john61ct said:
CC stage AKA Bulk, is before the batt hits the max-V setpoint.
the battery does not decide the voltage, the charger does.
john61ct said:
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.
john61ct said:
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.
john61ct said:
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.
john61ct said:
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..
john61ct said:
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.
john61ct said:
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.
john61ct said:
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.
john61ct said:
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.
john61ct said:
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.
john61ct said:
But that does not change the facts.
indeed, but that does not seem to stop you form making up some of your own.
john61ct said:
* damage defined as "reducing longevity"
lifepspan is dicated my several factors, keeping a cell floating at a specific voltage is just one of them.
john61ct said:
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)