Chris Walby Posted September 24, 2022 Share Posted September 24, 2022 Noticed on another thread some comments regarding lipo care/storage charge etc and it reminded of an occasion when I purchased an E-flite Carbon Yak and three 4S3300 (E-flite) lipos as I didn't have any that size. When I got home and checked the individual cell voltages, they were very different within packs and between packs. Balanced charged, and discharged to storage and two of the three lipos did not improve. Contacted retailer and replaced FOC although I needed to do a 40 mile round trip so not best please and never used said supplier again. The questions to the forum is how do you knacker a lipo in storage or in use? Must admit I re-maiden a edf model with the timer set for 4 minutes, clubmate commented he heard the fans back off on a downwind pass so I landed immediately, 3min 10sec on the timer and 6% in the lipo...that lipo was never the after that.. How long can you store a lipo...clearly not indefinitely as my E-flite died on the warehouse shelf? What do people discharge their packs to (% or voltage) on a regular basis e.g. general target Lastly, these lipo things are a con are they not.... If I buy a gallon of glow fuel then I get to use the entire contents, but with a lipo that's not the case. I buy a 4S3300 then I can never use the full 3300mAh without fear of fire or unrecoverable damage to the battery. So the optimum I can get is 2475mAh on every flight and thus I am being short-changed every flight by 25%. Is there anywhere else on this planet where you buy something of a certain size or weight, but never get to use all of it should you want to? Should the pack not be advertised as a 4S2475 mAh pack with the guidance that the voltage should not the discharged beyond x voltage, so that you actually get what you are paying for? Quote Link to comment Share on other sites More sharing options...
John Lee Posted September 24, 2022 Share Posted September 24, 2022 (edited) That is a discrepancy the car industry seems to be struggling with. The quoted size of the batteries installed in electric cars are increasingly being quoted as 'gross' & 'net' with the 'net' being the useable after the safeguarding circuitry puts a buffer on the 'gross', but it is not fully adopted as yet. Edited September 24, 2022 by John Lee Quote Link to comment Share on other sites More sharing options...
Don Fry Posted September 24, 2022 Share Posted September 24, 2022 Perhaps a little more accurately John, the car industry are increasingly getting into trouble with the advertising standards people over the porkies they claim. There are not too many brutally honest suppliers of anything. Successful purveyors of emperors new clothes are generally more successful, pushing the boundaries of the law. Legislators are lacking imagination. I reckon a sentence, solitary, comfortable space, television on a loop of the offending advert, start out at 24 hours just in case longer is defined as torture. No off switch. Quote Link to comment Share on other sites More sharing options...
Simon Chaddock Posted September 24, 2022 Share Posted September 24, 2022 Exactly! LiPo suffer from "marketing hype". What you can effectively use is what you get, not what it says on the packet. Some LiPo, even of the same brand, are better than others but you can only find out which by "sick it and see" at your own expense. Perhaps the best solution is to treat LiPo like an ESC and leave a 30% "headroom" on claimed capacity and even more (50%?) on their C rating.😲 Quote Link to comment Share on other sites More sharing options...
PatMc Posted September 24, 2022 Share Posted September 24, 2022 6 hours ago, John Lee said: That is a discrepancy the car industry seems to be struggling with. The quoted size of the batteries installed in electric cars are increasingly being quoted as 'gross' & 'net' with the 'net' being the useable after the safeguarding circuitry puts a buffer on the 'gross', but it is not fully adopted as yet. The quoted & actual mpg of ic powered cars is analogous to electric car battery quoted & actual capacity. Quote Link to comment Share on other sites More sharing options...
PatMc Posted September 24, 2022 Share Posted September 24, 2022 (edited) 8 hours ago, Chris Walby said: Lastly, these lipo things are a con are they not.... If I buy a gallon of glow fuel then I get to use the entire contents, but with a lipo that's not the case. I buy a 4S3300 then I can never use the full 3300mAh without fear of fire or unrecoverable damage to the battery. So the optimum I can get is 2475mAh on every flight and thus I am being short-changed every flight by 25%. Is there anywhere else on this planet where you buy something of a certain size or weight, but never get to use all of it should you want to? Should the pack not be advertised as a 4S2475 mAh pack with the guidance that the voltage should not the discharged beyond x voltage, so that you actually get what you are paying for? You're not making a like for like comparison. A gallon of glow fuel is source of a percentage of potential energy + a percentage of total loss lubricant. Most ic flyers waste a fair percentage of fuel in starting & running their engine when it isn't moving. So whilst you are getting the full gallon of "what it says on the tin" that you paid for, in reality you're not getting a gallon of flying time energy. A fully charged lipo battery may be capable of supplying the stated capacity but not necessarily at the current level we use. But when it is used at our required output level the used energy is replaced by a usually appreciably smaller amount than the battery's stated total capacity. Edited September 24, 2022 by PatMc Quote Link to comment Share on other sites More sharing options...
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