David Hall 9 Posted March 21, 2017 Share Posted March 21, 2017 Around 6 months ago, I bought 3 new 4s 2650mAh packs for a new model. I had used only two when it was damaged. The batteries were left as they were (expecting an early repair). Now the one that was fully charged is still at 99% but is swollen, seems to be just gas gas inside the sleeve. The other two are both around 40% and have no sign of swelling. Many of my other packs have a similar gas swelling, even though none are over discharged or run overrated. Most times, the batteries are recharged immediately following a session, so spend 97% of their life fully charged. I suspect that it's leaving them fully charged that is creating the gas swelling. Anyone else see this effect? Quote Link to comment Share on other sites More sharing options...
MattyB Posted March 21, 2017 Share Posted March 21, 2017 Yes, leaving Lipo batteries at a high SOC (state of charge) is bad for them and will cause premature death; despite some naysayers in the hobby world who will tell you this is incorrect there is tons of real world evidence from industry (particularly electric cars) showing this effect is real. The premature swelling problem seems to be more prevalent with the higher C rated packs that have more of the gel component in their construction. If you want the very best life from your packs you should discharge any unused packs to storage level (3.75-3.8V V/cell) asap after use unless you intend to use them again within 24-48hrs. I do this with all my batteries except the very smallest ones, of which I keep a few fully charged for impulsive parkflying (they are cheap enough not to matter). As a result I seem to get very high cycle lifes out of my packs, though to be fair I do not push them as hard as some power users using them in EDFs, multi-task gliding etc. More discussion in this thread... Edited By MattyB on 21/03/2017 12:50:32 Quote Link to comment Share on other sites More sharing options...
John F Posted March 21, 2017 Share Posted March 21, 2017 One of the most important aspects of battery care is to never store batteries fully charged but discharge them to about 40 - 50%. Storing fully charged batteries is well documented to lead to the puffed packs that you see. Quote Link to comment Share on other sites More sharing options...
MattyB Posted March 21, 2017 Share Posted March 21, 2017 Here is a good page from Battery University on the subject - a quote from halfway down... "Lithium-ion suffers from stress when exposed to heat, so does keeping a cell at a high charge voltage. A battery dwelling above 30°C (86°F) is considered elevated temperature and for most Li-ion a voltage above 4.10V/cell is deemed as high voltage. Exposing the battery to high temperature and dwelling in a full state-of-charge for an extended time can be more stressful than cycling. Table 3 demonstrates capacity loss as a function of temperature and SoC." Quote Link to comment Share on other sites More sharing options...
Chris Walby Posted March 21, 2017 Share Posted March 21, 2017 IMHO so just fire away, but my comments are based on my experience. No difference if you store lipos partly charged (above 25%) or fully charged to total life Cycling lipo's will shorten their life be it in use or discharging from full to storage, what is important how fast/hard the charge or discharge is....the closer to the C rating the less cycles you will get out of them in total life span. I have lipos that at are very puffy and have reduced less than 5% of total capacity...knackered I think not I have lipos with less than 50 cycles, just as puffy as above and have reduced by 30% capacity...u/s in my book Advice - take a look at the lipo for physical damage, if it is dispose of it and if still performs in capacity and discharge capability the keep going whether its puffy or not. Questions Who would store a lipo at +60C for over 3 months...really! get real Okay if you store them in the fridge, then take it out to fly, then put it back in the fridge what effect does the thermal shock cause to the life span of the lipo... Ever tried discharging a cold lipo.. it can result in catastrophic cell failure & who said its only IC's that dead stick! Quote Link to comment Share on other sites More sharing options...
David Hall 9 Posted March 21, 2017 Author Share Posted March 21, 2017 I lashed up a discharger for my 3s batteries from a car bulb and one of those cheap discharge warning devices,,,,now to use it.. Thanks. It just makes it all a bit of a push having to charge ALL my batts before an outing, but worthwhile for longer LiPo life, I guess. Thanks for the detailed info.... Edited By David Hall 9 on 21/03/2017 14:59:34 Quote Link to comment Share on other sites More sharing options...
