'on board' 1.5kW charger. Which alibaba supplier?
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flippy
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yes you did. paraphrasing: you clearly stated that "according to the datasheets" you should terminate the charge with a charger or it kills the cell.fatty said:
otherwise there is no difference between using a "proper" charger with cutoff or a simple CC/CV psu like every charger sold on the market today is and your whole argument about charge termination falls apart. you know, that U3 bullshit you kept mentioning on that image that a non-charger somehow does differently then a charger....
serious_sam
10 kW
We're not talking about resting voltages. We're talking about no current flow. I used 4.2V as an example, but it could just as easily be 4.0V, or whatever max charge voltage you prefer.fatty said:
If the cell is charged to say 4.05V and "rests" to 4.0V vs. just charged to 4.0V and held there until no current is flowing, there's really no practical difference. Both cells are now "resting" at 4.0V, and no current is flowing in either case.
The 4.05V case was "overcharged" by 0.05V to get it to 4.0V, and the "held" case was charged to the final 4.0V a little slower.
At that point the argument actually becomes "at what voltage do you charge to", and the evidence is pretty clear, lower is better for longevity.
So at that point I think the case is clear that holding the cell at a voltage with no current flowing doesn't do shit, for all intents and purposes, and the charge voltage has a many orders of magnitude greater effect.
I think saying holding a cell to no current flow reduces cycle life is being pedantic.
serious_sam said:
We're talking past each other. As above, I'm talking about constantly topping a cell back off to 4.2V, which obviously requires current flow, however minimal. And as every other thread attests to, this isn't healthy or good practice.
flippy said:
You can't "paraphrase" and then write something completely different. It's disappointing we can't even have a cogent discussion on here.
We already agreed that the specified charge/discharge conditions are necessary to get the rated lifespan and capacity (not "kill the cell"):
fatty said:
I'm glad it elicited the dangerous delusion that you can "change the specifications", but I'm otherwise disappointed that I got drawn into this meaningless termination argument. If the pack is already healthy enough to pass the initial safeties, holding the cells at 4.2V isn't going to cause a house fire (though it's obviously not good for cell life). You conveniently ignore the PSU-charger differences I originally wrote would prevent a house fire:
And if a pack is damaged and can't get to U2, the charger doesn't just pump huge current into the damaged pack.fatty said:
I can't believe I'm debating this.
/thread
flippy
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fatty said:
if you took even a cursory look at what i wrote or took the time to find a external source you would understand that it does not matter in the slightest what label has been put on the energy source.
do you understand the concept that during the CV phase its the BATTERY that controls how much current it will absorb? NOT the power source?
do you understand that a charger set to 10 amps at 84V does EXACTLY the same thing as a "psu" set to 10 amps at 84V?
do you understand that there is no difference AT ALL between these 2 devices for the battery? the battery does not give a frock what you call a charger or not.
keep the charging to 4.2V wear the cell out crap out of this consversation. you dont seem to understand the very basics of power supplies so gettin into a argument if charging to a certain voltage is good or not is WAY beyond your skill level right now.
if you dont understand that a charger and a CC/CV power supply are defacto exactly the same device you need to explain what it does in VERY plain text without adding all kinds of other bullshit like wear. you wanted to die on this hill so now you shall. either explain it properly or say you dont understand these very basics and are just talking out of your ass because you saw a pretty picture that you dont even understand.
fatty said:
yes it does and will moron, the charger does not know there is somthing wrong with the battery. that is the job of the bms.
fatty said:
Exactly, floating lithium at the maximum spec high voltage for any length of time is **by definition** very stressful, aka harmful to longevity.
For chemistries that naturally settle in a 100% Full state to a voltage level much lower than the charging setpoint, even more so.
Just **sitting isolated** at that Full condition for any length of time is harmful to longevity
a few hours is of course less damaging than a few days.
Everything is relative, the impact of these care factors (avoiding the voltage shoulders) can just be lost in the statistical noise
if the average cell lifespan is already greatly reduced by other factors, like high C-rates.
In a use-case arena like propulsion, where such abuse is just normal usage, even the most experienced expert will not be used to taking these finer points into consideration.
