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Battery %s


Dave Wood

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Why do so many riders constantly recharge/topup their wheels, is there any particular reason other than the speed throttling that people generally ain't using their wheels below 50% and instead choose to charge it back up?
 
im not sure what counts a full battery cycle but that last 40/50% of battery is a hell of a lot of potential range people are missing out on aswell as possibly shortening your battery life because your ultimately charging more than you need to.
Edited by Dave Wood
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I'm guilty of topping my wheel off after nearly every ride. For me, I like to keep mine here at 100% and ready to go at all times. I rarely plan anything. At any time I may grab a wheel and find myself 50% battery away from home. Tho rarely do I go more than a couple miles, I surely dont want to reach for a wheel, only to realize its not at max cap. I could very possibly be hurting my batteries by doing this, but I am FOR SURE going to be pissed when I go to grab a wheel on a perfect day, only to realize its not ready.  Throttling around 25% battery, isnt much a concern for me, its the total mileage available that I worry over.  I also prefer more power on tap, as I routinely ride around tiltback, and its my understanding that Im less likely to overpower my battery, IF it has more electrons in it. As for watching these people ride for miles and miles, then barely charge a wheel while at a diner... not something I have done.  I treat all 3 of my wheels the same way. If i turn on one of my Ks18L's and even one batt indicator light isnt lit up, it pisses me off. I'd imagine I would do the same thing, even on a 3kw monster. I mean hell, if i don't think I'd need 100% of the battery at ANY given time, I could save some weight and money and buy a smaller battery instead.

Edited by ShanesPlanet
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From my understanding, with modern chargeable battery, you don't need to discharge the battery til certain level before you can charge it.
Also, charge from 50% to 100% will not count as 1 cycle.
 

Quote

The typical estimated life of a Lithium-Ion battery is about two to three years or 300 to 500 charge cycles, whichever occurs first. One charge cycle is a period of use from fully charged, to fully discharged, and fully recharged again. Use a two to three year life expectancy for batteries that do not run through complete charge cycles.


So I just charge the wheel whenever I have time (just avoid overnight charging).

It always good to leave the house knowing I have more than 90% battery.

Edited by Phong Vu
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I rode for 40 miles with 80% to 25%. I still got range anxiety because I didn't start my ride at 90%+. Originally planned was 30 miles but GF on the ebike wanted to go explore more. 

But most of the time, I'd ride until 40%ish then charge up. I feel safer knowing more juice is in the tank so I don't somehow overpower it in a random encounter steep incline. 

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16 hours ago, Dave Wood said:

Why do so many riders constantly recharge/topup their wheels, is there any particular reason other than the speed throttling that people generally ain't using their wheels below 50% and instead choose to charge it back up?

Batteries cannot support the same "power" with lower charge states. Beside having lower voltages leading to lower top speeds and by this to lower safety margins.

Especially with lower capacity wheels this can be very noticable.

16 hours ago, Dave Wood said:

im not sure what counts a full battery cycle

From 0-100% is one cycle. Partial cycles add up by their "fraction". (Wheel reported charge % only roughly correspond with battery charge state)

16 hours ago, Dave Wood said:

but that last 40/50% of battery is a hell of a lot of potential range people are missing out on aswell as possibly shortening your battery life because your ultimately charging more than you need to.

Yes. Stopping when reaching around 50% takes them a lot of range. But if it is enough for them and allows them to drive having more fun and/or safe feeling, why not?

As written above partial charging cycles add up by their fraction so there is no difference in baattery life charging cycles by either method.

Having the batteries often at high voltages could stress them.

Having the batteries often at low voltages could stress them.

Pushing batteries at lower voltages could advance imbalance.

There are "endless" points to consider and one will only arrive at compromises. So as long as the battery works, one should drive and charge as one feels save, has fun and the wheel fulfills it's purpose.

Just overdischarging, storing a wheel fully charged at high temperatures or ignoring battery problems (noteable reduced range, not charging to full voltage, etc...) should be avoided.

And not charging the wheel full (saturation charge) often enough hinders the battery to balance (again).

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18 hours ago, Dave Wood said:
im not sure what counts a full battery cycle
 
A full li-ion battery cycle is different than a full wheel charge cycle. MSX 0% = 3.3V, 18XL 0% = 3.0V. While a full charge cycle isn’t an exact specified measure, usually a full battery cycle is down to what the cell is rated for. I think it’s usually down to something like 2.7V.
 
possibly shortening your battery life because your ultimately charging more than you need to.
 
More often yes, but simply more, no. You don’t use more gasoline on a car if you fill the tank up more often.
 
@Chriull already mentioned situations that shorten battery life. Keeping the charge always between 40-80% would give more capacity after 20000km, but the battery packs would be destroyed by unbalance long before that.
 
