I absolutely am thankful for all of your videos! You are a treasure to the RUclips world. I dont comment, however - I do click the "Like Button" , and I do watch all of your videos. Thank You for your time and efforts !
I have 4x 5.1kw LFP batteries. I have been charging them with solar to 100% every day and discharging down to normally between 30-50% overnight. The BMS tells me that the SOH (state of health) is 99% after a full years use. Couldn't be happier.
Looking at hundreds of videos on youtube, you are the only one with who I'm fully in agreement. Congratulation, your lessons are great ! Peppe from Napoli.
Thanks Will for the great info. I currently own an EV, 3 ebikes, 2 electric scooters and 3 litime batterys for my boat. A person could drive themselves crazy trying to over manage these batteries. I store my stuff inside during the winter off season at around 60% and check on them monthly for self discharge and don't really obsess over it. I like your approach and will start to charge to full more often as well. Great video as usual I really appreciate your content!
Good to know - I bought four LIFEPO4 Ecoworthy 12V 100Ah last month to put into my battery boxes that are paired with foldable solar panels, but have them stored in a cabinet. I'll take them out to fully charge them this weekend. Thanks Will!
Great and to the point. The hilarity of only using 60% of your capacity now to so your battery has 1% more capacity 5 years from now when that battery is going to cost half the price as today can't be ignored!
I come from a tech background and I approve Will's explanation. 👍 But, I want to add, LFP (LifePO4) batteries have a narrow voltage range between 0% and 100%. Your BMS reads voltage to estimate SOC (State Of Charge), 25%, 85% etc. Easy for the BMS on a typical NMC battery with a wider voltage range. Besides cell balancing, for LFP, it's crucial to charge to 100% at least every 4th or 5th charge cycle so the BMS can say "Ok, that's 100%, got it!" and can count down reporting the SOC more accurately. And for those afraid of 100% charging your LFP batteries, keep this in mind. A 100% charge on LFP is at about the same voltage as an NMC at 50%. Very little stress on the cells.
I am off-grid and use four Enjoybot 12v Lifepo4 batteries setup in series 24v (2 bats 24v ) and paralleled hooked up to a 5000 watt inverter to run my 1hp water pressure tank. The charge controller is a Renogy 40 amp . I set up the charge controller in manual mode with the charge set at 13.7 volts , if I set it any higher the inverter trips because the voltage is too high. 13.7 x2= 27.4v. It's a 24v inverter. The Enjoybot batteries have been doing well now for two years. Thanks for all of your helpful videos!!
I used to do cell phone repair and had the 80/20 conversation with many customers. Even if you save a bit of wear on the battery, you are giving up 40% of your overall capacity to do so. Batteries are a consumable item, and can be replaced in 99% of cases. Use it, enjoy it, and fix it when it breaks.
"People seem to think they know more than the engineers who designed these things." Unfortunately very true. Also, might I add that by the time these batteries hit their 10 year mark, they will still hold most of their capacity and by that time, new tech or cheaper cells hit the market and you STILL have your Lifepo4 batts.
Thank you so much Will for sharing your expertise and know how. I pretty much learned how to hook up a solar system thanks to you! I bought your book and it is amazing how much knowledgeable info is in there. Thanks again buddy, I truly appreciate what you do. God bless my friend 🙏
Good point on the BMS - I bought 3 wall mount batteries a couple years back - all 3 of them had a BMS failure! The vendor replaced each of them under warranty, but it still surprised me how they all failed, almost one after another.
Very useful advice here about using LiFePo batteries. I also used to think the 80/20 rule applied with them after moving over from an NCM lithium set up. Great to know i can go to 100% and use the full voltage range on discharge.
The Picture of Will Prowse/Dorian Grey. You don't seem to age. Been watching your channel for a while. I'm jealous, you don't seem to age. Where do you hide your painting?
Great information, Will. I have the EG4 LL-S battery. Living on the southern border of Arizona.... and being over paneled my battery rarely drops below 60% SS tech advises to discharge down to 20% twice a year.... I do it once a month, but after listening to you here, I will change my low setting to 10%. thx again
Been watching you for years always great content really appreciate all your information. They really loving your new videos. You take care and God bless.
Will, Thanks for all you do on your channel , following since later part of 2022. Because of your expertise I have built a complete solar system for off grid operations. Cheers
Same here. When I first started posting on Will's forum I was absolutely beyond clueless. I was uploading my "plans" for this huge 12V system for our off grid cabin that look nothing like what we have today thanks to the education I got there from the forum members. It took two years on his forum (I'm slow) to finally get comfortable, but what we came away with is a super great 48V system that powers our off grid cabin and heats it with an electric heat pump. In Alaska! With our solar arrays located 600 feet away from our cabin. And we installed all the DC stuff ourselves all from research on his forum. DIYSolarForum is a must for anybody wanting to learn about off grid solar.
I agree with everything you said except for DOD to zero. Although LiFePO4 have a much higher usable capacity than lead acid, the grafts still clearly show the relationship of DOD cycles and life expectancy. What am i missing? Thank you.
