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Battery Condition


Lutalo
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I have 900+ miles on my KS18. When the charging device glows green, the wheel log App is showing that 630wh battery pack in my KS has charged to a mere 65%. 

Are there possibilities other than needing a new battery pack because the batteries have become too worn to charge past 65%? 

Elucidate me. I am hopeful, but prepared to embrace the worst. 

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You should get many more miles from a 630Wh pack than 900 but much depends on age and how it has been stored. How long have you owned the wheel? Do you leave it fully charged for long periods? Do you leave it in hot environments? These are things that can kill a battery quickly.

I would check that the output from your charger is at the rated voltage listed on the specs sticker. Chargers have been known to go bad and put out a lower voltage than is needed to attain a full charge. If charger output is OK you could fully charge the wheel (as much as it will go) and then measure the battery voltage to see if it is the expected 67.2V. If so then the on board chip in the wheel that detects and reports voltage has gone bad. KS has a history of over/under reading voltages. You'd need a new mainboard to resolve that.

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I forgot to add that as I understand it (and I could be wrong) even well aged cells should still reach 4.2V per cell just like a new ones even though the older cell will hold much less energy. As such if your charger output is tested as being good and the battery itself is not showing 67.2V after a full saturation charge (meaning leave the charger hooked up for several hours beyond when the green light comes on) when measured with an independent device then something is badly wrong. Maybe a BMS issue within the battery pack.

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i was concerned about my wheel storage because i’m keeping them in the old homestead where i’m not running the ac. i doubt the temps in there go much above 90 degrees f, if that high, but please correct me if i’m wrong, it seems from this chart that while it might not be optimal, serious degradation shouldn’t happen.

29067604588_7723eacd6f_b.jpg

 

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I'm not sure that chart is detailing capacity degredation over time at different temperatures but ideally for long ter storage a LiIon battery should be kept in the upper 30's or low 40s. For storage of a wheel that you use frequently keeping it between 50F and 68F would be a good compromise between degredation and compromised performance from cold cells. Degredation appears to accelerate exponentially when you get in to the 70s and higher. 

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i’ve got an old working refrigerator and i thought about using it because that’s what it would take but the condesation would be damaging to the other parts.

i was concerned about temps with my brand new wheels because when i started using them in january, i was afraid my garage caused the readings of 90% and 92%, but i’m convinced now that it’s not the batteries but it’s the bms and firmware that kingsong uses since i’ve been able to get the 16s up to 100% from 92%. still only 94% for the 18s.

battery university says 60% charge is best for longevity.

i think since high charges and high temps are bad and since i don’t have a fancy charger and don’t need long range charging anyway, i’m just gonna pull the plug on an estimated 80 to 90 percent charge or try to figure out how to use my charge doctor duo.

maybe @Jason McNeil will give me the customer discount now on that fancy charger he sells if he ever gets them in since i’m buying two wheels from him. hint.

no hurry.

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3 hours ago, WARPed1701D said:

I forgot to add that as I understand it (and I could be wrong) even well-aged cells should still reach 4.2V per cell just like m even though the older cell will hold much less energy. As such if your charger output is tested as being good and the battery itself is not showing 67.2V after a full saturation charge (meaning leave the charger hooked up for several hours beyond when the green light comes on) when measured with an independent device then something is badly wrong. Maybe a BMS issue within the battery pack.

WARPed1701D, thanks for the info. Appreciate you taking the time to respond. I found a forgotten, well-aged, but barely used charger buried in my basement. I switched them out and VOILA! The device charged up to 100% (normally I charge to 80-90% depending upon where and how I plan to ride). So, your suggestion to check the charger hit nail on the proverbial head. Thanks again man.

 

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38 minutes ago, Lutalo said:

How do I check the firmware? In the wheel log app?

first u install the kingsong app ver 1.47 i think for android, u can do a search in this forum for the download site, and then connect to the wheel, if the firmware needs upgrading it will tell u.

i think somebody said 1.07 was out for the 18s.

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3 hours ago, Lutalo said:

WARPed1701D, thanks for the info. Appreciate you taking the time to respond. I found a forgotten, well-aged, but barely used charger buried in my basement. I switched them out and VOILA! The device charged up to 100% (normally I charge to 80-90% depending upon where and how I plan to ride). So, your suggestion to check the charger hit nail on the proverbial head. Thanks again man.

