I ran my battery down and this is what happened

Dallant

Well-Known Member
I totally agree on the taking of advice and the implementation of any practice.
And I too would have a little more confidence in my setup if it was produced by a major manufacturer that undoubtedly went through some process of coordinating the design of the battery /BMS /charger than the off the shelf systems many of us on the lower end of the market have.
The guessed interval is based on some experience in the time it takes a battery and/or charger to shed any heat build up and I don't know of any reason that harm could possibly come from it.
That said... play at your own risk 🙃
I certainly understand and, frankly, I wish Trek & Bosch (and tech companies generally) were both more forthcoming about sharing their knowledge base about specific products. As a consumer and a former training curriculum developer for government and corporations, I’m frustrated with the ever more skimpy information as tech becomes ever more complex. User manuals these days are generally a joke and service manuals are becoming almost impossible to buy. I chalk it up to them just trying to drive business to the LBS.
 

Handlebars

Well-Known Member
Ok, I just charged it to light turning to full. It took about 9 minutes from when it first read 100%. I disconnected it immediately and let it sit for 30 minutes. It showed 98% after that rest. I plugged back in and it charged for a couple of minutes till turning off...then fell to 99%. I'm going to find out with meter soon, but I'm going to replug in 15 minutes. I'd prefer that the bike co. had supplied a slower charger than the 3A model. I'd prefer a 2A model.
It had fallen to 98% after some time. Then after longer plug-in with no charging showing on the charger it's reading 100% on the display. I think it may indeed trickle charge when plugged in and light does not show charging.
 
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Gionnirocket

Well-Known Member
If the charger is working as it should the current should decline substantially and the voltage should be constant as it enters the balance stage. Without monitoring current and voltage throughout the process we are all just guessing.
This is the information I intend to gather with some experiments.
 

BlackHand

Active Member
...and that is $3.04 USD. Maybe we should switch our currency. USD/St Hubert Pie exchange rates sounds more advantageous. We could just withhold pies until they fold under the pressure. Proven strategy.
I tried to google this mythical pie and apparently they don't even let Americans see it !

Access Denied​

You don't have permission to access "http://www.st-hubert.com/en/grocery-products/pot-pies-quiches/frozen-tourtiere-800g.html" on this server.

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Herr Wolf

Member
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.
Mike what is the process for charging batteries then? I'm new to e-bikes and we hear conflicting information. Is there a FAQ or a quick summary you can advise on.

"We hear never fully charge them"
"Don't let them fully drain"

And what about storage when not in use? How long can a battery retain it's charge when storing it because you're not using your bike?
 

Handlebars

Well-Known Member
I didn't get as good mileage for the first kms on a different trip, as I did last time when I only charged to 90%. I checked the display often. Still the mileage seemed improved; 24km with 69% left in the tank.
So it's very inconclusive because my usual expectation as I've been watching lately would be about 16 km for 31 % to be used.
It's different from my usual expectation but it's only one isolated round trip ride.
What definitely WAS different, something I had never seen, was what I mentioned, of it not taking 100% charge on that first charge. Maybe because I was timing from 100% to light going out, I unplugged much sooner than ever before. Or maybe the battery changed somehow after going to so low voltage.
I'm now plugging it in till 100% and will unplug immediately after light goes out. One more time to see what it shows.
 

Handlebars

Well-Known Member
So again I noticed that when charging light turned off, the battery was not at 100% . After some more time with charger still attached it became 100%.
On my usual 7 km run the range was back to the old 2% burned for each km traveled. 7 km, 86% charge remained. Put on another 4 km and only dropped 3% to 83% charge.
This is the usual poor performance out of the gate on full charge, and then a bit of an improvement in the 80% range.
 

Gionnirocket

Well-Known Member
You really should be taking voltage/wattage readings if you want to experiment and have a clearer understanding of what is going on. There can be many reasons for your perception of what is happening here. A cheap or poorly calibrated display can be one just as the possible premature charger cut off can be another issue all together.
I personally would not continue to stress myself or possibly the battery without a more technical approach.
 