Absolutely disagree. And if you're hitting zero you should probably make your battery bigger. Probably did not calculate days of autonomy correctly. There is reduced degradation but who cares. Use the battery and stop worrying about it. You'll use it now or you'll use it later
Very few use cases actually do 100% DOD on a daily basis, so we are left with... well, what about those few weeks in a year where you might need a 100% DOD? Will that effect cycle life? Answer: NO. So there is no need to program your battery to cut-off at 80% DOD. Definitely allow 100% DOD from the battery itself, particularly if you don't actually use 100% DOD on a daily basis. Most setups barely use 25% DOD on average. In anycase, the DOD cycle life calculation to 80% is theoretical and assumes constant temperature and constant C-rates. Most actual use cases have neither. Even using a baseline 3000 cycles at 100% DOD, 3000 cycles, cycled daily, is still 8 years. That would be an extremely heavy use of the battery, only grid-scale battery systems might even come close to that. But temperature has a huge effect. A lower temperature (but still above freezing, obviously), exponentially increases the cycle life. A higher temperature vastly reduces the cycle life. But again, its an average. Just because it might 100F during the day means buckus if it drops to 60F overnight. As an example. So in terms of battery health, if you have the choice of storing the battery in a conditioned space verses an unconditioned space, you generally choose the conditioned space. But unless the battery gets too cold, an unconditioned space isn't the end of the world. -Matt
This is good to hear. I have 8 Pylontech US5000 in Alaska stored in a root cellar and in the summer time they stay at pretty much 100% all summer long (except over the short nights) and I had thought perhaps this would degrade them. Sounds like it's a good thing!
The EcoFlow Delta Pro recommends 30-90 (within the app parameters) but i ignore that and go 0-100 as they advertise themselves that the unit is good for 3500 cycles while retaining 80% capacity. I questioned them and asked by cycle do you mean from 90-30-90 or from 100-0-100 and they said the latter. So why on earth then would i follow the 30-90 threshhold? I dont get it. After hearing this video i now know with confidence that what i was already doing is right. Good stuff Will thanks ❤ Tom (United Kingdom)
Most of these battery and power station brands don't actually have anyone on staff who is a battery expert, so they often get it wrong when it comes to LiFepO4. In fact, in the early days, these companies were using standard lithium-ion (NMC) and that probably got them into some bad habits when they finally switched to LiFePO4, which is a completely different chemistry. There was a famously bad battery company... a company that actually built LiFePO4 cells in the early days. Really early days (like 20 years ago) who had little understanding of the chemistry they were building. I forget the name but they had ridiculously high charge targets listed in their literature which caused many a battery failure. Over the years they kept dropping the cell charge targets over and over again. Took years before they actually specified proper voltages. Many early (and even still some modern) LiFePO4 battery chargers use a 3.65V/cell target that basically fights the BMS disconnect voltage at the end. Not ideal. So many still haven't learned that there is no need to charge past 3.55V/cell.
Another great video.. I keep my batts around 50% and this week I did a load test on a 100 Ah Chinns that I purchased in Sept 2021 and it still had 103 Ah capacity. BTW that shirt thread on your neck is badley distracting me ;)
I use my ecoflow delta 2 almost daily. Did set the charge and discharge points at 90% then 10%. Also lowered charging speed to 400 watts. Didn't realize the balancer won't kick on, looks like i need to change my settings
Oof! I bought a 24v 100 amp hour battery from Ampere Time through Amazon a little over 2 years ago. It’s still unopened in its box because I wanted to buy a second one in addition to a 24v all in one inverter(like on Will’s video). Medical bills forced the DIY project on hold. I suppose I need to buy myself a 24v charger to see if the battery is still any good? Quick edit…. Thanks as always for the easy to understand and informative videos as always!
Good video! I have this koi pond at my place in Vegas and I always stress that the outdoor battery that controls the pumps will fail when I leave Vegas for the summer. I put a cctv camera on the pond to check it every day, but 3 summers in and I'm still good to go (knock on wood)
so glad i go to 100%, whatever free energy coming in i want it. many say 20-80% to make them last, as you say. i didn't buy these batteries to lose 20% off the top end. I already lose some % off the bottom end as voltage starts to drop and certain loads need min volts. I seldom go to 0% as i always want something in the bank, but it does happen. And i expect the bms to handle these things. tyvm Will that was perfect, i was curious. And yeah i figured a good named company uses a good bms and design and have way more engineering than myself (and the random youtube vids).
It would be very interesting to see you build a diy battery and set the settings in the bms to charge the way you mention in this video with the data sheet of the cells and all.
Thanks for all the work you put into this channel!! I'm looking into a solar system with battery back-up. Can I expand or add an extra battery bank two to three years after initial install or will these new batteries mess with the cell balance?
When you think about it, lithium iron phosphate batteries are almost magically perfect. They have been running my household for over two and a half years and they just keep working. I haven't noticed any decrease in capacity over that time.
Love the info. I’m about to build out my first system and think I landed on going with the EG4 indoor wall mount battery. I’m curious if I start off with 1 and add on more down the road, 1-2 years, would this cause any degradation or should I hold off to when I’m able to purchase all batteries at the same time?
What maintenance charger would you recommend to keep the batteries at 50% state of charge while not in use? Would it be sufficient to use a normal 12V charger, say a 1 Amp DC power supply?
