How does your battery perform after a while ?

[Cloud]

I am wondering what everyone experience is with the battery performance and associated maximum distance over time ( after certain number charging cycles)?

this should be an interesting statistics as it shouldnt depend on the riders weight or riding style or riding conditions, as presumably these wont change much over time.

Expressed in percents of the new battery performance, ( or original max, distance ) How did your battery perform after, say, 100 charging cycles? After 200? 300? 400? Of course, the ambient temperature will have an effect, so maybe lets avoid statistics taken around extreme cold conditions. type of wheel and battery would be interesting to know as i imagine different wheels have different batteries.

i have estimated to have done about 100 cycles in about 3-4 months and it appears that the battery performance has gone down, quite noticeably recently. It discharges much faster now but i still need to do a max. Distance test - cant seem to get around to it because its colder and harder to ride for longer periods of time. Will try to test soon.

[Keith]

Cloud,

I would think twice about unnecessarily pushing the battery to its limits in very cold conditions.

I can't comment on battery life, having had my wheel only a month, but I do have more than 10 years experience of operating Lithium Polymer batteries in radio controlled planes and helicopters in the UK. Admittedly this is slightly different technology and I do push them to their limits - average flight times are around 6 minutes i.e. the batteries are averaging a 10C discharge and often peaking at 25-30C. They are also charged at 1C. What I have found with them is that, regardless of cycles, I don't get more than 2-3 years out of them and they always degrade significantly in the winter. Specifically, operating them in very cold conditions seems to result in a progressive increase in internal resistance which does not recover the following summer. 

I don't expect the Lithium Ion batteries in EUC's to be anywhere near as bad, but the trends are likely to be similar. Cold is, obviously, made a lot worst in aircraft by having a whacking big cooling fan built in. The lower current demands of EUC's will certainly help and If it is kept in the warm conditions before use that will help as well.

[Cloud]

14 hours ago, Keith said:

Cloud,

I would think twice about unnecessarily pushing the battery to its limits in very cold conditions.

I can't comment on battery life, having had my wheel only a month, but I do have more than 10 years experience of operating Lithium Polymer batteries in radio controlled planes and helicopters in the UK. Admittedly this is slightly different technology and I do push them to their limits - average flight times are around 6 minutes i.e. the batteries are averaging a 10C discharge and often peaking at 25-30C. They are also charged at 1C. What I have found with them is that, regardless of cycles, I don't get more than 2-3 years out of them and they always degrade significantly in the winter. Specifically, operating them in very cold conditions seems to result in a progressive increase in internal resistance which does not recover the following summer. 

I don't expect the Lithium Ion batteries in EUC's to be anywhere near as bad, but the trends are likely to be similar. Cold is, obviously, made a lot worst in aircraft by having a whacking big cooling fan built in. The lower current demands of EUC's will certainly help and If it is kept in the warm conditions before use that will help as well.

Thanks Keith,

i dont always push the battery but at the same time i dont like recharging it when its only half full as in my mind i am wasting another charging cycle, which i could have gone another day on the same charge. Besides, i know very little about batteries, but i always thought these batteries tend to "remember " their state and if not charged full or not discharged fully, will tend to stay within these parameters in the future.

Anyway, today i did a maximum distance test and the results are less that satisfying...i was only able to do about 10 miles ( nearly half of what the new battery was able to provide). There was some acceleration and braking but nothing crazy, a bit of wind at times and the ambient temperature is 7celcius. Is this how a 3-4 month old battery is supposed to perform after about 100 cycles or is it just that i ate too much over thanksgiving last weekend?

would love to hear opinions.

thanks.

p.s. Also I dont fully understand why the cold will affect the battery performance that much. When i touched the plastic covering the battery compartment today it was very warm. If the battery is warm because the wheel is in use, how will the ambient cold affect it? Maybe only when once is starting out to ride or leaves the wheel out in the cold turned off? If the wheel is always in use in the cold weather, is it safe to assume that the cold will not have an effect on the battery?

[Aaron Corsi]

34 minutes ago, Cloud said:

Thanks Keith,

i dont always push the battery but at the same time i dont like recharging it when its only half full as in my mind i am wasting another charging cycle, which i could have gone another day on the same charge. Besides, i know very little about batteries, but i always thought these batteries tend to "remember " their state and if not charged full or not discharged fully, will tend to stay within these parameters in the future.

