I ran my battery down and this is what happened

[Handlebars]

It's getting twice the mileage it was getting before it ran down, 1yr old.
Over many charges I've noticed that from a full 100 % charge the battery very quickly drained to near 80 % where it started to work more normally although not like new..it was getting one kilometer for every 2 % of charge. Use 20%, get 10 km.
My habit is to charge to about 80% and every so often try to long charge it "to balance it". Never going low. Once I was at about 20%.
Yesterday's ride took me lower on the battery charge than I've ever been..down to 11% when riding.After resting it went up to 17%.
Charged it to 40% last night then to 65 % this morning and later to 90%.
For the first time in a long time, the battery didn't drain 4% on the first hill after my driveway, and up to 14 % on the 7 km round trip to the store and back. Today it took 7% for the 7 km round trip. 1 km for 1%. Twice as good. Like new.

That is all. I have no idea why, unless taking it to that low % did a balance job like taking it to 100% and long charge never did.

 

[reed scott]

Hoping some knowledgable soul can chime in and explain this.

 

[6zfshdb]

This trick used to work with the old NiCd batteries. Running them dead and then charging to 100% was a way of maintaining capacity without causing "memory effect". I've not heard of this happening with Lithium batteries however. It may well have something to do with the BMS balancing the cell strings.

Ravi Kempaiah is our resident battery guru. Perhaps he could offer an explanation.

 

[Handlebars]

This trick used to work with the old NiCd batteries. Running them dead and then charging to 100% was a way of maintaining capacity without causing "memory effect". I've not heard of this happening with Lithium batteries however. It may well have something to do with the BMS balancing the cell strings.

Ravi Kempaiah is our resident battery guru. Perhaps he could offer an explanation.

Right. Maybe you've explained the phenomenon.
I have watched the 2 for 1 "percentage charge used to km ridden" result happening every day recently, for a month or so, setting the trip odometer to zero each time I charge. The biggest exception would be at the highest charge levels, where the battery would deplete noticably faster that average.
I'll ask how to test the hypothesis, whether running a check by not doing the big depletion or long charge again, and seeing if the effect lasts, would logically be the first way to test the hypothesis.
First I'll use the battery down a good percentage to help confirm the apparently much better mileage as a general effect achieved. It was always the first use from 100% down to near 80 that had the highly noticeable quick drop.
The relatively low discharge suited LG cells are supposed to be good for many more cycles than some of the higher discharge suited cells so that loss of mileage was a bit puzzling to me. I was thinking I damaged the battery in the winter cold.

 

[6zfshdb]

Keep in mind that truly accurate battery measurements are best made via bench testing with a fixed load. Data obtained via field testing is subject to many variables such as temperature, pedal effort variance, wind resistance, surface conditions, tire pressure, etc.

 

[Handlebars]

Keep in mind that truly accurate battery measurements are best made via bench testing with a fixed load. Data obtained via field testing is subject to many variables such as temperature, pedal effort variance, wind resistance, surface conditions, tire pressure, etc.

Yep. The big "tell"here is the super quick drop from 100% change over the same route as I most often travel. Last evening's ride was certainly not high effort and I had a shoulder bag with pies inside on the way home, so my pedalling home was very restrained. The first small hill out of the gate told me that the almost-instant 4 % drainage there was changed. Temperature was consistent with previous days and weeks. Same surfaces. So, fairly easy to rule out some variables.
I'm going to do that trip again today. More pies. Mmmm. St. Hubert meat pies. Exceptional. $4 on sale from about $10 regular.

 

[Dallant]

This trick used to work with the old NiCd batteries. Running them dead and then charging to 100% was a way of maintaining capacity without causing "memory effect". I've not heard of this happening with Lithium batteries however. It may well have something to do with the BMS balancing the cell strings.

Ravi Kempaiah is our resident battery guru. Perhaps he could offer an explanation.

Agree. This was an old trick with my Anton Bauer professional video NiCad bricks. Had to run them out completely now and then and then charge them fully to try to “refresh” the memory. Li-ons came along, in part, to fix this.

 

[Taylor57]

Yep. The big "tell"here is the super quick drop from 100% change over the same route as I most often travel. Last evening's ride was certainly not high effort and I had a shoulder bag with pies inside on the way home, so my pedalling home was very restrained. The first small hill out of the gate told me that the almost-instant 4 % drainage there was changed. Temperature was consistent with previous days and weeks. Same surfaces. So, fairly easy to rule out some variables.
I'm going to do that trip again today. More pies. Mmmm. St. Hubert meat pies. Exceptional. $4 on sale from about $10 regular.

