18XL inbound. Any advice about charging?

[erk1024]

After some shenanigans with customs, my 18XL is on the way, should get it mid next week.

I'm just curious if there is anything I should know about charging. The KS instructions are very terse about--well everything actually. 

• Should you charge it to 100% the first time (they recommend that for phones, for example) or does it matter?
• After a ride, should you wait for the batteries to cool down a bit before charging?
• In general, should you charge to 80% or 90% to lessen wear and tear on the battery?
• I plan to use the eWheels 5A quick charger, is there anything about that I should know? Just go for  the full 5 amps right?
• How much charge does a wheel typically arrive with?

And thanks for all the great information on my previous newbie questions--it's a big help.  

 

 

Edited April 25, 2019 by erk1024
Added question

[meepmeepmayer]

In general, babying batteries seems to be quite overrated.

22 minutes ago, erk1024 said:

• Should you charge it to 100% the first time (they recommend that for phones, for example) or does it matter?

Can't hurt, but doesn't matter.

The idea is: if the cells are imbalanced, you can only charge up to the least common denominator cell, so you might lose some capacity in the worst case. Balancing only happens at full battery. All that means that occasionally charging to 100% and keeping it there for an hour might fully solve a problem that doesn't exist anyways. Nothing is lost if you don't charge to 100% right away, though you might want to test to confirm that your wheel charges fully.

22 minutes ago, erk1024 said:

• After a ride, should you wait for the batteries to cool down a bit before charging?

No. Never heard of that. Charging current is much lower than riding current. What's it supposed to do that riding doesn't?

22 minutes ago, erk1024 said:

• In general, should you charge to 80% or 90% to lessen wear and tear on the battery?

Nothing worse than wanting to use your full range and then the wheel is at 90% and needs to be charged for 2 hours (the last % charging is always slow, regardless of charger) to be full.

Storing batteries very empty or very full for a long time is supposed to be bad, but Marty does it (100%) and he notices... nothing. I store my wheel at 90%, just because it can't hurt, and charge it to 100% the day before or overnight if I know I might go riding the next day. If you ever find yourself questioning whether you should fully charge your wheel or might not need that soon, charge away, lest you be stranded with a battery that could be full but isn't.

22 minutes ago, erk1024 said:

• I plan to use the eWheels 5A quick charger, is there anything about that I should know? Just go for  the full 5 amps right?

Just charge.

23 minutes ago, erk1024 said:

• How much charge does a wheel typically arrive with?

You'll see

In theory, you're supposed to ship batteries at some low number (<30%, <40%, or something). Whether KS does that is another question.

-

TLDR: Treat your wheel like you'd treat a dog (e.g. don't keep it in freezing temps or a hot car), and if you don't use it for weeks, if it is not near 100% (or very empty), that can't hurt. Charge if you might need the range.

[Lutalo]

I will be group riding all weekend; Saturday and Sunday. I will put 80 to 100 miles on my wheel between the two days. 

I slow charged my XL overnight last night to have it ready for Saturday (one 84v brick through one charging port). In perspective, it's has/will sit fully charged all day today, and tomorrow before finally riding on Saturday. I charge the wheel when I think of it.

If I bring it home from a big ride with about 50-40% battery, I will leave it there and run it down over a few days tooling about the neighborhood to 30-25%.

Given that I have been/will be most likely expedition riding two to three times per week through Halloween, by the time I work it down to 25% it's time to slow charge it again anyhow. 

Personally I always slow charge to 100% if I know I am expeditioning. If on an expedition ride and I want to recharge (want is key here. I have yet to need recharge ), I'll fast charge to 80 or 90% and keep it moving. My ride schedule is pretty frequent and predictable, and so to is my charging cycle. 

In terms of how wheels are shipped; I have never received a fully charged wheel, and I have bought several. I have never bothered with measuring they do seem to ship with about 30 to 40% battery. 

Edited April 26, 2019 by Lutalo

[Dave U]

4 hours ago, erk1024 said:

Should you charge it to 100% the first time (they recommend that for phones, for example) or does it matter?

Big YES on this one, you want to condition your batteries first charge. Use the slow charger that comes with the wheel, I know waiting for that first ride sucks!