Chris Walby Posted March 21, 2017 Share Posted March 21, 2017 David, I would not go to the trouble, the risk of over discharging a lipo (and knackering it) + having to watch them while you do it + watching them when you charge them before flight. Double checking that you haven't put a low charge lipo in your model...cost of a lipo compared with the model... Life is too short, if you want them to last....store cold and don't use! Store at 20C, fully charged and at every opportunity go and fly.... have fun. And when you have worn it out, pat on the back and buy another, you have probably flown for about 30 hours in total Quote Link to comment Share on other sites More sharing options...
David Hall 9 Posted March 21, 2017 Author Share Posted March 21, 2017 Are the LiPo packs in many TXs any different in this respect? My 9XR has a 3s 2200 1.5C pack. Is this in danger of swelling if left fully charged? Quote Link to comment Share on other sites More sharing options...
MattyB Posted March 21, 2017 Share Posted March 21, 2017 Yes, the low C rated lipos are much less likely to puff due to storage at elevated SOC, so probably not worth worrying about on that pack. LiFes are even better in that regard though, although their very flat discharge curve does mean it's difficult to set the low voltage alarm. Quote Link to comment Share on other sites More sharing options...
MattyB Posted March 21, 2017 Share Posted March 21, 2017 Posted by David Hall 9 on 21/03/2017 14:58:53: I lashed up a discharger for my 3s batteries from a car bulb and one of those cheap discharge warning devices,,,,now to use it.. Thanks. It just makes it all a bit of a push having to charge ALL my batts before an outing, but worthwhile for longer LiPo life, I guess. Thanks for the detailed info.... It is possible to create a much more advanced discharge rig relatively cheaply from commercially available units - I am going to finish off my 300W setup tonight, and will post some pics in a new thread when I do. This combined with a high wattage PSU powered charge setup means I can charge all the batteries I need for an afternoon's flying in ~45 mins and discharge any leftovers afterwards in a similar time safely and simply. Edited By MattyB on 21/03/2017 16:30:42 Quote Link to comment Share on other sites More sharing options...
ken anderson. Posted March 21, 2017 Share Posted March 21, 2017 I've been using lip's since they first come out(£44.00) for a 2200/3s and the instructions used to say you would get a 100 cycles out of them..and that would be RIP for them.the only time I've had lipo's puff up is if I've pulled the max out of them for the duration of the flight..... I store mine fully charged... ken Anderson...ne...1 ....... lipo dept. Quote Link to comment Share on other sites More sharing options...
MattyB Posted March 21, 2017 Share Posted March 21, 2017 Comments embedded below... Posted by Chris Walby on 21/03/2017 14:48:34: IMHO so just fire away, but my comments are based on my experience. No difference if you store lipos partly charged (above 25%) or fully charged to total life Posts on this topic always go this way; those that believe in discharging to storage can quote lots of evidence from the likes of the electric car and renewable energy industries, but those who say that's incorrect only ever quote from their own experience. When I read a citable source proving scientifically there is no loss of cycle life or increase in IR from storage at elevated SOC I will happily eat my words, but til then I am believing the likes of Nissan and Tesla who have millions invested in the technology. It is also interesting that everyone I meet who uses really big, expensive batteries and/or use them at very high C ratings keep their lipos at elevated SOC for the minimum amount of time; this is very evident if you read the Batteries and Chargers forum on RCGroups. Those whose biggest battery is a 3S 2200 are much more inclined to store at full charge for convenience. Cycling lipo's will shorten their life be it in use or discharging from full to storage, what is important how fast/hard the charge or discharge is....the closer to the C rating the less cycles you will get out of them in total life span. Right, which is why discharging to storage does very little damage to a lipo - the C rating is very low, no real heat gets generated so there is next to no negative. Storage at elevated SOC though causes anode degradation and dendrite growth, both of which have an impact on capacity and IR. In extreme cases batteries have been known to short out internally from dendrite growth, not something you would want in your house I am sure. The safety aspect is the #1 reason I do not store my batteries fully charged - 4x fully charged 6S 5000s in close proximity has an awful lot of energy inside at full charge. I have lipos that at are very puffy and have reduced less than 5% of total capacity...knackered I think not I have lipos with less than 50 cycles, just as puffy as above and have reduced by 30% capacity...u/s in my book Advice - take a look at the lipo for physical damage, if it is dispose of it and if still performs in capacity and discharge capability the keep going whether its puffy or not. There I totally agree - just being puffed does no mean it is by default U/S, similarly not being puffed does not mean it is performing well. Puffing is however an indication that the pack should be treated with caution moving forward and monitored carefully on charge and discharge Questions Who would store a lipo at +60C for over 3 months...really! get real Those are the results of a scientific experiment, and in experiments you push the boundaries to see what happens. Sure, no-one is likely to do that, but it does show the impact of temperature on the internals of the battery in an extreme environment. Okay if you store them in the fridge, then take it out to fly, then put it back in the fridge what effect does the thermal shock cause to the life span of the lipo... Ever tried discharging a cold lipo.. it can result in catastrophic cell failure & who said its only IC's that dead stick! The OP posted about the effects of storage at elevated SOC, not temperature. I am inclined to agree that storing in the fridge is not necessary (at least not in this country), but look at the numbers at 25C - if stored at full charge the battery capacity could be degraded by up to 16% vs. if it had been stored at 3.85V/cell. Edited By MattyB on 21/03/2017 16:56:57 Edited By MattyB on 21/03/2017 17:15:24 Quote Link to comment Share on other sites More sharing options...
