The discharge graph is a standard for lifepo4 battery.The flat spot is where you want to keep your batteries at.Charge to just before the voltage shoots up and discharge to where it drops suddenly.I knew this as soon as I saw that graph and you Andy have done excellent work to teach this to people because the battery manufacturers do not tell you this.Its insane how they want you to charge up to 57V knowing it shortens the life of the battery.Thanks

Thumbs up and subscribed! No one is breaking it down like this on youtube, thanks!

Great video - I have intuitively known that - charging was complete at 3.4 volts since settling Voltage is around 3.35 - 3.37 V anyway and this confirms that fact. Thanks for posting .

Great video Andy! I really enjoy your channel. Thanks for being so perseverant in doing your testing and analysis!

Just a thanks for your videos. Bought this, through your link, and am doing a cell test tonight. Wouldn't have got it started without your very thorough instructions, and google of course.

thank you you're the most intelligent review of this product I've seen after watching almost 60 videos everybody's trying to revive a damaged battery pack and the whole time I'm thinking it's a support module not a replacement for a dead cell battery you're the only person that actually tested full charge and that was an awesome video I learned a lot

So cool! I love the software and this charge-discharge too is very nice! That is alot for the 100ah! This clarifies the LiFePo4 discharge curve nicely! Thanks so much Andy! Cheers and sunny days bro 🌞 ⛅ 🌞

That is a really useful tool! A very good way to test and learn how the chemistry works, keep up the awesome content!

I'm very impressed!!! This answers all my questions with my LiFePO4 batteries wooooh! I don't really watch videos more than 10 minutes but I did! I'm enjoying listening to you and learning at the same time. I already watched your other videos specially on charging the cell to 3.4v VS 3.5v amazing!! Watched it 4 times LOL :D

I have learned so much from you. Thank you so much. I am gaining the knowledge and confidence to build my own 280ah lipo 24v bank!

Awesome video! Thats a pretty neat charger/discharger and like the way it graphs everything out!!!

Great test Andy. You opened my eyes. I'm building a off-grid 48v battery for the house. So I'm soaking every bit of information I can find to make the cells last forever :). Bless you.

Danke für die Ausführliche Erklärung und das Zeigen!!!! Ich hatte gerade Panik, weil meine Zellen bei 3,333 V seit einer Stunde sind und gefühlt nichts mehr passiert... jetzt weiß ich Bescheid. Also vielen Dank für dein Video!

Great video Andy. This is really useful information.

What a brilliant tool allowing you to answer do we need to charge to higher volts and what does it give us? I’m pleased to say that I’ve now watched every one of your videos and eagerly awaiting more. Have liked all of them and subscribed too!

You only charged at 5A but if you say charged at 20A then the voltage will have been higher on all points in that curve due to voltage drop inside the cell based on cell internal DC resistance. To be sure that cell is fully charged no matter the cell internal resistance and cell charge rate (within reason) then is good to have a voltage termination at least at 3.5V on that fastly increasing part of the curve at the end. For my SBMS I selected the 3.55V as a good end point for most cases and LiFePO4 batteries to be sure cell is full then charging completely stops as absorption and float are detrimental to Lithium batteries. Also the SOC is set to 100% in case some small errors accumulated since last charge as the SOC is calculated and not based on voltage (as you seen is just not possible to guess SOC from the voltage with LiFePO4).

Awesome! This proves all of my hours of watching my batteries and learning (The hard way!) I also determined it was not worth squeezing every little bit out of the batteries. My settings for my pack are 50v (3.125v/cell) at the bottom. and 56v (3.5v/cell) at the top. The top voltage in my opinion could be lowered to 3.4v/cell with very little loss of ampacity. Thanks for sharing this. Very interesting!

You always make informative and entertaining videos, Andy! Well done! You briefly mentioned the voltage discrepancy between your multimeter and the charger/discharger. Could you please show some details of the calibration features in this device? I'm very close to the "shut up and take my money!" stage with this device, and possibly the big brother. Lol.

Very good demonstration...👍

Definitely a nice and capable tester/evaluator for LiFeSO4 battery! I would want one if I felt I would use it more than once. 👍🤪

Thanks Andy, another great video

Yes Andy. More tests, please.

thanks for this insightful video, bud

this is why you need to top end balance a battery, This tester would be ideal to test my Yinglong LTO cell

Thanks very good insights in chemistry!

