'on board' 1.5kW charger. Which alibaba supplier?

[amberwolf]

The modern world now tolerates, if not celebrates, neuro-diversity.

Not really. But I force myself upon it anyway.

 

[DogDipstick]

How do you have 2000 posts and not know this?
From this very thread, if you cared to read it:

now explain what a "psu" like a meanwell ELG/HLG does different then a charger.

and i know it. you dont. i actually went to school for this shit. you didnt. i just want you to learn you something so this BS argument between chargers and "psu's" can finally stop.

Lol Flippy the "Meanwell" is the same as a "Lithium charger"? I do see, from the schematic ZIhave seen they operate very similar. .

For one...
Chargers ( like the typical Kingpan) have selfstart winding ( wont start without a circuit to facilitate the start of power to the chip) and use a specific chip.. a TL494.. a Texas Instruments PWM controller . THey all have it.. just about every charger I seen. Do Meanwells use them too ( A TL494) or some other PWM chip?

Many many have the TL494. I have never seen anything like a TL494 inside any switch mode power supply? IDK maybe im wrong. Nor a "selfstart winding" that is used to power (said) chip?


Here is a reference to the literature that is (10) years old and the chip is on there, on a post from NeilP. The Meanwell seems to use the same chip. Schematics look eerily similar. Lol. Even down to the chip power.

Kingpan: ( see Tl494)

meanwell ( see: Tl494)

Huh mebbe u r right.

 

[amberwolf]

Using a specific chip doesn't distinguish one usage of an SMPS from another.

Also, lithium chargers in general are SMPSs, as are LED PSUs, etc., simply because it's much smaller, lighter, and more efficient than "linear PSUs". You may find some very small "wallwart" style chargers (like a Black-and-Decker cordless screwdriver I have here) that are still made as "linear" types (with a simple large transformer, bridge rectifier, and ripple-filter capacitor), but almost all are SMPSs.

Some (many? but not all) SMPSs that are specifically named as lithium chargers by their manufacturers also have a detector circuit in them that disconnects the output (or shuts down the SMPS) once current flow drops below a certain threshold, and this same circuit is also often used to indicate end of charging (sometimes this circuit is *only* used to indicate end of charging, and does *not* disconnect the output (or shut down the SMPS); it often is also used to control the fan).

There are versions of the "kingpan" (also available under other names) chargers that do not have this circuit, specifically so that the BMS in the battery can continue to trickle-balance as long as is necessary. The board is usually the same, except that the socket on the board for the detector circuit is not populated. (this circuit in those chargers is often a separate daughter board). There's a number of threads where Dnmun and others helped out people with batteyr and/or charger problems that discuss the details of this, if you're interested. I don't have any links, though. Somewhere around here I have at least one of those chargers in the non-shutdown version, and at least one in the shutdown version.

A list of all Dnmun's posts with "kingpan" in them
https://endless-sphere.com/forums/search.php?keywords=kingpan&terms=all&author=dnmun&sc=1&sf=all&sr=posts&sk=t&sd=d&st=0&ch=300&t=0&submit=Search
there's a lot of good info in there on fixing them if you ever need it.


Regarding usage of TL494 in SMPS designs, there's too much stuff out there to sort thru (even if I had time and energy), so I'll just post the searches if you are interested in (a lot of) reading:
https://www.google.com/search?q=TL494+inside+any+switch+mode+power+supply
https://www.google.com/search?newwindow=1&q=Tl494+SMPS

 

[serious_sam]

Really, it's fcking stupid to argue about this.

The bottom line is if it can be used to put charge into your cells, then it is a charger, as far as the cell is concerned. Might not be "good". Might not be "smart". Might not even be "safe". But if it can be used to charge a cell, then you're going to have a hard time explaining to the cell that it's not connected to a charger. The cell doesn't care what you call it.

Particularly if the power supply has current and voltage limiting ability, then it makes it ideal for charging lithium. If it doesn't auto cut-off, then it might not be a "smart" charger, by your definition. But what about if a little light comes on below a certain current flow ? Do you consider that a charger. Where do you draw the line ? Just the ability to terminate ? Talk about fcking arbitrary.

 

[john61ct]

It seems that specifically in the ebike world, so many users do top balancing with devices that need a long time to complete the process

the distinction can mostly be ignored in that context.

However that does not change the meaning of words out in the rest of the world of electrickery.