Im not Will of course... but IMHO best practice for batteries that you are not using and cycling (in other words stored for when needed) is to charge to 100% every 6-9 months and right after that, discharge to 50%. You need a battery monitor or way to measure the Ah drawn to get to 50%.
The first LFP battery I got was back in 2009. I actually got one of my early LFP batteries to go 14 years before I retired it and that was a cheap Chinese battery duct taped and shrink wrapped together with major issues with the balance leads. Kind of surprised really how much abuse that battery took before I finally had to put it into retirement. Was getting ~80% capacity and soft cells towards the end after many issues of balance leads making poor contact while charging, leading to individual cells overcharging. Eventually pack becomes a heater box as in you dump charge in and it gets hot until it discharges. I am sure a modern battery that is built to much better standards and treated better will just go and go, at least cell wise. What I do now is use the current LFP battery for extra power to run an all electric kitchen. That keeps its usage regular enough and then I can take it with me when I need power somewhere.
You forgot a use case: a battery backup where a load is 24/7 connected to the LFP. I think the trickle voltage in this case matter, and an active BMS might be appropriate, but I might be wrong. One thing for sure, I will not keep my LFP at 3.6V 24/7 unless I have proof it is safe.
For UPS style applications (I have several LiFePO4's used that way)... you charge normally (3.55V/cell), then drop to a float level (3.35V to 3.375V/cell) and the load-support occurs at the float level. The battery will remain at 95%+ SOC while being held at float after being fully charged. UPS style applications cannot hold LiFePO4 batteries at any specific SOC, they must always fully charged the battery, then drop to float, then perform any load-support at the float voltage. A regular (e.g. Victron) charge controller can easily do this task. What I do is for 12V devices like my alarm system and cable modem is: * USB-C PD port plugged into the wall * A 19VDC USB-C cable wired to the "solar" input of the Victron * Output of Victron connected to the 12.8V LiFePO4 battery and device. * Victron programmed to limit charging current to (typically) 2A or 3A (24 or 36W), which is typically what the USB-C cable at 19V will allow. So the average 24x7 power draw from the device cannot exceed that, obviously, but the burst power consumption can consume up to what the battery is able to support. Done. -Matt
My wife has a Chevy Volt. We park it for up to two months at a time while traveling. I'm trying to figure out if we should have it at 50% state of charge when we leave, fully charged or plugged in. It is parked in a mild climate, generally 40º to 80ºF year round. Also, it hasn't been showing the same range after charging as it once did. The cost of battery replacement is more than the car is worth. Should we try to have the BMS changed or checked?
I have recovered cells from as low as 0.3v back to full capacity. It takes time but it is possible. Some BMSs really aren't good at balancing if you don't allow them to do it regularly. A correctly set active balancer really does help in batteries that are regularly partially charged. If you run them completely flat the problem can be not charging them up afterwards although, as I mentioned, they can be recovered but NOT just by a normal charge, that will ruin them. Badly set up BMSs can be serious problem and some manufacturers don't have them set ideally. Low voltage overcharging can also be an issue if you use a voltage below the BMS cutoff, such as vehicle alternators, where the battery gets held at a high voltage after charging is complete. This is particularly a problem with batteries bought, or rather sold, as 'drop in replacements' when there really isn't such a thing. Hybrid with lead acid is about as close as you can get to that but then you do need to set the BMS up correctly for it.
1. Do not let them get wet 2. Do not expose them to direct sunlight 3. Do not feed them after midnight ... Oh, wait, those rules are for something else.
The actual degradation science says: - calendar degradation is mostly based on average SOC, keep under 50% for longest life but once a month go to 100% for balancing. - high charge/discharge rate has big influence - temperature during operation is also huge for LFP, more than most other chemistries. Keep above freezing and as close to room temperature as possible.
Didn't realize BMS was replaceable. Are they generic to particular chemistry or would I have to obtain from original manufacturer. Do you have a video on replacing BMS?
Hi folks. Since many years I heard "do not charge over 90% and discharge under 10%" to have a long lasting battery. So what should I do now ? Do manufacturers say as you're telling us ? I'm Lost, so I'm gonna drink a beer to solve this problem ! 😊 Best regards from France 👌👌
Depends on the cell chemistry. For example, you don't want to drain a lead-acid battery below 50%, and you generally don't want to charge a NMC (standard lithium ion) battery above 80%. But LiFePO4 is a different chemistry, none of that applies to LiFePO4 and if a manufacturer says differently, they don't know what they are talking about (very common with all of the fly-by-night battery brands out there, actually). A LiFePO4 battery can and should be charged to 100%, and can (if desired) be drained to 0% (not 0V, zero percent), on a regular cycle without any worries. The only issue when draining a battery to a low SOC level is that if you forget to charge it up, it now doesn't have to fall very much further before cell voltages get too low. If you are cycling regularly such as with a solar system, cell voltages will never get too low so it just isn't an issue. it will lift off the instant the sun comes up in the morning. -Matt
With LifePo4 you state "down to 0%" am I correct your are referring to SOC, or 10V? Also, with LifePo4 did I understand correctly that it is good to keep at 100% or bring to 100% for cell balancing and then discharge to 50% for storage?
