THE TRUTH about the BEST LIPO cutoff voltage to SAFELY get the most out of your batteries
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- čas přidán 29. 09. 2023
- There is an abundance of opinions, articles, and "spec sheets" that tell you all about discharge values. In this video, I'm going to show you test results with data and teah you how to find the correct value for your batteries.
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#RCVideoReviews - Věda a technologie
Man, you have hands down the BEST most comprehensive videos about this hobby. And second isn’t even close.
Thanks for all your work!
Would love to see you do this exact test/experiment with several brands, same size. IE: SMC, Liperior, CNHL, HRB, Spektrum 6S 5000mAH…
We actually all know about it, but you nailed it. Plain and simple. There is no reason to stretch if you got nothing to stretch with. Good show of reality. I got similar software coming with Elprog Pulsar chargers. That discharger analyzing software you use is cool too. Time to put them to work and investigate these LI-Ion batteries. They drive me nuts.
YES! What's the point of pushing past the mark if it's nothing but downside for a marginal extra bit of flying. Oooh--Li-Ion, I have some of those to test too!
Yup I have done this analysis many years ago and came to 3.6v. Been using that multiple based on cells for all my planes and drones. I find that it makes a big flight time improvement by flying to this number and landing. After this number the exponential drop off really kicks in at 3.4v which gets dangerous and will ballon your lipos. I have all my batteries with hundreds of flights logged with no ballooning. However lots of guys at the club still fly only to 3.8v which still baffles me since you loose a good chunk of flight time.
Very happy to hear independent validation. Thanks for taking the time to share.
You have changed my RC life! Thanks to you, I feel better about any choices I make based on your videos, all my purchasing and common practices have changed for the better. Can't thank you enough for what your doing for us!
WOW! I'm certainly glad to hear this. It's kind of the reason I run this channel. Thank you.
I agree with your conclusion on 3.6V. You effectively say it is okay to go to 3.6V under load, however, it does depend on the load. When racing FPV drones and flattening a 1500mAh 6S in 90 seconds then you will be seeing figures in the goggles well below 3.6V for a while but still recovering above 3.6V when you either land or come back to a gentle hover in the landing area. So if I'm cruising for 8 minutes I will be happy to go near that 3.6V value under load but in racing, 3.4V under load might be fine as long as I'm aware it is due to voltage sag under heavy load and not an actual low load or resting voltage.
I have found the best way for fixed wing is to set to set two voltage alarms. The higher alarm will only trigger if the value is below the threshold for at least 2 seconds. That allows some high throttle moments without false alarms. Once that has gone off I know my time is limited and to start the lading process. The other alarm has a lower voltage and a shorter sustained duration. That is the LAND NOW alarm.
We are of like mind. Of course the higher the load the greater the sag. See this video: EdgeTX Snippet • Delayed Voltage Sag Alert
czcams.com/video/Q5s7zB0NDCQ/video.html
I use 6 seconds for fixed wing and that has proven to be quite effective over the last year getting me on the ground with a rebound to 3.8.
first 😏Also, this is by far the best, most comprehensive, and easiest to interpret LiPo analysis I've seen so far. Extremely helpful.
Wow, thanks! I'm glad to have helped. Thank you for the very nice comment.
Perfect intro music.
Love it!! Very calm and relaxing.
Great video and info ❤
Glad you enjoyed it!
Good analysis. I believe that all things being equal, physically smaller lipos always have higher IR due to the smaller surface area to conduct electricity. It’s normal to for a 2200 mah pack to have a higher IR than a 5000.
I don’t order too many smaller batteries these days but I’ll keep an eye on this now over time.
