LIFEPO4 batteries longest Life cycle possible 9 years vs 16 years the 20-80% Rule
HTML-код
- Опубликовано: 10 фев 2025
- I have 2 of each of these batteries
amzn.to/3NRRlP8
amzn.to/3tEek9p
amzn.to/47rZP6a
amzn.to/3vppjUF
All products reviewed in my videos are listed UNDER my AMAZON storefront for easy access - www.amazon.com/shop/twowheelsandahalf
(Commissions Earned)
As an Amazon Associate, I earn from qualifying purchases or if you like this content NOW YOU can Support this Channel with any Donation VIA PAYPAL by clicking on this LINK - www.paypal.com...
Link to Facebook account - / tiberiu.iepan
Link to Instagram account - @vegasromaniac - / vegas_romaniac
Link to tweeter - / romaniacvegas
I am sure there are many who have already done the calculations and some experiments, I am not one of those, but I have been doing the same as you, reading other information and watching videos Here is what I think I have learned and where I am leaning to go:
1) Your 12.8 to 13.3 charge/discharge range seems in line with others
2) Adding a 12 volt, lead-acid battery into the bank via an isolator that regulates that charge/discharge between the LFP and Lead-acid
3) Trying to find the correct ratio of Lead-acid to LFP for best efficiency
Hope that helps jump start a conversation for all of us to learn, keep up the good work!
Dude that's crazy, I'm going to pin this one because I know it's wrong but I'm sure the people will love to read and give their opinion on it I hope you're ready 😁
I read somewhere that Lifepo4 and Lead acid in parallel works because the lead acid will keep trying to bring down the voltage of the Lifepo4 to close to 12.8v which is the resting voltage of Lead Acid. They have to be around the same SOC(100% full charge using same charger) when you initially connect the two different battery chemistries in parallel. It is advised that a smart charger that doesn't have equalization feature be used so the mixed battery bank stopped charging at a specific voltage(like 14.4v).
From all my studies, I personally would NEVER use lead-acid with my LiFePO4 batteries! The only time this is useable is if one gets a DC to DC charger that allows one charge the LiFePO4 battery bank from an alternator.
Voltage of LiFePO4 batteries cannot be used to calculate SOC. It is impossible. Once the voltage in the cell rises above 3.4V, you're already at 96%SOC or above. Below that, there is no way to tell if the cell is at 80%SOC or 40%SOC by just measuring the voltage.
These LFP cells have 6000cycles+ at 100% DOD, so fully cycle them once a day will give you 16+ years. Then they have reached 80%SOH.
Forget about the 20-80%SOC rule. This was important with Li-ion cells, but not with LiFePO4.
Charge them to 3.45V/cell, let them balance for 30min and drop the voltage to 3.35V/cell (Float). They will last forever.
At the bottom, when they hit 3.0V, you have about 7% capacity left. That's when I stop discharging (if the batteries ever go that low).
I have found that, so long as the battery isn't charging and has a low rate of discharge, you can get a good approximation of SOC from resting voltage but you are looking at 100ths of a volt rather than 10ths. The JBD BMS has a lookup table so that it can guess at an SOC when it can't coulomb count. Certainly I agree that while charging the voltage is fairly meaningless as there is another variable affecting the voltage, namely current, which distorts an already pretty flat 'curve' On my BMS I did a voltage based guessometer of SOC based on the curve being relatively straight (not flat) between 12.8v and 13.4v with the algorithm only having a look if there was no charge and the discharge was below a certain amount. It tallied fairly well with the actual coulomb counted SOC which I know to be accurate, particularly in summer with daily full charges to synchronise it. Ps I do watch your channel and have got some useful info from your experiments to help inform my own and I thank you for that.
Great advice
I’m ganna give that a go Andy
@@alanblyde8502how is the set up holding up so far?
I think you can come up with a better gift for your grandchildren than 20yo LFP battery. :)
Run it 100-0 and forget about this micromanagment. Why? Because - maybe you forgot - the 3000 cycles of "life" does not mean that then the battery is dead. This is the rating of getting to 80% original capacity. It's still usable.. for another 5000 cycles easily after that.