Ahh Will you are my favourite Nerd you rock dude and I would love to watch your gun vids but I understand why it could cause an issue for your channel.
You mentioned that it is okay to cycle a battery 100% every day. At that rate, usually these batteries are said to last ten years, and then degrading to about 80% of nominal capacity. I am wondering if cycling them at 50% per day would increase the longevity of the cells enough to make them last fifteen to twenty years, or if it wouldn't make that much of a difference.
I'm actually charging my LiFePO4 battery at around 100% but not at the full voltage. I saw that his built-in BMS triggers the balancing at around 3.35V per cell so I've set the bulk and the float to 3.425 V per cell. After 2.5 years that battery keeps the cells balanced and the capacity is as new. Still, I'm a bit afraid to go full voltage because of the risk that the BMS will not always be able to keep up with the increasing voltage so maybe one or more cells could shoot up too much....? Thanks for the insight!
I have one of the $15 PWM charge controller with a 12v 1000ah LipO battery with a 100 watt solar panel ( will upgrade to 400w down the line ), should i be concerned about overcharging or degradation?
For those of us that have our ecoflow battery generators and are preppers that mostly keep these stored. Every 3 months do we charge it all the way to 100% for the battery balancers? And then discharge it down to 50% for storage? Or just charge it up to 100% and leave it every 3 months? I think you mentioned that the proper percent to store it at is 50%
Hey Will, does the theory of charging to 100% fall into the same procedure of my Rivian R1T Quad motor battery? I believe mine is the large pack which is Li Ion. Just wondering because the MFG's always suggest charging to no more than 80% for daily driving. (maybe to reduce warranty costs for degrading?) Thanks again for educatin' the masses.
What is 100% though? I've limited the charging voltage to avoid bms disconnects on partly cloudy days. Also had to limit the charging current to avoid solar charge controller shutdowns (Victron). The charge controller is too slow to catch the overcurrent when the sun comes out from behind a cloud so I dropped it 1 or 2 amps to avoid shutdown. I have it over paneled so charge controller max is 580 watts and panels are 2x 410 watt.
Oh dude. I had that exact problem storing a battery for 2 years. And YES I tried to use later and it worked but was very erratic but unpredictable. Hard to diagnose. This was the issue
If it is being flaky on and off after sitting for 2 years you may have a cell that leaked or a cold weld that gave up the ghost. If you have an old old AM radio you can use that to detect the spark if it is a weld that gave out by tapping on the thing.
Is it bad to be at 100% SOC *all* the time? I'm building a UPS with a EG 4 LL-S and a Multiplus II, so it'll only ever discharge a few times a year when the power goes out.
Can I store a battery at -40 for a couple of months with the charge discharge turned of and charged to 80%. Battery has an internal heater and would it come on and off over those few months and kill the battery
Good info, but living in a northern climate the Lifepo4 batteries were more trouble than they were worth for freezing winter use, still use and rely on my AGM's.
0:00 Intro and BMS Basics
1:31 #1 Cause
3:34 #2 Cause
6:44 #3 Cause
7:47 #1 Hardware Failure
8:58 Basic Guidelines to Follow
Be sure to join the forum if youre a beginner! Check it out here: diysolarforum.com/
Hi@@WillProwse
Are you recommending going from 3.55 v up to 3.65v?
What about using them in an RV environment. You'll never discharge to 0% in an RV because you need to have that power available at all times.
@@nitrox58 With a battery that has a built-in BMS, the better way to look at it is a 12.8V LiFePo4 battery should be charged up to at least 14.4V.
I absolutely am thankful for all of your videos! You are a treasure to the RUclips world. I dont comment, however - I do click the "Like Button" , and I do watch all of your videos. Thank You for your time and efforts !
I've seen all kinds of opinions about charging to 100% or discharging to 0%. I trust you the most, so thanks for this video.
The GOAT of diy solar!
Didn't know about self discharge. 😮 Running down to the basement to hook up my charger right now! Thanks.🏃♂
I have 4x 5.1kw LFP batteries. I have been charging them with solar to 100% every day and discharging down to normally between 30-50% overnight. The BMS tells me that the SOH (state of health) is 99% after a full years use. Couldn't be happier.
These are the videos I like the most! Getting back to the basics. Thanks again Will!
This has been a topic that I've been unsure about while setting up my solar system. Thanks for the explanation.
Really informative and easily understood. Thanks for taking the time to help educate us!
This was your best show yet
Good job young man
Looking at hundreds of videos on youtube, you are the only one with who I'm fully in agreement. Congratulation, your lessons are great ! Peppe from Napoli.
Thanks Will for the great info. I currently own an EV, 3 ebikes, 2 electric scooters and 3 litime batterys for my boat. A person could drive themselves crazy trying to over manage these batteries. I store my stuff inside during the winter off season at around 60% and check on them monthly for self discharge and don't really obsess over it. I like your approach and will start to charge to full more often as well. Great video as usual I really appreciate your content!
if you hang some sheets, or even better, blankets, it will absorb the sound and kill that echo. or audio foam absorbing panels
You are on a roll with the videos lately!!! :)
So much good info in one place
Good to know - I bought four LIFEPO4 Ecoworthy 12V 100Ah last month to put into my battery boxes that are paired with foldable solar panels, but have them stored in a cabinet. I'll take them out to fully charge them this weekend. Thanks Will!