Excellent information/vid! Thk u so much! This is EXACTLY the kind of information I've been looking for for a LONG time! Like you, I've seen a million opinions, and as someone who doesn't belong to a club, all I have for help is the internet. As it turns out, I decided to fly my M2 heli down to a reported voltage (telemetry) of 10.8, which works out to: 3.6/cell! How cool/weird is that?! Most ppl I watch on YT say, NEVER go below 80% discharge. Then I found a guy who's been flying since he was a child and he said, not true, you can go MUCH lower than that, so I decided to go down to 10%. The way *I* look at it, WHY waste useable capacity just cuz "everyone" says so. I, too, have observed that if I don't get my model on the ground by 10.8 volts (reported, under load, ofc), the voltage is gonna drop off a cliff, which, when flying a heli, is VERY SERIOUS! I *HATE* crashing/repairing, so I take EVERY precaution to TRY to insure that I *DON'T* crash ... EVER! I've been flying my M2 for 2 years (daily during the summer) and I've NEVER crashed it, a fact that I'm EXTREMELY proud of.
Your experience counts as much as anybody else's experience. So use it. Data helps too. And I agree on the helis, not something to be taken lightly when it comes to voltage getting low.
Good work shows the best reason not to use 3.3v as the limit. I fly to the storage voltage rested after flight. Saves having to boost to storage and keeps the battery safe
Nice. I use small 2S packs, and I've been running them to a 3.6v cutoff for a few years. I found I was able to almost double the number of cycles I could get from them. They're HV, but I charge them to 4.2v. I figure that the car manufacturers' way of handling their packs - don't fully charge, cut off at a high voltage - was the way to go. Good to see my hunch has numbers to back it up.
Its been awhile since ive learned something as valuable as this. Awesome video. You never cease to provide quality content.
Makes my day when someone says they learned something. Glad to help.
Thanks John awesome info as usual , now I have a better understanding why my battery’s are giving up more than I expected
You're welcome.
Great info. Thank you for yet another useful video.
You're very welcome and thank you for the kind comment.
Very, very informative! Thanks! Liked and subscribed.
You're welcome, and welcome to the channel.
I got a couple of brand new gens ace 5000 6s packs last year, andi decided to actually try and treat them carefully (cause they are so damn expensive now).
They spend most of the week on a 3.85V storage charge, only getting charged to 4.20V on the morning of a flying day, flown to around 3.80-3.85V, left to cool, and then put back on a storage charge in the evening. Flying to 3.80V gets me 6 minutes of flying on my T-Rex 550x with a bit of safety margin.
Both batteries have 50-ish cycles on them and still look and feel like brand new packs, it will be interesting to see how long they last compared to most of my other packs that have been properly thrashed
That pretty well describes how I fly mine most of the time with one mod: I usually peak charge to 4.18 vs 4.20. According to a study I ready by MIT, this can extend LIPO life by 85%.
Have you noticed the difference for 4.18? I haven't been flying long enough to retire a battery.
Half the time the battery is at 4.19 after charging and before flying anyway. I haven't noticed much of a difference at 4.18.
Outstanding, i didnt have graphs but i got curious with some Socokin 5200mah 6s batts, i was noticing i was not getting good flight times, so i drained it down to 10% and on a chrage was only getting 2900MAH on 2 batteries. So this is very important to check. Great video and awesome info. 👍👍
Oooh yeah that sounds like some lost capacity. Thanks for the comment.
Friggin fascinating are batteries !!! I've lived off-grid for almost 40yrs and devolvements across the board in these later years are finominal along with many misconceptions..... thankyou for this video !!!!!!!! I'm horrified at some things I hear and see regarding different battery types...... sometimes ive asked people if they know what year it is........ I'm also happy to admit what I don't know or aren't sure about....... You've answered many of my puzzling thoughts........Again thankyou !!!! Two thumbs up from New Zealand 😉😎
Well I'm certainly happy to have helped. Thanks for watching and for the comment. Appreciate it.