That said, while plenty of PSUs and DCDC converters are excellent **used as charge sources**,

so long as the user **needs to stand by and watch** for the charging process to reach his chosen stop-charge condition

it doesn't matter if it's watching a DMM + ammeter or trusting blinky lights

That is not a proper charger.

Those using balancing methods that do **not** require sitting feeding current at the top end long past when endAmps have been reached

will get better longevity out of their cells by stopping earlier.

Even avoiding CV / Absorb stage, using whatever charge source

by auto-terminating the charge cycle using an adjustable HVC

 

[flippy]

can we all agree that the battery does not give a shit about what chips are inside the charger?

so long as the user **needs to stand by and watch** for the charging process to reach his chosen stop-charge condition

the battery decides when its had its fill of current, not the charger.

Those using balancing methods that do **not** require sitting feeding current at the top end long past when endAmps have been reached

the balacing tech used has no bearing on the actual charging process of the cell. you are not feeding current in, the cell/battery TAKES current.

it seems to bear repeating: THERE IS NO END AMPS LIMIT.

you cant damage a cell by feeding it too little current.
(and no, we are going to keep academic fringe edge cases out of practical applications here)

and considering only people with RC style batteries that use balance leads directly connected to the charger is the ONLY group your comment applies to and litteraly every other product on the market works liek a normal CC/CV dumb charger with a bms you really need to make some disticntions if you want to have a meaningful conversation.

will get better longevity out of their cells by stopping earlier.

that is a COMPLETLY different subject.

Even avoiding CV / Absorb stage, using whatever charge source

use the correct terminology when discussing lithium cells, its CC/CV. period. a term like absorbtion means nothing in the level of conversation you are trying to have. batteries are not daipers, kitty litter of feminine hygene products.

that said, you using the term absorbsion implies you do seem to understand the concept that current is demanded, not given.

by auto-terminating the charge cycle using an adjustable HVC

you do understand the concept of how "CV" actually works right? because if you say things like that i dont think you think what it means what is actually means.

once you get out of the CC part of a charging battery you enter CV, and the voltage will rise absolutly no further then that.


i think you need to learn some basic electronics here.

Q: are you in the posession of a simple lab power supply?

 

[john61ct]

CC stage AKA Bulk, is before the batt hits the max-V setpoint.

CV AKA Absorb stage, is after the V setpoint is reached, charge source regulator holding to that voltage as max,

battery pulling less current as its ESIR climbs.

Yes of course the battery pulls the current level, I don't know why you think this would be news to anyone?

With LI chemistries, assuming no balancing required, and assuming optimising longevity is desired*

the sooner you stop after the CC-to-CV transition point the better.

Holding a long AHT is just as damaging*

as going up to the vendor maximum spec voltage in your charge source profile setpoint.

Again, overcharging* is not just voltage, but also holding Absorb too long, allowing current to drop too low.

Personally if I allow any CV at all, my endAmps preference is 0.05C, going down so far as 0.02C is probably fine, but why? no reason.

Yes the battery will happily keep pulling current long after the point where doing so causes damage*.

That is why the charge cycle must be terminated before that point. Ideally automatically, not relying on human attention / memory.

There are many reasons why this ebike community apparently ignores this issue, already discussed many times.

The prevalence of balancing at the top is a major one, cheap low balance-rate devices require continuing the cycle long past the damage* point.

But that does not change the facts.


* damage defined as "reducing longevity"

If you are already abusing cells with very high C-rates, or do not care about optimising longevity, then just ignore all the above.

And none of this changes in the RC hobby world, batteries are batteries, I am not talking about using any particular type of charge source, using a BMS or not, just principles of care.

 

[flippy]

CC stage AKA Bulk, is before the batt hits the max-V setpoint.

the battery does not decide the voltage, the charger does.

CV AKA Absorb stage, is after the V setpoint is reached, charge source regulator holding to that voltage as max,
battery pulling less current as its ESIR climbs.
Yes of course the battery pulls the current level, I don't know why you think this would be news to anyone?

because ytou keep mentioning that a charger is putting current INTO the battery.

With LI chemistries, assuming no balancing required, and assuming optimising longevity is desired*
the sooner you stop after the CC-to-CV transition point the better.

how is that? you are muddying the waters again. if i charge a battery with 1mA, i will basically NEVER reach the CV stage until the cell is filled.
stop making these broad claims.

more reasonable: if you charge a cell of say, 2500mAh with 1A and up to 4V, will that cell live shorter or longer then the same cell charged with 300A at 4V? according to you the cell should live a long time, the CC portion will be extremely short will it not? so that way of charging must be FANTASTIC for the cell.