A fully charged pack gives more power, more speed, and more freedom to go wherever you decide at the next corner.

 

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6 hours ago, Chriull said:

From 0-100% is one cycle. Partial cycles add up by their "fraction". (Wheel reported charge % only roughly correspond with battery charge state)

Just want to chimp in here that a cycle will include discharge as well.
So, one cycle = 100% to 0% + 0% to 100%

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Think of a battery as  blow-up air balloon that is full (100% battery) or semi-full but not empty (0% battery).

The power of the air streaming out is what you can utilize.

Full is better for fun and safety. I think battery babying concerns are not worth it as long as you don't abuse the battery. If you have to think about it in earnest, just charge and ride.

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It probably varies from wheel to wheel. For my current wheel, even through they have done some FW updates to correct the LED display to more accurately reflect the true battery life, it is still not right on, probably an artifact of battery variance issues...not sure. Also, you don't want to be stuck anywhere with low battery, like putting gas in your car. So best practice is keep a good reserve of juice.

But the main reason I recharge is that at 40% battery life, when I ride fairly aggressively (over 20mph) , I will get the warning alerts to slow down...which tells me that my battery is getting stressed. I tend to recharge regularly at 30-40%. I think I've only run it down to 20% once or twice...just to see what I could squeeze out...but at that V , it's not pretty...hitting those warnings quickly.

 

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24 minutes ago, Circuitmage said:

But the main reason I recharge is that at 40% battery life, when I ride fairly aggressively (over 20mph) , I will get the warning alerts to slow down...which tells me that my battery is getting stressed. I tend to recharge regularly at 30-40%. I think I've only run it down to 20% once or twice...just to see what I could squeeze out...but at that V , it's not pretty...hitting those warnings quickly.

Although li ion cells perform at low charges not as good as fully charged, the main problem is their lower voltage!

They'd need to supply more current for the same power output. So they are somewhat more stressed by this.

The lower voltage is also the reason for the warning beeps - maximum reachable speed lowers proportional with battery voltage. With empty batteries it's more than 20% lower as with full batteries - so the wheels firmware has to warn earlier...

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14 minutes ago, /Dev/Null said:

I tend to keep my batteries between 35-75% most of the time.  Works well enough for me.  If I am going to need longer range I charge right before I ride to > 80% to top off, but I usually don't need that.

You know that by this the cells never get balanced? Once an imbalance starts and cells drift apart the lifetime will be much shorter as one could ever gain by keeping the pack at not full and not low charge states.

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From my understanding, in order to prevent imbalance you have to leave the charger on for a while after the charge reaches 100%. How long should that be? I have also heard different frequencies for how often you should fully charge it, ranging from every 3 to 10 full cycles. I know there is no need to baby our batteries that much but I would like some feedback on these guidelines.

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35 minutes ago, Kryziss said:

From my understanding, in order to prevent imbalance you have to leave the charger on for a while after the charge reaches 100%. How long should that be?

Some 2-3 hours. About once the led becomes green. But they are mostly not really "adjusted"... So maybe half an hour after it got green?

35 minutes ago, Kryziss said:

I have also heard different frequencies for how often you should fully charge it, ranging from every 3 to 10 full cycles.

That's also not really known and depends mist probably on the state of the battery.

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On 5/6/2020 at 11:41 AM, RagingGrandpa said:

Life can be simple...

"Charge overnight before a ride"

Don't charge after a ride, unless you're going to ride again immediately. (Minimizes storage SOC.)

I truly think this is all that would be needed for most EUC owners to keep their packs happy. If they knew this and nothing else, I think we'd be in a better place than today.
Perhaps some Z10's would self-discharge during long-term storage and need manual recovery... but if you put a Gotway in the basement at 3.3V/cell (unridable), come back 6mos later and I think you'll find it happily resting at 3.0 and ready to recharge.

The only remaining concern is fire safety... I'm comfortable charging indoors overnight (with me sleeping upstairs), for unmodified EUCs, that aren't soaking wet, using OEM chargers.
Start adding jenky untested custom stuff, and 'sleeping upstairs while charging' would stop.

^

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1 hour ago, Kryziss said:

I have also heard different frequencies for how often you should fully charge it, ranging from every 3 to 10 full cycles.

I wasn't very militant with precision, but I did a balancing charge on my 16S about every 10 full charges, and it simply wasn't enough. First dead cell group at 4000km. Second pack at 8000km.

 

42 minutes ago, Chriull said:

Some 2-3 hours. About once the led becomes green. But they are mostly not really "adjusted"... So maybe half an hour after it got green?

I think I measured a regular 67.2V brick turning green at around 700mA. I leave the charger on for much longer than half an hour after green, but we don't know very precisely what the best practices would be.

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