 

4 hours ago, erk1024 said:

After a ride, should you wait for the batteries to cool down a bit before charging?

No, you could plug it in soon after. Slow charge it unless you plan on riding it right away, then use your fast charger.

 

4 hours ago, erk1024 said:

In general, should you charge to 80% or 90% to lessen wear and tear on the battery?

 Correct, You should keep your battery between 95% to 30% and after every few charges go for 100%.

 

4 hours ago, erk1024 said:

I plan to use the eWheels 5A quick charger, is there anything about that I should know? Just go for  the full 5 amps right?

No, you want to charge at the lowest amp possible to keep your battery healthy, only charge at higher amps depending on how fast you want to get back on the road. HEAT kills batteries. The lower the amp charge, the cooler your battery charges, as you go higher on your amps, so will the battery heat build up. Another thing, you should always use your factory charger to charge your wheel at home unless you need that quick charge to ride again. I want my EWheels 5 amp fast charger for longevity (only use when needed). When I go on long rides I always bring my fast charger but I only get <32 miles out of my 18L. You will be good with >50 plus miles on your 18XL.

 

4 hours ago, erk1024 said:

How much charge does a wheel typically arrive with?

My KS18L arrived with around 40%. I checked it before I did my slow charge to 100%.

[svenomous]

I agree that there's no need to be overly paranoid/OCD about this topic, but  if you're interested in maximizing the battery pack's total useful lifetime it doesn't hurt to remember the following:

KS18XL uses Samsung 35E 18650 cells in 20s6p configuration (so 120 cells total). See https://www.orbtronic.com/content/samsung-35e-datasheet-inr18650-35e.pdf for cell specs.  Hence, the pack's nominal voltage is 72V (20s*3.6V), its charge cutoff voltage is 84V (20s*4.2V), its discharge cutoff voltage is 53V (20s*2.65V), its "KingSong 0% definition" voltage is 60V (20s*3.0V), and its capacity is 21Ah (6p*3.5Ah) at nominal 72V, which translates to 1,512Wh (21Ah*72V).

The official measure of useful lifetime is "cycle life."  This is the number of full-charge-to-full-discharge cycles a cell can sustain before permanently losing a stated percentage of its total design capacity.  The 35E has a 3500mAh design capacity, and its specs indicate it can sustain 500 cycles before losing 40% of its design capacity.  However, that's under worst-case conditions of full charge and full discharge.  Cycles that occur fractionally are much easier on the cell.  For example, 10 times from 80% to 30% is the equivalent of 5 full cycles, but is much easier on the cell than 5 actual 100% to 0% cycles.  Under heavy non-storage use with deep cycling you can expect to get 500 cycles before noting significant capacity loss, but with a little care you can extend that to 1,000 or more cycles.  So:

Charging: if you're don't need maximum range for your next "mission," charging to 80% or 90% is better.  A full charge to 100% has a small but cumulative impact on the total cycle life, but if you need the range, by all means do a full charge, and don't fret too much about doing it when it's needed.

Storage: storing long-term at 100% is not good. It can cause a permanent loss of capacity of 20% or so over 1 year of storage. Storing at very low charge level is also not good, primarily because there's a danger one or more cells will fall below 2.5V and end up "dead" (cannot be charged at all anymore).  There's a small amount of constant self-discharge, and the wheel electronics are also always doing a little bit of parasitic drain, so cell voltage will inevitably decline while in storage.  A dead cell causes an entire pack series to become useless, so in a 6p pack like this one, the failure of just one of the 120 cells means you lose 17% of the pack's capacity.  The ideal storage level is around 40%, and in the case of long-term storage there should be periodic "top-off" to prevent falling below 20-30%.  Note that even under ideal conditions lithium ion chemistry will slowly lose capacity over time.  Store a new cell under ideal temperature and charge level conditions for 5-7 years, and what you end up with is just about useless, and that's with zero cycles!  The nature of the chemistry is that it degrades over time, and all we can do is slow down the degradation.

Discharging: deep discharges are bad for batteries of this chemistry (actually, all chemistries, even so-called "deep cycle" lead acid batteries).  If you routinely drain to 20% or less, you will have significantly reduced cycle life compared to draining to only 40% for example.