50% not 100%)
And cycle it once or twice before storage to balance cells 0-100-0-100-50 , good luck
Great and to the point. The hilarity of only using 60% of your capacity now to so your battery has 1% more capacity 5 years from now when that battery is going to cost half the price as today can't be ignored!
I come from a tech background and I approve Will's explanation. 👍 But, I want to add, LFP (LifePO4) batteries have a narrow voltage range between 0% and 100%. Your BMS reads voltage to estimate SOC (State Of Charge), 25%, 85% etc. Easy for the BMS on a typical NMC battery with a wider voltage range. Besides cell balancing, for LFP, it's crucial to charge to 100% at least every 4th or 5th charge cycle so the BMS can say "Ok, that's 100%, got it!" and can count down reporting the SOC more accurately. And for those afraid of 100% charging your LFP batteries, keep this in mind. A 100% charge on LFP is at about the same voltage as an NMC at 50%. Very little stress on the cells.
I am off-grid and use four Enjoybot 12v Lifepo4 batteries setup in series 24v (2 bats 24v ) and paralleled hooked up to a 5000 watt inverter to run my 1hp water pressure tank. The charge controller is a Renogy 40 amp . I set up the charge controller in manual mode with the charge set at 13.7 volts , if I set it any higher the inverter trips because the voltage is too high. 13.7 x2= 27.4v. It's a 24v inverter. The Enjoybot batteries have been doing well now for two years. Thanks for all of your helpful videos!!
I used to do cell phone repair and had the 80/20 conversation with many customers. Even if you save a bit of wear on the battery, you are giving up 40% of your overall capacity to do so. Batteries are a consumable item, and can be replaced in 99% of cases. Use it, enjoy it, and fix it when it breaks.
"People seem to think they know more than the engineers who designed these things."
Unfortunately very true. Also, might I add that by the time these batteries hit their 10 year mark, they will still hold most of their capacity and by that time, new tech or cheaper cells hit the market and you STILL have your Lifepo4 batts.
Have really been loving your recent videos Will! Keep doing what you're doing.
Thank you so much Will for sharing your expertise and know how. I pretty much learned how to hook up a solar system thanks to you! I bought your book and it is amazing how much knowledgeable info is in there. Thanks again buddy, I truly appreciate what you do. God bless my friend 🙏
Good point on the BMS - I bought 3 wall mount batteries a couple years back - all 3 of them had a BMS failure! The vendor replaced each of them under warranty, but it still surprised me how they all failed, almost one after another.
Holy cow!!! What battery was that?
Very useful advice here about using LiFePo batteries. I also used to think the 80/20 rule applied with them after moving over from an NCM lithium set up. Great to know i can go to 100% and use the full voltage range on discharge.
Got your book brother and I use it as my solar bible. Using your 400 watt setup. Thanks for helping to educate us.
Great advice, Will
The Picture of Will Prowse/Dorian Grey. You don't seem to age. Been watching your channel for a while. I'm jealous, you don't seem to age. Where do you hide your painting?
The trick is the picture is a single frame from one of his RUclips videos
Great information, Will.
I have the EG4 LL-S battery. Living on the southern border of Arizona.... and being over paneled my battery rarely drops below 60%
SS tech advises to discharge down to 20% twice a year.... I do it once a month, but after listening to you here, I will change my low setting to 10%.
thx again
Thanks Will! I guess you already know you are a brilliant young man. So, what are you going to do?
Thanks for the very clear video!
Another great video! Thanks
Thx for reminder
#1 view Thank you Will for your info. I have bought your recommended batteries and have been very happy
Been watching you for years always great content really appreciate all your information. They really loving your new videos. You take care and God bless.
Thank you.. very helpful..
Super helpful as always!
I don’t charge to 100% every time, maybe every five times, are you saying that’s bad?
That's totally fine
Will, Thanks for all you do on your channel , following since later part of 2022. Because of your expertise I have built a complete solar system for off grid operations. Cheers
Same here. When I first started posting on Will's forum I was absolutely beyond clueless. I was uploading my "plans" for this huge 12V system for our off grid cabin that look nothing like what we have today thanks to the education I got there from the forum members. It took two years on his forum (I'm slow) to finally get comfortable, but what we came away with is a super great 48V system that powers our off grid cabin and heats it with an electric heat pump. In Alaska! With our solar arrays located 600 feet away from our cabin. And we installed all the DC stuff ourselves all from research on his forum. DIYSolarForum is a must for anybody wanting to learn about off grid solar.
This is exactly how I run my LiFePO4 batteries but I love hearing it from you. :)
Great video. Thanks.
I agree with everything you said except for DOD to zero. Although LiFePO4 have a much higher usable capacity than lead acid, the grafts still clearly show the relationship of DOD cycles and life expectancy. What am i missing? Thank you.
