THE TRUTH about the BEST LIPO cutoff voltage to SAFELY get the most out of your batteries 

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!

Very happy to hear independent validation. Thanks for taking the time to share.

We are of like mind. Of course the higher the load the greater the sag. See this video: EdgeTX Snippet • Delayed Voltage Sag Alert ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-Q5s7zB0NDCQ.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.

WOW! I'm certainly glad to hear this. It's kind of the reason I run this channel. Thank you.

Wow, thanks! I'm glad to have helped. Thank you for the very nice comment.

Makes my day when someone says they learned something. Glad to help.

I don’t order too many smaller batteries these days but I’ll keep an eye on this now over time.

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.

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 😉😁😎

Glad you enjoyed it!

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.

4c discharge results are posted on discord. No change to the curve outside of occurring quicker. I haven’t tested Turnigy further.

Oooh yeah that sounds like some lost capacity. Thanks for the comment.

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.

Awesome! Sounds like you've got a good system in place. I agree on 4.17/4.18 for peak too.

You're welcome.

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.

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.

You're very welcome and thank you for the kind comment.

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🤣🤣🤣

100% agree.

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.

I usually let them rest to ambient temperature although TBH I don’t have any data to back that up. Just what I do.

You're welcome, and welcome to the channel.

You're welcome

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.

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

You're welcome. Thanks for the comment.

Setting your peak to 4.18 can improve the life of the battery up to 85%. Taking them down to 3.6 is fine.

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.

You're welcome!

Sorry, I switched from Windows to Mac a few months ago, so I don't really have any older versions of software saved anywhere.

I haven't had to install any drivers for the Charge Master software to work. Have you tried different USB cables? I know it sounds weird, but they're not all data capable.

I think this should help: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-Q5s7zB0NDCQ.html

@@RCVideoReviews thank you very much.

Yes, 3.75-3.85 is a good range for storage. Anywhere in that range is fine.

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.

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: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-Q5s7zB0NDCQ.html

Now I understand your 3.6v flight time. I use Vbar and fly to 30% batt mAh capacity remaining.

THANKS

No problem 👍

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.👍💯

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.

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.

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.

Internal Resistance for the pack and per cell.

That is measured in Ohms? @@RCVideoReviews

milliohms

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 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.

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.