Hello, I just purchased two of the EcoFlow Delta Pro Battery systems along with the Double Voltage Hub to join the two EcoFlows together to provide 220 volts to my 10 circuit stand by electric panel. I also purchased two EcoWorthy Solar Tracker systems and mounted 4 of the 440Watt Magnus Solar Panels on each Solar tracker system. After watching a few of your very informative videos is: What should I set the charge limit to and what should set the discharge limit to? From What I learned from your videos I have set the Charge limit to 95% and the discharge limit to 5%. I want to get the most life from the EcoFlow Units and get the most energy from them. Thank You for taking time to educate the public.

As always… Thanks Andy 👍

love your vids, so useful, thank you sir

Thank you Andy for the capacity test using the tester. I'm also looking to buy a similar tester.

Thanks mate a nice test a test like this is helping me a lot with questions I have sure i am going to use it in my serie connection to 500 volt. no i do not have all the answers but battery behavior matters..

Thanks for sharing!

I am very impressed love it.

Great work. Thanks a lot.

Great video, very useful! I would love to see you doing the same test on one of the EVE280 cells! I am in the middle of top balancing my 16 280’s. All in parallell with 10A, they have stayed at 3,35v all weekend now. 😂 Starting my setup with Multiplus and other charge controllers very soon, and I am very uncertain how high to set the cut of voltage. As mentioned in the comments, balancing can only be done at the high (or low) end. But in the other hand, I do not want ro stress the cells. I guess I will end up with a fairly low cut of voltage (3,4?) and then adjust that to 3,65 in between, if/when the cells get out of balance. I really love your videos, it makes my day. Keep exploring! 😊

Thanks!

Great video.

Great job! Just the info I was looking for to set the cut of voltage for my inverter. Looking at 75% DOD. Thanks

this tester will work on 24v100amp ready made battery thank you andy i ordered should get mon oct 4 dhl please let me know keep up the great work

I am from INDIA , Namaste 👃👃Very help full video to understand LFP Cell Charge and discharge AH and volt profile, before we used volt meters they shows full voltage actually at that time battery drained to 90% after running 8 to 10 km. of E rickshaw Battery shut downs, after watching video we replaced volt meters with True capacity meters they measures each amp hour during charge and discharge thank you very much for making such a nice videos.

very nice tool. good job

Scored an EBC-A10H for $60. Yess!

Tq. Great video/info. 👍👍💪

Thanks so much for posting this data, well done. It confirms the very limited information that was available a couple of years ago. I had set up my Schneider Conext 6848 XW+ to 54.4 Volts (3.4V/cell) and have found that is good enough to get about a 95% charge. There is NO need to push the cells to 3.65V. Nice tester by the way.

Andy, It's you! How things have changed after the Outlander! Best wishes, John Poxon

And now you know why using voltage targets to get to a known state-of-charge when charging at a very low C-rate (0.05C at 5A for a 100Ah cell) is nearly impossible without counting the actual watt-hours going into the battery. The curve will look a bit different when charging at 0.2C, and it will look different again when charging at 0.5C. Generally speaking, the higher the charge rate, the higher the voltage target you can set to get the same state-of-charge result. And, consequently, the lower the charge rate, the lower the voltage target you need to set to get the same result. And, as I've said in prior posts, charging at ultra-low C rates runs up against what is basically a no-win situation, because of two things. (1) You wind up having to set such a low voltage target that you hit up against that flat part of the curve and it literally becomes impossible to achieve any sort of reliable state of charge based on only measuring the voltage. And (2) At low voltage targets the battery's current acceptance can easily drop well below what even minimal solar panels could deliver, and you wind up leaving solar energy sitting on the table instead of going into the battery. Plus, as the cells age, those voltage levels all shift. What might work with very fine tuning on a new cell will stop working within a year, requiring re-tuning every year or two. So how does one deal with this problem? Generally speaking, by having a charge controller + BMS combination that is able to actually count the watt-hours going into or out of the battery and stop the charge when the appropriate capacity is reached (regardless of voltage). This way the charge controller can use a higher voltage (hence increasing the battery's current acceptance and using all the energy available from the solar panels), and the charge controller can count (net) watt-hours going into the battery and cut-off the charge based on that to avoid over-charging it. Either the charge controller will have a separate set of terminals for the load and an internal shunt, or the BMS will have a separate set of terminals for the load (and an internal shunt), or you D.I.Y. the shunt and one or the other has sensor terminals for an external shunt (usually requiring a calibration sequence). And then either the charge controller or the BMS with the appropriate feature can be programmed with a capacity limit. If the charger controller handles it then it simply cuts charging off. More likely though the BMS handles it and simply cuts off the charge controller (causing the charge controller's output voltage to instantly reach its target). Without counting watt-hours, the poor-man's solution is to set a voltage target on the low end and then set a non-zero absorption time at that target to try to achieve the desired state of charge. -Matt

