Bob Cotsford Posted May 18, 2013 Share Posted May 18, 2013 Last winter I neglected to unplug the two LiFe packs from the regulator/switch in the King Altair, with the result that when I checked the model out at the start of the (reported) spring the two batteries had ballooned. They took a charge but no way was I going to trust them so they were replaced. What to do with two questionable packs? You could just dump them in salty water for a couple of weeks, but where would the fun be in doing that? In the name of scientific research I took them up the garden, placed them on a slab and whacked them with the pointy side of a garden rake. What a disappointment, Even total penetration of both cells by two tines just resulted in some vigorous gassing, no flames, no clouds of smoke - pretty unimpressive all in all. They are now resident in a bucket of salt water and I feel even happier about charging them in situ. Remember this was with small 1100 mAHr LiFe packs, not LiPo which are downright nasty when punctured/over charged/over discharged! Edited By Bob Cotsford on 18/05/2013 14:50:13 Quote Link to comment Share on other sites More sharing options...
Pete B Posted May 18, 2013 Share Posted May 18, 2013 Let's hope the neighbours weren't watching, Bob - would've confirmed what they already suspect, I suppose..... Great to see you advancing the cause of science, though! Pete Quote Link to comment Share on other sites More sharing options...
Bob Cotsford Posted May 18, 2013 Author Share Posted May 18, 2013 hey, someone has to provide the cabaret! Quote Link to comment Share on other sites More sharing options...
crispin church Posted May 18, 2013 Share Posted May 18, 2013 should of charged them use for bench testing ? Quote Link to comment Share on other sites More sharing options...
Bob Cotsford Posted May 18, 2013 Author Share Posted May 18, 2013 bit late I'm afraid Crispin. I have a few old nimh packs or a variable power supply I use for setup and I did think this research was sorely needed. Quote Link to comment Share on other sites More sharing options...
Erfolg Posted May 18, 2013 Share Posted May 18, 2013 I do not think there are many if any batteries that can be subject to physical abuse which results in the casing being breached without the creation of a hazard in some form. Be it dilute sulphuric acid in addition to lead in the case of a car battery. I personally think that the environmental hazards of Lipo batteries are over stated by the modelling community compared for example to Nicads. Quote Link to comment Share on other sites More sharing options...
Bob Cotsford Posted May 19, 2013 Author Share Posted May 19, 2013 Erfolg, my understanding was that lithium is less toxic than nickel but that's only really relevant when it comes to disposing of batteries - they all need to go for recycling anyway. The problem with LiPo batteries is the dramatic consequence of abuse. Metal canned batteries are inherently more robust, whether Nixx or A123, but soft cell LiPo packs can be provoked into generating large volumes of oxygen very easily, and when the pressure bursts the soft package you have an incendiary bomb. I was really surprised the LiFe didn't burst into flames in the same way as LiPo would, but I have to admit I did once charge a LiFe soft cell pack as LiPo and was alerted by the smell of frying plastic. It got ripped out of the model toot sweets and lobbed up the garden where it just sat there all innocent until it cooled down. I don't think I'd have got away with massive overcharging if it had been LiPo. Not to say that Nixx are totally safe, they will explode with sufficient provocation but they don't generate the flammable gasses that make LiPo fires so dramatic. Quote Link to comment Share on other sites More sharing options...
Erfolg Posted May 19, 2013 Share Posted May 19, 2013 Bob In some respect the soft shell of a Lipo can be safer than an exploding car battery if a naked light is put to it whilst gassing/charging, such some have done when looking into cells. I expect a bag to burst, not to fragment into hard shards which could be hazardous if projected from an explosion. There have similar impressive pictures of exploding Nicad packs, notwithstanding the residual toxic material distributed about. You could well be correct in that fire can be a hazard with lipo cells. I do not know. Yet it just seems a particular hazard that is pertinent to the battery type. Again other battery types have there issue. Yet with issue of fires, I have seen lipo packs that have been breached, without fire. I have seen fires with model aircraft due to fire where high current draw, or a short of some type has lead to fa fire. I am interested how the molecular oxygen can be induced to break from the molecular structures and how much there really is in a typical Lipo pack. As this would give some measure of understanding the scale of the issue. It was not long ago, that modellers talked about Lipos, that the slightest mishandling would lead to the formation of a black hole in the universe. Quote Link to comment Share on other sites More sharing options...
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