Rich too Posted March 21, 2017 Share Posted March 21, 2017 Posted by David Hall 9 on 21/03/2017 16:00:15: Are the LiPo packs in many TXs any different in this respect? My 9XR has a 3s 2200 1.5C pack. Is this in danger of swelling if left fully charged? No problem, I charge my trans when I want to use it, so don't leave it fully charged. This thread reminds me of why I like flying petrol models ! Quote Link to comment Share on other sites More sharing options...
MattyB Posted March 21, 2017 Share Posted March 21, 2017 All power systems have their pros and cons. Battery usage and care can seem like a pain I agree, but then when I look at this and other forums there seems to be a far higher variety of issues with IC than electric (plumbing issues, carb problems, blocked/dirty pipes, tank positioning etc) - that variety seems to make it harder to troubleshoot any issues that do occur. PS - Despite using almost exclusively cheapo motors I have never had an electric motor do this either... Edited By MattyB on 21/03/2017 18:30:54 Quote Link to comment Share on other sites More sharing options...
eflightray Posted March 21, 2017 Share Posted March 21, 2017 On the TV program 'Fake Britain' they should some fake Lipo batteries, (not the original manufacturers), for cameras, phones, lap-tops etc, saying how dangerous they could be. They showed how they can explode if misused. How ?. They put them on a hot plate and cooked them until they gassed and/or exploded. Taking them into the 'thermal runaway' region. What they didn't do was do exactly the same test using an original manufacturers battery, which I am pretty sure would react exactly the same. A totally stupid test, unless you want to just frighten people. Edited By eflightray on 21/03/2017 18:57:16 Quote Link to comment Share on other sites More sharing options...
Rich too Posted March 21, 2017 Share Posted March 21, 2017 Posted by MattyB on 21/03/2017 18:30:14: All power systems have their pros and cons. Battery usage and care can seem like a pain I agree, but then when I look at this and other forums there seems to be a far higher variety of issues with IC than electric (plumbing issues, carb problems, blocked/dirty pipes, tank positioning etc) - that variety seems to make it harder to troubleshoot any issues that do occur. PS - Despite using almost exclusively cheapo motors I have never had an electric motor do this either... Edited By MattyB on 21/03/2017 18:30:54 haha! yes, but batteries require regular maintenance, and the issues you mentioned for IC are one off's. My petrol lawnmower has gone three summers without any maintanence whatsoever...just fires right up after being in the shed all winter. Quote Link to comment Share on other sites More sharing options...
Denis Watkins Posted March 21, 2017 Share Posted March 21, 2017 Swollen packs are quite common And readers, like me, have looked for solutions here, and information Still unsure if they are of concern I really don't need IC information from a "swollen pack" thread Start an IC thread if need be Quote Link to comment Share on other sites More sharing options...
john stones 1 - Moderator Posted March 21, 2017 Share Posted March 21, 2017 Cheap shot dragging Adrians ? misfortune into the thread, his installation n maintenance are the envy of many scuze me for getting puffed about it John Quote Link to comment Share on other sites More sharing options...
john stones 1 - Moderator Posted March 21, 2017 Share Posted March 21, 2017 Puffed packs ? I've only had two, i put those down to me ignoring the timer when i was enjoying the flying (lesson learnt) I don't do owt special or follow strict regimes, i just follow what the bumf tells me. John Quote Link to comment Share on other sites More sharing options...