Holding a long AHT is just as damaging as going up to the vendor maximum spec voltage in your charge source profile setpoint.

i dont know what AHT means. and the voltage is not relevant in the actual charging process. that is a lifespan discussion we are not currenty having.

Again, overcharging* is not just voltage, but also holding Absorb too long, allowing current to drop too low.

how can a battery be "overcharged"? unless you have some magical cells then a cell simply stops taking in current when its full/reached its set charge voltage.
as the SoC is dependant of the voltage set you need to stop making such claims as they fall apart as soon as you do a partial charge to a lower set voltage. you cannot "overcharge" a regular lithium cell if you "charge" it to 3.6V and just hold it there. or at 4.2V for that matter..

Personally if I allow any CV at all, my endAmps preference is 0.05C, going down so far as 0.02C is probably fine, but why? no reason.

good for you, have a lolly.
that is not what we are discussing.
you decide to stop charging the battery BEFORE its full to the voltage/capacity you have set it. its simple as that.

Yes the battery will happily keep pulling current long after the point where doing so causes damage*.

explain how this works. you are going off the deep end here. so watch out. explain how a battery keeps pulling current AFTER its filled. note that we are discussing lithium based batteries. not SLA.

That is why the charge cycle must be terminated before that point. Ideally automatically, not relying on human attention / memory.

no, that is not why. if you dont know, ask someone that actually studied for this crap.

There are many reasons why this ebike community apparently ignores this issue, already discussed many times.

they are ignoring it because you have convinced yourself of soemthing that is simply so far away from reality that its hard to even know where to start.
your argument is like hearing a oil specialist talking about how oil is a renewable resource.
sure, you probably know a lot about oil, but you are going fully off the rails here.

The prevalence of balancing at the top is a major one, cheap low balance-rate devices require continuing the cycle long past the damage* point.

who said its a damage point when you have not even concluded that any meaningful damage is actually done? you aregument falls compleltly flat when you dont even consider the actual voltage of the cell.

But that does not change the facts.

indeed, but that does not seem to stop you form making up some of your own.

* damage defined as "reducing longevity"

lifepspan is dicated my several factors, keeping a cell floating at a specific voltage is just one of them.

If you are already abusing cells with very high C-rates, or do not care about optimising longevity, then just ignore all the above.
And none of this changes in the RC hobby world, batteries are batteries, I am not talking about using any particular type of charge source, using a BMS or not, just principles of care.

correct. but you do LOVE to mix and confuse by ignoring far creater factors in this discussion that DO matter. we are not discussing lifespan, care or whatever metric. not how far or anything else, just HOW to charge. and several seem to claim that a regular CC/CV supply charges a cell differently then a "real" charger. you need to actually stop adding a load of stuff and just focus on this specific subject and no go off on lifespan or whatever.

for ease of discussion and terminology we shall use a single cell in further discussion if that is all right with you.
so no bms or whatever. just a single 18650 cell and a basic use case. lets take the samsung 29E as a base for the cell basic specs.:


Nominal Capacity: 2,850mAh (0.2C, 2.50V discharge)
Typical Capacity: 2,850mAh (0.2C, 2.50V discharge)
Minimum Capacity: 2,750mAh (0.2C, 2.50V discharge)
Charging Voltage: 4.20 ± 0.05 V
Nominal Voltage: 3.65V (0.2C discharge)
Charging Method: CC­CV (constant voltage with limited current)
Charging Current: Standard charge: 1,375mA
Charging Time: Standard charge: 3hours
Max. Charge Current: 2750mA (not for cyclelife)
Max. Discharge Current: 2,750mAh (continuous discharge), 8250mAh (not for continuous discharge)
Discharge Cut­off Voltage: 2.50V

how would your "cut out the CV portion for lifespan" exactly work with this cell if i were to simply charge this cell with 1mA to 4.2V? (excluding the fact it would take 10 months to charge)

i know that this cell charged with ~8A (its absollute max) will switch to CV at around the 3.9V when its at rest. explain the difference between just charging slower to 3.9V and hold it there until to stops taking current and your method of just firehosing the cell and see what the charge level is? (ignoring any lifespan issues from just pumping amps into the cell)

 