Absolutely disagree. And if you're hitting zero you should probably make your battery bigger. Probably did not calculate days of autonomy correctly. There is reduced degradation but who cares. Use the battery and stop worrying about it. You'll use it now or you'll use it later
Very few use cases actually do 100% DOD on a daily basis, so we are left with... well, what about those few weeks in a year where you might need a 100% DOD? Will that effect cycle life? Answer: NO. So there is no need to program your battery to cut-off at 80% DOD. Definitely allow 100% DOD from the battery itself, particularly if you don't actually use 100% DOD on a daily basis.
Most setups barely use 25% DOD on average.
In anycase, the DOD cycle life calculation to 80% is theoretical and assumes constant temperature and constant C-rates. Most actual use cases have neither. Even using a baseline 3000 cycles at 100% DOD, 3000 cycles, cycled daily, is still 8 years. That would be an extremely heavy use of the battery, only grid-scale battery systems might even come close to that.
But temperature has a huge effect. A lower temperature (but still above freezing, obviously), exponentially increases the cycle life. A higher temperature vastly reduces the cycle life. But again, its an average. Just because it might 100F during the day means buckus if it drops to 60F overnight. As an example.
So in terms of battery health, if you have the choice of storing the battery in a conditioned space verses an unconditioned space, you generally choose the conditioned space. But unless the battery gets too cold, an unconditioned space isn't the end of the world.
-Matt
This is good to hear. I have 8 Pylontech US5000 in Alaska stored in a root cellar and in the summer time they stay at pretty much 100% all summer long (except over the short nights) and I had thought perhaps this would degrade them. Sounds like it's a good thing!
How bad is it to be charged to 100% for long term storage? I don't get why 50% is recommended. Tks!
The EcoFlow Delta Pro recommends 30-90 (within the app parameters) but i ignore that and go 0-100 as they advertise themselves that the unit is good for 3500 cycles while retaining 80% capacity. I questioned them and asked by cycle do you mean from 90-30-90 or from 100-0-100 and they said the latter. So why on earth then would i follow the 30-90 threshhold? I dont get it.
After hearing this video i now know with confidence that what i was already doing is right.
Good stuff Will thanks ❤
Tom (United Kingdom)
Most of these battery and power station brands don't actually have anyone on staff who is a battery expert, so they often get it wrong when it comes to LiFepO4. In fact, in the early days, these companies were using standard lithium-ion (NMC) and that probably got them into some bad habits when they finally switched to LiFePO4, which is a completely different chemistry.
There was a famously bad battery company... a company that actually built LiFePO4 cells in the early days. Really early days (like 20 years ago) who had little understanding of the chemistry they were building. I forget the name but they had ridiculously high charge targets listed in their literature which caused many a battery failure. Over the years they kept dropping the cell charge targets over and over again. Took years before they actually specified proper voltages.
Many early (and even still some modern) LiFePO4 battery chargers use a 3.65V/cell target that basically fights the BMS disconnect voltage at the end. Not ideal. So many still haven't learned that there is no need to charge past 3.55V/cell.
do a segment on which LiFePo batteries have swappable BMS's, and how to do it
Technically they all do if you’re determined enough
Accurate information
Great informative article just one enquiry, Is this the same principle for grade B cells
Another great video.. I keep my batts around 50% and this week I did a load test on a 100 Ah Chinns that I purchased in Sept 2021 and it still had 103 Ah capacity. BTW that shirt thread on your neck is badley distracting me ;)
I use my ecoflow delta 2 almost daily. Did set the charge and discharge points at 90% then 10%. Also lowered charging speed to 400 watts. Didn't realize the balancer won't kick on, looks like i need to change my settings
I like lifepo4
Oof! I bought a 24v 100 amp hour battery from Ampere Time through Amazon a little over 2 years ago. It’s still unopened in its box because I wanted to buy a second one in addition to a 24v all in one inverter(like on Will’s video). Medical bills forced the DIY project on hold.
I suppose I need to buy myself a 24v charger to see if the battery is still any good?
Quick edit…. Thanks as always for the easy to understand and informative videos as always!
Good video! I have this koi pond at my place in Vegas and I always stress that the outdoor battery that controls the pumps will fail when I leave Vegas for the summer. I put a cctv camera on the pond to check it every day, but 3 summers in and I'm still good to go (knock on wood)
so glad i go to 100%, whatever free energy coming in i want it. many say 20-80% to make them last, as you say. i didn't buy these batteries to lose 20% off the top end. I already lose some % off the bottom end as voltage starts to drop and certain loads need min volts. I seldom go to 0% as i always want something in the bank, but it does happen. And i expect the bms to handle these things. tyvm Will that was perfect, i was curious. And yeah i figured a good named company uses a good bms and design and have way more engineering than myself (and the random youtube vids).
It would be very interesting to see you build a diy battery and set the settings in the bms to charge the way you mention in this video with the data sheet of the cells and all.
Great video❤
I use my batteries everyday with my two Victron inverters and solar array to power my critical loads.
Great info
Great video
Charging my super tough Jetson Bolt Pro now. Had it for some months without topping off
Thanks for all the work you put into this channel!! I'm looking into a solar system with battery back-up. Can I expand or add an extra battery bank two to three years after initial install or will these new batteries mess with the cell balance?
Nice information...
Hi Will, great info but based on your concern about BMS failure then the big question is which models allow easy access to change the BMS?
