Another Battery Fire in AT&T's Network

An anonymous reader writes "AT&T has disclosed another fire started by one of the 17,000 Avestor batteries in its broadband network. The first fire caused a violent explosion in suburban Houston. This second incident occurred just 20 miles away."

Re:Wow

[gratemyl]

Don't be silly - nobody would make an unreasonable conclusion that this was a terrorist attack - after all, everybody knows that Al Qaeda planned this attack so carefully that nobody would notice.

Re:Why that kind of battery?

[zeromorph]

You have to distinguish between two types of lead-acid batteries and then the whole thing is not that optimal anymore.

With wet-cell lead-acid batteries [wikipedia.org] you'll get evaporation and resulting loss of capacity. Beside that you have a precipitation of lead(II) sulfate that can ultimately kill your battery.

With maintenance-free (sealed) batteries like Valve Regulated Lead Acid batteries you do not get these problems but you could get thermal runaway [hanford.gov] and they do explode. Gel-batteries [wikipedia.org] are less inclined to explode but especially older ones do that too.

On the other hand lithium metal polymer are said to [allaboutbatteries.com] "have service lives as long as 10 years, under ambient temperatures from -40C to +65C."

Re:Why that kind of battery?

[Anonymous Coward]

The lead-acid batteries I'm familiar with are large, have clear cases, lots of room below the plates and probably quite wide spacing between the plates. Banks of them fill large rooms. They are one of the reasons that POTS (plain old telephone service) works even when the power goes out everywhere else. They are also the reason why air traffic control towers continue to work even if the diesel generator doesn't start quickly. All of the problems you mention don't affect them.

Having said the above, even regular car batteries last a very long time in backup service. There's not a lot of current happening so they don't have much of a problem with sulphation. You do have to check the water level every x months. My former employer had a lot of remote equipment and used heavy duty car batteries for backup. In the ten years I spent with them, I don't remember having to replace even a single battery.

The one thing I do remember having to address was acid vapor. The batteries were never in the same space as the equipment.