Anyway, today i did a maximum distance test and the results are less that satisfying...i was only able to do about 10 miles ( nearly half of what the new battery was able to provide). There was some acceleration and braking but nothing crazy, a bit of wind at times and the ambient temperature is 7celcius. Is this how a 3-4 month old battery is supposed to perform after about 100 cycles or is it just that i ate too much over thanksgiving last weekend?

would love to hear opinions.

thanks.

p.s. Also I dont fully understand why the cold will affect the battery performance that much. When i touched the plastic covering the battery compartment today it was very warm. If the battery is warm because the wheel is in use, how will the ambient cold affect it? Maybe only when once is starting out to ride or leaves the wheel out in the cold turned off? If the wheel is always in use in the cold weather, is it safe to assume that the cold will not have an effect on the battery?

Cloud, you might find some interesting info in this post I made recently: http://forum.electricunicycle.org/topic/1909-when-do-you-recharge-40-20-10/#comment-20439

To sum it up: you don't need to worry so much about when to charge your EUC, just charge your battery when it's convenient.

[HoverboarderHQ]

My battery life has diminished a little over the past year but nothing like my iPhone lol.

[Cloud]

1 hour ago, Aaron Corsi said:

Cloud, you might find some interesting info in this post I made recently: http://forum.electricunicycle.org/topic/1909-when-do-you-recharge-40-20-10/#comment-20439

To sum it up: you don't need to worry so much about when to charge your EUC, just charge your battery when it's convenient.

Thanks. Great, this is very comforting to know. Charging whenever i feel like it sounds good to me.:)

but the question remains : why has battery nehavior changed and why am i getting shorter distances now?

[Aaron Corsi]

Lithium batteries work by moving lithium ions from one side of an electrolyte to another. When you charge it the ions move from side A through the electrolyte to side B, then when you use the battery the ions move from side B through the electrolyte to side A. Over time a barrier forms in the electrolyte that makes it more difficult for the ions to move from one side to another, this means that less of the ions can move freely which is what makes the battery appear to have less capacity. There are the same number of lithium ions inside, but not as many are able to flow through the electrolyte from one side to the other to put out usable energy. This also results in a higher internal resistance which can make your battery less capable of putting out a high current (moving lots of ions through the electrolyte very quickly) which means you are actually slightly more likely to see cut outs on a very old battery. 

That is why your battery has different behavior and gets shorter distances now @Cloud

[Cloud]

1 minute ago, Aaron Corsi said:

Lithium batteries work by moving lithium ions from one side of an electrolyte to another. When you charge it the ions move from side A through the electrolyte to side B, then when you use the battery the ions move from side B through the electrolyte to side A. Over time a barrier forms in the electrolyte that makes it more difficult for the ions to move from one side to another, this means that less of the ions can move freely which is what makes the battery appear to have less capacity. There are the same number of lithium ions inside, but not as many are able to flow through the electrolyte from one side to the other to put out usable energy. This also results in a higher internal resistance which can make your battery less capable of putting out a high current (moving lots of ions through the electrolyte very quickly) which means you are actually slightly more likely to see cut outs on a very old battery. 

Thank you Aaron

i apologize, i realize my question was confusing , i wasnt really trying to ask what underlying physical phenomenon makes the battery perform worse over time. What i meant was , i am trying to understand if it is normal for a ewheel battery to only achieve about 40 max distance in about 4 months and about 100 charging cycles, with a temp. Drop from about 25 clcius to 7 due to seasonal changes. And if other are having similar experiences. What i understand from a couple of responses that other are seeing an dcrease in their battery capacity but over a longer period of usage and the decrease is not as drastic.

this is why i am asking why this is happening

[Aaron Corsi]

3 minutes ago, Cloud said:

Thank you Aaron

i apologize, i realize my question was confusing , i wasnt really trying to ask what underlying physical phenomenon makes the battery perform worse over time. What i meant was , i am trying to understand if it is normal for a ewheel battery to only achieve about 40 max distance in about 4 months and about 100 charging cycles, with a temp. Drop from about 25 clcius to 7 due to seasonal changes. And if other are having similar experiences. What i understand from a couple of responses that other are seeing an dcrease in their battery capacity but over a longer period of usage and the decrease is not as drastic.

this is why i am asking why this is happening

Ah, I see. Most likely it has to do with the quality of the electrolyte in your battery, your usage patterns, and the design of the motor driver in your EUC. These all contribute to how quickly the barrier in the electrolyte will form. 