[DogDipstick]

for ease of discussion and terminology we shall use a single cell in further discussion if that is all right with you.
so no bms or whatever. just a single 18650 cell and a basic use case. lets take the samsung 29E as a base for the cell basic specs.:


Nominal Capacity: 2,850mAh (0.2C, 2.50V discharge)
Typical Capacity: 2,850mAh (0.2C, 2.50V discharge)
Minimum Capacity: 2,750mAh (0.2C, 2.50V discharge)
Charging Voltage: 4.20 ± 0.05 V
Nominal Voltage: 3.65V (0.2C discharge)
Charging Method: CC­CV (constant voltage with limited current)
Charging Current: Standard charge: 1,375mA
Charging Time: Standard charge: 3hours
Max. Charge Current: 2750mA (not for cyclelife)
Max. Discharge Current: 2,750mAh (continuous discharge), 8250mAh (not for continuous discharge)
Discharge Cut­off Voltage: 2.50V

how would your "cut out the CV portion for lifespan" exactly work with this cell if i were to simply charge this cell with 1mA to 4.2V? (excluding the fact it would take 10 months to charge)

You left something out ( either by mistake, or by convenience, but yes .

Samsung 29E EXPLICITLY STATES a termination current in the datasheet under "STANDARD". The data you provided above was "cherry picked" and not acknowledge the termination current, explicitly stated as standard, as per the data sheet, On that datasheet:

7.1 Standard Charge This "Standard Charge" means charging the cell with charge current of 1,375mA and constant voltage 4.20V at 25°C, 0.02C cutoff.

There you go. Cannot just cherry pick the data off the sheet. That data is there for some reason, us non-battery-experts assert: however, you , the employed-battery-expert, do not seem to acknowledge at this point.

I dont get it. Termination current, as I know it, is explicitly laid out in that datasheet. I dont know why you chose not to include it in your ex.

1,375mA = Standard Charge ( per datasheet)
1,375mA (x) 0.02 (C) = 27.5mA is the termination current for that cell, as per the manufacture specs, on the datasheet.

...also known as (C/?) termination current. (C/50) , (common in some lesser quality cells, I have seen), (I have seen even as high as C/100 specified for complete fill @ resistance climbing) .

I dont understand the rest of your argument, even though I am sure it has given credence with your knowledge.

Its in every sheet. Lol.

My reference sheet pulled from Liionbattery.com

https://cdn.shopify.com/s/files/1/0697/3395/files/29E.pdf?8108166701558616789

Imma just gonna shut up anymore. IDk. Im not an expert.

I do wish I knoew what makes once cell ok with "C/5" on teh datasheet, vs " C/50" for another cell on a differnet sheet. Why do they even put that in it it doesnt matter?

( dont tell me testing purposes, the sheet is for selling, not testing. Plus I specifically pulled that out of section 7, when section 6 refers to testing. Datasheets facilitate selling, not testing, ImO, you know this. )

On another note: Lol @ 45mOh / cell. Thats high as a Crack-hed on Methamphetamine. Lol.


On another note: I do not see the reference to 8AMPS charge for that Sammysung 29E?!?!?!?!? Sheet says 1C MAX!

i know that this cell charged with ~8A (its absollute max) will swit

-FLIPPY

Discharge, yes, but the data ( that you explicitly linked, quoted, show us) says the maximum charge is

2750mA (not for cyclelife)

.... And now you are telling us that you can really charge that cell at 8 amps? Wow how cool is that. I would nave never thought, that you could charge a Sammy29E @ 8 AMPS! Wow. I dont try to charge cells at ~3x the datsheet max. Lol. I would think that is a FIRE hazard.

Imma go outside and charge me up some Sammy 29E ( single, cells, ) with 8A.

 

[flippy]

You left something out ( either by mistake, or by convenience, but yes .

Samsung 29E EXPLICITLY STATES a termination current in the datasheet under "STANDARD". The data you provided above was "cherry picked" and not acknowledge the termination current, explicitly stated as standard, as per the data sheet, On that datasheet:

7.1 Standard Charge This "Standard Charge" means charging the cell with charge current of 1,375mA and constant voltage 4.20V at 25°C, 0.02C cutoff.

There you go. Cannot just cherry pick the data off the sheet. That data is there for some reason, us non-battery-experts assert: however, you , the employed-battery-expert, do not seem to acknowledge at this point.