@@RCVideoReviews hiya Man...I didn't expect a reply but thankyou.....it's such a fascinating subject..... I've found a lot of cheap batteries or going to be dumped ones with usally 1 failed cell......I'm sure their other cells are most likely compromised..... however I've decided to tinker with soldering and spot welding the seemly ok cells back into packs and figure a simple cheap testing method.... but after watching your video I'm starting to doubt the most likely outcome as I feel battery health, management etc etc etc by many of us is severely under-rated ..... and as you expressed finding reliable sound information on the interwebs is questionable.... the mind-blowing thing you found for me is the common drop off point around 3.6 , this has been a for most question in my mind since being introduced to lipo etc.... The things I've seen in the solar industry regards battery's is scary and usually costly to the participant.dearly... purchasing share's in the battery industry can only be a sound investment.....
So is it you playing the wanderfull piano intro to your excellent video's ?😉 ok many thanks for your awsum contributions to the hobby !!!!!. Love from New Zealand 😉😁😎
Excellent vid! TY!!
Thanks. Very useful information.
You're welcome
Great video, thanks for sharing
You're welcome. Thanks for the comment.
Love to see these tests replicated at a discharge C rating much higher than 2C - nearer what we are actually using in flight
Also did the new Turnigy battery improve after a few cycles- or is this also just a myth?
4c discharge results are posted on discord. No change to the curve outside of occurring quicker.
I haven’t tested Turnigy further.
very good video I always keep my battery voltage above 3.5 and set the alarm at 3.6 cause as u said its risky zone below 3.5 volts cell that's 100% accurate below 3.5 the voltage drops too fast u don't even get a chance to land your craft calmly u have to rush it so I have to keep a reserve on battery so I don't accidentally damage the cells
100% agree.
Lots of useful information in layman’s terms great video 👍🏻😎
Awesome! Thanks Fred, and thanks for the good question. Glad we got that answered.
@@RCVideoReviews right that was something I’ve thought about for a while now.
What an insightful video! I’ve made the mistake of having way too many packs in circulation, that it becomes complicated to properly manage them.
This video gives enough ammo to do some nice bench tests with some of the suspicious packs as to determine how they’re behaving.
I have some inexpensive HRB packs and some more expensive ManiaX packs, time to compare if the additional cost is justified! Thanks for this 🙏🏼
You're welcome. I'm glad to hear the video gave you some ideas on how to manage your packs! That's the best reward I can get for making content like this.
@@RCVideoReviews I'm going over your data, as I attempt to gather some results myself; where/how did you calculate/get the WH value for each battery from?
V*A=W. V*AH=WH
For volts, use nominal voltage.
mAh/1000=AH
@@RCVideoReviews
Thank you!
One more question 🙂:
I'm going over a few of my HRB packs. The Vs. Rated for all the ones I've tested (discharging to 3.4/cell) is over 100%, which sounds good so far.
The one thing that has me concerned is that one of the packs has an AvgIR of 12.2 (the rest range from 2.8 - 3.7). What does an AvgIR of 12.2 tell me about the state of the battery? I was still able to draw 5159 mAh at 3.4 volts/cell.
I have been using your cut offs etc for many years now and have batteries that are working great after 200+ cycles some well over 300 cycles.. I actually try to end at 3.65 or higher. Something to note I always charge at 2C and so far has not been an issue for me. Many at ouirt club say Im ruining my batteries but I get WAY more cycles then they do. Another difference is I only charge to 4.17 volts not 4.2. That last little bit has been shown by others to reduce battery cycle life. I do not charge at home, only at the field, and take may batteries home at a 50% storage charge (3.85v / cell ) EVERY TIME. The nay sayers at my field will charge at home, often leaving their batteries fully charged if not used or taking them home a very low charge and storing them that way. Both are VERY BAD for longevity of battery health . The last point Ill make is resistance is a crucial measurement of battery health. I have pulled many batteries out of our clubs throw away bin that were slightly puffed but had low resistance and used them for upwards of 100+ flights. Someone was told "Oh you need to throw that away blah blah blah" and in reality it was still very usable .