Lets get some pictures of the next batch of meat pies. Sounds deelish! My kind of Ebiker-Pie hauler

 

[Deleted member 4210]

Well

It's getting twice the mileage it was getting before it ran down, 1yr old.
Over many charges I've noticed that from a full 100 % charge the battery very quickly drained to near 80 % where it started to work more normally although not like new..it was getting one kilometer for every 2 % of charge. Use 20%, get 10 km.
My habit is to charge to about 80% and every so often try to long charge it "to balance it". Never going low. Once I was at about 20%.
Yesterday's ride took me lower on the battery charge than I've ever been..down to 11% when riding.After resting it went up to 17%.
Charged it to 40% last night then to 65 % this morning and later to 90%.
For the first time in a long time, the battery didn't drain 4% on the first hill after my driveway, and up to 14 % on the 7 km round trip to the store and back. Today it took 7% for the 7 km round trip. 1 km for 1%. Twice as good. Like new.

That is all. I have no idea why, unless taking it to that low % did a balance job like taking it to 100% and long charge never did.

duh!

It's a known fact that lithium batteries will never be fully and properly balanced when you don't charge to 100 percent full on a regular basis. This is because every single cell has its own specific voltage characteristics, and there are enough variances between all of them, that when you don't charge to 100 percent, the cells working in conjunction with each other and how the BMS functions with them, will drastically impact overall useable output. Likewise, while you can improve battery life by not fully draining the battery everytime before charging, it is best to let it drain fully on occasion. The battery killer though is not charging to 100 percent, as the cells can get permanently out of whack with each other, and cutting the battery life significantly. And please don't compare what you do with your single battery cell phone in terms of charging to the multi cell ebike battery pack. Two entirely different animals here.

So your ' habit' of charging to 80 percent is a very bad one. Wherever you heard that from, you were highly mis-informed. You've already shortened the entire life of the battery, not just your range. So just stop doing it, unless you want to brick your battery prematurely.

Thanks though for proving the results to the EBR audience the very poor practice of short charging your ebike battery pack. If you want a full technical explanation why all this happens, rather than a lay person read, pm me, and I'll direct you to some credible links on the topic, not the bs on this topic that's all too frequently posted here at EBR.

 

[Handlebars]

Well

duh!

It's a known fact that lithium batteries will never be fully and properly balanced when you don't charge to 100 percent full on a regular basis. This is because every single cell has its own specific voltage characteristics, and there are enough variances between all of them, that when you don't charge to 100 percent, the cells working in conjunction with each other and how the BMS functions with them, will drastically impact overall useable output. Likewise, while you can improve battery life by not fully draining the battery everytime before charging, it is best to let it drain fully on occasion. The battery killer though is not charging to 100 percent, as the cells can get permanently out of whack with each other, and cutting the battery life significantly. And please don't compare what you do with your single battery cell phone in terms of charging to the multi cell ebike battery pack. Two entirely different animals here.

So your ' habit' of charging to 80 percent is a very bad one. Wherever you heard that from, you were highly mis-informed. You've already shortened the entire life of the battery, not just your range. So just stop doing it, unless you want to brick your battery prematurely.

Thanks though for proving the results to the EBR audience the very poor practice of short charging your ebike battery pack. If you want a full technical explanation why all this happens, rather than a lay person read, pm me, and I'll direct you to some credible links on the topic, not the bs on this topic that's all too frequently posted here at EBR.

Thanks Mike. It does not, however, to my inexperienced self, explain the phenomenon of the battery performance being restored by after the big depletion. Afterward I did not long charge at 100%, or even just barely charge to 100%. Charged only to 90%.
Perhaps the effect of ( apparently) being over 90% for a short time while charger was still charging ( the reading drops a bit as soon as charger is unplugged) , did something?

 

[Gordon71]

Well

duh!