Things that could accelerate battery wear:

• Drawing lots of current quickly (by driving your EUC very hard on a regular basis)
• An undersized battery powering a high demand motor
• Drawing lots of current quickly when the battery is too hot or too cold
• A charger that charges too quickly
• A poor quality electrolyte that breaks down quickly (a cheap battery)
• Discharging the battery completely
• Storing the battery fully charged or with very low charge for extended periods

Generally a top quality rechargeable lithium battery like you'd see in a high end laptop will retain 80% capacity after 1000 charge cycles under optimal conditions with a very good battery management system. It's also normal to see less usable energy in your battery in very low temperatures.

[Cloud]

8 minutes ago, Aaron Corsi said:

Ah, I see. Most likely it has to do with the quality of the electrolyte in your battery, your usage patterns, and the design of the motor driver in your EUC. These all contribute to how quickly the barrier in the electrolyte will form. 

Things that could accelerate battery wear:

• Drawing lots of current quickly (by driving your EUC very hard on a regular basis)
• An undersized battery powering a high demand motor
• Drawing lots of current quickly when the battery is too hot or too cold
• A charger that charges too quickly
• A poor quality electrolyte that breaks down quickly (a cheap battery)
• Discharging the battery completely
• Storing the battery fully charged or with very low charge for extended periods

Generally a top quality rechargeable lithium battery like you'd see in a high end laptop will retain 80% capacity after 1000 charge cycles under optimal conditions with a very good battery management system. It's also normal to see less usable energy in your battery in very low temperatures.

Thank you

from the list above, the following will apply:

• Drawing lots of current quickly (by driving your EUC very hard on a regular basis) YES, I DROVE IT HARD BUT NOT ALL THE TIME, MAYBE HALF OF THE TIME
• An undersized battery powering a high demand motor NO, MY BATTERY IS 680wh
• Drawing lots of current quickly when the battery is too hot or too cold. MAYBE. MY WHEEL OVERHEATED OFTEN, BUT I GUESS THE HIGH TEMP. WAS MORE IN THE CONTROL BOARD. I RODE IN THE SUMMER WITH TEMPERATURES BETWEEN 20-30 CELCIUS. NEVER RODE IN EXTREME COLD.
• A charger that charges too quickly NO. I USED THE SLOW CHARGER MOST OF THE TIME
• A poor quality electrolyte that breaks down quickly (a cheap battery). DONT KNOW. THIS IS KINGSONG. I ASSUME THE BATTERY IS DECENT.
• Discharging the battery completely. MAYBE. I DID THAT MAYBE 30 PERCENT OF THE TIME. HOWEVER KINGSONGS DOESNT ALLOW YOU TO FULLY DISCHARGE -IT TILTSBACK WHEN THERE IS STILL JUICE LEFT IN THE BATTERY
• Storing the battery fully charged or with very low charge for extended periods. NO. I NEVER STORED THE BATTERY. I WAS PRETTY MUCH ALWAYS USING THE WHEEL. ALMOST EVERY DAY.

what do you think? Enough to reduce the performance by nearly 35-40%?

[Aaron Corsi]

16 minutes ago, Cloud said:

Thank you

from the list above, the following will apply:

• Drawing lots of current quickly (by driving your EUC very hard on a regular basis) YES, I DROVE IT HARD BUT NOT ALL THE TIME, MAYBE HALF OF THE TIME
• An undersized battery powering a high demand motor NO, MY BATTERY IS 680wh
• Drawing lots of current quickly when the battery is too hot or too cold. MAYBE. MY WHEEL OVERHEATED OFTEN, BUT I GUESS THE HIGH TEMP. WAS MORE IN THE CONTROL BOARD. I RODE IN THE SUMMER WITH TEMPERATURES BETWEEN 20-30 celcius
• A charger that charges too quickly NO. I USED THE SLOW CHARGER MOST OF THE TIME
• A poor quality electrolyte that breaks down quickly (a cheap battery). DONT KNOW. THIS IS KINGSONG. I ASSUME THE BATTERY IS DECENT.
• Discharging the battery completely. MAYBE. I DID THAT MAYBE 30 PERCENT OF THE TIME. HOWEVER KINGSONGS DOESNT ALLOW YOU TO FULLY DISCHARGE -IT TILTSBACK WHEN THERE IS STILL JUICE LEFT IN THE BATTERY
• Storing the battery fully charged or with very low charge for extended periods. NO. I NEVER STORED THE BATTERY. I WAS PRETTY MUCH ALWAYS USING THE WHEEL. ALMOST EVERY DAY.