Gionnirocket

Well-Known Member
Mike what is the process for charging batteries then? I'm new to e-bikes and we hear conflicting information. Is there a FAQ or a quick summary you can advise on.

"We hear never fully charge them"
"Don't let them fully drain"

And what about storage when not in use? How long can a battery retain it's charge when storing it because you're not using your bike?

Welcome 'Wolf
I think you'd be better served reading here.. Battery Guide
For a more technical read... Battery University and additional links on the page.
As for storage which is covered in the above, I charge to Samsung Specifications 55-65% approximately 46.8V on a 48v pack
And you do need to fully charge them occasionally to facilitate balancing the cells as this is accomplished at the end of the charge cycle... but you are correct in not letting them drain to 0
 
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Handlebars

Well-Known Member
I happened to find this chart posted by "Zinfandel", over in the "Known issues & problems Ride 1 Up" thread. I don't know how the data was obtained, regarding taking the voltage reading per 0.1 step of % reading, but it gives me a starting point when I do some small amount of testing of volts vs battery indicator %. I'm interested in seeing if there is any noticeable change of the ratio during the first 20 % usage of my battery.

Later: On this chart a drop of 10% capacity reading is accompanied by a 1.1V drop in voltage - as if the values were calculated vs being observed. I'm not sure why I should have expected any different method, though :)
 

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Gionnirocket

Well-Known Member
I happened to find this chart posted by "Zinfandel", over in the "Known issues & problems Ride 1 Up" thread
bikes. I don't know how the data was obtained, regarding taking the voltage reading per 0.1 step of % reading, but it gives me a starting point when I do some small amount of testing of volts vs battery indicator %. I'm interested in seeing if there is any noticeable change of the ratio during the first 20 % usage of my battery.

Do you have a 48V pack?
If so the chart is incorrect as you should be starting at 54.6v for 100%..
If you know the brand of cell in your pack then you can Google the data sheet for it and have a more accurate spec.
 

Handlebars

Well-Known Member
Do you have a 48V pack?
If so the chart is incorrect as you should be starting at 54.6v for 100%..
If you know the brand of cell in your pack then you can Google the data sheet for it and have a more accurate spec.
Thanks G. Yes, I have 48V pack and I know the cell is LG M36 and I have the data sheet on that. I had considered it but my assumption was that 100% on the capacity reading on the display is when the display first reaches 100%, and that that occurs earlier than when the charger turns off, i.e, approximately the final capacity reading that would be obtained by a meter reading after unplugging.
 
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BarryS

Active Member
Thanks G. Yes, I have 48V pack and I know the cell is LG M36 and I have the data sheet on that. I had considered it but my assumption was that 100% on the capacity reading on the display is when the display first reaches 100%, and that that occurs earlier than when the charger turns off, i.e, approximately the final capacity reading that would be obtained by a meter reading after unplugging.
There's a Video Court made awhile back : Where he was speaking to Specialized I'm pretty sure : The guy he was interviewing stated you should at least Once every 6 months : Take your battery all the way down : Twice a Year if you can ride year round : Can't seem to find it now :
 

Gionnirocket

Well-Known Member
Thanks G. Yes, I have 48V pack and I know the cell is LG M36 and I have the data sheet on that. I had considered it but my assumption was that 100% on the capacity reading on the display is when the display first reaches 100%, and that that occurs earlier than when the charger turns off, i.e, approximately the final capacity reading that would be obtained by a meter reading after unplugging.
And that's why I don't bother with a % reading. I leave my display showing Volts all the time.
 

Handlebars

Well-Known Member
There's a Video Court made awhile back : Where he was speaking to Specialized I'm pretty sure : The guy he was interviewing stated you should at least Once every 6 months : Take your battery all the way down : Twice a Year if you can ride year round : Can't seem to find it now

There's a Video Court made awhile back : Where he was speaking to Specialized I'm pretty sure : The guy he was interviewing stated you should at least Once every 6 months : Take your battery all the way down : Twice a Year if you can ride year round : Can't seem to find it now :
That is interesting. I might just look around for that.