Charge current: the rule of thumb for a lithium ion 18650 is that 0.5C or less is "OK," and the cell specs confirm this (it says that 1,700mA, just a tad less then 0.5C, is the "standard" charge current). The specs also say that the cycle-optimized charge current for this cell is 1,020mA, which translates to 6.12A (6p*1.02A) for the pack. So, a 5A quick charger at its highest setting is great for cycle life.  If you feel rushed to charge as fast as possible, the specs set an upper limit of 2,000mA on charge current, which is 12A for the pack.  However, per KingSong (confirmed in another thread from the horse's mouth), the wheel's maximum safe charge input is 10A (probably due to wiring or the ESC in use), so don't exceed that.  Up to 10A if you really have to, otherwise stick to 6A or below for best cycle life.

Occasional full charge, deep discharge, storage at 100%, or charge at greater than "optimal" charge rate isn't a big deal.  Do it if you have to.  If you make it your routine, though, to always charge to 100, always discharge to 10, leave the wheel in a corner for weeks at 100, etc., you will have a noticeable impact on the battery's long-term capacity/life.

One related piece of advice: charge to 80% or 90% if your next ride will involve any significant downhill early on.  There needs to be available spare capacity in the battery pack to take the regenerative braking input for decelerations, or risk "overload" warnings from the wheel as it bumps up against the battery's charge cutoff voltage and has to stop using the motor for deceleration.  It can get bad enough that the wheel forces you to dismount and walk it down the hill (that's my understanding, anyway).  If you're off on an uphill or level grade, you're fine with 100%, but e.g. my commute to work starts with a nearly 2 mile long downhill at 6-12% grade.  Starting that ride on an EUC with battery at 100% would be a bad idea, not that I've tried it yet since my own KS18XL (and very first EUC ever!) doesn't arrive until tomorrow.

[Unventor]

Just tossing in a few things to think about changing and EUC behaviour.

This is what I do: 

I never charge overnight when a sleep or even unobserved. Though the risk is minimal with KS wheels, I don't want to rish having a fire when the wheel not at my attention.

So I slow charge it when eber possible. Do I need fast charging, I use 2 orginal stand chargers. 

Most time I charge it at work. Next to my desk.

THIS IS IMPORTANT TO KNOW: I tend to charge it between 95-98%. This is to avoid riding down hill at 100% which can result in a cutout. Going downhill, the wheel will act as a dynamo to store energy, but it can only do this if there is capacity space in battery pack. 

Lastly get ready to enjoy a hole new world. EUCs are simply amazing and awesome devices. Ride on😎😉

[svenomous]

Dang, I should have read that last response from Dave before hitting Submit!  Two reactions:

• Yes, occasionally charge to 100% despite what I said in my post, because the ESC has a balance circuit that parasitically drains power from cells through resistors to achieve voltage balance, and it only does this when the pack is at or near full charge (otherwise it would constantly parasitically drain down the pack).  The point is that a battery works best when all its cells are at the same voltage, but due to slight differences in manufacture and other little factors of how the charge and discharge is applied to each cell, the voltages get slightly unbalanced over time.  Balancing is the solution.  The ESC method is to watch for cell voltages to come up near charge cut-off, when the charger goes into CV mode to do the float stage of the charge, and to drain down the higher-voltage cells to be equal to the lower-voltage cells, all while the charger continues to pump in power at ever-decreasing amperage.  Charging to only 80% basically stops the charge at the end of the bulk phase, before float charging begins and before the cell voltages are high enough for the balance circuit to engage.  So yes, every 10-20 charge cycles one should consider a 100% top-off.
• On smaller battery packs than this one I would agree with Dave's comments about the quick charger, but in this case based on cell specs and count, and pack configuration, I don't.  As I said in my previous post, about 6A is right at the level the cell specs indicate to be "good for cycle life."  It's true that even lower amperage theoretically increases cycle life even further, but IMHO the curve is asymptotically approaching zero in terms of temperature reduction and cycle life gains when going below 6A.  5A is already well below this value, so the eWheels "quick" charger isn't really as quick as it seems for a pack of this size. 

