Jeffrey Cottrell 2 Posted March 26, 2020 Share Posted March 26, 2020 Hi Guys Saw a video on YT recommending that, during this period of enforced abstinence, LiPo's should be stored at storage charge (3.8v/cell). Lots of good reasons for doing this, but I have an issue. One of my LiPo's has been on my discharger for some 6 hours now and is still showing over 4v/cell. Last count I had some 14 packs needing to be stored. At that rate, by the time I have them all at storage it will be time to get back to flying. So, what's the general thinking ? Worth doing? Cheers Jeff Quote Link to comment Share on other sites More sharing options...
Gary Manuel Posted March 26, 2020 Share Posted March 26, 2020 Why not just restrain a model and run it at half to three quarter throttle until 3.8v is reached? If you overdo it, the ESC will cut out at 3.3v or whatever it's set to, then just recharge to 3.8v. Quote Link to comment Share on other sites More sharing options...
David Hall 9 Posted March 26, 2020 Share Posted March 26, 2020 I found that it is worth doing. Those that I left for long periods tend to gas up and are those that fail earlier. I can't wait for my discharger to do the job, so I discharge into a car headlamp bulb... I just have to watch it carefully to stop it going too far. Recently, I have attached my low battery sounder as a safety measure. Quote Link to comment Share on other sites More sharing options...
Allan Bennett Posted March 26, 2020 Share Posted March 26, 2020 It's definitely good to store at 'storage' charge (usually quoted as 50%, or 3.85v per cell) for two reasons: First, it prolongs the life of the battery; second, if anything goes wrong there's less energy in the battery to fuel the fire. The only reason I know of for not storing batteries empty (say 3.7v per cell) is that over time they can slowly self-discharge, and might go to such a low voltage that they can't be recovered. My usual routine is to store my batteries at whatever voltage they finish at after a flight -- usually 22% to 25% capacity remaining. For a prolonged storage I'll be checking voltages from time to time to make sure they haven't sunk too low. Quote Link to comment Share on other sites More sharing options...
Martin McIntosh Posted March 26, 2020 Share Posted March 26, 2020 A charger with a storage program is cheap enough, thought most of them had this now. Certainly worth doing, I have been keeping mine fully charged ready to go and now have loads which only hold 2/3 capacity. Quote Link to comment Share on other sites More sharing options...
Keith England 1 Posted March 26, 2020 Share Posted March 26, 2020 By far the best site for ALL your battery questions is Battery Universe, in this case:https://batteryuniversity.com/learn/article/how_to_store_batteries. To answer two things that have come up here. I moved house last year and was in the temporary accommodation whilst a new house was built. I ended up not flying for almost a year. Not one battery that I left at storage charge of 3.8V/cell had degraded at all and had not dropped more than 0.1V in that time, self discharge in Lithium Polymer is almost non-existent. One battery, only a month old when I stored it, I accidentally forgot to discharge and was fully charged, that was puffed and much higher internal resistance. in the early days of LiPo flying the perceived wisdom was that it was harmful to leave LiPo’s discharged so, I always charged them straight back up when I got home. This was great, I could go flying at a moment’s notice, AND NOT ONE SINGLE BATTERY LASTED MORE THAN TWO YEARS, and it was always winter that killed them. Fully charged and very cold or very hot is a very bad combination, very cold and storage charge is ideal. Bearing in mind a 6S 5000mAh was over £200 then it was pretty awful. These days, I’ve got a lot of batteries, so most only get around 50 cycles a year, I always bring them up or down to storage charge within a day of flying and I’m still using batteries purchased in 2012. note: Lithium Iron (LiFePO4) batteries do have a higher self discharge. Those should be checked every couple of months or so in storage. Edited By Keith England 1 on 26/03/2020 13:12:24 Edited By Keith England 1 on 26/03/2020 13:12:46 Edited By Keith England 1 on 26/03/2020 13:18:49 Quote Link to comment Share on other sites More sharing options...
John Lee Posted March 26, 2020 Share Posted March 26, 2020 Finished doing mine yesterday with a ISDT discharger. Don't forget to bring your Transmitters down also if they have Lithium batteries. Quote Link to comment Share on other sites More sharing options...
MattyB Posted March 26, 2020 Share Posted March 26, 2020 Posted by Jeffrey Cottrell 2 on 26/03/2020 10:28:46: Hi Guys Saw a video on YT recommending that, during this period of enforced abstinence, LiPo's should be stored at storage charge (3.8v/cell). Lots of good reasons for doing this, but I have an issue. One of my LiPo's has been on my discharger for some 6 hours now and is still showing over 4v/cell. Last count I had some 14 packs needing to be stored. At that rate, by the time I have them all at storage it will be time to get back to flying. If you are going to be discharging large packs the average charger will tak a long time - many can't discharge at any more than 20-30W. That means you either need to discharge in the model (tethered of course), buy a unit like that above or fashion your own discharge rig. I have done the latter using commercial units I found via RCGroups, lots of info in another thread I remember posting too - two secs... Quote Link to comment Share on other sites More sharing options...