Best advice ever .. you are the man
The problem with charging to 13.3v (26.6v) is that this is the resting voltage for 80% you have to have a voltage overhead on your charge system to be able to get there. One of the great advantages of lithium is it’s ability to accept any charge that’s available but to do that it needs some ‘push’ (voltage) behind it to get it in. I use solar mainly and occasionally the engine but when charging at reasonable rates, say a good solar morning, the voltage rises noticeably higher to get the available power in and then, when it stops, the voltage falls back to reflect the state of charge. I have found the best compromise cut off voltage to be about 14v. If charging with the engine at around 0.25C (200A into 800Ah) then I increase this to 14.2v and this gives around a 90% SOC by the time it cuts off when the voltage then drops back to one that reflects that SOC. I datalog my system every minute and have been doing so for around 4-5 years and have used this data to determine the setting that give least stress to the batteries along with best charge acceptance. The aim is to get away from the absorption current taper of lead acid that wastes so much charging resource. At the moment for instance the batteries are at around 80% with a 0.025C charge rate yet are at 13.4v. I think you are probably having a max charge of somewhat less than 80% with the other risk which is that you never get the cells into the top ‘knee’ which is where they need to be to balance. I have a 12v low voltage disconnect but with a recommendation to start charging at 12.8v or 20%. I use a home built BMS to give me quick easy access remotely to change any parameters and because I also wanted to look at protecting from low voltage overcharge which actually turned out not to be a problem with the settings I use. I hope you find some of those thoughts useful. I have a home built battery of various cells in multiple P4S with about 2500W solar and around 200A alternator charging as a backup. I also run hybrid with a 12v lead acid however that is only there to stabilise the charging sources when the BMS cuts charge and enables me to use lead acid charge setting on everything so saving cost in the conversion from lead acid and enabling alternator charging which would otherwise have needed either dc-dc converters (work of the devil) or expensive alternator controllers.
That's great info .. Yes that's what I've set up my charge controller to stop 27.8 It seems to be the magical number with mine but I think it's about 0.2 off my voltmeter so basically we are in line with what you were saying, unfortunately when I set up my charge controller in lithium iron phosphate mode it only has a charge voltage and that's it It doesn't give me any floating or bulk or any other stuff
@@VegasRoManiacReviews You don't actually need float although if you do have a charger with it then 26.6-26.8v would be about right. It is important that the charge gets cut at your set voltage and not held there. Some controllers with a "lithium profile" just hold the voltage there and don't disconnect. This is why I tend to say to people that they need a 'valid' lithium profile as many simply are not and don't do the battery any favours. "Bulk" is actually not a setting, its a state before the absorb / boost setting is reached and is the 'constant current' part of the charge cycle where it charges with whatever current is available until the 'absorb' voltage is reached when the voltage is regulated and, as a consequence, so is the current. Some controllers can be used on a lead acid setting so long as you can control how long it stays in absorb for (a few minutes is fine) and also control the float level (26.8 / 27v or so) and also control the boost / bulk reconnect which can be just below float.
@@philbrooke-little7082so what would you advise say if I am using a victron mppt smart charge controller? My current settings are at 28.4 absorption voltage and 27.0V float voltage. I noticed that indeed the current is cut down for the two hours that the battery is in 'absorption mode'. What I'm not sure is if this affects the inverter or the inverter pulls the required energy to run the loads from the panels.
@@dancerehab1092 with those I would go for a 28.4v absorb but with a 5 min absorb, as it really isn't needed for best life, 26.8v would be fine for float if the batteries are in constant use and a 0.1v and a re-bulk offset voltage of 0.1v turning off adaptive / battery safe. You need to go into 'expert mode' to do this
@@philbrooke-little7082 thanks, let me make adjustments right away and monitor how the bank behaves tomorrow. I will be harvesting all available energy yes?
I am not extremely knowledgeable about the chemistry in these batteries, but my intuition says it would be useful to charge to 95-99% about every 10th cycle (day), just to keep their capacity fully exercised. Likewise, they should be ran down to 20% every so often. I think Lithium Ion battery experts say that, and it should be similar for LiFEP04 chemistry.
