breathsavers Posted July 24, 2015 Share Posted July 24, 2015 So I bought an Airwheel on Craigslist because I wanted to try out a unicycle before I spent a ton on a nice one. It was only $100. Didn't come with a charger because it came with a Chinese charger and the guy plugged it into a US outlet and fried it. He claims the unicycle worked after that but that he just never bought another charger so he hadn't ridden it since the battery died (about 3-4 months ago).So it works fine while plugged in, but when I unplug it and hit the power button, it makes what sounds like a "startup beep" with the battery lights and then immediately just fades to nothing. The battery pack was quite hot when I unplugged it so maybe when he fried the charger it fried the battery too? Any suggestions on fixing it or should I just get my money back? Thanks!! Link to comment Share on other sites More sharing options...
John Eucist Posted July 24, 2015 Share Posted July 24, 2015 So I bought an Airwheel on Craigslist because I wanted to try out a unicycle before I spent a ton on a nice one. It was only $100. Didn't come with a charger because it came with a Chinese charger and the guy plugged it into a US outlet and fried it. He claims the unicycle worked after that but that he just never bought another charger so he hadn't ridden it since the battery died (about 3-4 months ago).So it works fine while plugged in, but when I unplug it and hit the power button, it makes what sounds like a "startup beep" with the battery lights and then immediately just fades to nothing. The battery pack was quite hot when I unplugged it so maybe when he fried the charger it fried the battery too? Any suggestions on fixing it or should I just get my money back? Thanks!!I think if you let the battery sit that long at a discharged state, the batteries will become permanently dead. I'm not expert but that's what I heard. Others here know a lot more about batteries than I do. Hopefully they'll chime in. Link to comment Share on other sites More sharing options...
esaj Posted July 24, 2015 Share Posted July 24, 2015 Like John said above, if the batteries sit idle for a long time, they drop below the critical voltage (usually 2.5V) and can become (permanently) damaged. Sometimes the cells can still be "revived" with special "smart" chargers, but probably not with the regular ones.But, I don't think the cells should heat up. Becoming warm is probably normal if using higher charge current or riding around, but if it became very hot, that's not a good thing (the worst case is that cells in the battery self-ignite/explode in a "thermal runaway" if it becomes hot enough). Also the battery BMS (Battery Management System) itself could have damaged when the original charger fried. Better get new battery pack and take the current one to somewhere where it gets properly recycled/destroeyd (don't just dump it into trash).Do not boot lithium-based batteries back to life that have dwelled below 1.5V/cell for a week or longer. Copper shunts may have formed inside the cells that can lead to a partial or total electrical short. When recharging, such a cell might become unstable, causing excessive heat or showing other anomalies.http://batteryuniversity.com/learn/article/low_voltage_cut_off Link to comment Share on other sites More sharing options...
hobby16 Posted July 24, 2015 Share Posted July 24, 2015 @SamWhat was the charging time ? It's the most important information to provide. As Esa said, a (moderately) hot battery after charging is ok.Charge, let the BMS balance cells one night. And repeat several times if needed.Shunting the BMS helps too (see my signature). Link to comment Share on other sites More sharing options...
breathsavers Posted July 24, 2015 Author Share Posted July 24, 2015 @hobby16 It seemed to take about two hours which is a little longer than the 90 minutes that I read online but not by much. It did get quite hot, as in hotter than I would think it should be. Couldn't hold my hand on the pad without discomfort. Are you saying to charge the battery, let it sit overnight, then repeat if necessary? Do you think shunting the battery could get it working? Maybe I'll take the thing apart and see what I can see? @esaj do you know where I could purcahse a replacement battery in the US and how much it might cost? I only paid $100 for the whole Airwheel so I don't really want to spend $200 in a new battery right after purchase. I'd rather return this one to the seller and just buy a brand new one. Link to comment Share on other sites More sharing options...
esaj Posted July 24, 2015 Share Posted July 24, 2015 Maybe I'll take the thing apart and see what I can see? @esaj do you know where I could purcahse a replacement battery in the US and how much it might cost? I only paid $100 for the whole Airwheel so I don't really want to spend $200 in a new battery right after purchase. I'd rather return this one to the seller and just buy a brand new one.Probably best to return it, if you can (I understood you bought it used?). The battery is usually one of the most, if not the most expensive part (or maybe the motor when comparing to smaller packs < 200Wh?), but I can't say what they cost in the US, might be hard to find in general. A little under 200Wh pack custom-made to my wishes and dimensions costs me more than $200 without shipping per piece here... But that's different than mass produced, so can't really tell (and we have high taxes, that's with 24% VAT). Link to comment Share on other sites More sharing options...
hobby16 Posted July 24, 2015 Share Posted July 24, 2015 @sam,Yes, wait a night or 24h for the BMS to balance in background, then restart several times if needed. It may restore the capacity.Two hour of charge is a lot. What counts is the charge duration until the green led on the charger, not the connection duration.A battery heating so much is definitively bad, as long as we don't know more about its health, you must NOT leave the battery unattended while charging and leave it in the house. You may have triggered a thermal runaway (the cell may generate its own heat for hours, and may trigger thermal runaway on the adjacent cells and the heat may be on in the pac for days !) so follow the temperature.The BMS has a thermal protection. The heat might have triggered it, that's why you have a power cut.Don't shunt for the moment otherwise, you can't have the wheel refunded. Try several charge cycles as described above, measure the charging time and check the temperatures (no accuracy needed, cold, hot, too hot, how long... are enough to decide). Link to comment Share on other sites More sharing options...
breathsavers Posted July 24, 2015 Author Share Posted July 24, 2015 Thanks so much for the responses guys!! Link to comment Share on other sites More sharing options...
breathsavers Posted July 25, 2015 Author Share Posted July 25, 2015 So the guy I bought it from is refusing to give me a refund. He said that I bought it "as is" even though he told me I could have a refund if it didn't work. So frustrating!!Anyways, I have emailed airwheel and they say that since they dont know if it's an official airwheel, they won't repair it AND they dont sell replacement batteries. So my plan now is to get into the thing and see if I can tell what's going wrong. Maybe I'll post some pictures so you guys can give your opinions. Thanks again for the help. Link to comment Share on other sites More sharing options...
esaj Posted July 25, 2015 Share Posted July 25, 2015 At least funnybike.fr (in France) sells battery packs for F-Wheel (160-320Wh), with price range of 149-195€ (Around $163-214 at current rate), don't know how much is the shipping. Also, you would need to check that the connectors fit, or replace them with ones that fit. Maybe ask them the voltages (nominal should be around 60V, depending how they mark them, could also be 57.6V or 59.2V), and cell configuration (I'm guessing 16S1P for the 160 and 200Wh and 16S2P for 320Wh). If it's something else (15SxP or lower voltage, like 55V), it's probably not suitable.http://funnybike.fr/16-accessoiresScroll down a bit, use Google Chrome's built-in translation or Google Translate (the site's in French). Link to comment Share on other sites More sharing options...
breathsavers Posted July 25, 2015 Author Share Posted July 25, 2015 I got it open and it has a 16S1P battery. Found them on banggood for $68 which is awesome. Going to test the current battery with multimeter and confirm issue, then order replacement and hopefully that will fix it! Link to comment Share on other sites More sharing options...
hobby16 Posted July 25, 2015 Share Posted July 25, 2015 @breathsaversHere is how cg looked at his BMS : http://forum.electricunicycle.org/topic/626-generic-oem-unicycle-a2/?do=findComment&comment=6130 Link to comment Share on other sites More sharing options...
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