You are finding exactly what I have found. No need to go below 3 volts, and above 3.4 volts, there's almost nothing outside that range. You are still limited by the weakest cell, but that is true no matter what charge and discharge profile you use. You can easily get 90% of capacity without placing any stress on the cells. I had found out using the bigger tester that my laptop battery won't last long enough to record a complete test, so for the last month I have been waiting on the parts for an 11th generation in NUC to be able to save the graphs. They just released it about two weeks ago, so I finished building it yesterday. Had to use a dummy HDMI plug so it can boot headless, and I just remote desktop to it. So I have only completed 2 recorded tests, despite having it for a month now (Eve cells), but have done lots of manual tests and was reaching the same conclusions as you about the time you did the videos on charging and float voltages. On a 280AH cell (measures 278.8) I am finding about 5 amp hours above 3.4, and 5 amp hours below 3.0. I think I like your 3.1v cutoff better.

Thanks Andy

Excellent info, 3.50 to 3.55 seems best in general for these type cells

Now if you had a time machine, you could repeat the test after a few years use and see how well the battery holds up with such accurate data to compare, as always, thanks for the great video.

god bless U man .. greetings from Iraq..

Very helpful, I am from Portugal and I am building small battery bank to support peaks on my solar installation. Only 2K battery 48V. My doubts was till wich level charge and discharge. Your videos are fantastic, keep going.

Fun video

When the LiFePO batteries have been at rest for a few hours, I can always tell the difference between 'below 55% capacity' and 'above 70% capacity', because there is a 1% difference in open circuit voltage. This 55-70 bump in the curve is true for all LiFePO batteries I've tested. However, the bump will become harder to see during fast charge or discharge.

very nice video

I have always questioned the "rule of thumb" figures thrown out for charging and discharging cutoff. This is the first instance I have seen of someone closely examining the charging and discharging curves. Of course, this is only the base data, I assume that you will try adjusting the cutoffs to see how much it impacts the capacity. Determining how various cutoff points affect the longevity of the cells might take longer than we have left in our own lives. Thank you for your efforts.

The reason for charging to a high voltage of 3.65 is for speed. Generally you will charge to 3.65 and stop the charging at .05C (5 Amps). The voltage will sag over time to about 3.4v. Knowing that a fully charged cell sits at around 3.4 volts, You could just charge to that voltage until you hit 0 amps and have a fully charged cell. This however would take much longer to achieve the same result.

Hi Andy! I have no previous experience with any BMS device. I am confused about the operation of the JK BMS device because I have mixed up the device: Situation 1) The measured capacity of the cells is 307Ah, but I originally wrote the BMS "Battery Capacity" value as 280Ah and I have also tried the values 307Ah and 300Ah for that point. It seems that changing this value completely messes up the calculations. A real example: When I set "Battery Capacity" to 280Ah and "Remain Battery" = 100% and "Remain Capacity" = 280Ah. Then I change "Battery Capacity" to 300Ah so "Remain Battery" = 69% and "Remain Capacity" = 193.2Ah. This seems completely counterintuitive! Situation 2) I charged the battery directly through its main terminals - that is, I did not put the negative wire of the charger in the "-P" port of the BMS device, but directly in the terminal of the battery. While doing this, I noticed that the voltages of the cells do increase, but the BMS does not increase the "Remain Battery" and "Remain Capacity" values at all, even if I charge with a 25A charger for 40 minutes. So the information about the actual booking amount is completely out of place? Could there be a programming error or flaw in its software for Situation 1 that they never noticed? But anyway, I'm asking for advice: - Can I safely forget about these readings like "Remain Battery" and "Remain Capacity" and just focus on monitoring things like "Ave. Cell Volt." value to see what the actual battery charge is? - Would it be wisest to use the battery in the interval where the pole voltage moves gently to decrease or increase - and not discharge it so empty, where the voltage drops quickly, and not charge it so full, where the voltage rises quickly? - Which voltage values would be the best for the OVP and OVPR and UVPR and UVP points of the cells? Thank you!

To answer your question, you need to get the charging voltage above the knee to properly top balance the cells. In case you don't already know, you can change the title on the graph from "EB Tester Software" to whatever you like. I number my cells and change the title to the cell number so i know which cell was tested. You can also save an image of the graph that you could print and attach to the cell of you want. Having test data for each individual cell is important when you need to put cells in parallel. I have a battery with groups of 2 in parallel and 4 groups in series. Having individual cell data is important to make each group's capacity as close as possible to get the maximum capacity out of the battery.