Yes that's good information and I think lithium iron phosphate are a little bit more durable and less picky than lithium ion
Consider cell balancing. Usually balancing only happens as the batteries pass 95%. You cannot go many cycles before an unmatched battery of cells starts to unbalance. Only you and your set of batteries can tell how much balancing your cells need.
Some batteries have cell balancing , also there are boards you can buy that take care of that on the fly ..
But yeas cell balancing is a thing ..
Run down to 12-12.2 charge to 13.8
The problem is you can’t really utilize voltage as a reference with this chemistry until your within 10 to 15% of empty or full.
good advice ! I like it
The issue is not hitting the higher voltages above 13.4 which is required to balance the cells and therefore allows them to degrade equally. The real issue was staying at that high voltage for multiple weeks. If you’re cycling your batteries every day it’s something you never have to worry about. The sheer degradation over time which happens for batteries, even not in use and even stored at 50%, is gonna factor in Way before the degradation of daily use factors of going too 100% charge. The real way to kill one of these batteries is to leave it under voltage for an extended period time, meaning weeks. That is almost impossible nowadays with these new BMS nearly all have built into them now. LFP batteries are something you should just not worry about cycling if they are used every day for solar.😊
I got a 25.6V 150Ah LFP battery. I usually discharge it to 50% of its capacity every day, and use the grid until the next morning. I have programmed the Grid Disconnection feature to switch to solar at 26.8V, and to grid at 26V. While discharging, it is not accurate that it will be at 50% DOD at 26V everytime. If there is around 300W of load, it is almost close to 50%. But if I put double the load, say 600W, the voltage will drop faster, and I will switchover at 40% DOD or 30% based on the amount of load on the battery.
During charging, I set the Bulk to 28V and the float to 27.2V. I loose around 10 Watts of charge when the voltage drops to 27.2V from 28V. I can set the Bulk to 27.2V, but the problem is during the charging, I get around 500W - 1000W depending on the load that is used in parallel. At 27.2V, at 60% state of charge, I will not be able to push more than 500W into the battery, and the MPPT will have to adjust its Solar MPP to reduce the power harvested from the solar.
During Cloudy days those few moments where the suns pops out of the clouds and shines on the cool panels for couple of minutes, the 28V Bulk will help me to dump all the power coming from the solar into the battery without any limitation, as it can take 80 Amps of charge.
Every LFP battery is different, so the Bulk, and Float voltages needs to be set based on the internal resistance of the battery.
My charge control doesn't even have options to set any other things when it's set up into lithium so there's no float there is no absorption It's just stop charging at this voltage and stop using the battery at a certain voltage and that's it
why not use more than 50% of your solar? what a waste
Which voltage setting in the Charge Controllers settings determines the maximum charge? I have two different chargers. Is it, "equalize charge", "Boost Charge", "Float charge" or "Overvoltage", "Limit charge voltage", which are settings from two different chargers.
I use a powerbank for camping and yardwork. I'm going to use a life extending charge scheme to maximize longevity. Reason? That will give the longest time for a new and better yet compound to emerge to replace LiFeP04. This was a useful video!
One thing you didnt talk on is also by keeping batterys in the 80 to 20 percent range cell drift is minimal also
1:00 LiFePO4 batteries, when bought with their own BMS, are set to top balance the cells inside at the top of the charging cycle: 14.6 on a nominal 12V system, or 29.2 on a 24V system. If you don't charge them up to full for at least two hours at least once a week, they can get way off balance, which will REDUCE their total lifetime. Not using them too low WILL extend their life, though. Most of these batteries are rated for at least 10 years, and that is if one charges and discharges them fully each day. I designed my system so that the battery bank will hold over 80% capacity most of the time. I only see lower capacity in the middle of summer when I use my larger air conditioner most of the day. I am living in an off-grid community in the Southern CA desert, so we do rely on the systems I've designed for my RV, my work truck, and my girlfriend's shuttlebus, especially when it can get over 120F here!
