will be much worst if the battery is close to empty - when it matters - and least when the battery is half full - when it doesn’t much. When the battery is completely full the first drop is very steep, however I suspect most algorithms see something like 4.1 volts as 100% to hide that. The below graph is for small 800mAh cell at different temperatures and quite low discharge rate. If instead different output loads were used then a higher current at constant temperature would look very similar to the lower temperature curves here.
  8. Braking/Stopping Practice

    This is something we always advise beginners to practice - before they find out the hard way when something hazardous happens right in front of them. Braking hard, from the point of view of the wheel and electronics, should put no greater load on the wheel than accelerating hard and it will be for a shorter period of time so unlikely to cause as much heat as, for example, prolonged acceleration up a hill. What I would not advise is repetitive hard acceleration-braking-acceleration-etc. as that may result in overheating. The one danger is if the battery is close to full. Braking regenerates energy back into the battery, if there isn’t the headroom to take it the wheel may fail to balance. This is the ONLY time I have ever faceplanted due too my EUC. I was showing off the acceleration with a full battery, leaned back to brake in order to turn around and the wheel just went “floppy”. I’ve never quite worked out why I came off forwards not backwards though?
  9. Not quite sure how this Inmotion V10 thread ended up as LiFePO4 but never mind. The one BIG feature of LiFe cells, which Uniwheel do point out, is that internal cell resistance is VERY low. They hold voltage superbly under load even when nearly empty. This means an EUC powered by a LiFe battery will have good strong power right down to 10% charge or even lower. So whilst it might have half the range of a similar weight and size LI Ion all that range is comfortably usable. The voltage of a Li Ion 18650 pack will have dropped by the time it’s got down to 40% or so to the point where power, top speed, etc. are reduced enough to not be nice to ride - in reality you might actually only really get 10 or 15% more usable range from a Li Ion pack of twice the capacity of a LiFePO4 pack AND, discharging LiFePO4 packs right down does way, way less harm to them than Li Ion packs which, ideally, you do not want to regularly discharge below 30%. Actually that very good voltage holding does have a down side as well, the packs I use as model aircraft receiver packs hold 3.3V per cell from around 90% capacity right down almost to the death, which means it is damn difficult to actually know how much range is left in a pack. Ideally you are going to need a Wattmeter to measure battery capacity based on how many watt hours you have consumed since last charge.
  10. Absolutely not, never ever. There is damn all capacity to exaggerate about between 3.3V and 0V maybe 1 or 2%. How battery capacitor is rated and stated is well documented in various places such as http://web.mit.edu/evt/summary_battery_specifications.pdf As is the tendency for manufacturer’s to, perhaps exaggerate - not the least by stating nominal voltage as 3.7V instead of 3.6V. However these ‘exaggerations’ will have only a few percent effect on the usable capacity. Typically the rated capacity of a battery is at a quite low discharge rate often only 1C or even 1/10 C and at a favourable temperature. Higher discharge rates will reduce actual usable capacity somewhat. Low temperature will have the biggest effect and below 10F (-12C) you might be lucky to get 50% of the battery capacity. http://batteryuniversity.com/learn/article/discharging_at_high_and_low_temperatures Because batteries have internal resistance, voltage off load and voltage under load are very different things, a battery protection circuit can only function under load so it has to make an assumption exactly how much current the wheel is going to be consuming and set a tilt back voltage accordingly - this is why no two articles or devices state the same low voltage cut of voltage - it can be anywhere from 3.5-2.5 volts depending on how much load the manufacturer thinks the device will be taking. However, again, this will only make a something like 10%, perhaps 20% tops, difference to capacity. Given where you are, it is safe to assume low temperature isn’t a problem, even accumulating everything I’ve said above, other than temperature, there is no good reason for a rated 350Wh battery to give less than (say) 300Wh - however, unless you are as light as a chimp ,10 miles or so is pretty much all most European/American weight people get out of a 340-350Wh battery before it significantly speed reduces - it is certainly all I get out of mine so 95Wh for 8 miles seems a very low estimate unless riding very very slow, it’s not much more than 12Wh/mile it should be nearer 20-25 (or much higher if very fast or heavy). Finally, draining a battery down to 3.05V off load (?) regularly will knock your capacity down very quickly, doing it in the first 3 or 4 charge cycles will knock it down even quicker.
