Charging Strategy - Levels and Frequency

[owheely]

I read mixed things about the best charging strategy for the Solowheel 3.

 

I've heard generally that lithium batteries (all devices) get the longest lifetime when stop charging at 80%, but always keep it above 20%.

For Solowheel I've read that once a month you still want to leave it on the charger for 100%+ charge.

I also glean that the charge % floor is 40% (as in, do not operate below 40% no matter what).

 

Is there any authority on this? Max daily charge %, full 100% charge frequency, and charge % floor?

[US69]

15 minutes ago, owheely said:

I read mixed things about the best charging strategy for the Solowheel 3.

 

I've heard generally that lithium batteries (all devices) get the longest lifetime when stop charging at 80%, but always keep it above 20%.

For Solowheel I've read that once a month you still want to leave it on the charger for 100%+ charge.

I also glean that the charge % floor is 40% (as in, do not operate below 40% no matter what).

 

Is there any authority on this? Max daily charge %, full 100% charge frequency, and charge % floor?

That lithium batterys have longest life on 20-80% usage goes for all EUC's...

What also is true, that on all 10 - 15 charges you need to top up to 100%, because your serial batterys need to balance (each cell same voltage) and balancing will only work on the last bit of a full charge. Balancing is needed because the cells should not differ to much in voltage....

So thats where the "once a month" comes from....

 

 

[Keith]

1 hour ago, owheely said:

I also glean that the charge % floor is 40% (as in, do not operate below 40% no matter what).

Just to add to @US69‘s spot on answer. Charge floor is ambiguous to put it mildly.

A manufacturer will take a decision on what they consider is a safe minimum voltage for the battery to reach under load. A Lithium Ion battery off load is pretty much flat at around 3.3V, so in theory 3.3V is 0% (not zero volts as you might think) but at high load, internal cell resistance could take that as low as 2.5V. The more cells you have in parallel, the lower the internal resistance and the lower the current flow the less the voltage drops. Either way the alarm or tiltback voltage would need to be higher in these cases. Add to the mix that you probably have 40 cells comprising 20 series cells in 2 parallel, then individual cells may be lower than others so a “Fudge” factor for that is also needed. In practice many wheels, I do not know if this includes the Solowheel, see 3.4 or 3.5v per cell as the alarm point, under load that could easily be 40% unusable capacity anyway. So adding an additional 40% to that would be pretty pointless. 

You can see by the above that talking in terms of low end percentage is not really helpful. If someone says that the batteries should not be discharged below (say) 3.6V per cell off load, then that is a value that has a clear meaning, 40% really does not unless it is set against some baseline first.

[owheely]

3 hours ago, US69 said:

That lithium batterys have longest life on 20-80% usage goes for all EUC's...

What also is true, that on all 10 - 15 charges you need to top up to 100%, because your serial batterys need to balance (each cell same voltage) and balancing will only work on the last bit of a full charge. Balancing is needed because the cells should not differ to much in voltage....

So thats where the "once a month" comes from....

 

 

@US69 Do you have a personal technique for tracking your charging events?

I feel like it's almost worth keeping a log and counting off every 15 charges.

[Marty Backe]

8 minutes ago, owheely said:

@US69 Do you have a personal technique for tracking your charging events?

I feel like it's almost worth keeping a log and counting off every 15 charges.

I have a log book for every wheel. Whenever I charge a wheel I make an entry for the date and the battery level when I started the charge.

 

[owheely]

1 minute ago, Marty Backe said:

I have a log book for every wheel. Whenever I charge a wheel I make an entry for the date and the battery level when I started the charge.

 

@Marty Backe , what's the insight you get out of noting the % charge at the start of the charging?

 

Do you indicate charges that you go up to 80% versus 100%?

[Marty Backe]

1 minute ago, owheely said:

@Marty Backe , what's the insight you get out of noting the % charge at the start of the charging?

 

Do you indicate charges that you go up to 80% versus 100%?

I only charge to 100%

Probably not much insight. I just want to know how many full charges I've put on the battery and how often I ride that particular wheel. I'm a geek and kind of anal - need I say more 

[MacPara]

14 minutes ago, Marty Backe said:

I only charge to 100%

Probably not much insight. I just want to know how many full charges I've put on the battery and how often I ride that particular wheel. I'm a geek and kind of anal - need I say more 

And I thought I was the Uber Geek. You clearly redefined the meaning of that term (which I just made up) for me. 

[The Wizard]

9b1 c+, 1000miles.

I have read all the best charging posts that I can find. I want my euc to last as long as possible. The battery seems to be of concern to most people and it's expensive. Then there's all the safety considerations on riding low batteries. I diffinatly don't like riding on the lower side of 50% although I've done it many many times. Even pushed it down to 10%.