Awesome! Sounds like you've got a good system in place. I agree on 4.17/4.18 for peak too.
Very interesting. For many years now when flying planes with 2200 or smaller batteries I have been setting the flight time by taking an 80% of stated capacity and measuring the flying current with a watt meter at zero airspeed on the ground and using those figures to give me my flight time. I assume the motor unloads in the air and I am not always at full throttle when flying. Looks like that was pretty conservative but I have noticed that when I check my batteries after flying they are always above 3.7 to 3.8V/cell. I guess that my conservative approach was right in the past when data such as this was not available. Gives me room for a go around if I need to as well. Never wanted to go too low as I am usually using BEC and I have an urge to have a working radio in my plane!!
I realise you were setting test parameters for consistency. I guess that you do not use the packs in flight at 2C. Would be interested to see a similar test done at discharges nearer to your flying current and then see where the drop off occurs.
Another great video.
I think 2c is a reasonable average discharge rate over the course of a normal flight. In any case, higher discharge will result in more sag, but the curve will remain consistent.
Interresting video! The higher the internal resistance of the battery and the higher the current, the lower the measured voltage will be. The discharger used in this test is limited to 250 W, which limits the maximum current you can use to discharge. It would be interresting to test with higher currents on the lower cellcount batteries (because of the maximum wattage you can discharge with) to see what the cellvoltages will be. I just wonder if you will see the same 3.6 V... Ofcourse you tested with different currents, but the batteries got a comparable load (all at 2C).
You're talking about sag. I don't believe it will change the curve outside of the time it takes for the discharge to take place. You should test and show your results.
@@RCVideoReviews I don't have such a discharger that can monitor the voltages like the BD250. If you or someone else with such a device could do a test with 4C (given the capacity of the discharger it is ofcourse limited to smaller capacity cells or less cells in serial) then it's easy to confirm your findings or confirm what I think may happen. 😉
PS. When I discharge batteries and tell it to stop at 3.85 V per cell, it highly depends on the discharge current if it will stop at the right moment. Measuring afterwards often shows the voltage is still too high in unloaded condition. So discharging at higher currents means I have to set the discharge cell voltage lower to be able to get to approx. 3.85 V per cell in unloaded condition. My charger has limited discharge voltage settings, so it's mostly a two step process (start with higher set current, then end with lower set current).
I did the test and posted the results in discord. The curve is identical, just occurs over a shorter period of time.
@@RCVideoReviews Thanks, was just checking in at your discord, but I can't seem to find the new results.
Very good information. 3.6 for me from now on! I now use Life packs for my gasser (Lipo's for electric) 6.6v suits my ignition module and servos. I use two in this airplane. I'm new to Life batts and just like you said about lipo's, there's tons of different opinions out there regarding cut off and more. It would be fantastic if you would be prepared to do a similar test on Life batteries. Oh, and can you explain the difference between Life and LifePO4? Apparently they're the same but I just don't get it!! Thanks...
The only LIFE batteries I own have BMSs installed. So charge/discharge levels are governed by the BMS. LIFE and LIFEPO4 are the same thing.
Great video, discharge to 3.6v looks good. Do you then charge to storage voltage after and what storage voltage?
Yes, 3.75-3.85 is a good range for storage. Anywhere in that range is fine.
awesome video and study! I wonder if under higher load and more sag that it would be okay to go lower? maybe closer to 3.5, since it would rebound more, or maybe we would still see the same drop off. thinking in context of an fpv quad
The whole point of a c rating is to establish the sustainable discharge rate of the pack. At higher current the discharge will take less time and the rebound may be more dramatic but the curve will remain. My voltage alarm uses the premise of a no sag alert. Ie my alarm triggers after voltage remains below my configured value for a set period of time. In fixed wing I’ve found 6 seconds to be a good indicator. If my alarm goes off when I remove power, I keep flying. If it doesn’t, I land. But I’m still looking at the same voltage level regardless of how fast I got there.
oh wow i didn't know they had lipo alarms like that! which one are you using if u dont mind me asking? @@RCVideoReviews
amzn.to/46zTZA0
Man, you saved my but! I just ordered the BD250. New to lipos and this vid was very informative. What is a good resting time?