When I was designing my 48V system, I planned on making my batteries last around 20+ years.
Great info .m thank you
Wow ambitious
It is a reaaaly useful information for who think about to buy them and set a system at home... Thank yout
Yeah, unless there's a good reason why something performs better when it is pushed to a limit, it's best to give it a nice buffer to ensure that it lasts longer. Lead acid batteries need to be charged at a higher voltage and then maintained at their full voltage or they degrade. You can do so with a LiFePO4 battery as well, but doing so degrades it faster than giving it a gentle charge and discharge.
Interesting info
You are partially correct. Charging a LiFePO4 battery at the limit of 50% Capacity can lower the lifetime, but if you charge it at 20% Capacity, will allow it to last longer. Discharging at a lower rate is probably a good idea, but not as important as charging at the lower rate.
you need to charge to 100% if you want to balance the cells, no?
Yes if the BMS does and has balancing
Well not only voltage levels but the temperature also matters in the lifespan
Did you buy 4 different brands of batteries just to test which are better than others? Or did you just go with whatever the best price was?
I was looking for deals and when the sales came I got more so that's how I ended up with different brands
What will happen if I change the battery at 14.4v and after charge the battery if I use the battery 60-70% of energy...
Is the battery life will be more than 12 years????
I have some 36 volt battery packs. I am wondering if the inverters in this particular setup will run and produce a/c power with 36 volt battery packs.
No. This model can't .. they are picky on voltage 24 to 31 volt max
I've been looking for any info. You are the only one I've found asking questions.
Can i keep my batteries 100% charged on solar?
Yes you can , these batteries are super durable
@TheCrazyRomanian thanks, you're the only one to answer. I've been reading manufacturers info and asking others no one can say for sure but, i have not found one manufacturer who warned against it.
When I'm not using the system i disconnect all inputs. When i am using it even sparingly i leave the solar charging. It frequently hovers at 90-100%.
@TheCrazyRomanian was thinking, RV's have solar connected all the time don't they. Maybe that's why they burn sometimes. I just don't trust these batteries quality enough to leave the solar connected.
@ you can keep at 100% they will lose ah over time anyway. but when storing make sure to keep them 50% at least
I started with a large 48V battery bank and i wish i had gone with 24V and fewer batteries. 1) Higher voltage chargers and inverters cost disproportionately more than lower-voltage chargers. 2) I experience far fewer power failures than expected, better to invest in infinite-shelf-life propane and a propane generator.
Batteries are best for storing energy from an infinite supply like the sun.
Propane may have a long shelf life, but it gets used up very fast when there is no resupply, and it is not rechargeable.
Great info
According to the Voltage/State of charge chart from Battle Born Batteries, 13.6V is 100% resting, and 14.4V is 100% while charging. I believe you need to do more research!
Good info
The price of these batteries is falling all the time now! Personally I’d rather capture the energy from the sun ☀️ 😊
That's the best way
Just use batteries as a buffer. Put most of the electric load on daytime. Invest in low power applience for eveing would be cheaper.
Not to mention get rid of my wife she has a TV running on some stupid aquarium with fish in it 🤣 at this point we'll be cheaper to just get fish
go full ham and spend $10k for 31kwh of batteries/rack ... run for 10 years ... $85/month ... 16 years ... $52/month ... adjust these numbers for your requirements ... put whatever $ amount you come up with in your solar savings account ... the $ will be there waiting for your next round of batteries ... do not sweat the details
I actually only need about 10 kilowatts a day because the sun shines half the day here in Vegas so very rarely is cloudy and the 10 kilowatts last me throughout the night easily but my family is small and I don't have an electric car
i like that shirt
Great shirt .. nice and warm
okay okay ... do not go full ham ... build your own with eve 280ah raw cells ... build 3 batteries for $6000 which equals 43kwh ... now what are you looking at? ... 10 years ... $50/month ... 16 years ... $32/month ... and if you only build 2 batteries for 29kwh ... holy hell ... $4000 ... 10 years/$33month ... 16 years/$21month ... lol ... crazy
Good breakdown