I charge to 100% every time. This regardless of how low it got. Now I probably have 100-200 plugins.

I would like to charge just to 80%  but heck, that really limits the longer rides. I routinely run down to 50-40% often and that's starting with 100% not 80%. Starting with 80% is just not practical.

My Question, my Concern:

I ride And Charge 3 or 4 times every day with out exception. (Yes, I love my euc!)

I almost feel I am damaging my batteries longevity by charging so often daily and to such a high 100%. Yet we all know the dangers of hills and braking on low batteries, so 100% seems like a must do situation.

What do you long time, expert riders recomend? What are Your thoughts?

Then there that pesky Cycle definition. 

Example:

0% to 100% = 1 cycle?

0-50% and 50-100% = 1 cycle?

0-25%, 25-50%, 50-75%, 75-100% = 1 cycle?

Does 90-100% still = 1 cycle?

Or is 1 cycle anytime you stick something in the hole?

(Ok ok guys.... This is a G Rated forum)    

 

 

[Chriull]

5 minutes ago, The Wizard said:

9b1 c+, 1000miles.

I have read all the best charging posts that I can find. I want my euc to last as long as possible. The battery seems to be of concern to most people and it's expensive. Then there's all the safety considerations on riding low batteries. I diffinatly don't like riding on the lower side of 50% although I've done it many many times. Even pushed it down to 10%.

I charge to 100% every time. This regardless of how low it got. Now I probably have 100-200 plugins.

I would like to charge just to 80%  but heck, that really limits the longer rides. I routinely run down to 50-40% often and that's starting with 100% not 80%. Starting with 80% is just not practical.

My Question, my Concern:

I ride And Charge 3 or 4 times every day with out exception. (Yes, I love my euc!)

I almost feel I am damaging my batteries longevity by charging so often daily and to such a high 100%. Yet we all know the dangers of hills and braking on low batteries, so 100% seems like a must do situation.

If you ride quite "immedeate" (within days) there should be no problem charging to 100%.

There are mainly two situation li ion batteries absolutely dislike:

charging to 100% and letting the batteries sit at really high temperatures (>30°C) for longer times (several month)
Let them sit at real low voltages for longer times.

Letting them discharge below ?2.5V? means immedeate death.
Quite every detail about them can be found at www.batteryuniversity.com

5 minutes ago, The Wizard said:

...Then there that pesky Cycle definition. 

Example:

0% to 100% = 1 cycle?

yes

5 minutes ago, The Wizard said:

0-50% and 50-100% = 1 cycle?

yes. These are two 50% cycles giving one in total.

5 minutes ago, The Wizard said:

0-25%, 25-50%, 50-75%, 75-100% = 1 cycle?

the same - 4 times 25% cycle giving in total 1 cycle

5 minutes ago, The Wizard said:

Does 90-100% still = 1 cycle?

no - thats 10% of a cycle

 

[The Wizard]

5 minutes ago, Chriull said:

If you ride quite "immedeate" (within days) there should be no problem charging to 100%.

There are mainly two situation li ion batteries absolutely dislike:

charging to 100% and letting the batteries sit at really high temperatures (>30°C) for longer times (several month)
Let them sit at real low voltages for longer times.

Letting them discharge below ?2.5V? means immedeate death.
Quite every detail about them can be found at www.batteryuniversity.com

yes

yes. These are two 50% cycles giving one in total.

the same - 4 times 25% cycle giving in total 1 cycle

no - thats 10% of a cycle

 

Wow, very good. And simple too. Thank you.

[Shad0z]

On ‎5‎/‎9‎/‎2018 at 7:38 PM, Marty Backe said:

I have a log book for every wheel. Whenever I charge a wheel I make an entry for the date and the battery level when I started the charge.

 

Thats a sweet idea! Im always looking for statistics that i dont have. I'll do that too from now  

but its gonna be hard to write so much with all these rides  

[The Wizard]

So, just to be clear...

All this talk of only charging to 80% (not 100%) is for people only occasionally or infrequently riding? Idel for weeks or months at a time. Because long periods of non-use is hard on batteries just sitting there at 100%?

Otherwise, people riding daily should (can) charge to 100% regardless of battery level or multiple times daily?

[Shad0z]

12 minutes ago, The Wizard said:

So, just to be clear...

All this talk of only charging to 80% (not 100%) is for people only occasionally or infrequently riding? Idel for weeks or months at a time. Because long periods of non-use is hard on batteries just sitting there at 100%?

