Jump to content

Li Ion Memory Effect and general handling


FreeRide
 Share

Recommended Posts

8 hours ago, FreeRide said:

There is no memory-effect with Li-Ion cells

There is a weak memory effect. Such characteristics do not advertise. But the manufacturer indicated in the user manual that it disclaims responsibility when the battery is not fully discharged:

...damage caused by over-discharge or under-discharge will not be covered by the Limited Warranty.

MRN76, you specified the application to check what confuses you?

Link to comment
Share on other sites

2 hours ago, IhKa said:

There is a weak memory effect. Such characteristics do not advertise. But the manufacturer indicated in the user manual that it disclaims responsibility when the battery is not fully discharged:

Absolute bollocks. That is a hangover from NiCad Cells. There is NO memory effect on Lithium Ion as @FreeRide has already said. All that will happen is the batteries will be aged faster if fully cycled. Fully discharging a pack also risks real damage to some cells if they are already lower than others, by taking them below their safe minimum voltage or even reverse charging them.

The only thing preventing them being seriously damaged by being completely discharged is that the BMS idea of fully discharged is usually still with 10% or 20% or even more capacity left in the battery to prevent them actually fully discharging.

i would love to see a copy of where in a Ninebot user guide it tells you that you must fully discharge the cells?

Edited by Keith
  • Like 2
Link to comment
Share on other sites

43 minutes ago, Keith said:

i would love to see a copy of where in a Ninebot user guide it tells you that you must fully discharge the cells?

I brought the line from the user manual, page 15 at the very bottom. Maybe I get it wrong.

http://at-de.segway.com/getmedia/a726eb7b-c8a9-433b-88d8-8df42fa8e5c2/NinebotOne-S2-UserManual-English-09-06.pdf.aspx?ext=.pdf

Link to comment
Share on other sites

28 minutes ago, IhKa said:

I brought the line from the user manual, page 15 at the very bottom. Maybe I get it wrong.

http://at-de.segway.com/getmedia/a726eb7b-c8a9-433b-88d8-8df42fa8e5c2/NinebotOne-S2-UserManual-English-09-06.pdf.aspx?ext=.pdf

The sentence you refer to on page 15 is presumably:

"damage caused by over-discharge or under-discharge will not be covered by the Limited Warranty"

I also don't really understand what they could mean by under/over-discharge? As they wrote before on page 15 "completely draining the battery may cause permanent damage", so this "under-discharge" should mean this discharging too much (under some threshold). Over-discharge could be a typing error and mean in reality over-charge, since this would be a second way to destroy li ion cells ? Especially as the write in the sentence before that "Electronics inside the battery record the charge-discharge condition of the battery" were they mention charge and discharge!?

But this sentence can not have the meaning, that the battery has to be discharged! This is either a typing error, some weird translation or just complete bollocks.

Maybe some native english speaker could find some nicer interpretation or some easy explanation?

For battery knowledge i'd recommend https://batteryuniversity.com/ and not wheel manuals...

 

  • Like 1
Link to comment
Share on other sites

there are many schools of thought about the correct use of the charge and discharge of lithium batteries, the seller has cormed me not to bring down the percentage of the same below 40% and then keep them well loaded so the duration of charge / discharge cycles is reduced. According to technical considerations also lithium have a small problem of memory effect .... booo I do not know who to pay attention to.
However, I have never had problems so far, I'm finding them only now that I have done agg. FW I think to reconsider the fate of restoring everything as original and check if the problem reoccurs again.

Link to comment
Share on other sites

1 hour ago, IhKa said:

I think manufacturers are simply reinsured. I met similar recommendations in manuals for laptops. And the reason for this was most likely the research.

https://www.psi.ch/media/memory-effect-now-also-found-in-lithium-ion-batteries

The article also stated that the effect is insignificant.

 

1 hour ago, capoccio1 said:

.... According to technical considerations also lithium have a small problem of memory effect .... booo I do not know who to pay attention to.
...

This is one study from 2013 regarding LiFePo4 cells (which were only used in early Solowheels?). And there was another study from 2016 which somehow analyses the origin of this effect? (just a fast and easy search on google...)  And as IhKa said:

1 hour ago, IhKa said:

The article also stated that the effect is insignificant.

So nothing to worry or even think about as customer!

1 hour ago, capoccio1 said:

there are many schools of thought about the correct use of the charge and discharge of lithium batteries, the seller has cormed me not to bring down the percentage of the same below 40% and then keep them well loaded so the duration of charge / discharge cycles is reduced. 

...

There are maybe many thoughts and rumours about charging and discharging li ion batteries - but there is be just one "correct school of thought" which is physically proven.

empty li ion cells degrade (1), fully charged li ion cells degrade (especially at high temperatures), below a certain voltage empty li ions cells die, above a certain voltage (overcharge) too.

There exist some medium ("equilibrium") voltage which provides the longest life for the cells.

So just using some "small" charge around this medium voltage prolonges battery life (but takes the fun since one cannot drive as far anymore...).

Normally one should not waste too much thought on that - the cells live more than long enough. Chances are very high that one has already the next wheel before the effect is grave - if not and one loves his wheel, one can buy a new battery pack...

A graver effect is introduced by the series configuration of the cells - as they are often not or just insufficiently balanced. This is the number one reason for battery degradation. Only thing to do against this is to fully charge the battery (from time to time) and leave it on the charger for an hour/some hours and hope for the best ;)

Edit (1): did not find why and don't remember something in detail about this - so maybe just a rumour or some minor influence or just complete bollocks? 

Edited by Chriull
  • Like 1
  • Upvote 1
Link to comment
Share on other sites

4 minutes ago, Chriull said:

empty li ion cells degrade

Would you have a reference for this (beyond the obvious harmful overdischarge)? I found plenty of infos on degradation from high states of charge and wide charge cycles, but none on low states of charge specifically.

Link to comment
Share on other sites

18 minutes ago, Mono said:

Would you have a reference for this (beyond the obvious harmful overdischarge)? I found plenty of infos on degradation from high states of charge and wide charge cycles, but none on low states of charge specifically.

Not really as it seems. Just found "In terms of longevity, the optimal charge voltage is 3.92V/cell. Battery experts believe that this threshold eliminates all voltage-related stresses; going lower may not gain further benefits but induce other symptoms. " from https://batteryuniversity.com/index.php/learn/article/how_to_prolong_lithium_based_batteries

As i did not find anything else while trying to do a quick scan over the related articles this seems to be no real problem. Or no problem at all and i somehow invented this (a new school of thought without any proove ;) )?

Or it could be originating from the recommendation to not leave the cells at a too low voltage, so that by self discharge the battery won't "under-discharge"?

  • Upvote 1
Link to comment
Share on other sites

1 hour ago, Chriull said:

Or no problem at all and i somehow invented this (a new school of thought without any proove ;) )?

I am sure you were not the only one suggesting this, so we need more proof that it is actually your invention :smartass:

1 hour ago, Chriull said:

Or it could be originating from the recommendation to not leave the cells at a too low voltage, so that by self discharge the battery won't "under-discharge"?

That was my thought as well.

Link to comment
Share on other sites

Some battery wisdom explained, insights which are hard to find otherwise. He also says explicitly at 23:03 that for the battery life, cycling 0%<->60% is better than cycling 20%<->80%.

Other highlights of this vid I commented on here:

 

Edited by Mono
  • Like 1
Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

 Share

×
×
  • Create New...