what do you think? Enough to reduce the performance by nearly 35-40%?

If you get around to testing it and find you're really only getting 60% capacity and you've done 100 charge cycles then it's possible you could have a defective battery on your hands, yes. I suspect the King Song firmware probably doesn't let you get it much below 15% when you are really trying to run it on empty so that's probably not it, though below 20% is where you start to see the most damage done (especially if you aren't babying it at that level with very slow accelerations and low top speeds). I also suspect the battery is probably of decent quality.

If it's something you did and not just a bum battery then the most likely culprit would probably be hard driving and driving it outside of its ideal temp range. Batteries heat up when you use them due to the internal resistance, they will heat more depending on how much current you draw. This is also true of the driver board and the motor itself so if your wheel is overheating it probably means all of the parts are overheating, not just the control board, even though the temperature is likely only measured in one spot.

One thing to keep in mind is that an electric motor is essentially always driving a battery pretty hard because motors are inherently very high current devices. Just driving any motor at all is hard on a battery. Batteries ideally want to be charged and discharged as slowly as possible, and that's definitely not the usage pattern we have with EUCs or any electric vehicle so wearing out our batteries is just going to be the cost of doing business for us.

Sorry to hear you're getting lousy performance out of your battery.

[Cloud]

Thank you. We will see what happens in the future. My wheel has been peculiar in some ways) Maybe the capacity will magically return some day:)

[esaj]

6 hours ago, Cloud said:

Thank you. We will see what happens in the future. My wheel has been peculiar in some ways) Maybe the capacity will magically return some day:)

Have you been able to measure the voltage of the battery after fully charged? Or if you have a Charge Doctor, have you measured the total Wh charged into the batteries after fully discharged. I'd expect King Song to use quality cells, but one or more defective cells not charging to full voltage could probably cause the battery to "run out" faster. Cold temperature and head wind also contribute to the battery running out a lot faster (see my ranges in my signature; with strong head-wind and colder ambient temperature I could get around 30% less range!).

After 400-500 cycles, my original Firewheel batteries (Sony US18650V3)  still charged to above nominal capacity from totally empty (268.xWh vs. 264Wh nominal) and could get full ranges.

[Cloud]

7 hours ago, esaj said:

Have you been able to measure the voltage of the battery after fully charged? Or if you have a Charge Doctor, have you measured the total Wh charged into the batteries after fully discharged. I'd expect King Song to use quality cells, but one or more defective cells not charging to full voltage could probably cause the battery to "run out" faster. Cold temperature and head wind also contribute to the battery running out a lot faster (see my ranges in my signature; with strong head-wind and colder ambient temperature I could get around 30% less range!).

After 400-500 cycles, my original Firewheel batteries (Sony US18650V3)  still charged to above nominal capacity from totally empty (268.xWh vs. 264Wh nominal) and could get full ranges.

No i havent checked the voltage but i will check thru the app. I dont have a charge doctor but would like to get one. Yes i can see how much wind can affect battery productivity. So how cold is cold? Should the battery perform much worse at 7c?

[esaj]

1 hour ago, Cloud said:

So how cold is cold? Should the battery perform much worse at 7c?

