I ran my battery down and this is what happened

Gionnirocket

Well-Known Member
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.
 
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Handlebars

Well-Known Member
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 charing to 100% more often important to keep the battery cells balanced.
The trouble I find in thinking about it is that even though I routinely every so often did the long or very long 100% charges past when the charger light indicated full,
the terrible perfomance from 100% down to about 80 and the low performance all the way, never improved until I gave it the bad treatment 2 days ago and did NOT 100% charge it since.
 

Handlebars

Well-Known Member
When I long charge it to 100% at night and the next day(s) it's raining or otherwise I can't use the bike, I cringe about the keeping the battery at full charge for so long. I might be overly paranoid about it :) but my lack of dependable knowledge makes it worrsome for me. In that case I sometimes when possible take the bike out for short spin just to deplete it a bit. :)
 

Gionnirocket

Well-Known Member
If the charger light indicates full, it has turned off and is no longer doing anything.
Though I understand what you are saying, perception can often be deceptive, especially since there are so many variables and without properly measuring and documenting over time it easily becomes blurred
 

Handlebars

Well-Known Member
If the charger light indicates full, it has turned off and is no longer doing anything.
Though I understand what you are saying, perception can often be deceptive, especially since there are so many variables and without properly measuring and documenting over time it easily becomes blurred
Thanks for that info
I was following instructions given on the forum here. In that case, it must have been repeated plugging in of charger after shutoff, that finally balanced the cells.
 

Handlebars

Well-Known Member
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.
I'm sure it did not balance merely by charging to 100% and charging indicator light change. It took repeated charges one after the other without discharge, to inch the cells up together at last. I'm now getting pretty sure your appraisal of what is at fault (BMS) is good.
 

6zfshdb

Well-Known Member
When I long charge it to 100% at night and the next day(s) it's raining or otherwise I can't use the bike, I cringe about the keeping the battery at full charge for so long. I might be overly paranoid about it :) but my lack of dependable knowledge makes it worrsome for me. In that case I sometimes when possible take the bike out for short spin just to deplete it a bit. :)

When this happens to me, I hook up these 48V LED bulbs and discharge the battery on the work bench:

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I connect the bulb to the battery connector using alligator clips on a temporary lamp socket:


216z7H-BZ9L._AC_.jpg

At 15 watts (30 if you use both bulbs), it takes a couple of hours. The rig also comes it handy for temporary lighting during a power outage.
 

Handlebars

Well-Known Member
When this happens to me, I hook up these 48V LED bulbs and discharge the battery on the work bench:

View attachment 67855

I connect the bulb to the battery connector using alligator clips on a temporary lamp socket:


View attachment 67861

At 15 watts (30 if you use both bulbs), it takes a couple of hours. The rig also comes it handy for temporary lighting during a power outage.
I had thought of turning on the head and tail lights but I thought maybe I'd burn them out prematurely. I'll take that idea, thanks.
 

Handlebars

Well-Known Member
To garner the most info using just a volt meter, I'm now trying to devise the most useful test. First I'm going to run the battery down to 30% and see what mileage it gets on my usual routes usual temps usual pedalling usual PAS habits.
Next I'm not sure whether to do a normal 80% charge, redo the 90% charge like yesterday, or take it right to 100% to test voltage or if not fully balanced, then do repeated charging till it reaches whatever it can wrt to balanced and full.
 

Handlebars

Well-Known Member
If the charger light indicates full, it has turned off and is no longer doing anything.
Though I understand what you are saying, perception can often be deceptive, especially since there are so many variables and without properly measuring and documenting over time it easily becomes blurred
Many times with used single cell LiPo batteries on basic cheap charging plugs they stop charging and the light changes before reaching 4.2 volts. Unplugging and replugging often can get them to take more charge. That's what the bike battery reminds me of, when replugging gets the battery pack to take more charge in what they called "balance charging".
Really unsure that such replugging is a good idea. Now that I've been disabused of my previously adopted forum "knowledge", I'm at least going to desist on what is a useless practice of keeping the battery plugged in long past when the light changes and also desist on the replugging part that could possibly cause damage to cells. With cheap single cell LiPos that are wearing out I don't care much. For my bike battery, I'll revert to full charging every week and plugging in only once, session ended when the light changes.
 

antboy

Well-Known Member
I'm going to do that trip again today. More pies. Mmmm. St. Hubert meat pies. Exceptional. $4 on sale from about $10 regular.
So good. And $4 St. Hubert meat pie consumption is more important than bike battery consumption. :)

I wish St. Hubert was still around here.
 

Handlebars

Well-Known Member
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.
If the long long charge after the charging light shuts off isn't doing anything then might the remedy be to repeatedly plug in so long as the charging light still indicates the battery is taking more charge?
 

Handlebars

Well-Known Member
So good. And $4 St. Hubert meat pie consumption is more important than bike battery consumption. :)

I wish St. Hubert was still around here.
...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.
 

Gionnirocket

Well-Known Member
If the long long charge after the charging light shuts off isn't doing anything then might the remedy be to repeatedly plug in so long as the charging light still indicates the battery is taking more charge?
What is your battery voltage after the charger shuts off?
I wouldn't drive myself crazy worrying about this and I wouldn't repeatedly unplug it. If you want you can wait 30-45 minutes and plug it in again and it typically will take a little more charge.. but I wouldn't do this more than once or twice.

I'm actually in the process of setting up an experiment to have a better understanding of what is going on here... But this is more to keep me and my mind busy, not that I'm stress'd out about it. You're time is probably better spent getting more pies ;)
 

Handlebars

Well-Known Member
What is your battery voltage after the charger shuts off?
I can't remember how much short it came up, as it was last year that I used a meter on it. I bind the battery to the bike with steel ties to deter theft. I'll be buying more steel ties and then cutting the battery free sometime this week, so I'll be checking it out with the meter under several differing circumstances then. Meanwhile, on the forum I might be able to find what I posted about it last year.

Later: It charged to 54.2V last year, but went up to full in increments when I replugged it and left it plugged in for hours a few times.
 
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Gionnirocket

Well-Known Member
My charger seems to do the same and I wonder if that is enough to balance as it seems it is done in the very last stages of a full charge.
The standard BMS info that I come across states a typical Balance Detect Voltage of 4.18V. That is 54.34V in a 48V battery.
I'll let you know what my experiments come up with.. though without opening up the battery to measure each cell group, I don't know if it can be definitive.
 

Dallant

Well-Known Member
As a member of numerous forums through the years I’ve learned to really take any technical advise with a whole bunch of salt. A classic example is oil change intervals with modern cars/oil weights. Lots of folks love to say the recommendations of the manufacturer are bunk. The charging of these batteries falls into the same category. I’m hardly going to screw around with trying to unplug/replug the Bosch charger from my Allant at guessed-at intervals unless I’m getting specific info from them that its necessary or even safe. Till I hear different, I’ll plug in till it finishes charging, period. When storage time comes I‘ll charge it about halfway and call it good.
 

Gionnirocket

Well-Known Member
As a member of numerous forums through the years I’ve learned to really take any technical advise with a whole bunch of salt. A classic example is oil change intervals with modern cars/oil weights. Lots of folks love to say the recommendations of the manufacturer are bunk. The charging of these batteries falls into the same category. I’m hardly going to screw around with trying to unplug/replug the Bosch charger from my Allant at guessed-at intervals unless I’m getting specific info from them that its necessary or even safe. Till I hear different, I’ll plug in till it finishes charging, period. When storage time comes I‘ll charge it about halfway and call it good.
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 🙃