[TomOnWheels]

2 hours ago, svenomous said:

I agree that there's no need to be overly paranoid/OCD about this topic, but  if you're interested in maximizing the battery pack's total useful lifetime it doesn't hurt to remember the following:

KS18XL uses Samsung 35E 18650 cells in 20s6p configuration (so 120 cells total). See https://www.orbtronic.com/content/samsung-35e-datasheet-inr18650-35e.pdf for cell specs.  Hence, the pack's nominal voltage is 72V (20s*3.6V), its charge cutoff voltage is 84V (20s*4.2V), its discharge cutoff voltage is 53V (20s*2.65V), its "KingSong 0% definition" voltage is 60V (20s*3.0V), and its capacity is 21Ah (6p*3.5Ah) at nominal 72V, which translates to 1,512Wh (21Ah*72V).

The official measure of useful lifetime is "cycle life."  This is the number of full-charge-to-full-discharge cycles a cell can sustain before permanently losing a stated percentage of its total design capacity.  The 35E has a 3500mAh design capacity, and its specs indicate it can sustain 500 cycles before losing 40% of its design capacity.  However, that's under worst-case conditions of full charge and full discharge.  Cycles that occur fractionally are much easier on the cell.  For example, 10 times from 80% to 30% is the equivalent of 5 full cycles, but is much easier on the cell than 5 actual 100% to 0% cycles.  Under heavy non-storage use with deep cycling you can expect to get 500 cycles before noting significant capacity loss, but with a little care you can extend that to 1,000 or more cycles.  So:

Charging: if you're don't need maximum range for your next "mission," charging to 80% or 90% is better.  A full charge to 100% has a small but cumulative impact on the total cycle life, but if you need the range, by all means do a full charge, and don't fret too much about doing it when it's needed.

Storage: storing long-term at 100% is not good. It can cause a permanent loss of capacity of 20% or so over 1 year of storage. Storing at very low charge level is also not good, primarily because there's a danger one or more cells will fall below 2.5V and end up "dead" (cannot be charged at all anymore).  There's a small amount of constant self-discharge, and the wheel electronics are also always doing a little bit of parasitic drain, so cell voltage will inevitably decline while in storage.  A dead cell causes an entire pack series to become useless, so in a 6p pack like this one, the failure of just one of the 120 cells means you lose 17% of the pack's capacity.  The ideal storage level is around 40%, and in the case of long-term storage there should be periodic "top-off" to prevent falling below 20-30%.  Note that even under ideal conditions lithium ion chemistry will slowly lose capacity over time.  Store a new cell under ideal temperature and charge level conditions for 5-7 years, and what you end up with is just about useless, and that's with zero cycles!  The nature of the chemistry is that it degrades over time, and all we can do is slow down the degradation.

Discharging: deep discharges are bad for batteries of this chemistry (actually, all chemistries, even so-called "deep cycle" lead acid batteries).  If you routinely drain to 20% or less, you will have significantly reduced cycle life compared to draining to only 40% for example.

Charge current: the rule of thumb for a lithium ion 18650 is that 0.5C or less is "OK," and the cell specs confirm this (it says that 1,700mA, just a tad less then 0.5C, is the "standard" charge current). The specs also say that the cycle-optimized charge current for this cell is 1,020mA, which translates to 6.12A (6p*1.02A) for the pack. So, a 5A quick charger at its highest setting is great for cycle life.  If you feel rushed to charge as fast as possible, the specs set an upper limit of 2,000mA on charge current, which is 12A for the pack.  However, per KingSong (confirmed in another thread from the horse's mouth), the wheel's maximum safe charge input is 10A (probably due to wiring or the ESC in use), so don't exceed that.  Up to 10A if you really have to, otherwise stick to 6A or below for best cycle life.

Occasional full charge, deep discharge, storage at 100%, or charge at greater than "optimal" charge rate isn't a big deal.  Do it if you have to.  If you make it your routine, though, to always charge to 100, always discharge to 10, leave the wheel in a corner for weeks at 100, etc., you will have a noticeable impact on the battery's long-term capacity/life.