I guess this depends on the actual cell chemistry, any additives the manufacturers might use that might affect this, discharge rate etc., but here's some graph I pinched off Google image-search:

Quickly glanced over the page I got it from ( http://www.richtek.com/en/Design%20Support/Technical%20Document/AN024 ), it doesn't state what cell this exactly is (except that it's Li-ion), so the curves could be a bit different for different cell chemistries etc, but this should give a general idea how the voltage "behaves" with constant discharge rate at different temperatures. It looks like the voltage starts to drop faster especially after the temperature drops below 0 Celsius (32 Fahrenheit), and you get a lot less capacity out from the cell before the voltage drops below useable level (in here, they've used 3.0V as cut-off). The total capacity differences above freezing point aren't that big as when you go to negative Celsius-degrees, but still noticeable if you compare 0 Celsius to 23 Celsius (around room temperature, 73.4 Fahrenheit). Don't know how the temperature affects voltage sag when the discharge rate goes up (acceleration, hitting a bump or climbing a hill with our wheels), but it could be that the sag is even deeper (the voltage drops more) the colder the cells are.

[Cloud]

Thank you!  The graph is pretty explicit, pretty much, uncharted waters below freezing point. 

I did notice that the voltage sag got worse too.

 

[Cranium]

The graph that @esaj posted is related to the temperature of the battery.  While it is 100% accurate in general as it relates to battery performance in the cold, this would not really apply to the temperature outside given the EU application. In the capacity test for temperature, they don't mention the discharge rate.  I'm guessing it is at a low discharge rate to maintain the temperature for the graph.

 In an EU, the battery is a little insulated so won't be as affected by the outdoor temperature.  If you are starting your ride from your EU indoors the battery is at your indoor temperature.  As you go outside and ride, even at cold temperatures, the batteries will stay warmer than the outside temp due to the current flow and will not be adversely affected to such a degree by the cold outside unless it is extremely cold or you stop for periods of time allowing them to get cold.

[esaj]

2 hours ago, Cranium said:

The graph that @esaj posted is related to the temperature of the battery.  While it is 100% accurate in general as it relates to battery performance in the cold, this would not really apply to the temperature outside given the EU application. In the capacity test for temperature, they don't mention the discharge rate.  I'm guessing it is at a low discharge rate to maintain the temperature for the graph.

 In an EU, the battery is a little insulated so won't be as affected by the outdoor temperature.  If you are starting your ride from your EU indoors the battery is at your indoor temperature.  As you go outside and ride, even at cold temperatures, the batteries will stay warmer than the outside temp due to the current flow and will not be adversely affected to such a degree by the cold outside unless it is extremely cold or you stop for periods of time allowing them to get cold.

True that, the graphs are probably related to the cell (surface-?) temperature, not ambient temperature. While the cells do sort of "warm themselves" due to power dissipation caused by internal resistance (especially when high currents are in play), it may or may not be enough to keep the packs warm. I do know that vee uses separate battery warming circuits with thermostats to keep the batteries at "comfortable" temperatures during winter to be able to ride (do note that the ambient temperature here during winter can be as low as -30 C / -22 F).

[Cranium]

1 hour ago, esaj said:

I do know that vee uses separate battery warming circuits with thermostats to keep the batteries at "comfortable" temperatures during winter to be able to ride (do note that the ambient temperature here during winter can be as low as -30 C / -22 F).

That is extreme!  LOL  And yeah, I agree that the battery warming would be nowhere close to enough to keep them warm at that extreme.  

I live in Florida where a cold day is 10°C or 50°F.

 

[Cloud]

On 1 декабря 2015 г., 5:19:18, esaj said:

Have you been able to measure the voltage of the battery after fully charged? Or if you have a Charge Doctor, have you measured the total Wh charged into the batteries after fully discharged. I'd expect King Song to use quality cells, but one or more defective cells not charging to full voltage could probably cause the battery to "run out" faster. Cold temperature and head wind also contribute to the battery running out a lot faster (see my ranges in my signature; with strong head-wind and colder ambient temperature I could get around 30% less range!).

After 400-500 cycles, my original Firewheel batteries (Sony US18650V3)  still charged to above nominal capacity from totally empty (268.xWh vs. 264Wh nominal) and could get full ranges.

