DaveThomasPilot Posted April 6, 2017 Author Share Posted April 6, 2017 You make a good point, Christoph. The current (hence power) doesn't change much when the lights go off. It could be that the resolution or absolute accuracy of the ADC isn't sufficient to accurately measure current at the low end of the scale. However, 300 ma isn't a lot of current, even if a switching regulator is used to power the electronics board. So, it could be the power required for the voltage regulator and control board is more than the LEDs that are seen in the front and rear lights. I wish it was possible to load the battery from the connector, but when I tried last summer I determined the connector pins are diode isolated from the battery. So, current can only flow into the connector, not out. I recall I tried disassembling the wheel to find a place "downstream" of the diode where I could put a load on the battery, but I got stuck at some point. I don't recall specifically at this point. But, the charge curve should really "tell the story". The shape of the voltage curve versus time with charge current that the charger doctor should provide will indicate whether the control board's notion of battery voltage is to be believed. Today, 61.7 volts. Thanks! Link to comment Share on other sites More sharing options...
DaveThomasPilot Posted April 13, 2017 Author Share Posted April 13, 2017 The Charger Doctor still hasn't arrived. I'm impatient to ride again, so I decided to use a DVM to monitor the charge voltage. I soldered a pair of wires to he output of the battery charger, on the pcb, insided the charger case. I used a DVM and recorded the charger output voltage and the battery voltage as reported by the KingSong App. I would expect the battery voltage to be lower than the charger output. There should be a diode drop + the IR drop of the wire that's between the charger pcb and where the KingSong measures the battery voltage. At least a volt difference, I'd guess. But, as I suspected, the charger voltage (as measured by the DVM) is lower than the app reports. It started at 1.6 volts lower than and was 2.0 volts lower when I turned the charger off at a DVM voltage of 62.1 volts. Here's a plot of the charger voltage and battery voltage (as reported by the App) versus the time on the charger: So, the control board's notion of the battery voltage is inconsistent with what I measure on the battery charger output. I'll work with Jason to see what I should do next. I could use the Charger Doctor to terminate the charge at a low enough voltage so that the KS doesn't think it's too high. I'd have to stay low enough to prevent tilt back going down hills. I'll have to look at some battery curves to determine how much capacity that would sacrifice. Image didn't paste, so here it is as a .png attachment Link to comment Share on other sites More sharing options...
DaveThomasPilot Posted April 13, 2017 Author Share Posted April 13, 2017 I should have read my email before posting. Jason had already said he would send a new control board. Awesome, given how long it's been since I purchased the wheel! 7 minutes ago, DaveThomasPilot said: Link to comment Share on other sites More sharing options...
DaveThomasPilot Posted April 15, 2017 Author Share Posted April 15, 2017 The Charger Doctor arrived in the mail today. The voltage it reports is 1 volt lower than what I see on my DVM. I'd expect it to be lower, due to the IR drop of the wire and connector pings between the charger pcb and where the Charger Doctor is plugged. So, the Wheel's internal measurement voltage is off by over 3.0 volts. Link to comment Share on other sites More sharing options...
Jason McNeil Posted April 16, 2017 Share Posted April 16, 2017 On 4/13/2017 at 10:43 PM, DaveThomasPilot said: I'll work with Jason to see what I should do next. I could use the Charger Doctor to terminate the charge at a low enough voltage so that the KS doesn't think it's too high. I'd have to stay low enough to prevent tilt back going down hills. I'll have to look at some battery curves to determine how much capacity that would sacrifice. You're right, in 'normal' conditions a fully charged KS reports 66v internally & 67.2v from the charger. That voltage sensor has to be wrong! Replacement board should do the trick. Link to comment Share on other sites More sharing options...