 

You're very welcome. Glad it was an easy fix. 

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4 hours ago, novazeus said:

first u install the kingsong app ver 1.47 i think for android, u can do a search in this forum for the download site, and then connect to the wheel, if the firmware needs upgrading it will tell u.

i think somebody said 1.07 was out for the 18s.

Cool, thanks. I uninstalled the KS app about a year ago. I will reinstall the app and upgrade the firmware. Appreciate the help.

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On 6/21/2018 at 11:55 PM, Lutalo said:

WARPed1701D, thanks for the info. Appreciate you taking the time to respond. I found a forgotten, well-aged, but barely used charger buried in my basement. I switched them out and VOILA! The device charged up to 100% (normally I charge to 80-90% depending upon where and how I plan to ride). So, your suggestion to check the charger hit nail on the proverbial head. Thanks again man.

 

If you've got a multimeter, it's relatively easy to check the charger output, just set the multimeter to measure DC voltage above 67.2V or 84V (depending on whether the wheel is 16S or 20S, but usually the next suitable range is up to 200V anyway), ensure the probes are set correctly for voltage measurement and not for current, and push the probe tips inside the charging connector when the charger's plugged into wall. You've got the right "two-out-of-three" holes when it shows something other than "0V" (or whatever it shows when the probes aren't connected to anything). It might show negative voltage (the polarity is opposite to what the probes are connected to, ie. positive one is in the 0V/common ground hole and negative is in the positive output), but that's not dangerous.

 

On 6/21/2018 at 8:53 PM, novazeus said:

i’ve got an old working refrigerator and i thought about using it because that’s what it would take but the condesation would be damaging to the other parts.

That might work, although you don't want to keep the batteries below freezing temperature (for water, 0 Celsius or 32 Fahrenheit), or if you do, at least let them warm up to room temperature before charging. Normal room temperature (around 20...25 Celsius / 68...77 Fahrenheit) should be just fine, as long as they're not empty or fully charged.

Quote

i was concerned about temps with my brand new wheels because when i started using them in january, i was afraid my garage caused the readings of 90% and 92%, but i’m convinced now that it’s not the batteries but it’s the bms and firmware that kingsong uses since i’ve been able to get the 16s up to 100% from 92%. still only 94% for the 18s.

It seems that some wheels use very high resistance voltage divider for reading the battery voltage, and apparently the filter capacitors aren't that good sometimes, so the current leakage through the capacitor can cause the voltage measurement of the wheel to show lower values than what the real state is.

 

Quote

battery university says 60% charge is best for longevity.

I'm pretty sure the Battery University articles suggest something around 30...50%, but could be wrong. The main point is not to store them full charged, but not empty either.

 

Quote

i think since high charges and high temps are bad and since i don’t have a fancy charger and don’t need long range charging anyway, i’m just gonna pull the plug on an estimated 80 to 90 percent charge or try to figure out how to use my charge doctor duo.

If you don't need a full charge, charging less should make the battery lifetime longer, just remember to fully charge every now and then (ie. let it charge for an hour or two even after the charger light's gone green) to ensure that the cells stay balanced. If only partially charging all the time, the cell voltages can start to drift apart and some cells might get overcharged / overdischarged and die sooner than the others, ruining the pack. Can't say what would be "optimal", but doing that once a month or something like that (of course depending how often you ride in general, if riding a lot, do it more often) wouldn't probably be a bad idea. Of course don't leave the wheel then fully charged for a long while, maybe take it out for a ride after that to use at least some of the charge before storing it.

 

Edited by esaj
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1 hour ago, esaj said:

If you've got a multimeter, it's relatively easy to check the charger output, just set the multimeter to measure DC voltage above 67.2V or 84V (depending on whether the wheel is 16S or 20S, but usually the next suitable range is up to 200V anyway), ensure the probes are set correctly for voltage measurement and not for current, and push the probe tips inside the charging connector when the charger's plugged into wall. You've got the right "two-out-of-three" holes when it shows something other than "0V" (or whatever it shows when the probes aren't connected to anything). It might show negative voltage (the polarity is opposite to what the probes are connected to, ie. positive one is in the 0V/common ground hole and negative is in the positive output), but that's not dangerous.