One related piece of advice: charge to 80% or 90% if your next ride will involve any significant downhill early on.  There needs to be available spare capacity in the battery pack to take the regenerative braking input for decelerations, or risk "overload" warnings from the wheel as it bumps up against the battery's charge cutoff voltage and has to stop using the motor for deceleration.  It can get bad enough that the wheel forces you to dismount and walk it down the hill (that's my understanding, anyway).  If you're off on an uphill or level grade, you're fine with 100%, but e.g. my commute to work starts with a nearly 2 mile long downhill at 6-12% grade.  Starting that ride on an EUC with battery at 100% would be a bad idea, not that I've tried it yet since my own KS18XL (and very first EUC ever!) doesn't arrive until tomorrow.

Amen ! Thanks for this post @svenomous ! Very interesting and really good explanation ! Thank you for taking your time for it. I will keep this post as a reference for people asking questions about EUC batteries ! 

[svenomous]

Welcome, @TomOnWheels.  I'm a bit of a battery geek after years with LiPos (RC helicopters), not to mention the olden days with NiCd and NiMH rechargeables for various uses.  I also dabble with LiFePO batteries and solar panels for other purposes like camping and power outages, and I even have a bunch of loose Panasonic 18650's that some of my gear uses.

[erk1024]

5 hours ago, TomOnWheels said:

Amen ! Thanks for this post @svenomous ! Very interesting and really good explanation ! Thank you for taking your time for it. I will keep this post as a reference for people asking questions about EUC batteries ! 

I completely agree! Thanks everybody for the useful and informative replies. 

About storing the batteries at 100%, the DJI drones will automatically start draining their "smart battery" packs down to 75% if you don't use them within 10 days.

Edited April 26, 2019 by erk1024

[Ather]

A while back, I read it somewhere that KS wheel was tested for 1k or 10k battery cycles (don't know the exact figure but it was pretty high) with minimal battery life difference. The point is don't worry about battery life. It will last you years. 

I got my last KS wheel with 50% battery, which is plenty if you want to learn to ride right away. It depends how passionate you are about your wheel. It is possible that you can go on some what balance yourself the first or second day. 

[svenomous]

Btw my KS18XL arrived this morning, and it's charging right now.  It was initially at 45% according to the KS app.  The eWheels charger pumped almost exactly 5A into it until the battery reached just over 83V, then started tapering down as it transitions from CC mode to CV mode.  Right now it's at 83.7V and still putting in 3.7A.  996Wh charged so far, and clearly we're tapering toward full charge, so 30-40% initial state of charge looks about right.  In a little while I'll take my first tentative stumbles/falls as I begin the learning process!

[erk1024]

1 hour ago, svenomous said:

In a little while I'll take my first tentative stumbles/falls as I begin the learning process!

Good luck with that! I hope you have your protective gear sorted out. Probably some ankle protection is in order along with the other stuff. I've seen a couple photos of new riders getting wacked in the ankles by the pedals.

I'll start my stumbles / falls on Wednesday. I plan to cover my wheel in some bubble wrap. I'm going to use gaffer's tape, so it will come off without leaving a residue. It will be gawdawful ugly probably but at least it won't get as banged up. Thanks for all the charging advice!

[esaj]

17 hours ago, svenomous said:

I agree that there's no need to be overly paranoid/OCD about this topic, but  if you're interested in maximizing the battery pack's total useful lifetime it doesn't hurt to remember the following:

KS18XL uses Samsung 35E 18650 cells in 20s6p configuration (so 120 cells total). See https://www.orbtronic.com/content/samsung-35e-datasheet-inr18650-35e.pdf for cell specs.  Hence, the pack's nominal voltage is 72V (20s*3.6V), its charge cutoff voltage is 84V (20s*4.2V), its discharge cutoff voltage is 53V (20s*2.65V), its "KingSong 0% definition" voltage is 60V (20s*3.0V), and its capacity is 21Ah (6p*3.5Ah) at nominal 72V, which translates to 1,512Wh (21Ah*72V).

