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

[Ampster]

I baby my batteries because the economics of solar are improved if I can divide the battery cost by 2500 cycles rater than 1000 cycle. It is simple math, not a drag race.

 

[sirslayer]

it’s not a drag race , keeping your refrigerator or water pump on without resorting to a generator is ideal and you want to use a gas generator to save cycles on your batteries.. it’s about surviving and being independent from using gasoline which is harmful to our environment. Yes you will be saving the disposable batteries in the long term if life cycling the batteries while doing nothing is your plan.

 

[Ampster]

it’s not a drag race , keeping your refrigerator or water pump on without resorting to a generator is ideal and you want to use a gas generator to save cycles on your batteries..

I don't use a generator. I sized my pack so I had reserves. The benefit mathematically was that reserve also served to increase the life of my pack. My point was that 2500 cycles is a lower overall cost per kWh than 1000 cycles. Simple math.

 

[Ampster]

Discharge until it indicates 10% - that's your low voltage threshold.

Charge until it indicates 90% -

I have two Coulomb counters and they drift apart unless reset. I use voltage of 3.45 per cell at the top and a combination of voltage and SOC at the bottom. My LVD is 3.1 volts per cell but my inverter does not wait for solar if I gets to 50%. It begins charging from the grid.

 

[Maintenance guy]

Ampster; He seems completely clueless.​

Quote; "I guess if you want to baby your batteries and let them rot to death in a slow long term torture from shelf life"

Excuse me but this is the most ignorant statement I have ever heard. If you want to pound your batteries every single day and get 1000 cycles then that is your prerogative. personally I think backing off just slightly and getting 3 to 4000 cycles is an much smarter economically sound way to go. Mind you this is WITHOUT a generator so no Gasoline involved. you kind of remind me of a friend I used to have that had one speed only in his vehicle driving like a bat out of hell. "He" was simply clueless as to why his truck was always broke down always whining and crying about it. So finally one day I was tired of hearing him whine about it and I called him a dumb ass to his face and told him he had absolutely so sense what so every and "HE" was the problem of why his truck was broke down all the time. Needless to say we are no longer friends and the dumb ass still has a broke down truck. some people NEVER LEARN.
Quote; "Yes you will be saving the disposable batteries in the long term if life cycling the batteries while doing nothing is your plan"

Another ignorant statement if you ask me. you have no clue as to the type of system he has yet you spout garbage and personal views at everyone. The system's I have designed for a few people do not use a generator maybe once or twice a year and that is just maintenance. they systems were tweaked to back off just slightly and keep the batteries cool during the summer months. they will get 12 years easily out of their systems so go try telling them their doing it wrong and need to pound their batteries getting only 1000 cycles.

Moral of the story; Treat things with some respect and in turn things last longer. Or you can travel your path pounding your batteries every single day then purchase a new set every three years while I laugh at you because I am getting 12 plus years out of my batteries.

 

[minerva]

I think the argument here is based on wrong premises. You won't go from 1000 cycles with a reasonable use pattern to 2.5 times as many with babying them. You just won't. Then, getting to 80% capacity is not the end of a cell.

 

[Ampster]

You won't go from 1000 cycles with a reasonable use pattern to 2.5 times as many with babying them.

I believe you can get at least full 2500 cycles or 5000 half cycles from Grade B cells with a reasonable use pattern. Perhaps there are differences of opinion about what "reasonable" is? I do not have long term data to prove my assumption but having a six year old EV with less than 10% degradation gives me hope.

 

[minerva]

I believe you can get at least full 2500 cycles or 5000 half cycles from Grade B cells with a reasonable use pattern. Perhaps there are differences of opinion about what "reasonable" is? I do not have long term data to prove my assumption but having a six year old EV with less than 10% degradation gives me hope.

You are confirming my point. You don't need to baby your batteries and try to squeeze every last cycle to get 2,500 cycles. This is 7 years of reasonable use to get to 80% capacity.

 

[Ampster]

This is 7 years of reasonable use to get to 80% capacity.

Yes, in one of my iterations I used seven year old Nissan Leaf modules that still had 80% left. I used them for another two years and by then it was such a Frankenpack because of the modules that I added. I randomly tested a few modules and was surprise at how much capacity they had left. I recently sold them to someone who was going to add some to an RV and others to some electric scooters.

 

[Gazoo]

I hope I get 1000 out of it in the end

Curious if you have you studied any of the manufacturers spec sheets? Typically, cells are rated for at least 2000 cycles at full C rates. EVE makes high cycle claims depending on C rates.

If I only got 1000 cycles out of a LFE cell I would be severely disappointed. Granted the cells don't need a lot of babysitting but the consensus is keeping the cells voltages between the knees is one of the best ways, if not the best way, to extend cycle life. Of course ideal temps also enters into the equation.

 

[curiouscarbon]

cell above 3.0 V
cell below 3.65 V
avoid long time above 3.45 V
cell above 0 C
cell below 35 C

this recipe seems to be decent to get plenty of capacity and life from LiFePO4 cells

cell warming up too much seems to be a factor in early cell degradation

 

[Ampster]

cell warming up too much seems to be a factor in early cell degradation

One of the factors that can create warming is high C rate charges or discharges.

