Batteries the Focus of AT&T Investigation

An anonymous reader writes "AT&T is focusing on the batteries supplied by Avestor as the cause of its 2006 equipment explosion in a suburban Houston neighborhood. The carrier says it has 17,000 of those same batteries still in its network. Some photos of the equipment that was shredded in the blast are also available."

Comments

The real reason for the explosion?

[Lost Penguin]

All that NSA snooping equipment was designed to self destruct if proof was recorded that the Neocons were behind 9-11.....

Sounds alot like

[JamesRose]

"It's 1 year later, and we still don't have a clue waht the hell is going wrong, it could happen again any time, so what we're going to do is blame a relatively cheap component manufactured by a third party and replace it.

Re:Sounds alot like

[Firethorn]

My thought would be: What else in the cabinet could cause such an explosion? I mean, the equipment should be fused; there should be enough circuit breakers and fuses in the lines to prevent electricity from creating such a large bang; so a short or capacitor shouldn't do it. Properly constructed circuit boards aren't even all that flammable, much less explosive enough to destroy a cabinet.

What's the most reactive chemical area around? The battery. It's a lithium type - and warns that it could catch fire/explode if damaged.

It's certainly not a 'cheap component' - it's stated to be more expensive than other battery types.

Awesome case mod !

[Anonymous Coward]

See...
http://www.lightreading.com/document.asp?doc_id=13 1210&page_number=1&image_number=8&site=

for a totally over-the-top case mod. It's Unreal meets Terminator.

Hydrogen + Spark = Bad

[effigiate]

I'm not sure what types of batteries they were using, but standard lead-acid batteries vent hydrogen during charging. If you don't make provisions for the removal of it and it builds up in the cabinet, one tiny spark and you've got yourself a little bomb sitting there.

Re:Hydrogen + Spark = Bad

[Anonymous McCartneyf]

And the phone lines are near the power lines, so lots of opportunities for little sparks...
But I hear that the batteries in question are li-poly. I don't think they vent hydrogen; they just appear to have unfortunate internal similarities to C4 explosive when they're made wrong.

Re:Hydrogen + Spark = Bad

[NoMaster]

Not so much of the "little sparks"; yes there are relays still inside that sort of gear, but they're reed relays with the contacts sealed in a nitrogen atmosphere.

What you do find, however, is cct breakers and contactors on the main power feed & internal distribution. But the usual explosive trigger is the sparks from the cells themselves as they self-destruct...

We used to get 1 or 2 incidents like this a year in Aus, mostly in the far north. The SLA batteries used here don't take kindly to temps above ~ 35C (easily found inside cabinets even in colder areas) - battery life is dramatically reduced, and the usual failure mode is thermal runaway causing internal shorts &/or case splitting. The end result was usually just acid vapour destroying everything inside the cabinet. Occasionally, as I said, we'd get one that went boom.

It certainly wasn't unusual for the batteries to to from "visually OK, passes all discharge / internal impedance test" to "case on the verge of rupture" in as little as 1 month. We usually checked them every 3 months, and that was considered by both the manufacturers and my superiors as "excessive".

Having said that, what freakin' idiot decided Li-Pol cells were a good idea in that sort of environment! The things are barely stable at room temperature, requiring very careful feeding and care of charge / discharge rates even then (which is why every single consumer-use Li-Ion/Pol battery sold has a charge controller & thermal monitor cct built-in to the battery itself). Essentially, from a non-technical POV, Li-Ion & Li-Pol cells are little containers of metallic fire that will self-destruct at the slightest provocation. I certainly can't imagine any really safe way of using them in a online / continuous float application like that...

(Ex-telco senior switching, CAN, and battery maintenance tech.)

Re:China: Possible Source of Problem

[DaleGlass]

That'd be very unsurprising, but not terribly enlightening.

I don't remember ever seeing a product "Made in America". Nearly everything comes from China these days, including the vast majority of the things sold under american brands.

Re:China: Possible Source of Problem

[ScrewMaster]

No kidding ... for several months while I had AT&T Broadband for cable service I never could get a decent picture. Internet speeds were nothing to write home about either. Techs came out a number of times (usually contractor types, not AT&T-trained) and one of them put in an amplifier. Which worked just fine at amplifying the noise (and he stuck $90 on my bill.)

Finally I called to cancel my service because I wasn't getting that for which I was paying. The operator convinced me to give them one more try ... I said OK. Next day (a Sunday, believe it or not) this cherrypicker truck pulls up, with AT&T emblazoned on the side. This time I got a technician that had been through AT&T's in-house training program and wasn't afraid to get off his ass and climb a few poles. So he spent about three hours going down the street, pole-by-pole, until he called down and said "Whoops! Here's your problem" and tossed down a few feet of burned and blackened cable with squirrel toothmarks all over it, right down to the bare copper. It was a mess. So he replaced the cable for the whole block and we all got a great picture (and I got my 4 mbits/sec back.) Guy was pretty cool, really knew his stuff. It was like dealing with the AT&T of old. He also took the price of that stupid wideband amp off my bill -and- let me keep it! So I kept my service for a few more years until I moved.

I never found any squirrel bones, but I hope the 90 VDC feed cooked the little bastard.

Batteries.

[Al Young]

It's quite amazing that we still have problems manufacturing 'safe' batteries.

Anyone else remember the issues with Toshiba/Sony/Apple laptop batteries?

'Close your eyes and you'll burst into flames'.