Another great video 👍 thanks for sharing
When you think about it, lithium iron phosphate batteries are almost magically perfect. They have been running my household for over two and a half years and they just keep working. I haven't noticed any decrease in capacity over that time.
Love the info. I’m about to build out my first system and think I landed on going with the EG4 indoor wall mount battery. I’m curious if I start off with 1 and add on more down the road, 1-2 years, would this cause any degradation or should I hold off to when I’m able to purchase all batteries at the same time?
What maintenance charger would you recommend to keep the batteries at 50% state of charge while not in use? Would it be sufficient to use a normal 12V charger, say a 1 Amp DC power supply?
Im not Will of course... but IMHO best practice for batteries that you are not using and cycling (in other words stored for when needed) is to charge to 100% every 6-9 months and right after that, discharge to 50%. You need a battery monitor or way to measure the Ah drawn to get to 50%.
Thanks for sharing 😅
i got a spare set of bms in faraday bag
The first LFP battery I got was back in 2009. I actually got one of my early LFP batteries to go 14 years before I retired it and that was a cheap Chinese battery duct taped and shrink wrapped together with major issues with the balance leads. Kind of surprised really how much abuse that battery took before I finally had to put it into retirement. Was getting ~80% capacity and soft cells towards the end after many issues of balance leads making poor contact while charging, leading to individual cells overcharging. Eventually pack becomes a heater box as in you dump charge in and it gets hot until it discharges. I am sure a modern battery that is built to much better standards and treated better will just go and go, at least cell wise.
What I do now is use the current LFP battery for extra power to run an all electric kitchen. That keeps its usage regular enough and then I can take it with me when I need power somewhere.
You forgot a use case: a battery backup where a load is 24/7 connected to the LFP. I think the trickle voltage in this case matter, and an active BMS might be appropriate, but I might be wrong. One thing for sure, I will not keep my LFP at 3.6V 24/7 unless I have proof it is safe.
For UPS style applications (I have several LiFePO4's used that way)... you charge normally (3.55V/cell), then drop to a float level (3.35V to 3.375V/cell) and the load-support occurs at the float level. The battery will remain at 95%+ SOC while being held at float after being fully charged.
UPS style applications cannot hold LiFePO4 batteries at any specific SOC, they must always fully charged the battery, then drop to float, then perform any load-support at the float voltage.
A regular (e.g. Victron) charge controller can easily do this task. What I do is for 12V devices like my alarm system and cable modem is:
* USB-C PD port plugged into the wall
* A 19VDC USB-C cable wired to the "solar" input of the Victron
* Output of Victron connected to the 12.8V LiFePO4 battery and device.
* Victron programmed to limit charging current to (typically) 2A or 3A (24 or 36W), which is typically what the USB-C cable at 19V will allow. So the average 24x7 power draw from the device cannot exceed that, obviously, but the burst power consumption can consume up to what the battery is able to support.
Done.
-Matt
If I had the talent to make videos like this, I'd be a RUclips star by now. But I'm just watching🌺
My wife has a Chevy Volt. We park it for up to two months at a time while traveling. I'm trying to figure out if we should have it at 50% state of charge when we leave, fully charged or plugged in. It is parked in a mild climate, generally 40º to 80ºF year round. Also, it hasn't been showing the same range after charging as it once did. The cost of battery replacement is more than the car is worth. Should we try to have the BMS changed or checked?
I have recovered cells from as low as 0.3v back to full capacity. It takes time but it is possible. Some BMSs really aren't good at balancing if you don't allow them to do it regularly. A correctly set active balancer really does help in batteries that are regularly partially charged. If you run them completely flat the problem can be not charging them up afterwards although, as I mentioned, they can be recovered but NOT just by a normal charge, that will ruin them. Badly set up BMSs can be serious problem and some manufacturers don't have them set ideally. Low voltage overcharging can also be an issue if you use a voltage below the BMS cutoff, such as vehicle alternators, where the battery gets held at a high voltage after charging is complete. This is particularly a problem with batteries bought, or rather sold, as 'drop in replacements' when there really isn't such a thing. Hybrid with lead acid is about as close as you can get to that but then you do need to set the BMS up correctly for it.
1. Do not let them get wet
2. Do not expose them to direct sunlight
3. Do not feed them after midnight
... Oh, wait, those rules are for something else.
Haha gremlins
I forgot about that movie
The actual degradation science says:
- calendar degradation is mostly based on average SOC, keep under 50% for longest life but once a month go to 100% for balancing.
- high charge/discharge rate has big influence
- temperature during operation is also huge for LFP, more than most other chemistries. Keep above freezing and as close to room temperature as possible.
Any plans to review a Sodium-ion battery soon?
nice work on this one, very helpful for those of us who just wanna keep it simple
Didn't realize BMS was replaceable. Are they generic to particular chemistry or would I have to obtain from original manufacturer. Do you have a video on replacing BMS?
Generic to some degree, usually by cell chemistry - lifepo4, lto, NMC.
