luckylou Posted April 23, 2015 Share Posted April 23, 2015 Hey guys, I currently have an off brand airwheel x8 and for whatever reason it randomly turns off. I have been thrown several times due to this and now have to carry my charger with me everywhere. At first I thought that I was improperly using it, So I started driving slower and more carefully hoping this would solve it. Unfortunately, it did not help at all. The other day I was waiting for cars to pass while holding a pole for balance. Just as I began to lean forward it shut off completely. I have no clue what to do and have barely received a response from the manufacturer. If anyone has any ideas on how to fix this please let me know it will be greatly appreciated. Link to comment Share on other sites More sharing options...
dmethvin Posted April 23, 2015 Share Posted April 23, 2015 So when it cuts out, the only way to reset it is to connect the charger? Sounds like the protection system on the battery pack may be too sensitive. Or maybe there is a problem with some of the cells in the pack itself. There is some discussion about that problem here: When you say "off brand Airwheel X8" you mean something that looks like an X8 but isn't? Maybe they used really cheap batteries. Link to comment Share on other sites More sharing options...
ironfox Posted April 24, 2015 Share Posted April 24, 2015 you need to shunt the 3 MOSFETs for the undervoltage protection on the BMS Link to comment Share on other sites More sharing options...
dmethvin Posted April 24, 2015 Share Posted April 24, 2015 Does anyone know if shunting the MOSFETS also defeats the short circuit protection? When my FireWheel failed it did so with a short on the controller board. If the BMS had not been able to disconnect it would have fried everything. Link to comment Share on other sites More sharing options...
ironfox Posted April 24, 2015 Share Posted April 24, 2015 The overvoltage protection should be realized by the same MOSFET that is responsible for turning off after reaching the final loading voltage. It is just triggered by a different sensor and/or limit value. Link to comment Share on other sites More sharing options...
hobby16 Posted April 25, 2015 Share Posted April 25, 2015 Does anyone know if shunting the MOSFETS also defeats the short circuit protection? When my FireWheel failed it did so with a short on the controller board. If the BMS had not been able to disconnect it would have fried everything. I confirm, shunting the mosfets = no short circuit protection anymore. But this protection happens for currents more than 60A, so if something is shorted, it would fry anyway (and quickly end the short). It was never intended to protect what's downstream but only to protect the LiIon cells from overdischarge, a good feature for an electric bike assembled from off-the-shelf parts, but the stupidest idea you can imagine for a monowheel! Even bikelec users complaint about capricious BMS cut-off (especially with cold temperatures) so imagine that with our wheels. Note that Gotway has scrapped this protection entirely from its new BMS (see pictures by vee73), so you can rest assured that shunting the mosfets is the thing to do to have a safe wheel. What's important is to shunt the several mosfets of the overDIScharge protection circuit and NOT to shunt is the lone mosfet of the overcharge protection circuit (explanations here : http://trottinetteselectriques.heberg-forum.fr/ftopic870-0.html). @luckylou, Airwheel's BMS definitevely have the problem and must be shunted. It has been successfully done on X3, X8, Q3... If when you do it, please take pictures and give feedback if possible. Link to comment Share on other sites More sharing options...
dmethvin Posted April 25, 2015 Share Posted April 25, 2015 Merci hobby16, I thought that might be the case. Since I am having problems with my Firewheel I don't think I will make the BMS change until it's out of warranty. Link to comment Share on other sites More sharing options...
luckylou Posted April 25, 2015 Author Share Posted April 25, 2015 @dmethvin, yes it looks like an x8 and has similar specs. I bought it with the intention to learn how to ride and then move up to better wheel. @hobby16, I will gladly take pictures and videos when I do it. I am not very savvy when it comes to this kind of stuff. If someone can explain how to do it that would be awesome. Unless this is what you mean, https://www.ifixit.com/Guide/Fixing+Rockwheel+Electric+Unicycle+Balance+Issues/28300 Link to comment Share on other sites More sharing options...
hobby16 Posted April 25, 2015 Share Posted April 25, 2015 @dmethvin, yes it looks like an x8 and has similar specs. I bought it with the intention to learn how to ride and then move up to better wheel. @hobby16, I will gladly take pictures and videos when I do it. I am not very savvy when it comes to this kind of stuff. If someone can explain how to do it that would be awesome. Unless this is what you mean, https://www.ifixit.com/Guide/Fixing+Rockwheel+Electric+Unicycle+Balance+Issues/28300 no, the ifixit guide is for calibrating the horizontal idle position, it has been described in this forum for Airwheels but this applies to Rockwheel, TG, and many other clones. To shunt the BMS, all you need to know how to solder (if you don't, avoid any tweaking of the battery, buy a new one). Follow the instructions & pictures in the French forum (use google translate). Here is what to do : http://trottinetteselectriques.heberg-forum.fr/sutra14180_solution-probleme-bms.html#14180 If you are not sure, post pictures and I'll confirm. Link to comment Share on other sites More sharing options...