I dont get it. Termination current, as I know it, is explicitly laid out in that datasheet. I dont know why you chose not to include it in your ex.

disclaimer: i only read the section i qouted. the rest i ignored.

please learn to read the frocking datasheet. i have been over this a dozen times already.

the section you point to only states the testing parameters used by the manufacturer to claim capacity and lifecycle. this is clearly stated in most datasheets as such.

sometimes you even get graphs or testing specs and their ratings on higher currents for example.

it does not say you MUST charge like that. its just what the manufactuer states on how you should test if you want to verify their claim as stated in the specs. that is specifically why these things are separated by chapters.

every datasheets is EXTREMELY clear on what NOT to do. dont overcharge, overcurrent, overdischarge, puncture it. whatever. NOWHERE does it say you must terminate the charging process to prevent damage or overcharging or anything else. the only time where termination is mentioned is in the parameters the manufactuer used to validate their product.

you are confusing what the datasheet says with what you WANT it to say.

if i get a batchj of cells i stick to the reference given in the datasheet to check a couple cells. but that does not mean i MUST use them in those constraints. why the frock else do you think they also mention shit like temperature and all those extra figures?

that you dont understand these kinds of documents is fine. these things can be expected. but dont read into them what you want them to say and claim some form of superiority. you dont have any. you dont even understand the very concept of CC/CV wich also already have been explained to you ad nauseam by several people already.

you really need to work on understanding the difference between "testing parameters/specifciations" and just "the specifications".

ps: this guy terminated his charges at 0.1A:
https://irp-cdn.multiscreensite.com/80106371/files/uploaded/file9.pdf

does that make all his testing invalid? or is he damaging his cells? samsung said you should terminate at a different current....

 

[serious_sam]

the sooner you stop after the CC-to-CV transition point the better.

You keep talking about this transition like it means something to the cell. It does not.

You do know that it is a completely arbitrary thing right ? Totally dependent on the cell IR and charge current.

Absolutely nothing to do with SOC.

The only thing that "cares" about that point is the charger, because that's when it starts to limit the voltage.

It would be a convenient point to design a circuit or program a uc to trigger at that point. Nothing else.

Like flippy said, if you charge at 1mA, you won't hit that point until the cell is basically full.

Or if you charge at 10C you'll hit it early and have SFA charge in the cell.

Same "transition" point, totally different outcomes for the cell/SOC.

 

[john61ct]

CC stage AKA Bulk, is before the batt hits the max-V setpoint.

the battery does not decide the voltage, the charger does.

No, it is negotiated, at start of Bulk depends in chemistry resistance SoC and current rate.

The charger is "striving" to reach CV setpoint, but the depleted battery may not get there for many hours depending on the above.

The CC-CV transition point may happen at 70% SoC or 98% SoC, and of course different usrrs may define their 100% differently.

 

[john61ct]

With LI chemistries, assuming no balancing required, and assuming optimising longevity is desired*
the sooner you stop after the CC-to-CV transition point the better.

how is that? you are muddying the waters again. if i charge a battery with 1mA, i will basically NEVER reach the CV stage until the cell is filled.
stop making these broad claims.

Yes, the lower the current rate, the higher SoC is once you get to CV.

If the charge rate is lower than the endAmps spec desired, then yes you can overcharge even at a much lower voltage than the usual setpoint.

Using LFP, spec of CV=3.45V, endAmps 0.01C

if charge rate is only 0.005C then you better drop the V setpoint to 3.36V or so, but still set a fixed max AHT to prevent going too long.


> more reasonable: if you charge a cell of say, 2500mAh with 1A and up to 4V, will that cell live shorter or longer then the same cell charged with 300A at 4V?

4.15 would be the lowest I'd use for li-ion

300A is a stupid example for a small cell, should not go over 0.4C here since the assumption is maximising longevity.

But say 3A vs 1A, if only doing CV (charge to and stop) then the former will be at a lower SoC, so likely healthier.

If any CV stage then the endAmpscutoff determines SoC, no matter the current, so the 1A rate is healthier.

 

[john61ct]

Holding a long AHT is just as damaging as going up to the vendor maximum spec voltage in your charge source profile setpoint.

i dont know what AHT means

Absorb Hold Time, Absorb stage is CV staging

a lower endAmps profile is longer

CC only AHT=0


> and the voltage is not relevant in the actual charging process. that is a lifespan discussion we are not currenty having.

I have stated, if longevity is not a concern then this whole discussion is moot, just ignore and move on, sit at 4.2 overnight until current is zero, and sleep well at night no problem.