Hi Andy, as I tested my batteries I did ccv with 3.4 V and 0,10 A as cut off. Some of my batteries did reach the cut off....and some stayed around 0,20 a for couple of days...and I stopped manually. I am sure my 16 cells are not all from the same producer....the company (BLS) I 've ordered via Ali Express seems to be a trader not a manufacturer. I will continue testing ...my batteries , divided in two blocks now been parallel connected for around 2 weeks. Now I will discharge down to 2.5 V cutoff and charg e then up to 3,65 V. I hope to find out witch cells are almost close from charge& discharge curve and so match best to build a batterie...It may take a while till I have results....looking forward to your next videos.....have fun experimenting...stay curious...;-)

Merci

Hi, thx for the video - have same device for testing..since the EBC-A20 offers also just to monitor cells - will it work with an external device for charging/discharging and if so, how many "external" amps it could coop with? the 5A loading and even 20A discharge is a pain for 310Ah cells...

Great video really interesting 👍 A coupla questions . . . Is it correct that you should try to keep the low point 20% and the high point to 80% . . . .amd if yes then how do you set up a system in a car to maintain those perameters? I have solar and ac charging setup but just trying to look after the battery as well as possible. Cheers Ben

Excellent Vid Andy setting up my workshp off grid: LiFeP04 48vdc 100Ahr with MPP Solar contro ller. From yor reasearch is the "best" to set the charge/discharge to cycle between 98 and 10% ? My place will be 15 to 20 degrees C at all Times year.

How you you know when to stop charging/discharging at a specific state of charge during a flat part of the I-V curve? You do coulomb counting - use software to keep track of how much energy goes in vs out to estimate where the battery should be at between deeper cycles to re-calibrate the algorithm and reset cumulative error.

Where can i find copies of the data (charge/discharge) that you generated. The curves were quite interesting. Seeing what the cycle degrade looks like would be interesting. Why put in more energy than what you take out---but, this probably changes so that's probably why they charge to higher voltage points. This was interesting. Thanks

A good test would be to compare the time it takes for a charge to 3.65 at 5 amp cut-off vs a charge to 3.4 volts with 0 amp cut-off.

Hi Andy, thanks for your test. One more wish, would you please also put the two CSV files on your homepage for download. Then we can have a look at the exact values at certain points. Thanks By the way, different "C" rates in the discharge will show different voltage values. My experience.

Brilliant, however I wonder if you could take your viewers through the whole process of setting up the tester and software as I also would like to obtain the big brother of the tester you have used in this video. Thanks, Ken in England

I do like the form factor of those cells too. Well, they are the ones I have so my opinion is a bit skewed. 16 fit perfectly in my battery tray so it was more about form factor for me. Nice tester.

For my Winston cells, I prefer 3.45V absorption voltage and 3.375V float settings for the Victron MPPT

The stepped curve as against smooth on the zoomed in part of the charge graph suggests an artifact associated with the electronics not the battery chemistry.

Nice video, cool tool , I am wondering what causes the small steps on the flat part of the charge curve. Chemistry in action?

Great video but darn it! Now I need to buy this tester, it is all you fault and the Frog.

Have you ever used that tester with EEL battery cells? That’s what I have ordered hopefully they are good cells?

An interesting test would be how the battery reacts to both high charge and high discharge for short periods. So near the bottom and you have a high discharge how much sag and where it's soc returns to. Same with charge.

Don't worry about voltage. Worry about high State-Of-Charge (SOC), THAT is what causes damage to Li-Ion cells with graphite anode (including LiFePo4). And another observation: Charge with 5 Amps to 3.4 volts, no absorption, gives you about 98% SOC Charge with 20 Amps to 3.4 volts, no absorption, gives you about 70 - 80% SOC, a bit unpredictable. Later edit: It is true that using higher voltages increases the risk that the battery would charge to 100% or maybe even overcharge a bit.

We only need to charge past 3.4 to top balance. However if you don't bulk/absorption charge at a high enough v/cell you will slow the charging down a lot from like 70% . I had it today, I'd turned the MPPT down to 3.4/cell as we had week of sun and couldn't use the power, but just had 2 dull days I'm about to have a wet week, and this afternoon it was sunny so went from 3.4 to 3.5/cell and went to charging at full power from 70% to top off the pack, was throttling the power - I can see it happen as the MPPT basically just moves away from the max power point. In this test stopping at 1A I think you missed a couple of amp hours.