luckylou Posted April 26, 2015 Author Share Posted April 26, 2015 @hobby16, Just opened it up. It doesn't quite look like yours..wanted to double check. Link to comment Share on other sites More sharing options...
hobby16 Posted April 26, 2015 Share Posted April 26, 2015 Shunt the 3 mosfets with a blob of solder at the red lines and you'll solve your cut-off problem. Don't touch the extreme-left mosfet. Please, give us feedback if it works (or not). Another problem is battery ageing which is what you may have. I've made a "charge doctor" to know exactly the battery health state : http://trottinetteselectriques.heberg-forum.fr/ftopic1000-0-asc-0.html But the first batch has been sold out immediatly. I'll make some others available in a week or two, if you are interested, please let me know. Link to comment Share on other sites More sharing options...
hobby16 Posted April 26, 2015 Share Posted April 26, 2015 While you are at it, if you can, check the voltage of each LiIon cell, you should have the same value for all 16 of them (between 3.6 and 4.2V). Link to comment Share on other sites More sharing options...
luckylou Posted April 26, 2015 Author Share Posted April 26, 2015 I have taken pictures of the battery internally and externally before soldering the mosfets. Will Post more after. UPDATE: Just finished shunting the mosfets and putting it back together.Now when I accelerate the wheel jolts forward or backward quicker than it is safely possible to ride. Immediately after jolting in either direction, it goes into this emergency mode and continuously beeps. I am able to turn it off and on now without using the battery each time so that is resolved,but it seems either I have created another issue or there was a bigger problem to begin with.. any ideas? Link to comment Share on other sites More sharing options...
hobby16 Posted April 26, 2015 Share Posted April 26, 2015 I am able to turn it off and on now without using the battery each time so that is resolved You mean "turn off & on without using the charger" I suppose ? The emergency mode you have is probably because of battery undervoltage condition. You may see now that it's much better that undervoltage is detected and dealt with by the controller board and not by the BMS! How about the led panel ? Before and after the wheel entering emergency mode ? As I said, you must have some problem with one of the LiIon cell and should have checked the voltage of each cell. Hard to diagnose further without more information. Link to comment Share on other sites More sharing options...
luckylou Posted April 30, 2015 Author Share Posted April 30, 2015 I soldered the three areas described. This solved the power problem with the electronics going off when tilted. However now it will not stabilize at all New Problem: My brother also at the same time bought the exact same model from the same vendor. After his tire blew out from ridding to hard we ordered another tire from the vendor. After installation of the inner tube and reassembly he powered it back on. Once on everything seemed normal. As soon as he stepped on the airwheel the same problem mine was having is now happening to his. Both now lunge forward and backward with no regard to tilt except for small small tilts that render it unman-able . We may not even try two feet without the wheel flying out from underneath us almost taking us off our feet. Very unsafe. Link to comment Share on other sites More sharing options...
Kristoffer Pehrson Posted May 11, 2015 Share Posted May 11, 2015 Did the mod as soon as I read about it! Sounds just lite problems that I have been experience on my "China wheel". It was really easy to do it and it took me 15 min. Is there any way to test if it works? I will try to upload some pictures as soon as my pictured are synced with my computer Link to comment Share on other sites More sharing options...
hobby16 Posted May 11, 2015 Share Posted May 11, 2015 the BMS cutoff problem is easily reproductible if your battery is cold. Ride until it's nearly empty, leave the wheel outside during the night when temperatures are below 10°C, then ride it in the morning when it's still cold. I got the cutoff systematically that way at each slight acceleration or on a steep slope. With a shunted BMS, you'll won't have such problem anymore, never. Link to comment Share on other sites More sharing options...
Kristoffer Pehrson Posted May 16, 2015 Share Posted May 16, 2015 Link to comment Share on other sites More sharing options...
Mike Buck Posted May 18, 2015 Share Posted May 18, 2015 Could someone explain to me what the reasoning is behind removing the over-discharge protection? Wouldn't this cause a dangerous undervoltage in the cell's? Or are we simply modifying the BMS to allow excess current? Link to comment Share on other sites More sharing options...
Frankman Posted January 21, 2016 Share Posted January 21, 2016 I think every good made EUC has its pedal tilt back function to warn the rider when it's time to slow down or to get off the wheel. And this protect the rider from a faceplant due to a battery over-discharge. So I don't think that shorting the mosfets is the best solution because furthermore can easly shorten the battery life. Probably the best solution to a battery failure or a BMS failure could be to have at least two battery packs in parallel, each with its BMS. Link to comment Share on other sites More sharing options...
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