MattyB Posted March 26, 2020 Share Posted March 26, 2020 Here you go - the cheap dischargers are available from here, and there is an RCGroups thread on how to connect them up in parallel to create larger discharger. If you buy all the stuff online it is only an evening or twos work of soldering and cutting the wood and you have a nice little rig. Edited By MattyB on 26/03/2020 14:34:57 Quote Link to comment Share on other sites More sharing options...
Richard Acland Posted March 26, 2020 Share Posted March 26, 2020 Posted by Jeffrey Cottrell 2 on 26/03/2020 10:28:46: Hi Guys Saw a video on YT recommending that, during this period of enforced abstinence, LiPo's should be stored at storage charge (3.8v/cell). Lots of good reasons for doing this, but I have an issue. One of my LiPo's has been on my discharger for some 6 hours now and is still showing over 4v/cell. Last count I had some 14 packs needing to be stored. At that rate, by the time I have them all at storage it will be time to get back to flying. So, what's the general thinking ? Worth doing? Cheers Jeff I bought a gizmo from Powerbox called Battlife guard. when connected to your Lipo it discharges to storage voltage. they have two types . One for 3s and one for 2s Quote Link to comment Share on other sites More sharing options...
Martin McIntosh Posted March 26, 2020 Share Posted March 26, 2020 I had some of those under the Kokam brand. They discharged to zero and made the packs scrap. Quote Link to comment Share on other sites More sharing options...
Mark H75 Posted March 26, 2020 Share Posted March 26, 2020 Posted by MattyB on 26/03/2020 14:34:05: Here you go - the cheap dischargers are available from here, and there is an RCGroups thread on how to connect them up in parallel to create larger discharger. If you buy all the stuff online it is only an evening or twos work of soldering and cutting the wood and you have a nice little rig. Edited By MattyB on 26/03/2020 14:34:57 I have several of these as they're cheap and they make short work of discharging lipos **LINK** Quote Link to comment Share on other sites More sharing options...
Martin McIntosh Posted March 26, 2020 Share Posted March 26, 2020 I just don`t get this discharger thing. Do they take them down to a preset level? You would then have to stand over a charger until they reached 3.8V/cell. Why not simply get a RC6S or similar from Overlander? Quote Link to comment Share on other sites More sharing options...
MattyB Posted March 26, 2020 Share Posted March 26, 2020 Posted by Martin McIntosh on 26/03/2020 19:34:58: I just don`t get this discharger thing. Do they take them down to a preset level? You would then have to stand over a charger until they reached 3.8V/cell. Why not simply get a RC6S or similar from Overlander? Yes, you can define the exact cell voltage you want and it will discharge all cells to that level, balancing the pack as it goes. This is superior to using your charger as a) you can discharge far faster (the RC6S you referenced can only dissipate 5W, nowhere near enough unless you only have tiny packs; my discharge rig can do ~350W) and b) discharging heats up your charger as it dissipates the energy, potentially shortening it’s life over a large number of cycles. Edited By MattyB on 26/03/2020 20:28:58 Quote Link to comment Share on other sites More sharing options...
Attilio Rausse Posted March 26, 2020 Share Posted March 26, 2020 Posted by MattyB on 26/03/2020 19:50:34: Posted by Martin McIntosh on 26/03/2020 19:34:58: I just don`t get this discharger thing. Do they take them down to a preset level? You would then have to stand over a charger until they reached 3.8V/cell. Why not simply get a RC6S or similar from Overlander? Yes, you can define the exact cell voltage you want and it will discharge all cells to that level, balancing the pack as it goes. This is superior to using your charger as a) you can discharge far faster (the RC6S you referenced can only dissipate 5W, nowhere near enough unless you only have tiny packs) and b) discharging heats up your charger as it dissipates the energy, potentially shortening it’s life over a large number of cycles. You can also use a parallel charging board with this discharger. Quote Link to comment Share on other sites More sharing options...
MattyB Posted March 26, 2020 Share Posted March 26, 2020 Yes, I can discharge 3x 6S 5000s to storage in 20 mins if needed. Try doing that on any commercially available charger! Quote Link to comment Share on other sites More sharing options...
Jeffrey Cottrell 2 Posted March 27, 2020 Author Share Posted March 27, 2020 Hi Guys Thanks for your ideas and suggestions. Got a discharger on order from RCmart but I doubt that'll arrive anytime soon, so meanwhile have to see what I can invent. Let battle commence! Jeff Quote Link to comment Share on other sites More sharing options...
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