The official measure of useful lifetime is "cycle life."  This is the number of full-charge-to-full-discharge cycles a cell can sustain before permanently losing a stated percentage of its total design capacity.  The 35E has a 3500mAh design capacity, and its specs indicate it can sustain 500 cycles before losing 40% of its design capacity.  However, that's under worst-case conditions of full charge and full discharge.  Cycles that occur fractionally are much easier on the cell.  For example, 10 times from 80% to 30% is the equivalent of 5 full cycles, but is much easier on the cell than 5 actual 100% to 0% cycles.  Under heavy non-storage use with deep cycling you can expect to get 500 cycles before noting significant capacity loss, but with a little care you can extend that to 1,000 or more cycles.  So:

Charging: if you're don't need maximum range for your next "mission," charging to 80% or 90% is better.  A full charge to 100% has a small but cumulative impact on the total cycle life, but if you need the range, by all means do a full charge, and don't fret too much about doing it when it's needed.

Storage: storing long-term at 100% is not good. It can cause a permanent loss of capacity of 20% or so over 1 year of storage. Storing at very low charge level is also not good, primarily because there's a danger one or more cells will fall below 2.5V and end up "dead" (cannot be charged at all anymore).  There's a small amount of constant self-discharge, and the wheel electronics are also always doing a little bit of parasitic drain, so cell voltage will inevitably decline while in storage.  A dead cell causes an entire pack series to become useless, so in a 6p pack like this one, the failure of just one of the 120 cells means you lose 17% of the pack's capacity.  The ideal storage level is around 40%, and in the case of long-term storage there should be periodic "top-off" to prevent falling below 20-30%.  Note that even under ideal conditions lithium ion chemistry will slowly lose capacity over time.  Store a new cell under ideal temperature and charge level conditions for 5-7 years, and what you end up with is just about useless, and that's with zero cycles!  The nature of the chemistry is that it degrades over time, and all we can do is slow down the degradation.

Discharging: deep discharges are bad for batteries of this chemistry (actually, all chemistries, even so-called "deep cycle" lead acid batteries).  If you routinely drain to 20% or less, you will have significantly reduced cycle life compared to draining to only 40% for example.

Charge current: the rule of thumb for a lithium ion 18650 is that 0.5C or less is "OK," and the cell specs confirm this (it says that 1,700mA, just a tad less then 0.5C, is the "standard" charge current). The specs also say that the cycle-optimized charge current for this cell is 1,020mA, which translates to 6.12A (6p*1.02A) for the pack. So, a 5A quick charger at its highest setting is great for cycle life.  If you feel rushed to charge as fast as possible, the specs set an upper limit of 2,000mA on charge current, which is 12A for the pack.  However, per KingSong (confirmed in another thread from the horse's mouth), the wheel's maximum safe charge input is 10A (probably due to wiring or the ESC in use), so don't exceed that.  Up to 10A if you really have to, otherwise stick to 6A or below for best cycle life.

Occasional full charge, deep discharge, storage at 100%, or charge at greater than "optimal" charge rate isn't a big deal.  Do it if you have to.  If you make it your routine, though, to always charge to 100, always discharge to 10, leave the wheel in a corner for weeks at 100, etc., you will have a noticeable impact on the battery's long-term capacity/life.

One related piece of advice: charge to 80% or 90% if your next ride will involve any significant downhill early on.  There needs to be available spare capacity in the battery pack to take the regenerative braking input for decelerations, or risk "overload" warnings from the wheel as it bumps up against the battery's charge cutoff voltage and has to stop using the motor for deceleration.  It can get bad enough that the wheel forces you to dismount and walk it down the hill (that's my understanding, anyway).  If you're off on an uphill or level grade, you're fine with 100%, but e.g. my commute to work starts with a nearly 2 mile long downhill at 6-12% grade.  Starting that ride on an EUC with battery at 100% would be a bad idea, not that I've tried it yet since my own KS18XL (and very first EUC ever!) doesn't arrive until tomorrow.

