Battery Thermal Runaway

[MountainDon]

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 
Document may also be downloaded/read from stored document link below

[DaveOrr]

I have had lots of computer UPS batteries swell so much that I need to pry them out of the case.
Have had them split and crack too.

Up here in the land North of 60 we keep our batteries in doors.
You don't get much power out of them in the heart of winter otherwise.
We even have battery warmers on our vehicles. I think mine is something like 90 watts @ 110V.

When out at the cabin in the dead of winter you have to haul the generator down to the truck to plug it in for an hour or so unless you have a remote starter that you can program to run a cycle every 4 hours or so. If you leave it over night the vehicle won't start once the temp drops into the -30's. 

[MountainDon]

As a former born, raised and lived for 30 year Manitoban I am all too well versed in the trials and tribulations of motor vehicles and winter weather. I did pride myself on the ability of my old 4 cylinder Volvo B18's to start at -40 w/o being plugged in. Not the diesel truck though.      Mobil 1 was a good winter friend.   I do not miss living through those winters though. Now I complain when it gets to 0 F.     But I still use Mobil 1.

[DaveOrr]

Mobil 1 in my rigs too.   

[hpinson]

Not seeing a link to the original article, what is the worst case result - fire? fumes? Case failure?

[MountainDon]

original source: sbsbattery 

[OlJarhead]

In Telecom all of our batteries inside and have been for decades. 

However, those banks are engineered and while failures occurr they are rare.  We need to replace a bank that had this very thing happen to it and the resultant spill has to be cleaned up.

I've also heard of CO battery banks exploading, but again very rare.

Having said all that my batteries are on my porch and will remain there until I can get them either into the new room where I can keep them a bove 50 degrees or somewhere else I can prevent them from freezing.