But actually with EoL cells higher risk of thermal runaway, so there's that.

 

[john61ct]

you decide to stop charging the battery BEFORE its full to the voltage/capacity you have set it.

As stated many times, "overcharge" here defined as "not optimal for longevity", aka doing damage.

100% Full as defined by the "do not approach" maximums on the maker data sheet

is way overcharging for those optimizing longevity.

It is up to the knowledgeable user to define their 100% Full

for purposes of normal daily cycling

and for stress testing/capacity benchmarking

will be very different profiles. The latter should not be done more often than a few times a year, say 50-100 cycles for li-ion

maybe 500 for LFP.

Yes the battery will happily keep pulling current long after the point where doing so causes damage*.

explain how this works. you are going off the deep end here. so watch out. explain how a battery keeps pulling current AFTER its filled. note that we are discussing lithium based batteries. not SLA.

See above.

 

[john61ct]

* damage defined as "reducing longevity"

lifepspan is dicated my several factors, keeping a cell floating at a specific voltage is just one of them.

Lithium should not be floated, full stop, and certainly not above the full at-rest voltage.

Even if it only degrades lifespan by a little, there is no reason to do so in any use case I've encountered IRL.

And yes I have acknowledged that other factors like C-rate are more impactful on lifespan, and stated if your usage is at very high C-rates, then just ignore this whole discussion.

 

[john61ct]

just a single 18650 cell and a basic use case. lets take the samsung 29E as a base for the cell basic specs.:
…
i know that this cell charged with ~8A (its absollute max) will switch to CV at around the 3.9V when its at rest. explain the difference between just charging slower to 3.9V and hold it there until to stops taking current and your method of just firehosing the cell and see what the charge level is? (ignoring any lifespan issues from just pumping amps into the cell)
…
how would your "cut out the CV portion for lifespan" exactly work with this cell if i were to simply charge this cell with 1mA to 4.2V?

What are you talking about?

A 8A charge rate is abusive, even with pre-warming. In normal temperate weather, 0.4C is what I would prefer, around 1A.

A 1 mA rate is stupid, since I'd use endAmps of say 0.05C anything under 140mV means risking overcharging.

Even using the more stressful 0.01C endAmps, works out to 29mA

 

[john61ct]

samsung said you should terminate at a different current....

The endAmps spec in the datasheet is the **longest** AHT allowed

beyond that point causes hard damage and increases fire risk in older cells

going all the way until current stops is just plain reckless

 

[Addy]

Lithium should not be floated, full stop

In your opinion, not in fact :wink:

If an insignificant amount of wear on the battery is acceptable, then floating is fine. When you float charge a lithium cell, the cell gets fully charged to the point where the only current flowing into the battery is a tiny amount of leakage current (self-discharge). This would be on the order of microamps unless your cell is very large. Also keep in mind that this self-discharge current is flowing whether you keep your battery on the charger or not.

 

[john61ct]

the sooner you stop after the CC-to-CV transition point the better.

You keep talking about this transition like it means something to the cell. It does not.

You do know that it is a completely arbitrary thing right ? Totally dependent on the cell IR and charge current.

Absolutely nothing to do with SOC.

The only thing that "cares" about that point is the charger, because that's when it starts to limit the voltage.

It would be a convenient point to design a circuit or program a uc to trigger at that point. Nothing else.

Like flippy said, if you charge at 1mA, you won't hit that point until the cell is basically full.

Or if you charge at 10C you'll hit it early and have SFA charge in the cell.

Same "transition" point, totally different outcomes for the cell/SOC.

Yess of course, all that is included in what I wrote, long known by, obvious to anyone with a clue.

And no contradiction with my points.

 

[john61ct]

Even sitting isolated at Full is causing damage

so why float?

When you float charge a lithium cell, the cell gets fully charged to the point where the only current flowing into the battery is a tiny amount of leakage current (self-discharge). This would be on the order of microamps unless your cell is very large. Also keep in mind that this self-discharge current is flowing whether you keep your battery on the charger or not.

Insane.

Self discharge is charge **leaving** the battery.

Floating above the resting full voltage is (stupidly) trying to stuff more charge **in**, but without actually increasing any usable stored energy.

If you don't have a load ready to really discharge, then letting the surface voltage dissipate - downward bounce-back - is healthier than floating.

The SoC at charge termination should actually never have even approached 100% capacity utilization

 

[Addy]

Even sitting isolated at Full is causing damage

so why float?