 

17 hours ago, svenomous said:

Dang, I should have read that last response from Dave before hitting Submit!  Two reactions:

• Yes, occasionally charge to 100% despite what I said in my post, because the ESC has a balance circuit that parasitically drains power from cells through resistors to achieve voltage balance, and it only does this when the pack is at or near full charge (otherwise it would constantly parasitically drain down the pack).  The point is that a battery works best when all its cells are at the same voltage, but due to slight differences in manufacture and other little factors of how the charge and discharge is applied to each cell, the voltages get slightly unbalanced over time.  Balancing is the solution.  The ESC method is to watch for cell voltages to come up near charge cut-off, when the charger goes into CV mode to do the float stage of the charge, and to drain down the higher-voltage cells to be equal to the lower-voltage cells, all while the charger continues to pump in power at ever-decreasing amperage.  Charging to only 80% basically stops the charge at the end of the bulk phase, before float charging begins and before the cell voltages are high enough for the balance circuit to engage.  So yes, every 10-20 charge cycles one should consider a 100% top-off.
• On smaller battery packs than this one I would agree with Dave's comments about the quick charger, but in this case based on cell specs and count, and pack configuration, I don't.  As I said in my previous post, about 6A is right at the level the cell specs indicate to be "good for cycle life."  It's true that even lower amperage theoretically increases cycle life even further, but IMHO the curve is asymptotically approaching zero in terms of temperature reduction and cycle life gains when going below 6A.  5A is already well below this value, so the eWheels "quick" charger isn't really as quick as it seems for a pack of this size. 

Very good information packed into a (relatively) small amount of text here!  This is pretty much what I've been telling people over the years, but probably in too many words, poor analogues and figures to get the message through, I guess most people just skip over my posts when they see the wall of text     

The only slight changes I'd make are

a) technically, it's not "ESC" (electronic speed control) but a "BMS" (battery management system) that watches over the battery packs in the wheels for overcharge etc. (but who cares, "some abbreviation with 3 letters", right? ) 

b) I wouldn't try 10A charging through a single port with any wheel.

The ubiquitous GX16-3 (or -4 in some cases) is rated for something like 5-7A maximum, meaning it could (maybe, the figures can be a bit conservative at times) overheat due to connection resistance if you push too much current through it. Likely it will make the port and the wiring a bit hot, in the worst case it can melt the plastic around the metallic port and/or melt the sheathing off the wiring. 5A is probably not enough to cause either, unless the charge-side wiring uses thin-gauge wires (some of the generics used really thin wiring for charging, probably not an issue these days).

c) The storage charge is highly dependent on time and storage temperature

Storing a wheel at 100% in room temperature for a few days likely doesn't cause much permanent degradation. But, if you live in a cold country like here, storing the wheel for ~6 months per year, you want to make sure to drain it down to around 30-40% charge before leaving it over the winter (in room temperature or below). The batteries will get a permanent capacity degradation of around 20% per year (*) if left at full charge to room temperature, whereas charged to around 40%, it's about 4% (*). But do notice the time scales, one year vs. six months vs. one month vs. one week vs a few days are a completely different matter in the end.   

* source: https://batteryuniversity.com/learn/article/how_to_store_batteries

 

I just took my KS16S & B from "storage" (AKA guest room corner) last weekend, either didn't need a charging in the 6-7 month period of being stored and had the same amount of LEDs (I didn't bother to measure the voltages when I put them there) still lighting up when turning them back on as when I left them there. Normally, all that's draining current when the wheel's off is/are the battery BMS(s), and it/they won't need but some tens of microamps. Ninebot Z-series is different, Ninebot f***ed up something, and it looks like they drain the battery like crazy in comparison (but it's still not much more than 1/100th or so per day? Still, it's likely a more than 1000-fold figure compared to most wheels).

Edited April 26, 2019 by esaj

[svenomous]

@esaj: oops, yes, BMS.  ESC entered my head from another world (RC), but even there there right term is BMS, while ESC does something completely different.  Thanks for the clarifications/corrections.

I just did my first session on my first wheel, but I'll start a new thread to share thoughts, as I must of course do (why else be on this forum?).

[invincible1300r]

Well, I got my wheel 18XL about a week ago and unboxed it finally.  1st charge I only got it up to 52%.  Currently doing some trouble shooting with Jason and William from Ewheels and trying to narrow it down to a faulty charger.  I ordered the fast charger as a potential remedy but we'll see where it goes from there.  So far they're being really helpful but I must admit it sucks having issues with this thing right out the box.