Carlos E Rodriguez Posted April 20, 2017 Share Posted April 20, 2017 On 10/16/2016 at 7:25 PM, 16bitSprite said: Sounds to me like your charger is ok but one of your 18650 cells in your battery pack has become disconnected/faulty or a fuse on the bms has gone. I had a similar problem a while back with a bad connection. Managed to fix it too with a bit if work. If you are feeling brave and you are comfortable doing it, I'd be opening up the battery pack and looking for a dodgy cell. Test the positive and negative of each cell. I usually test on the bms itself rather than the nickel strip or battery to make sure the connection is actually getting onto to the pcb. Hopefully it's just a bad connection because that is an easy fix with a bit if solder. If it's the cell itself you will need to remove and replace the bad cell. Kinda tricky. Again be careful of shorts especially on the positive ends of the batteries as the side walls of each cell are negative and can be easily tripped. Plus you will have some high voltage points in various places over the board eg. First and last cell in the series and at the charging and power switch connections to the bms. Gotta make sure all your cells are balanced too once you are done otherwise you may have 1 under charged or over charged cell. Quite frankly it's a lot easier and a lot safer just to but a whole new battery pack at this point. Just my two cents. The battery packs have a lot of energy. this little cells put out lots of amps when shorted so you need to know what you are doing. find and electrical engineer that understands and is whiling to do the exploratory surgery of the battery pack. find someone that know what to do. Your battery pack might be OK and you will ruin a $300 part. Link to comment Share on other sites More sharing options...
DaveThomasPilot Posted April 24, 2017 Author Share Posted April 24, 2017 On 4/20/2017 at 10:22 AM, Carlos E Rodriguez said: The battery packs have a lot of energy. this little cells put out lots of amps when shorted so you need to know what you are doing. find and electrical engineer that understands and is whiling to do the exploratory surgery of the battery pack. find someone that know what to do. Your battery pack might be OK and you will ruin a $300 part. . find and electrical engineer that understands and is whiling to do the exploratory surgery of the battery pack. find someone that know what to do. I happen to be an electrical engineer with decades of experience designing power conversion products like switching regulators and motor drivers. I think what I posted is pretty conclusive that the circuitry on the control board that measures the voltage has a problem. Link to comment Share on other sites More sharing options...
Dingfelder Posted April 25, 2017 Share Posted April 25, 2017 No wonder I don't know what you guys are talking about half the time. I'm trying to figure out electrical engineers discussing formulas but am the kind of guy who gets confused by the box directions on how to make instant pudding. Link to comment Share on other sites More sharing options...
Joker10 Posted April 22, 2018 Share Posted April 22, 2018 DaveThomasPilot. Did the replacement board help? Mine reads 76% on a full charge. Link to comment Share on other sites More sharing options...
DaveThomasPilot Posted April 23, 2018 Author Share Posted April 23, 2018 Yes, it fixed the issue. What do you mean it reads 76% on full charge? The app reports 76%? It's best to measure the voltage with a DVM so you can see if it's the charger or the control board that's confused about the voltage. You'll need a DVM and you'll also need to measure the voltage at the battery connector(s) or inside the charger while it's charging, or use a charge cable with place where you can measure the voltage. The voltage you measure at the charger will be maybe a .5V higher than the actual battery voltage. The voltage reported by the replacement board was a little low (not 24% low). But, I figured that was better than having the control board think the battery was overcharged and do the tilt-back thing. Link to comment Share on other sites More sharing options...
Joker10 Posted April 24, 2018 Share Posted April 24, 2018 The app shows 76% and 7 to 8 leds on the side light up when the charger is done. I have the quick charger and the regular charger both stop charging at the same point. The ewheels quick charger gives a voltage as it is charging and it is getting up to 67 volts at the end of the charge. So I think it’s the board that is not reading the battery voltage correctly. My only concern is that I think it reads it wrong as the voltage drops and cuts my rides a bit short. I am getting between 13.5 and 17 miles before it starts to limit my speed. Depends on the speed I am riding and the hills. I’m 210lb right now but my ninebot one e+ I can get 8.5 to 9 miles before I get to 20%. I just expected to get 18 to 20 miles before I got down to 20% with a battery that is about 2.5 times larger 340 vs 840. Link to comment Share on other sites More sharing options...
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