  11. O H. M Y. G O D. 2 hours after I posted the above, @Jason McNeil posts this: How is that for service 😀👍🏿. Or is it just spooky!!!!!!!!!!!!!!!!!!!!!!!!!!
  12. @Masterb8 I’m no expert on the Ninebot mini’s but I believe it is only the Pro that has the 310Wh battery - as you are showing. I’m not sure if you are also commenting on the cardboard outer box, however I would expect that to be correct to ensure it survives postage. Probably the best person on this forum to ask is @jojo33 and by linking his name like I just have he should be alerted to this question. He also discusses Mini/MiniPro batteries below:
  13. Absolutely, but that is very much a case of more than twice the price but more than 3 times the number of cycles. As others have said the lower voltage and energy density results in a much higher weight and volume than 18650 LiIon cells for the same range, or alternately, as in the Uniwheel, lower range. What I do find surprising is that many LiFe cell adopting companies supply chargers that refuse to charge if the batteries get too low,. Unlike LiIon cells, LiFe cells are not too badly damaged by low voltage, but they do have a very high (compared to LI Ion) self discharge and they can easily get too low to charge if not used for 6 months or so. This further discourages users who will not want to buy another expensive battery if it’s useless if not used for some time. I use 2S LiFePO4 cells in model aircraft as receiver batteries. Lithium Ion are too high a voltage as 2S and need a regulator which is something else to fail and too low with a single cell. I have one battery in a glider I rarely fly that has been in use since 2014 and has twice self discharged to less than 1 Volt when left a year unflown. I have to fool the charger it is a NiCad to get its voltage up enough to charge again, but it still gives over 90% of its rated capacity. Celestron, a famous astronomy telescope manufacturer, sent me an advert for their wonderful new LiFePO4 telescope battery, have a read of this link and see how many mistakes you can spot: https://www.celestron.com/pages/lifepo4-battery-chemistry?utm_campaign=WS2_NonPurchaser_INT+(NYRtfm)&utm_medium=email&_ke=ay5lbmdsYW5kQHZpcmdpbi5uZXQ%3D&utm_source=Welcome_Series_NonPurchaser_INT# . You would think they would actually understand the technology they are selling wouldn’t you? Below is what I think is wrong with this article (and emailed them to say so too - a week ago and they have done nothing about it!) :
  14. It rather depends upon stock levels. I learned a valuable lesson from a friend who ran a market stool at weekends. ( feel free to change £ to $ or € and p to cents in the below it still works) He purchased 2000 small earphone radios wholesale that were all the rage at the time for £1 each = £2000 He sold the first 1000 for £3 each, but then the market was fairly saturated and sales dropped off. The next week he put the others out for sale at 50p each - half what he paid for them. The guy on the next stool was furious, he had also paid £1 each and sure as hell was not going to sell them at a loss. My friend sold his last 1000 at 50p each OK, the guy on the next stool didn’t sell any more. My friend’s view was “I paid £2000 for the stock and when I sold them all I had a revenue of £3500 - a profit of £1500 - I absolutely did not sell at a loss, I just made sure I realised the best return I could.”
  15. This is my view as well. Unless, or until, we get to the position where the average Joe, or Jane, in the street can have experienced or, better still, learn to master an EUC before he buys it, then there is going to be a very finite limit to how much they are willing to “risk” on a Technology they will not be certain they can master or use successfully. High weight is also going to be a big put off to. For experienced riders then the quest for range and/or speed will drive their now knowledgable choices and I can see the V10 winning considerable support from them if the worst negative is only it’s weight. Really the biggest downer for the new user, especially the heavy new user is that an affordable wheel worth the risk of buying will not have sufficient power to be safe or comfortable to ride. We risk new riders being put off before they really get hooked. The ideal scenario is an affordable wheel with a relatively small battery but lots of motor power that can easily and simply be upgraded as required. For many, perhaps who cannot comfortably carry a high weight and/or need only to use it for last mile, maybe it’s spec will remain enough, for others being able to upgrade to increase the battery size would make the purchase a safer bet. If top speed was also limited by battery size as well such that an upgrade also released extra speed then I think such a wheel would really be a winner.
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