flyeruk Posted November 20, 2012 Share Posted November 20, 2012 I am now starting to fly electric edfs most weekends. I have got 8 lipos at the moment and only a single charger.Because i work all week,the only time i get to charge them is in the evenings.I do intend to get a better charger or should i say, a charger that can charge 4 batteries at the same time. In the mean time,is it okay to charge the batteries a week ahead so they are ready for the following week or not? Quote Link to comment Share on other sites More sharing options...
Paul Travis Posted November 20, 2012 Share Posted November 20, 2012 I do without a problem Quote Link to comment Share on other sites More sharing options...
Martin Harris - Moderator Posted November 20, 2012 Share Posted November 20, 2012 The experts say not to leave them fully charged for any length of time but I have abused LiPos for a few years now, leaving them charged or discharged for weeks at a time depending on what I've been flying and haven't noticed mine suffering unduly. Edited By Martin Harris on 20/11/2012 21:26:27 Quote Link to comment Share on other sites More sharing options...
Biggles' Elder Brother - Moderator Posted November 20, 2012 Share Posted November 20, 2012 In my experience its OK. I know that Lipos have a "storage" setting - but I feel that you only really need that if you are putting them away longer term, for a couple of weeks or more. One week, or even part of a week if you charge mid-week like I do sometimes, shouldn't be a problem I wouldn't think. Yes, the purists will tell you that you'll get some deterioration over the lifetime of the battery caused by this - and they may very well be right. But I've been doing it for 2 years now and haven't noticed any! BEB Quote Link to comment Share on other sites More sharing options...
flyeruk Posted November 20, 2012 Author Share Posted November 20, 2012 Thanks for the very fast replies. I have read different theories about doing this,but thought that a week or so would be okay. Quote Link to comment Share on other sites More sharing options...
Tim Hooper Posted November 20, 2012 Share Posted November 20, 2012 I keep my li-pos fully charged when not in use. I'm not sure on the stats, but I've intention of changing my regime. tim Quote Link to comment Share on other sites More sharing options...
Simon Chambers Posted November 20, 2012 Share Posted November 20, 2012 Unless I'm not flying the packs in 2 weeks time or more (i.e. I've broken the plane! ), I always keep my packs charged and ready to go. If you want hard figures on this, have a look through the Sony Lithium Ion Rechargable Batteries Technical Handbook (remember our LiPo cells are a type of Lithium Ion cells - their true name is actually Lithium-Ion Polymer cells. The Polymer part refers to the construction of the cells. It's an interesting read and doesn't get too heavy in the technical detail either (along as you have a basic knowledge of Electronics theory). Interestingly for long term storage to reduce cell degration, they state that 3.3v is preferable to 3.8v per cell. However if your storing it at that low a voltage, you'd need to make sure that it doesn't self discharge below 3v - otherwise you risk damaging the cell that way. Possibly why 3.8v tends to be recommended? Si. Edited By Simon Chambers on 20/11/2012 21:58:12 Quote Link to comment Share on other sites More sharing options...
Mike Rolls Posted November 21, 2012 Share Posted November 21, 2012 I'm another who 'charges and leaves'. To be fair, I have had some protest - one pack by puffing up (this was before cell balancing leads came along) and 3 or 4 who have had a cell die, but as I can only fly infrequently, the convenience of being able to go flying at a moment's notice far outweighs the downside. The batteries are kept in a fireproof safe, so I'm not worried about them getting more aggressive! Mike Quote Link to comment Share on other sites More sharing options...
ken anderson. Posted November 21, 2012 Share Posted November 21, 2012 i charge my lipo's after a trip to the field.....(2200's) ...... have done so for years.....some times flying in the afternoon.......home/charge and back in the evening........never had any prob's.......the thing is to get in to a routine and you'll be ok..... ken anderson .... ne..1 ....lipo dept... Quote Link to comment Share on other sites More sharing options...
Cirrus Posted November 21, 2012 Share Posted November 21, 2012 Personally I never charge in advance. Increases risk of fire and degrades life of pack. If you must do this, then ensure they are left in a constant temp environment and the cooler the better. Fully charged over 30 degrees C will degrade pack badly. Quote Link to comment Share on other sites More sharing options...
Wingman Posted November 21, 2012 Share Posted November 21, 2012 Posted by Simon Chambers on 20/11/2012 21:57:04: If you want hard figures on this, have a look through the Sony Lithium Ion Rechargable Batteries Technical Handbook (remember our LiPo cells are a type of Lithium Ion cells - their true name is actually Lithium-Ion Polymer cells. The Polymer part refers to the construction of the cells. It's an interesting read and doesn't get too heavy in the technical detail either (along as you have a basic knowledge of Electronics theory). Interestingly for long term storage to reduce cell degration, they state that 3.3v is preferable to 3.8v per cell. However if your storing it at that low a voltage, you'd need to make sure that it doesn't self discharge below 3v - otherwise you risk damaging the cell that way. Possibly why 3.8v tends to be recommended? Si. Edited By Simon Chambers on 20/11/2012 21:58:12 Very interesting document, Simon, thanx for that - I've down loaded a copy for future reference. Would be good to have a copy in the forum electric flight section but I suppose there would be copyright considerations. Quote Link to comment Share on other sites More sharing options...
PatMc Posted November 21, 2012 Share Posted November 21, 2012 I always charge mine ASAP at home after a flying session. The only time I discharge some of them to storage level is mid winter until they are next likely to be used. I store them in the garage in a couple of Pyrex type casserole dishes bought from Aldi or Lidl. Quote Link to comment Share on other sites More sharing options...
John Cole Posted November 21, 2012 Share Posted November 21, 2012 Simon: the technical data iin the handbook is in 3 sections, each dealing with one type of Li ion rechargeable cell. The first section is specifically about LiPos. See the section title: "2-5-1 Polymer (UP383562) Lithium ion rechargeable batteries with lithium cobalt oxide cathode and graphite anodes" This refers to hard-cased LiPos, not soft-packaged ones like we use, but the chemistry and therefore the characteristics are the same. If you are going to store your LiPos ffully charged or a long time, it's good advice to keep them COLD as this slows down the capacity-reducing process. Don't worry about freezing them. They CAN'T freeze. And yes, Sony recommend storage at 3.3 volts and that's a LONG way above the discharge-voltage that kills them (about 1.0 volts / cell - see section 6.1.2). This manual is the only place where I've seen the "killing" process explained - see section 4.2.2. Quote Link to comment Share on other sites More sharing options...
Reno Racer Posted November 21, 2012 Share Posted November 21, 2012 i generally leave mine stored at about 3.8v per cell, then charge the night before i intend to fly. Only problem is all that charging gets my expectations up, only to be dashed by the weather the following morning! Quote Link to comment Share on other sites More sharing options...
Former Member Posted November 21, 2012 Share Posted November 21, 2012 [This posting has been removed] Quote Link to comment Share on other sites More sharing options...
flyeruk Posted November 21, 2012 Author Share Posted November 21, 2012 Again,thanks for all the advice.I will carry on charging when i get back from flying. Saves worrying about charging at the last moment. Edited By flyeruk on 21/11/2012 19:54:26 Quote Link to comment Share on other sites More sharing options...
Tony Smith 7 Posted December 20, 2012 Share Posted December 20, 2012 I seem to remember that the problem arises if there's a change in temperature during storage after fully charging them, but I can remember which direction - I think it was bad if you fully charge at low temperature, then store at a higher temp. Quote Link to comment Share on other sites More sharing options...
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