And averagely ignorant users will swear up and down the proven correlations just don't exist.
None if which changes the basic scientific facts.
I have no idea who you're arguing with. We never debated how PSUs or chargers work. They're both CC/CV devices, but a charger has additional safety features we've already established.flippy said:
You keep ignoring reality:
No, a charger doesn't just pump huge current into the overdischarged pack -- it limits current to I1:fatty said:
How does this forum get by without an ignore function? Do people realize have the posts are nonsense and just leave?
It has one. Just add someone to your foes list by visiting their profile and clicking "add foe".fatty said:
Poof.
(FWIW, most of this thread is blank to me.
)
serious_sam
10 kW
That's what we do with you John.john61ct said:
flippy
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fatty said:
i think you are mixing up unregulated packs like the hobbyking pouches you need to charge with a dedicated device and are sold with balance leads from the factory with batteries that are supplied or built as a whole with a bms and a power supply like you have on an ebike or scooter or a car.
you need to be real specific in these matters. because if you are mixing the former and the latter at will then it just confuses everybody.
When you plug in the mains of a typical aliexpress/ebay charger the voltage in the battery plug measures the very same voltage that is the max pack voltage. There is no termination going on, but the flashy light goes green. I 8 different of these chargers. I can also use my 20S chargers to charge my 16S and 18S packs (I dont do this regularly, but did it SUPERVISED when I didnt have the correct charger). It just dumps whatever max current it is set to, voltage is decided by the battery pack. There is no soft start. I would say they are just a PSU with current and voltage limiters, and a red/green light. I dont have a "high end" charger to play with, but I guess that these are the charges that most of us here uses.
flippy
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HrKlev said:
that is how every charger that is sold works (no matter where its sold) apart from the hobbychargers that are designed to charge uncontrolled packs like you see in RC toys and have more funky options you only need with uncontrolled packs. or dedicated charger with canbus or whatever where the bms instructs the charger on what to do exactly. but those are on the very extreme end and not discussed here.
you can open most of the normal chargers up and turn a little pot inside to change the voltage so you can charge anything between reason. so a 16S charger often can go down to 10S or up to 20S for example just by changing the voltage trimmer inside. some sellers will mount a pot on the outside so you can control the voltage and current yourself if you ask them.
DogDipstick
100 kW
flippy said:
Oh?
Lol. Bhahahahahah :wink:
:wink: :wink: :lol: :lol: :lol: Ok then.
flippy
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DogDipstick said:Oh?
Lol. Bhahahahahah :wink:
Ok then.
yes, that is what proper datasheets tell you. first you get the nominal values of the product, then testing parameters that the manufacturer used to get the nominal listed specs and those are usually followed by things like absolute maximum ratings and the mandatory safety stuff. usually at that spot they also tell you that damage/explostions will happen when under and overcharged/overcurrent. but for some reason they NEVER mention you should actually remove the voltage source from the battery when charging is finished to prevent damage....
you would think they would tell you that keeping the cell floating actually damaged the cell in any meaningful way over its lifespan. something...something..lawsuits...
i understand that this stuff is unpopulair because of some ingrained beliefs some/most people have but that still does not make it true. there has been insane amounts of studies done towards this stuff and the end result from every proper study i have read say that you CAN measure some change but its simply too small to be of any relevance in its lifespan. other factors like charging and discharging and even simple lifecycle/age are a bigger part then keeping cells floating at a certain voltage. lowering the peak voltage was still the biggest factor in cell life. wich also matches lifecycle testing done by me and others as we share data on this forum.
fun fact: the reason why lenovo laptops have a 80% battery charge limiter in the bios is because nasa demanded it for use on the ISS to increase the lifespan of the batteries als laptops also float the cells at 4.2V normally, and the 80% would cut that down to a tad under 4V. handy when sending up a replacement battery costs 15.000 dollars for a single laptop. they have about 100 of them on the ISS so replacing them every 2 years would cost 1.5 million every time. now they last as long as the laptop wich is 5+ years and had single digit faillures in more then 15 years.
ps: the nasa studies done on their lenovo laptop batteries is insane. a good read if you want to go down the rabbit hole of nasa level testing of the panasonic PF cells that tesla also uses in their model S and X packs.
