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Best LifePo4 charge controller settings known to man for Maximum Service life and Minimum battery stress!!! 5,000-10,000+ cycles?

There is over a decade of real-world experience of how LiFePO4 cells act when in parallel, knock yourself out if you want to re-invent the wheel. (and yes - a decade ago people were using second hand EV cells - remember Thundersky’s? - in parallel for their house banks so the experience well and truly covers mismatched and dying cells)

At least i’m not seeing so many posts stating that parallel cells can have different voltages as was commonplace when i first started here.
 
@toms it does seem that cells from the past were better, not so many of today's claims of grade A which are of lesser quality or just rejects from the "A" batch.

I did enjoy reading and learning from old threads from the past that are gone from forums missing now.

Many new comers trying to reinvent the wheel that was tried and destroyed in the past. Sometimes setting up voltages for everyday use can be..... less is more. After 6+ years of everyday use I hope mine can live a useful life as yours and many folks from the past that don't even post on the internet. My batteries/ system acts/ delivery like they did when first installed. ;)
 
Yeah, especially car companies put fuses on parallel cells so if a cell decides to puke and short out then it goes out of loop...

One ref of many:

I don't run multiple cells in parallel (yet hehe), but it seems like fuses would be a good idea for our community as well even though LFP are not at risk for thermal runaway, it could stop a glowing bus bar meltdown leading to a potential fire at worse case...
Bus bars with Pyro fuses when become available for aftermarket will change how many you could do in parallel with no issues on safety. For EV they are down to 1mOhm resistance and have temperature probe also.
 
I usually if on the salvage yard will look to buy all of them they have at the time. And all of them are run on 12V DC if someone is interested. There is a lot of things that could be harvested for home battery banks . Just my loud thinking here.
Good luck hunting.
 
We're still tossing around confusing 100 year old lead acid terminology.
New LifePo4 has 2 charging states, boost and float.
Let bulk/absorb go away.
Charge controller says absorption not boost.. same as most peoples charge controllers.
 
We're still tossing around confusing 100 year old lead acid terminology.
New LifePo4 has 2 charging states, boost and float.
Let bulk/absorb go away.
Personally, I like the idea of actually using technical terms to describe things instead of arbitrary industry invented meaningless terms.
1) Constant Current
2) Constant Voltage
3) Float
 
Personally, I like the idea of actually using technical terms to describe things instead of arbitrary industry invented meaningless terms.
1) Constant Current
2) Constant Voltage
3) Float
I agree CC is like Bulk and the termination voltage is when it transitions to CV (Absorb or sometimes called Boost) Float is a lower voltage form of CV often at a lower current. Only used with Lithium sparingly.
 
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Float is a lower voltage form of CV often at a lower current. Only used with Lithium sparingly.
From what I’m reading I’m supposed to set a float voltage (if the charge controller has float) lower than the absorb voltage. So float would be used all the time. What do you mean by sparingly?
 
So float would be used all the time. What do you mean by sparingly?
Float is okay when supplied by solar because it turns off at sundown. It is typically used when there are loads and it keeps the cells from dropping below resting voltage. It is not needed all the time because Lithium does not self discharge as fast as Lead Acid.
 
From what I’m reading I’m supposed to set a float voltage (if the charge controller has float) lower than the absorb voltage. So float would be used all the time. What do you mean by sparingly?
Unlike lead acid, LFP doesn't "require" a float charge, but like @Ampster said, if you don't use the float on your solar charge controller you are not taking advantage of solar while the sun is out. Using float allows the power you consume during the day to be from the sun, rather than from your batteries.
 
No float charge. that is the third in the cycle. set it below absorption levels. the inverter manufacturers are killing everyones LiFePo4 cells prematurely using lead acid parameters.
Bulk, absorption only. Bulk is CC absorption is CV.
you can also lower your balance levels to coincide with the above parameters.
Absolutely agree

There is no bulk or absorption phase or Float phase with lithium

There’s a CC phase and a CV phase , CV phase with system with simultaneous load currents should measure tail currents . No float on completion of charge cycle , charger should disconnect

Charge greater then .15C and less then 0.5C

Depth of discharge has major impacts in LFP life , more recharging time promotes SEI layer growth and degradation

Low DOD cycles are best , recharge as an when needed.
 
Absolutely agree

There is no bulk or absorption phase or Float phase with lithium

There’s a CC phase and a CV phase , CV phase with system with simultaneous load currents should measure tail currents . No float on completion of charge cycle , charger should disconnect

Charge greater then .15C and less then 0.5C

Depth of discharge has major impacts in LFP life , more recharging time promotes SEI layer growth and degradation

Low DOD cycles are best , recharge as an when needed.
Wow. I'll just say there isn't much in that post that I agree with. I guess I'll leave it at that.
 
funny - chuckles.... just gotta....
Typical Day, my 30kWh bank is hitting Float by 13:00 hours. It trickles in 1 to 3 amps into the packs as the active balancers do their thing and get all the cells to <0.009V delta in all packs. The fridge or freezer kick on, and Float handles it and ups the Amps and the batteries are left alone. By 14:00 +/- all the battery packs will be static @ 3.415Vpc , not taking any charge or outputting anything UNLESS a Big Demand hits and Float cannot handle it, but immediately after, Float steps up and brings them back up "if they dropped".