Otherwise, people riding daily should (can) charge to 100% regardless of battery level or multiple times daily?

batteries operate the best between 80% and 20%

and that should be done the most possible.

but once about every 15 charge you need to deplete the battery very low. And charge it to 100%

charging to 100% is not ideal every time. Depleting to 0% is neither ideal. But its worse to let it sit at 100% or let it overcharge while at 100%

and if you need to store the battery for longer period of time its best to keep it at about 50%

 

this is a simple as it gets  

 

[Chriull]

9 minutes ago, The Wizard said:

So, just to be clear...

All this talk of only charging to 80% (not 100%) is for people only occasionally or infrequently riding? Idel for weeks or months at a time. Because long periods of non-use is hard on batteries just sitting there at 100%?

Otherwise, people riding daily should (can) charge to 100% regardless of battery level or multiple times daily?

More or less, yes.

If one has enough battery capacity which is not used up anyway and one does not drive "reckless" enough to need the full performance only available at 100% battery charge, charging to 80% could/should increase battery lifetime. But imo most EUC riders will have a new wheel before this is really noticable...

So otherway round, if one drives quite relaxed, only uses about 40-50% battery charge per ride and plans to use it frequently for more than lets say 5 years charging to only 80% should be very recommandable.

... But the real effects are not tested/verified? "Just" implications from the knowledge of for instance batteryuniversity.com ...

[Marcglider]

Just to put this in a little perspective from a source knowledgeable about batteries... If you charge the batteries full every time like @Marty Backe said he does, the life of the batteries is about 1000 cycles... Yes you can extend the life of the batteries greatly by only charging them to 80%.... 

SO, now this is my useless math... If I charge my wheel full every day, ride that wheel every single day of the year, the batteries should last me roughly 3 years... I think I personally am good with that, especially with everyone posting videos of new products coming out 

If the wheels are going to sit for a while or even a few days, it is best to leave them charged between 50% and 80%...

[Shad0z]

6 minutes ago, Marcglider said:

Just to put this in a little perspective from a source knowledgeable about batteries... If you charge the batteries full every time like @Marty Backe said he does, the life of the batteries is about 1000 cycles... Yes you can extend the life of the batteries greatly by only charging them to 80%.... 

SO, now this is my useless math... If I charge my wheel full every day, ride that wheel every single day of the year, the batteries should last me roughly 3 years... I think I personally am good with that, especially with everyone posting videos of new products coming out 

If the wheels are going to sit for a while or even a few days, it is best to leave them charged between 50% and 80%...

its actually closer to 500 cycles that the batteries will last if you charge to 100% but 500 cycles is until the battery has lost a major part of its capacity and doesnt work reliably anymore. But remember that the max charge keeps decreasing until those 500 cycles are completed. Its not like there is a certain number where the battery just totally stops working. Its a gradually gets worse

[Marty Backe]

8 minutes ago, Shad0z said:

its actually closer to 500 cycles that the batteries will last if you charge to 100% but 500 cycles is until the battery has lost a major part of its capacity and doesnt work reliably anymore. But remember that the max charge keeps decreasing until those 500 cycles are completed. Its not like there is a certain number where the battery just totally stops working. Its a gradually gets worse

All I know is that I charge my batteries to 100-percent, sometimes not riding the wheel for a few weeks, and over the last 2-years I haven't had any battery problems. Based on that any my personal wheel churn rate, I'm not going to worry about batteries.

[Marcglider]

2 minutes ago, Shad0z said:

its actually closer to 500 cycles that the batteries will last if you charge to 100% but 500 cycles is until the battery has lost a major part of its capacity and doesnt work reliably anymore. But remember that the max charge keeps decreasing until those 500 cycles are completed. Its not like there is a certain number where the battery just totally stops working. Its a gradually gets worse

I hear ya... if your wheel has a big battery or you don't plan on going long distance, it is no issue... I rode 26.5 miles on my 16S today with @JES, started with a full battery, started throttling back at 30% and ended with 26% at the end... that worked out well  and I was happy with it all... If I started out with 80%, it would have been a different story... I am getting my Tesla Wednesday so I will make a comparison as that battery is a little bigger, but so is the speed I will probably be riding it  I still plan on a full charge if I am going out on a long ride...

1 minute ago, Marty Backe said:

All I know is that I charge my batteries to 100-percent, sometimes not riding the wheel for a few weeks, and over the last 2-years I haven't had any battery problems. Based on that any my personal wheel churn rate, I'm not going to worry about batteries.

EXACTLY!!!! 

[Esash]

I think the full charge problem is more when the wheel is sitting for a couple days or more at full charge. If you're just charging it to 100% and riding it immediately/shortly after, I don't think it's that big a deal at all. 

But if you don't think you're going to ride your wheel for a couple days or more, just charge to 80-90% and top it off before your ride, or the night before you know you'll be riding.