I have never claimed that isolating the cells from a floating charge source
is required for any reason to do with safety
nor "damage" in the usual sense.
My point is simply that LI charge cycles should be terminated at or before the specified endAmps / desired trailing current is reached
when longevity is important.
Obviously that implies never leaving them hooked up until trailing amps =0
much less after that point.
______
Are you saying those Lenovo batteries used in space are kept constantly hooked up
to an active charge source at that 80% voltage spec
even when the laptop is fully powered down?
Or is the charge regulation circuitry still managed by the BIOS 24*7*365, IOW never **fully** powered down?
is required for any reason to do with safety
nor "damage" in the usual sense.
My point is simply that LI charge cycles should be terminated at or before the specified endAmps / desired trailing current is reached
when longevity is important.
Obviously that implies never leaving them hooked up until trailing amps =0
much less after that point.
______
Are you saying those Lenovo batteries used in space are kept constantly hooked up
to an active charge source at that 80% voltage spec
even when the laptop is fully powered down?
Or is the charge regulation circuitry still managed by the BIOS 24*7*365, IOW never **fully** powered down?
serious_sam
10 kW
Why can't you write like a normal person ?
Instead
of making everything
so spaced out.
unnecessarily.
Instead
of making everything
so spaced out.
unnecessarily.
serious_sam
10 kW
Whatever that means, it doesn't mean you shouldn't make an effort to learn how to communicate in a universally accepted manner. Particularly if your first/only language is "English", and we are communicating in English.john61ct said:
For example, no line breaks mid-sentence. A little punctuation wouldn't hurt. And did you know, paragraphs may contain multiple (related) sentences ?
It's about having a bit of respect for yourself (and other people, for whatever that's worth). A bit of pride in your work. I'm thinking you couldn't manage it. How about you prove me wrong ?
markz
100 TW
Talking is different then internet chat which goes inline with texting but texting is worse, is more short hand but then again that depends if the user is using a cell phone for forums or a keyboard with pc. Texting with cell phone is worse off texting or using cell for internet forums.
https://en.wikipedia.org/wiki/Neurodiversity
The problem with alibaba is that most times their English is not the best, and they might have one person with half ass English skills that is in the mopping of floors department rather then sales department.
https://en.wikipedia.org/wiki/Neurodiversity
The problem with alibaba is that most times their English is not the best, and they might have one person with half ass English skills that is in the mopping of floors department rather then sales department.
flippy
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john61ct said:
yes, these laptops are constantly left on the external chargers and the bios limits the charge level to ~4V wich means 80% for those cells.
fun fact: for the charging circuity it does not matter if you set it to 4. or 4.2V. its simply does not allow the voltage to rise further then what has been set. that being whatever voltage you want. so no. there is no cutoff current in any device. they will simply keep on trickling in current of the battery asks for it to keep that voltage at the set level. as long as current flows at the set level the SoC of that voltage level has not been reached.
and as most laptops dont have a 80% stop point like a car would have for example they will just keep the battery floating at the peak voltage whatever that has been set to. that keeping the voltage so high damages the cell is obvious. but that is because the voltage (or SoC) is that high. its simple lifespan reduction from high SoC, not because its being kept floating on its max voltage. because if you reduce the voltage to say 80% then suddenly the lifepspan increases by an order of magnitude. nothing has changed on the charger side, just the voltage to where it was set to.
yes. there is some degradation at the kathode when you keep it floating at high voltages (above 4-ish volts). but that damage is negible when it comes to the lifespan damage that the high voltage would do to it at that same voltage. would you really care about this when the difference is basically about a battery that lasts for 19.9 years instead of 20?
fun fact, i put a cheap usb meter on my phone while it was charging. it said it was 100% while it was still pulling a considerable amount of current even when the charger (that is in the phone) said it was full.
its almost like the designer is lying to the consumer about the real state of charge just so it can claim faster charge times...