Hi folks. Since many years I heard "do not charge over 90% and discharge under 10%" to have a long lasting battery. So what should I do now ? Do manufacturers say as you're telling us ? I'm Lost, so I'm gonna drink a beer to solve this problem ! 😊
Best regards from France 👌👌
Depends on the cell chemistry. For example, you don't want to drain a lead-acid battery below 50%, and you generally don't want to charge a NMC (standard lithium ion) battery above 80%. But LiFePO4 is a different chemistry, none of that applies to LiFePO4 and if a manufacturer says differently, they don't know what they are talking about (very common with all of the fly-by-night battery brands out there, actually).
A LiFePO4 battery can and should be charged to 100%, and can (if desired) be drained to 0% (not 0V, zero percent), on a regular cycle without any worries. The only issue when draining a battery to a low SOC level is that if you forget to charge it up, it now doesn't have to fall very much further before cell voltages get too low.
If you are cycling regularly such as with a solar system, cell voltages will never get too low so it just isn't an issue. it will lift off the instant the sun comes up in the morning.
-Matt
With LifePo4 you state "down to 0%" am I correct your are referring to SOC, or 10V? Also, with LifePo4 did I understand correctly that it is good to keep at 100% or bring to 100% for cell balancing and then discharge to 50% for storage?
Ahh Will you are my favourite Nerd you rock dude and I would love to watch your gun vids but I understand why it could cause an issue for your channel.
A question, it seems like most of these batteries that I see are sealed how do you go about changing a BMS that goes bad? Thanks
i want to see you tear apart a dee spaek battery. they one of the cheapest batteries right now and i just bought one. was it a good move or bad move?
What’s the best 12 volt battery balancer? I have a couple of small systems.
You mentioned that it is okay to cycle a battery 100% every day. At that rate, usually these batteries are said to last ten years, and then degrading to about 80% of nominal capacity. I am wondering if cycling them at 50% per day would increase the longevity of the cells enough to make them last fifteen to twenty years, or if it wouldn't make that much of a difference.
Thanks for the info! LiFePo4 is the best thing since microwave ovens. Where did you go to school? I've always wanted to know.
Self-taught for electronics. Has always been a hobby. Went to school for medicine but dropped out when I was disabled.
I'm actually charging my LiFePO4 battery at around 100% but not at the full voltage. I saw that his built-in BMS triggers the balancing at around 3.35V per cell so I've set the bulk and the float to 3.425 V per cell. After 2.5 years that battery keeps the cells balanced and the capacity is as new. Still, I'm a bit afraid to go full voltage because of the risk that the BMS will not always be able to keep up with the increasing voltage so maybe one or more cells could shoot up too much....?
Thanks for the insight!
I have one of the $15 PWM charge controller with a 12v 1000ah LipO battery with a 100 watt solar panel ( will upgrade to 400w down the line ), should i be concerned about overcharging or degradation?
For those of us that have our ecoflow battery generators and are preppers that mostly keep these stored. Every 3 months do we charge it all the way to 100% for the battery balancers? And then discharge it down to 50% for storage? Or just charge it up to 100% and leave it every 3 months? I think you mentioned that the proper percent to store it at is 50%
Hey Will, does the theory of charging to 100% fall into the same procedure of my Rivian R1T Quad motor battery? I believe mine is the large pack which is Li Ion. Just wondering because the MFG's always suggest charging to no more than 80% for daily driving. (maybe to reduce warranty costs for degrading?) Thanks again for educatin' the masses.
What is 100% though? I've limited the charging voltage to avoid bms disconnects on partly cloudy days. Also had to limit the charging current to avoid solar charge controller shutdowns (Victron). The charge controller is too slow to catch the overcurrent when the sun comes out from behind a cloud so I dropped it 1 or 2 amps to avoid shutdown. I have it over paneled so charge controller max is 580 watts and panels are 2x 410 watt.
Oh dude. I had that exact problem storing a battery for 2 years. And YES I tried to use later and it worked but was very erratic but unpredictable. Hard to diagnose. This was the issue
If it is being flaky on and off after sitting for 2 years you may have a cell that leaked or a cold weld that gave up the ghost.
If you have an old old AM radio you can use that to detect the spark if it is a weld that gave out by tapping on the thing.
Is it bad to be at 100% SOC *all* the time? I'm building a UPS with a EG 4 LL-S and a Multiplus II, so it'll only ever discharge a few times a year when the power goes out.
Question: if you are saying 0-100% doesn’t damage, and the battery should be charged to 100% as often as possible, why store them at 50%? Not 100%?
I have the same question and have always wondered. I hope he answers.
Because high states of charge for extended duration can increase the rate of capacity fade. But again, Don't worry about it. Just use the battery
If you drain to zero with a solar inverter, any tips on how to ensure my loads don’t keep redraining to zero repeatedly after bms reactivates?
Signature Solar has mine set to 99% if i charge to that and keep it there for 4 or so hours will my BMS balance my battery's?
What if you’re BMS dies on one of multiple set of batteries, is there a danger of fire or does the BMS and battery just shut down?
Can I store a battery at -40 for a couple of months with the charge discharge turned of and charged to 80%. Battery has an internal heater and would it come on and off over those few months and kill the battery
Good info, but living in a northern climate the Lifepo4 batteries were more trouble than they were worth for freezing winter use, still use and rely on my AGM's.
If you add a tad more Capacity to your battery bank, you should be able to run a heating pad, etc., to keep the batteries from freezing.