 

[WARPed1701D]

5 hours ago, Shad0z said:

but once about every 15 charge you need to deplete the battery very low. And charge it to 100%

 

This is not true. Li-Ion has no problems with memory. A full charge every 12 to 15 full cycles is recommended but only to allow the BMS to balance the cells in a serial configuration. It has nothing to to with individual cell health and depleting the pack fully will actually wear it out more and in our case increase the risk of a faceplant due to operating the wheel when it's ability to balance you is compromised. 

[Catlord17]

My understanding was that charging to 100% speeds up the creation of some sort of dendrites in the battery chemistry which eventually kills its ability to function, and that charge to 80% and discharge to 20% produces the maximum battery life, with a 100% charge being useful for balancing the packs about every 10th charge.

So charging to 100% every time should significantly shorten the life of the batteries, from what I understand.

Also, a charge cycle is the equivalent of charging to 100% and discharging to 0%, regardless.  So 80% to 20% counts as 60% of a full charge cycle.  Again, if I understand correctly.

[WARPed1701D]

6 minutes ago, Catlord17 said:

My understanding was that charging to 100% speeds up the creation of some sort of dendrites in the battery chemistry which eventually kills its ability to function, and that charge to 80% and discharge to 20% produces the maximum battery life, with a 100% charge being useful for balancing the packs about every 10th charge.

So charging to 100% every time should significantly shorten the life of the batteries, from what I understand.

Also, a charge cycle is the equivalent of charging to 100% and discharging to 0%, regardless.  So 80% to 20% counts as 60% of a full charge cycle.  Again, if I understand correctly.

This is also my understanding. 

[Chriull]

6 hours ago, Shad0z said:

but once about every 15 charge you need to deplete the battery very low. And charge it to 100%

As @WARPed1701D said, the depleting is not necessary for li ions in EUCs. Just devices that use "smart batteries" ( http://batteryuniversity.com/learn/article/inner_workings_of_a_smart_battery ) need this full cycles from time to time.

Euc's just need some charge to 100% with the charger still attached for an hour/some hours after the charger led has gone green for balancing!

[Keith]

13 hours ago, Shad0z said:

but once about every 15 charge you need to deplete the battery very low. And charge it to 100%

I agree with @Chriull and @WARPed1701D above, such a shame to ruin an otherwise excellent reply. Cycling batteries is a hangover from NiCad and NiMh day’s and does nothing but harm on Lithium batteries. Where it is also used to reset the counter of, so called, “smart batteries” it shows they ain’t too smart!

I’m a big believer in “Don’t get anal about these things” the wheel is there to ride after all and it would be madness to start a long ride at less than 100%. I.e there is nothing more useless than a dead battery miles from anywhere,  but not all of us have lots of spare cash to burn and the battery is a high cost item,  I certainly do not on my small pension and I can see already how much capacity my 2 year old wheel has lost. 

My one and only EUC is the only thing I have that is Li Ion 18650 cells powered, but I’ve been using LiPo’s in model aircraft since 2006. As far as everything I’ve seen and read they are VERY similar. In those early days we were emphatically told: “Do not leave the batteries fully discharged”. This was true, they degraded very quickly so, as soon as I got home I charged them all up, confident that I could fly at a moment’s notice as the batteries were all ready to go. Not one single battery lasted more than 2 years. Since I only tend to fly on a Saturday, and different planes used different batteries, that meant I often got less than 25 cycles out of them. That made the cost per flight totally unacceptable and I nearly stopped flying electric.

Once I understood these better and now ALWAYS bring them all up or down to storage charge after a day’s flying. I also try to not let them get below 3.7V/cell off load in use - I.e. I check them after a flight and if they are getting lower than that I adjust the countdown timer on my transmitter to shorten the flight. However I do, always, charge them to 100%  on a Friday/Saturday morning and I am still using batteries I purchased in 2012 - their capacity has, maybe dropped by no more than 10-15% and they get used at way higher currents than EUC’s typically an average of up to 10C. I.e. many of my planes can sustain average power for no more than 6 minutes, I have the countdown timer set to only countdown when the throttle is above 25% so flights can be a lot longer.

To me this tends to prove that deep discharging and keeping batteries at 100% does the most damage - my batteries, when they died,  invariably died in winter too which leads me to conclude that storage at 100% at near freezing temperatures is absolutely the worst problem, worst than very hot. (Cold temperature’s are ideal at a storage charge, but the batteries behave as if overcharged if fully charged and then stored cold.)

Puffing up badly (not something that would even be visible in 18650 cells which will probably just gas off electrolyte) and much higher internal resistance (to the point where power to the motor would be down 30-50%) plus huge differences in capacity between individual cells - i.e. massive cell imbalances at the end of a flight - were the usual death kneels.