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MtnDon
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# Posted: 5 Nov 2013 10:30pm - Edited by: MtnDon
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This article reinforces my opinion that batteries, be they flooded lead acid, sealed maintenance free or AGM, should never be stored/used in an indoor habitable space. Never. This article is about VRLA or valve regulated lead acid batteries which are what AGM and other sealed lead acid batteries are. Theoretically they are "safe" in an indoor environment. Theoretically.
Thermal runaway occurs when more heat is generated within the battery than can be dissipated through its case. Heat is generated internally by exothermic chemical reactions from excessive charge current pumped into the battery. This heat generation increases as the applied voltage and/or the battery's internal temperature increases. Power – in the form of heat transfer – is dissipated from the battery through its exterior case into the ambient environment. If the battery cannot reject as much heat as it generates, its internal temperature rises. As the battery's temperature rises, its internal power rises. This self-feeding mechanism can go out of control if the rate of increase of generated heat is greater than the rate of increase of dissipated heat. This heat/current cycle eventually causes the battery to bulge. .... more in article....
original source: sbsbattery
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silverwaterlady
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# Posted: 5 Nov 2013 11:31pm
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Does this mean if you have one battery in storage in your basement not on a trickle charger you are in danger?
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MtnDon
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# Posted: 5 Nov 2013 11:41pm
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The "not on a charger" makes it safe from the runaway issue. That only can happy with a charging input that goes awry.
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creeky
Member
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# Posted: 6 Nov 2013 08:38am
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another reason to hook up the temperature sensor on your solar charger.
but before anyone worries:
note that thermal runaway only occurred at very high ambient temperatures (40 degrees). With high voltage charge inputs (30v into a 24v battery). Over long periods of time (30 hours plus). So. If your charger is defective and has a power source other than the sun ...
For average users though, there is no real concern. 40 degrees is quite a bit hotter than your battery in the basement will ever get silverwaterlady. trickle charger attached or no.
note that you can ameliorate the possibility of this condition by leaving a space between your batteries and ensuring adequate air movement. so. don't pack your batteries tightly together in a sealed box and then leave them in the sun with a high voltage charge input for a really really really long duration.
also note that the thermal runaway was on a very specific type of battery. ie. vrla as noted above
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Truecabin
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# Posted: 6 Nov 2013 11:10pm
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first time i ever heard of it
thx for the note i'll pay attention but dont think i will change anything
hope this doesnt get into the code book
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