 

That might work, although you don't want to keep the batteries below freezing temperature (for water, 0 Celsius or 32 Fahrenheit), or if you do, at least let them warm up to room temperature before charging. Normal room temperature (around 20...25 Celsius / 68...77 Fahrenheit) should be just fine, as long as they're not empty or fully charged.

It seems that some wheels use very high resistance voltage divider for reading the battery voltage, and apparently the filter capacitors aren't that good sometimes, so the current leakage through the capacitor can cause the voltage measurement of the wheel to show lower values than what the real state is.

 

I'm pretty sure the Battery University articles suggest something around 30...50%, but could be wrong. The main point is not to store them full charged, but not empty either.

 

If you don't need a full charge, charging less should make the battery lifetime longer, just remember to fully charge every now and then (ie. let it charge for an hour or two even after the charger light's gone green) to ensure that the cells stay balanced. If only partially charging all the time, the cell voltages can start to drift apart and some cells might get overcharged / overdischarged and die sooner than the others, ruining the pack. Can't say what would be "optimal", but doing that once a month or something like that (of course depending how often you ride in general, if riding a lot, do it more often) wouldn't probably be a bad idea. Of course don't leave the wheel then fully charged for a long while, maybe take it out for a ride after that to use at least some of the charge before storing it.

 

Esaj, I appreciate the suggestion. I am pretty sure I have a multimeter around. I will dig it out and test the charger; see what I get when I compare the poorly performing charger to the one that actually charged the wheel to 100%.

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1 minute ago, Lutalo said:

Esaj, I appreciate the suggestion. I am pretty sure I have a multimeter around. I will dig it out and test the charger; see what I get when I compare the poorly performing charger to the one that actually charged the wheel to 100%.

If it's off from whatever voltage you need (67.2V or 84V), most chargers have "trimmer-potentiometers" (the kind you adjust with a flat-head screwdriver) inside to adjust the voltage. There's likely two or three potentiometers (one for voltage, one for current limiting, possibly one more for adjusting when the led turns green), if you aren't sure which is which, try turning one about quarter or half turn with the meter connected, and if the output voltage doesn't change, turn it back to where it was. Once you locate the correct trimmer, turn it until you get it to to voltage you want (or thereabouts, a basic cheapo multimeter won't be but up to +-1% accurate).

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1 hour ago, esaj said:

I'm pretty sure the Battery University articles suggest something around 30...50%, but could be wrong. The main point is not to store them full charged, but not empty either

no the 60% thing was what they were saying u should charge ur batteries to for longest life, not storage. of course they realize most people are gonna want more than a few miles range.

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1 minute ago, esaj said:

If it's off from whatever voltage you need (67.2V or 84V), most chargers have "trimmer-potentiometers" (the kind you adjust with a flat-head screwdriver) inside to adjust the voltage. There's likely two or three potentiometers (one for voltage, one for current limiting, possibly one more for adjusting when the led turns green), if you aren't sure which is which, try turning one about quarter or half turn with the meter connected, and if the output voltage doesn't change, turn it back to where it was. Once you locate the correct trimmer, turn it until you get it to to voltage you want (or thereabouts, a basic cheapo multimeter won't be but up to +-1% accurate).

Wow! Very cool and helpful tip. I will pop it open and try it. Thanks again.

 

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6 minutes ago, esaj said:

it's off from whatever voltage you need (67.2V or 84V), most chargers have "trimmer-potentiometers" (the kind you adjust with a flat-head screwdriver) inside to adjust the voltage.

how do u get into one of these brick chargers? no visible screws?

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2 minutes ago, novazeus said:

how do u get into one of these brick chargers? no visible screws?

There's likely a number of plastic "claws" inside... annoying as hell, sometimes very difficult to open without breaking them.

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2 minutes ago, novazeus said:

how do u get into one of these brick chargers? no visible screws?

It looks like there are four screws that are hidden under the four rubber pads at the bottom of the charger.

 

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4 minutes ago, Lutalo said:

It looks like there are four screws that are hidden under the four rubber pads at the bottom of the charger.

 

Good point, I totally forgot about those... I've opened one or two chargers in the past, but it's been a good while

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1 hour ago, novazeus said:

so mine from kingsong that stopped working, looked like they should have little rubber feet have none. they are junk now anyway, so i’ll crack one open. just curious to see what failed.

Cool. Minus the screws it probably opens the way that Esaj described. My chargers are also from Kingsong and they have them.

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