Float is NOT forcing anything into the battery packs, it just allows them to be fully saturated to the target voltage I set (the top of the Working Voltage Range) and services anything called for by the devices in the house/shop.

CASE IN POINT: Got a new Washing Machine and was excited to try out this new High Efficiency machine (old one was a monster pig). Mid Day, Batts all sitting in float with a low delta and happy. So in goes a Load & on goes the machine \\YAY// and observing the Midnite Status Panel (software) it's still in float but hauling down 48A roughly from the panels, 0 to batteries and my lights are on in the house, the washer is humming along and the fridge kicks on and Float served it all... End of day as the sun starts to head for its nap, my Battery Bank finally starts to be used and it starts at 3.400Vpc per pack, with a Cell Delta <0.010 (my setting on BMS).

I've been at his quite some time and have done extreme tests including Hard Thrash Tests with Max Loading & Charging, even with different BMS' to STRESS THEM to the edge. I depend on my systems because I am quite Rural & Remote and "shit happens" so I leave nothing to chance if at all possible... to the extent that I have 3 ways to generate power, draw water, heat my home etc (It's an Ex Military Thing, triple redundacy - damned triplicate.... LOL)

I am SORRY TO SAY, but there is some Clear Buffoonery Posted into this thread that deserves nothing less than a good Beatch Slappery ! and I am BEING POLITE.

From the Whitepapers:

Charging a Pack with a CCCV charger and a BMS
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Fully chanrging a Li-Ion battery pack with a CCCV (Constant Current / Constant Voltage) charger and a BMS requires three stages
  1. Full charge: charger is fully on (CC), until a cell reaches its maximum voltage
  2. Balance: charger goes off and on (CC), while BMS balances the cells, until all cells reach 100 % SOC
  3. Top off: charger stays on (CV), while the current is reduced exponentially down to 0
The Constant Voltage of the charger must be set to CV = number of cells in series x max cell voltage.

Wives Tales, along with Assumptions being turned into Conclusions and stated as fact only belong in the bottom of the Outhouse !
 
Wow. I'll just say there isn't much in that post that I agree with. I guess I'll leave it at that.
Why what I havd laid out re Li tech has been around a long time , CC followed by CV with optional tail current cutoff

The term bulk , absorption and float purely apply to lead acid

sei layer growth is one of the major cause of li failure low current charging is bad for li , DoD ( depth of discharge) is the major cause of in-cycle degradation, that’s clearly set out in all the scientific papers.
 
Lithium will get damaged if any voltage is impressed on the terminals whilst 100 % charged. The field effect alone starts lithium ion migration and plating sei layer growth etc.

Hence for optimum life once the designated charge cutoff point is reached no further voltage of any amount should be placed on the cells.

Balancing has nothing to do with charging Li. Balancing is merely a process of equalising cell terminal voltage so that battery chargers rather then cell chargers can be used.

Charging lithium’s is simple , much more simple then dumb lead acid

For medium charge rates ie 0.25C -> 0.5V the time spent in CV mode ( this is not absorption as Li does not actually have this phase ) is often very small and in fact can be ignored. Ie simple voltage cutoff is sufficient , however in certain setups simultaneous load currents are present so tail current monitoring is useful.

However charging to a voltage setpoint ( in medium high C applications ) will typically result in 95 % SOC , for good cycle life avoid 100% SOC anyway because sometimes the way that’s instrumented leads to over charging

I used to design industrial chargers for a while.
 
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Float is okay when supplied by solar because it turns off at sundown. It is typically used when there are loads and it keeps the cells from dropping below resting voltage. It is not needed all the time because Lithium does not self discharge as fast as Lead Acid.
Got ya so yeah (as I expected) float setting is used all the time (not sparingly) when charging with a solar charge controller
 
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Float is okay when supplied by solar because it turns off at sundown. It is typically used when there are loads and it keeps the cells from dropping below resting voltage. It is not needed all the time because Lithium does not self discharge as fast as Lead Acid.
For lead acid yes , for lithium , where the terminal voltage drop as SOC falls slightly is minuscule, no. Either you set the “float below the cell voltage and in that case the SCC will not power the load , or you have to set the float near the operating point of the cell and now you are charging the cell especially when the load is light.

The whole thing is a bad idea for Li , what you need to do is allow some discharge to occur ( often mis named as “ re-bulk” ) and restart the charge cycle. As I mentioned low DOD ( depth of discharge) percentages reduce degradation and improve life cycles , if possible where charge sources are available , lithium’s should be recharged as soon as a reasonable drop in soc can be detected.

People sometimes think a significant DOD should be allowed before restarting the “ bulk “ cycle , this of course not only wastes potential solar availability but actually is bad for Li tech. Sei layer growth occurs mainly on re-charge so minimising charge time ( short charges , ie low DOD or reasonable fast ones ) is important in extended cell life

This is why Li should never be trickle charged ( <0.1C ) except for 0% soc “ pre qualifying “ charge processes

There are some very interesting research papers doing the rounds on pulse charging Li and also variable setpoints based on charge rate and depth of discharge
 
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