Thanks for the amazing video. Is it enough if we charge lifepo4 battery upto 3.4V or we need to charge upto 3.6V?

As I already explained is full charging with Lifepo4 batteries at least from time to time beneficial to keep the spaces for the lithium ions open in the carbon material, otherwise they wither away when not used and then the remaining spaces will be jammed, which would lead to more expansion and degeneration. Also deep discharge is with lifepo4 batteries not as bad as for the "classic" Lithium batteries, cause in Lifepo4 is moving all the lithium from one to the other side, beside the classig lithium batteries, were only the half of lithium is moving and the other half is needed to keep the structure, where the lithium is docking on to it, when coming back.

I am looking forward to seeing if Andy agrees with me that 3.23 and 3.32 fits the 80% and 20 % depth of discharge rates I have calculated

Es gibt aber auch noch ein Mittelding zwischen dem kleinen 20er und dem 40er, nämlich den EBD-A20H. Damit kannst Du auch 20A laden und er geht auch bis 30V.

Hi Andy. If you just cycled the battery between say 3.35 and 3.1V (never discharge lower or charge higher), what would the actual capacity be then? In terms of preventing deterioration (and therefore increasing lifetime cycles), that seems optimal from these first curves. It seems to me that you are just 'derating' the cells by 10 or 12%. Did I understand that correctly?

I believe that GX 20 connectors on battery tester are rated up to 15A max...

I have a request Andy, when mentioning the temperatures of your equipment could you put down in the corner what that is in Fahrenheit? Celsius doesn't mean anything to me as I'm in the US. Thanks so much for your videos, I've learned so much from you.

That's a really nice tester and should give you something to do while enjoying a pint or 2.

What would be critical to point out is what max charge voltage and what min cut-off should we use to get most capacity while preserving battery life. What do you think about 3.45 and 3.0 V ?

Awesome tester, any chance you can do a 5 Amp discharge test on the 100AH lifepo4 battery, and share the csv. I would like to see the voltages during the discharge as they will be higher than discharging at 20 Amps. I'll sponsor the beer's for the test 👍

I just got my "new" battery cells from AliExpress and was obviously ripped off. Could you show the "resistance" test of your small (20A) battery tester? I own the same and would like to know which values to expect in new batteries. Depending on which current I use the result is between 3 and 10 mR, which is is way too high in my opinion. But maybe this tester doesn't work fine-grained enough.

Andy you maybe interestedin the icharge x6 or x8 charger/discharger as it has the ability to use a bigger battery as the load, so you can do discharge tests but capture that energy in your bigger battery.

How do you calculate the cut off voltage? I'm thinking of getting one of these testers to test the 24v batteries we use at work.

Hi, I have 8 Pylontech 2.4 kWh 48v 50Ah 15 cell modules and your videos clearly demonstrate just how safe they play it with the recommended charge/discharge cut off voltages, 53.3v charge cutoff and 47.2 v discharge cutoff which gives a cell voltage of 3.5533v maximum charge voltage and 3.1466 minimum discharge voltage. Is it possible to calculate the number of complete cycles by dividing the total kWh hours drawn from the battery bank ie 2,530kWh by the battery bank capacity ie 19.2kWh? Or do I need to access this data by connecting a lap top to the master battery data port?

Morning Andy, couldn't you sleep too mate. Good show as usual.

Which model battery are you testing?

what if I want to test my 48v battery ?

Just bought 16 x 280ah cells from Amy! Could this unit be used to bring each cell up to full charge and then ultimately top balance them?

First !

Would be interested in seeing how sealed lead acid batteries compare with LiFePo?

What does "Mr. Garage" say about a shallow discharge / charge cycle of an LiFePO4 battery? Example - A typical 2000WH SOGEN battery bank with an approximate 500 watt air conditioner load that is fed/charged with ~ 475 watts of solar. When the AC compressor cycles off, now fan only, (~40 watt load), the 475 watts are now charging the Sogen for ~ 5 minutes. Then after the AC compressor kicks back on, the use cycle is repeated. The Sogen display varies from about a 62% charge level when the AC compressor is on and the Sogen charge display increases to about 63-64% when the AC is "fan only". Does this usage pattern have any negative effects on the Sogen's LiFePO4 batteries???? Me AND all your other viewers may have a similar question about this "short cycle" use.... Thanks ahead of time for your experienced opinion....

15:10 Did you say that the ZKE-Tech EBC-A40L can't test a 4s battery, only single cells? But the smaller ZKE-Tech EBC-A20 can?

Sir plz mention discharge battery equipment name and model.I need to Discharge carbon zinc D type battery.