I checked it today, if i remember correctly after fully charged the voltage was 66.8 or 66.9. I wrote it down, will confirm tomorrow

i rode the wheel today and got slightly better results. Temperature was 12C, wind was much better, almost no wind and i rode more smoothly trying to avoid accelerations and braking. Id say that i got about 20-30 %less performance that the new battery used to do. Still noticeable

i sort of ran another guy over today:). Was riding on sidewalk, surface wet after a rain. Music on, i was hoping he would be aware of my presence. But he was standing there still looking at his phone. I was going at approx about 20- 25 kph. I have a clear path in between him and the light pole. When i was a few feet away, he suddenly moved into my path of travel. It was too late to stop and i couldnt make sudden manouvers because of the wet surface. I leaned back, slowed down as much as i could but at that point the collision was unavoidable. I only had a split second to decide what to do. It felt right at that moment to open my arms and get hold of the guy as i ran into him to try to hold him from falling down. My instincts were right. He actually didnt fall even though he dropped his phone. We sort of moved slid together for a couple of feet. Neither one of us was hurt.

for the first time in my life i was in another man's arms.

[esaj]

49 minutes ago, Cloud said:

I checked it today, if i remember correctly after fully charged the voltage was 66.8 or 66.9. I wrote it down, will confirm tomorrow

Around 4.175V per cell, sounds fairly normal to me (unless there's 4.25V / cell, except one of the 16 is at around 3V ). If it isn't down to other external factors like temperature and wind, it could be that the total capacity of the cells has lowered due to something (things that come to mind: storage in elevated temperature with too high charge, too high charging current, too high discharging current) ... or maybe you were just unlucky and got the "monday"-piece of the packs.

 

[Cloud]

22 minutes ago, esaj said:

Around 4.175V per cell, sounds fairly normal to me (unless there's 4.25V / cell, except one of the 16 is at around 3V ). If it isn't down to other external factors like temperature and wind, it could be that the total capacity of the cells has lowered due to something (things that come to mind: storage in elevated temperature with too high charge, too high charging current, too high discharging current) ... or maybe you were just unlucky and got the "monday"-piece of the packs.

 

Thank you  esaj,

Hmmm i always used regular slow charger except the last few times. Fast discharging? Maybe... I rode with rapid accelerations , high speeds quite often., also i am 100kg. I also went up steep hills sometimes. Also the wheel overheated very often, not sure if it has an effect. In the summer, i kept it sometimes at around 20-25C, maybe slightly higher, sometimes fully charged, but i was basically using it every day, wasnt really storing it.

i feel that it was fine for a while and only a month ago i noticed a decrease in performance, it was kinda rapid. But i am not sure one isolated event specifically could have caused it....hmmm

could it have be because the wheel was overheating very often? 

[SlowMo]

23 minutes ago, esaj said:

Around 4.175V per cell, sounds fairly normal to me (unless there's 4.25V / cell, except one of the 16 is at around 3V ). If it isn't down to other external factors like temperature and wind, it could be that the total capacity of the cells has lowered due to something (things that come to mind: storage in elevated temperature with too high charge, too high charging current, too high discharging current) ... or maybe you were just unlucky and got the "monday"-piece of the packs.

 

I might also have a "monday" set of packs. My IPS Zero charges full at 65.67v as per the Zero app although when I switch on the unit, It says that I am at 100% capacity even at 65.67v.

On the other hand, based on the charge doctor, my MCM2S charges full at 67.7volts? 

[Cloud]

Where can i get a charge doctor?

[esaj]

49 minutes ago, Cloud said:

Thank you  esaj,

Hmmm i always used regular slow charger except the last few times. Fast discharging? Maybe... I rode with rapid accelerations , high speeds quite often., also i am 100kg. I also went up steep hills sometimes. Also the wheel overheated very often, not sure if it has an effect. In the summer, i kept it sometimes at around 20-25C, maybe slightly higher, sometimes fully charged, but i was basically using it every day, wasnt really storing it.

i feel that it was fine for a while and only a month ago i noticed a decrease in performance, it was kinda rapid. But i am not sure one isolated event specifically could have caused it....hmmm

could it have be because the wheel was overheating very often? 

Your guess is as good as mine, hard to say for sure. If you can measure the voltages of individual cells, you could at least find out if one (or more) of the cells are at a lower voltage than others (or not). Here's a couple of articles in Battery University -article about what causes Li-ions to degrade: http://batteryuniversity.com/learn/article/how_to_prolong_lithium_based_batteries   http://batteryuniversity.com/learn/article/what_causes_lithium_ion_to_die

 

20 minutes ago, Cloud said:

Where can i get a charge doctor?

Hobby16 sells them, here's the topic:  http://forum.electricunicycle.org/topic/346-charge-doctor/