I usually let them rest to ambient temperature although TBH I don’t have any data to back that up. Just what I do.
If at all possible can you perform this same test on the (yowoo power) Graphene batteries? I just purchased 8 6s 4000mah batteries, and just completed the eighth break in cycle on 2 of them. and for some reason the IR Seems high to me. compared to a 10yr + old Align 2s 1900mah battery where the IR is consistently 9 IR each cell. The charger I'm using is an 208B icharger. If you could test these batteries along with a few others in the same manner that would be great...
Congratulations the best video explained about this topic and great channel.
I have a question and would like your advice. In order not to damage the battery or the plane, when establishing an alert at the minimum voltage, I have noticed that mid-flight the alert sounds, perhaps because the power momentarily increases, and when lowering the plane I notice that the voltage is higher than the established minimum, and that sometimes happens many times during a flight.
What can I do about it, at the first sound I lower the plane? How to handle variations with the power demanded? greetings.
I think this should help: czcams.com/video/Q5s7zB0NDCQ/video.html
@@RCVideoReviews thank you very much.
A LOT of good information! I am a bit older - trying to digest this. My main interest is having reliable packs and have those packs perform as long as possible. I have let the charger go to it's default charge of about 4.2 volts per cell. But it would be better to go slightly less? And I have flown to about a good storage value and quit. So, . . . you are saying that I could safely take a pack down lower. Ok. But does that seem to harm the battery if I start taking them down closer to your 3.6 volt cut off area?
Setting your peak to 4.18 can improve the life of the battery up to 85%. Taking them down to 3.6 is fine.
OK, so 3.6V is the LiPo cutoff voltage for 2C discharge, but what about 1C discharge? I assume the cutoff will be lower in that case, or, will it stay the same?
Thank You!
You're welcome!
I'm probably being a bit too conservative. I generally land with a battery that recovers to a good 3.8V and treat 3.7V as an absolute floor. I knew that the curve could plummet but assumed it was from 3.7V, not 3.6V so this video was illuminating. I guess I make up for being conservative by horribly abusing my quad batteries xD
That's pretty much what I used to do. 3.75 was my number. 22.5v is in almost every low voltage alert I have for 6s setups. I was surprised how much more was in the packs though. The good news on a 3.75v setup as your point out is rebound to 3.8 which means after a flight, no maintenance required. Battery is ready for storage.
Use the SkyRC D200 Nero with the D350 and then you'll see what each individual cell in the pack is doing.
Good STUFF!!
Thanks!
Just to see price I used your link and it had no price so I went to Skyrc and they are not showing it in their listing drop downs. It looks like they are no selling it anymore, oh well.
There are so many people who discharge their batteries to 3.4V or even lower and then complain that the brand is no good, and they don't want to realise that they are the problem. 🙄😵💫
I think in a far far greater sense more people need to learn to look in the mirror when searching for the actual problem.
@@RCVideoReviews So the human race is gonna get totally honest and take responsibility for themselves🤣🤣🤣
Thanks for the video.
I’m not understanding how you know when you are at 3.6 volts?
Is the data through telemetry then land? I know most fly via a “timed” flight.
I've completely converted my fixed wing models to ELRS and all of my ELRS receivers have VBAT (flight pack voltage) telemetry. I use this setup on my radio: czcams.com/video/Q5s7zB0NDCQ/video.html
Now I understand your 3.6v flight time. I use Vbar and fly to 30% batt mAh capacity remaining.