You can float charge at whatever SOC you want, it doesn't have to be at 100%.

Floating above the resting full voltage is (stupidly) trying to stuff more charge **in**, but without actually increasing any usable stored energy.

It's simply a consequence of using a simpler CC/CV charger and it certainly does increase usable stored energy compared to terminating when the charge current drops below some amount.

If you don't have a load ready to really discharge, then letting the surface voltage dissipate - downward bounce-back - is healthier than floating.

Yes, it's healthier as in you'll end up with 0.001% more lifespan out of the battery. Not worth arguing about, certainly not worth the many posts (borderline spam) that you fill up this thread with.

 

[serious_sam]

CC stage AKA Bulk, is before the batt hits the max-V setpoint.

the battery does not decide the voltage, the charger does.

No, it is negotiated, at start of Bulk depends in chemistry resistance SoC and current rate.

I mean, it's crystal clear by this statement that john has absolutely zero understanding how this works.

 

[flippy]

samsung said you should terminate at a different current....

The endAmps spec in the datasheet is the **longest** AHT allowed
beyond that point causes hard damage and increases fire risk in older cells
going all the way until current stops is just plain reckless

that you have ZERO clue about what you are even talking about: just say so.

lets just be absolutly clear about 1 thing: you have NO clue about what actually is going on during the charging process. and you are making up your own laws of physics and whatever to make it work inside your head.

its not a problem to say you dont know and are willing to learn how it actually works. if you have basic tools like a lab power supply you can even do some practical tests i can give you to learn what actually happens and the how and why's. but you must be willing to learn in the first place.

CC stage AKA Bulk, is before the batt hits the max-V setpoint.

the battery does not decide the voltage, the charger does.

No, it is negotiated, at start of Bulk depends in chemistry resistance SoC and current rate.

I mean, it's crystal clear by this statement that john has absolutely zero understanding how this works.

yeah, i know. and for some reason he seem to be unwilling or incapable of actually showing what natural laws of physics he seem to be using, because its not any of the laws that seem to be present in this universe.

i love to see the physics on how a battery magically "tells" the charger to regulate the voltage so something the battery wants just to name a thing.

 

[john61ct]

In order to get a higher delta between depleted and full

let's use LFP 23S a bit over 72V nominal, assume balancing done previously during a testing / maintenance session, or otherwise not currently needed.

69V would be a decent "working 0% SoC" for normal usage, not too high discharge say 1C

Charging setpoint for me would be 79V, charge rate (max available) between say 0.2 and 0.6C

If doing CC-only "charge TO and stop" then the maximum of 82.8V would not do damage, within an hour isolated, pack settles to closer to 76.5 rather that the 76.8V it might reach holding CV / Absorb for a while.

The difference in usable discharge energy between the two well under 0.4% capacity utilization.

At the beginning of the charge cycle, battery is at 71V, applying the charge source adjusted to 79V

within a few seconds the voltage at the battery posts (not relying on the gauge on the charge source) starts its climb to the setpoint.

A source capable of delivering 0.6C (A) that climb will be much faster than when available current is limited to (B) 0.2C

When A reaches the setpoint (Bulk / CC stage ends) more quickly,

compared to B doing so taking longer, SoC% is higher on B at that point.

However if using a termination controlled by endAmps (Absorb / CV stage) if both stop at 0.02C, the SoC% at termination will be identical,

both settling back down to say 76.7V at rest isolated.

If the pack is not going to be discharged until the next day, or dog forbid even longer

then a lower SoC% finish now would have been much healthier, for example a CC-only finish

maybe going to the top of capacity utilization just before the discharge

if every mAh is somehow important for the use case.

______
A longer AHT, trying to get to higher stored actually usable energy, stopping at say 0.01C or even 0.005C (as with many Pb profiles)

or by increasing voltage past

will increasingly just generate excess chemical activity and rising temperatures, not increasing usable capacity by more than a percent or two

and causing damage as I defined it

aka overcharging.

Especially the cray cray idea of continuing charge until current stops flowing.

All other care factors being equal and favorable, a pack that may have lasted 8000 cycles over decades

may only reach 6500. The length of time **sitting** at any high SoC is more impactful than the termination point.

If the use case requires higher C-rates, the delta might be "only" a few hundred cycles.

If this sort of difference in lifespan is not a worthwhile goal for you, say because the oack only cost a few hundred rather than over $10K

then of course do what you like.

But that does not change the facts.