MattyB Posted March 21, 2017 Share Posted March 21, 2017 Posted by john stones 1 on 21/03/2017 19:49:26: Cheap shot dragging Adrians ? misfortune into the thread, his installation n maintenance are the envy of many scuze me for getting puffed about it Nothing of the sort - did I say anything about it being a maintenance issue? My point was things can go wrong with any power system, and you need the right knowledge (sometimes quite specialist knowledge) to fix or avoid such problems. Personally I find electrics to be simpler and easier to troubleshoot, but if I had a lifetime of IC experience under my belt I would probably think the opposite. YMMV. Edited By MattyB on 21/03/2017 20:07:32 Quote Link to comment Share on other sites More sharing options...
John F Posted March 22, 2017 Share Posted March 22, 2017 Posted by eflightray on 21/03/2017 18:56:39: On the TV program 'Fake Britain' they should some fake Lipo batteries, (not the original manufacturers), for cameras, phones, lap-tops etc, saying how dangerous they could be. They showed how they can explode if misused. How ?. They put them on a hot plate and cooked them until they gassed and/or exploded. Taking them into the 'thermal runaway' region. What they didn't do was do exactly the same test using an original manufacturers battery, which I am pretty sure would react exactly the same. A totally stupid test, unless you want to just frighten people. Exactly the same issue with Kindles. Watchdog did this test thereby a "technical expert" dragged a 240 volt set of leads across a kindle motherboard to show how it destroyed the device - proving that Kindles are no good on aircraft flights due to static. What they didn't say was that any device on the planet is destroyed by doing the same. David, what kind of charger do you have for your lipo's? Many have a storage charge setting. I have an IMax B6 and it has a storage setting, which makes it much easier, less of a pain to calculate as it does it for you and lessens any worries. Quote Link to comment Share on other sites More sharing options...
Engine Doctor Posted March 22, 2017 Share Posted March 22, 2017 Fake Britain or Watchdog  like any other journalistic organisation will give fake or incomplete info to sensationalise their story . As said even the best quality items will fail if mistreated . Experts are consulted then quoted out of context or only partly quoted to make the story more frightening. Undoubtedly there are some dangerous electronic items being sold but giving fake,frightening info is not helping anyone.  What is an expert ? Well "ex" usually means they used to do or be then "pert" pronounced "spert" is a drip under pressure . So we have an ex drip under pressure to give us advice !  and then being misquoted by journalists who can't be trusted any more than most politicians. Joking aside though without programme like Watchdog or Fake Britain many of the issues with our purchases. Would be ignored by manufacturers so they are needed. Quote Link to comment Share on other sites More sharing options...
David Hall 9 Posted March 22, 2017 Author Share Posted March 22, 2017 Thanks for your valuable input guys.... As a practical and slightly lazy approach, now that I am aware of this, it is very easy for me to change my charging procedure to incorporate at least some "good practice". For packs that are to be unused for a while, discharge/charge to 40-50% cap. For packs that are in use regularly, that is expecting use every few days (weather permitting....we can go a week or two at the moment) I will now charge to storage charge after each session and only fully charge prior to flying. If I miss a session, I'll not discharge this set... So, If I'm going to charge 10 packs from storage to full the evening prior to each session, I'll now have to look for a more powerful charger than my 50w version..... Quote Link to comment Share on other sites More sharing options...
Don Fry Posted March 22, 2017 Share Posted March 22, 2017 Anyway I'm a couple of quid up. I have dug a pack out of the going to the tip bag, consigned there because it was puffy, and on assumption not a good one. And it seems it does perform. Numpty with batteries me. Quote Link to comment Share on other sites More sharing options...
Chris Walby Posted March 22, 2017 Share Posted March 22, 2017 David, All sounds reasonable (load of unnecessary faff IMHO, but each to there own!), only thing I would suggest is that you track (I think HK do a stick on red/greed indicator) for each lipo as the chances of arriving at the field with a part charged lipo is much higher. This translates into a higher chance sticking a part charged lipo in a model. The risk and consequence is not worth a model in my book as the ESC will self test at the cell count, but will shutdown/soft power cut under high load conditions....that will be on or shortly after take off! I have enough going on without the nagging thought of ....was that one fully charged! There are some nice quad chargers out there, that the other guys will recommend. Quote Link to comment Share on other sites More sharing options...
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