It's a known fact that lithium batteries will never be fully and properly balanced when you don't charge to 100 percent full on a regular basis. This is because every single cell has its own specific voltage characteristics, and there are enough variances between all of them, that when you don't charge to 100 percent, the cells working in conjunction with each other and how the BMS functions with them, will drastically impact overall useable output. Likewise, while you can improve battery life by not fully draining the battery everytime before charging, it is best to let it drain fully on occasion. The battery killer though is not charging to 100 percent, as the cells can get permanently out of whack with each other, and cutting the battery life significantly. And please don't compare what you do with your single battery cell phone in terms of charging to the multi cell ebike battery pack. Two entirely different animals here.

So your ' habit' of charging to 80 percent is a very bad one. Wherever you heard that from, you were highly mis-informed. You've already shortened the entire life of the battery, not just your range. So just stop doing it, unless you want to brick your battery prematurely.

Thanks though for proving the results to the EBR audience the very poor practice of short charging your ebike battery pack. If you want a full technical explanation why all this happens, rather than a lay person read, pm me, and I'll direct you to some credible links on the topic, not the bs on this topic that's all too frequently posted here at EBR.

The only time I've heard of charging to less than 100% is for winter storage. Is that still a correct thing to do?

 

[Gionnirocket]

I have witnessed similar phenomenon with cell phone batteries and Battery University attributes this to the smart management system of the battery not the battery itself. The same thing is not in play here.
I'd add that using the percentage reading is not as accurate as a voltage reading and depending on how it is calculated can be misleading.

 

[Handlebars]

I have witnessed similar phenomenon with cell phone batteries and Battery University attributes this to the smart management system of the battery not the battery itself. The same thing is not in play here.
I'd add that using the percentage reading is not as accurate as a voltage reading and depending on how it is calculated can be misleading.

When my bike was new I used a meter to check voltage and my battery had difficulty achieving full capacity. It took several very long "balancing" charges without discharging, to get it to read full. Now I don't use the meter because my battery is steel band tied onto the frame and duct taped over to deter battery theft.

 

[Gionnirocket]

When my bike was new I used a meter to check voltage and my battery had difficulty achieving full capacity. It took several very long "balancing" charges without discharging, to get it to read full. Now I don't use the meter because my battery is steel cable tied and duct taped over to deter battery theft.

That you can attribute to the very cheap BMS's / chargers that are used with our very expensive batteries.
This is in part as prolonging the battery charge time also piss's people off.

 

[Handlebars]

The only time I've heard of charging to less than 100% is for winter storage. Is that still a correct thing to do?

I'm surprised that you haven't seen the more commonly presented idea of keeping the battery between 80 and 40 or 30 percentages, except to do long "balancing" charges periodically...meaning keep charging even perhaps hours past when the charger light goes to "finished" signal.

 

[Taylor57]

I'm surprised that you haven't seen the more commonly presented idea of keeping the battery between 80 and 40 percentages, except to do long "balancing" charges periodically...meaning keep charging even perhaps hours past when the charger light goes to "finished" signal.

Yeah, I was subscribing to that strategy until last week, when I decided last minute to do a 30 mile ride. I had charged by battery to Im guessing 70-90% and unplugged before I went to bed. I started with most of the "bars" on my display and late in my ride I was down to 1 bar. From now on, I charge till that sucker is green!

 

[Gionnirocket]

Yeah, I was subscribing to that strategy until last week, when I decided last minute to do a 30 mile ride. I had charged by battery to Im guessing 70-90% and unplugged before I went to bed. I started with most of the "bars" on my display and late in my ride I was down to 1 bar. From now on, I charge till that sucker is green!

I don't think that is the answer either... and it's probably somewhere in between as there is a very strong argument for the 40-80% charge as well. Knowing what you are working with, your specific cell parameters, the BMS's balancing strategy and the chargers cut off voltage all play an important role here.

 

[Handlebars]

The only time I've heard of charging to less than 100% is for winter storage. Is that still a correct thing to do?

It's a confusing subject to me. Keeping a battery at 100% charge hurts it more than at a lower %, my understanding. However, merely CHARGING it to 100% most of the time ...that is a more complex discussion.

 

[Handlebars]

Could it be that running it down drained the cells that were usually higher voltage, because the usually lower voltage cells basically contributed nothing, so it, in effect, balanced the cells at a low point rather than the usually thought-of high point balancing?

 

[Gionnirocket]

IMO. The 80% charge is the better approach for most charges for the best battery life.
The problem arises when the cheap chargers we have shut down near the 100% mark but before the BMS has a enough time to properly balance the pack. Thus making charging to 100% more often important to keep the battery cells balanced.