 

[sirslayer]

I said 1000 cycles because of the constant charging of 3.65 volts per battery. I believe even at that voltage, my lithium phosphate should last longer then that. I do drain them down to 2.7 volts and they will last for many years . I think most folks do baby your batteries and I’m struck that most folks are not using their batteries to the max to save money and let them slowly die from shelf age.. well at least they still look new …

 

[Ampster]

I think most folks do baby your batteries and I’m struck that most folks are not using their batteries to the max to save money and let them slowly die from shelf age.

I resemble that comment about shelf age but I do try to stay active and not spend much time on the shelf. I hope to outlast my batteries.
It all depends on where you are standing.

 

[Samcat]

@Go2Guy - I hate to speak for @Steve_S (he does it pretty well himself) but I think the three main points he made - if I were to reduce them to bullet points - are:

1. Temperature matters, because colder cells will accept current (absorb energy) slower than warmer ones. This can be important when you have more than one parallel battery being charged.
2. With this chemistry, millivolts matter. In the case of AGMs or any other lead acid, you can get things to the nearest 1/10th of a volt and it's probably OK. Not so much with LiFePO4.
3. Recognize that there are voltage drops throughout your system, even with large wires. Because of #2 (millivolts matter), you need to know and account for those drops from your SCC and Inverter/Charger to your battery at different charge currents and as the charge cycle finishes.

I'm sure if I didn't get that right Steve will correct me.

I happen to work with laboratory tools and proper calibrated tools are very important. And after all checking was done all necessary terminals and connection inspected it goes through cycle discharge and charge while continously recording data on individual cells resistance and voltage with total pack voltage and resistance. And for residential use this was usually in 60% of max A bms is designed for if mosfet. Residential laboratory test are always done at 75°F.On EV battery packs there are different types of laboratory tests that include various different temperatures.
I have seen many YouTube videos where people don't really take good measures for voltage and resistance under load and also imagining thermal camera for any temperature raises because of weak terminal conditions. Calibrated volt meters that can measure three decimals are very important for lifepo4 chemistry. Discharging voltage drops even not very important are necessary to lower resistance. But for charging it is very important to adjust for mV drops across wiring and compensate this with MPPT.

 

[Nickatnyt]

it’s not a drag race , keeping your refrigerator or water pump on without resorting to a generator is ideal and you want to use a gas generator to save cycles on your batteries.. it’s about surviving and being independent from using gasoline which is harmful to our environment. Yes you will be saving the disposable batteries in the long term if life cycling the batteries while doing nothing is your plan.

Mining for all the metal ingredients that make up all kinds of batteries is harmful to the environment as well.

We all gotta pick our poison.

 

[Samcat]

Absorb time can be easily figured if you have run battery cell charge and discharge tests.
Example if you are after 3.330 to3.450 V absorb will be necessary if you want to bring lifepo4 chemistry to max energy at this conservative voltage level.
Also many need to understand that with this chemistry relying on flat voltage curve Voltage is not possible to determine +/- 3.000-3270 depends on AH battery cells . Columb meter (AH meter) would be necessary and one that highly accurate. But even then there should be algorithm in the BMS to know when battery was not used for quite some time ( Charging ot discharging) temperature between parallel banks to compensate for battery drift. Highly experienced members here can live with only good balancer, considering they have calibrated voltage tool to measure mV and low resistance quality tool. Regarding putting multiple batteries in parallel and hooked to side terminals make sure you feed one wire from the top post terminal and on another post from the bottom to the energy user's.

 

[toms]

I said 1000 cycles because of the constant charging of 3.65 volts per battery. I believe even at that voltage, my lithium phosphate should last longer then that. I do drain them down to 2.7 volts and they will last for many years . I think most folks do baby your batteries and I’m struck that most folks are not using their batteries to the max to save money and let them slowly die from shelf age.. well at least they still look new …

My cells cycle between 3.5V and 3.0V, with a 400ah pack i have regularly discharged 300ah from fully charged during a cycle.

They have never been charged when over 35°C.

They are approaching 11 years old now with no discernible difference in performance from new.

In that time i have seen many others using more aggressive parameters (especially disregarding high voltage/temps) have their batteries fail.

As for shelf life - i know of packs from 2007 that are still going - shelf life is unknown as it is untested in fractional C LiFePO4.

You can ignore the actual real life experiences of those that have been using these cells for a decade, and find out for yourself how to make a cell that should last for 15 years now last for 6 years.

 

[Samcat]

My cells cycle between 3.5V and 3.0V, with a 400ah pack i have regularly discharged 300ah from fully charged during a cycle.

They have never been charged when over 35°C.

They are approaching 11 years old now with no discernible difference in performance from new.

In that time i have seen many others using more aggressive parameters (especially disregarding high voltage/temps) have their batteries fail.

As for shelf life - i know of packs from 2007 that are still going - shelf life is unknown as it is untested in fractional C LiFePO4.

You can ignore the actual real life experiences of those that have been using these cells for a decade, and find out for yourself how to make a cell that should last for 15 years now last for 6 years.

Are you running cells in parallel and how many?

 

[toms]

Are you running cells in parallel and how many?

I use 2 cells in parallel to make 400ah