THANKS
I was struggling to understand what you're saying in the video but I think it's about what to set a cutoff voltage to for RC planes? I'm starting to get into RC car racing and learn about lipos
Thank u man 👏
No problem 👍
Personally, My end of flight voltage is as soon as a cell hits 3.75v It's time to land, I have never discharged a cell lower than 3.7v per cell, and my packs have been fine, Though I have to note that I have of course had packs that had bad cells in the pack. Oddly, the most expensive Optipower (UK) packs have been the ones that were most likely to have bad cells in the pack, with higher IR's on one cell than the rest of the cells in the pack. I no longer buy Optipower packs for my Helis.
What cut off voltage for life batteies? Do you know! I use them for receiver batteries. Thanks.
I found during testing the values on this page matched up pretty much exactly with the BMS on my 100ah batteries: footprinthero.com/lifepo4-battery-voltage-charts
In fact I printed the placards and taped them to my cells while I get used to the difference between LIFE and LIPO.
Thank you.
Have you ever used lihv batteries, or will you ever? With having more voltage to start, does that have a cutoff higher than 3.6 or the same 3.6?
I do have LIHV batteries and I did not put them through the same test. So my following comment is opinion: I believe the cutoff curve will be the same thing.
Discussing IR, what I've seen around is that 20 to 25 milliohms is when you should retire the pack. Do you agree with this?
I would say if you can correlate resistance to flight time and decided when a pack reaches a point where you aren't getting the flight time or the "punch" you want, then retire the pack. I know punch is definitely a subjective term; however, I have retired batteries based on in-flight performance feel from the sticks without any idea where the IR is.
@@RCVideoReviews Makes sense, thanks for the excellent video 👍
You're welcome.
Your link offers no help in getting access to purchase the SkyRC BD250 discharger.🤷🏻♂️
The link I posted worked when I posted it. It looks like they ran out of stock which is not unusual after I post links. Maybe try searching on google????
@@RCVideoReviews ok, I’ll try that route, thank you.👍💯
What does PackIR and AvgIR mean?
Internal Resistance for the pack and per cell.
That is measured in Ohms? @@RCVideoReviews
milliohms
Would be helpful to know the true point at which permanent, unrecoverable damage occurs - perhaps that could be another video 👍🏽
I think that requires some serious lab equipment to analyze. I won't be venturing into that space.
@@RCVideoReviewsWouldn’t it just be a matter of measuring the reduction in capacity after discharging to progressively lower voltages?
Is that normal wear and tear or is that due to some change in the chemistry/physical structure.
I've actually done some reading on this and it can be VERY complicated.
Well, I think if 1 or 2 samples are used as controls, that would answer the wear & tear aspect. And I’m sure chemical/structural changes are exactly what’s happening when discharging beyond a certain point. Was just a suggestion, if you don’t feel like doing it, that’s cool man. Just trying to be an engaged subscriber.
I appreciate ideas, but like I said, I've done some reading on this and it is a very complicated process.
I bet a bad 5000mah 4s pack could charge a LOT of good whoop & toothpick batteries, with the right mobile charger
Oh definitely a great reason to hold on to packs that aren't top performers in the air. I've actually done stuff like that before.
i almost always land at storage voltage lol
I have for a long time, but seeing this, I realize I've been leaving a lot of flight time on the table. Nothing wrong with stopping at storage though--it's certainly convenient.
but 3.5 for boats and planes to make time to come in safe.
Im out here smoking batteries down to 3.5 daily.
So the 3.6 is the cutoff when the motor is running or not running? I have a powerful funjet set and im sure the cells sag while WOT. The passes are only happening for 3 to 4 seconds. Doe sthis mean i need a higher cell count?
3.6 under load. You can't just upgrade cell count as that changes voltage and has implications for ESC/motor. If you're dealing with SAG, a higher C rated cell is worth considering.
Apparently the Vang brand batteries are awesome…,thanks allot!!!
3.6v Lipo cutoff it is!!!🫡🇺🇸🇺🇸🇺🇸👏