I read about how great the AGM batteries are on this board and no one ever seems to have a problem with AGM battries but me.
I am still working on my battery compartment where one vented taking out the other 5.
I have found out they do have problems sometime with the AZ heat and charging, I saw another RV that had one vent SAT at the RV dealer. ...
Clifford (and all):
I did not include this in the article, and in hindsight perhaps I should have, but it is unequivocal that one potential drawback to VRLA batteries (that includes both AGM and gel) is the possibility of a condition known as "thermal runaway." When a VRLA battery undergoes thermal runaway, it basically explodes, and I would guess this is what happened in your case.
The most common root cause of thermal runaway is excessive charge voltage/current under high heat conditions. This is one reason why it is recommended that you have a temperature-compensated charger, with a temperature sensor properly positioned on the batteries. Also, battery compartments for VRLA batteries should be temperature-controlled; whereas flooded batteries should always be outside the personnel space for gassing safety, VRLA batteries are often better off inside the personnel space to take advantage of the climate control.
Constant float is another factor that can "prime" a VRLA battery for a thermal runaway. Studies have been done on this:http://www.springerlink.com/content/v337108736332440/http://telephonyonline.com/wireless/mag/wireless_thermal_runaway/
This should be a consideration for anyone who spends a lot of time connected to a power outlet, where the batteries are on constant float (as opposed to away from power, where the batteries are regularly cycled).
I advise anyone, whether they have VRLAs or not, to disconnect the main battery charger when storing their coach, and, instead let the batteries cycle down, then top them up every couple of weeks to a month. Constant float is generally not good for batteries; in applications such as telecom where it is unavoidable, the batteries are watched religiously, and have different construction to tolerate this service (I do not recommend telecom batteries for bus conversions for this reason).
must have been a few years since you were in a central office.
A few, but not many, and I am still well connected.
now all are computer run with standby battery for the processor.
At the risk of derailing this thread, the most common class-5 offices (for the lay folks, those are the telephone switches at the end of your home phone line) are the Lucent #5ESS (a product on which I worked when I was at the labs), the Northern DMS-100, and the GTE GTD-5 EAX. All three of those switches, while "computer" controlled (we called them "processors"), are 48 VDC battery powered. Remote modules for those systems, which comprise now the majority of rural end offices, are also 48 vdc powered, including the computer controls.
The 5ESS, BTW, is controlled by a computer that AT&T briefly tried to sell as a stand-alone general purpose computer, the 3B20D (redundant duplex model; 3B20S was the simplex version). We had to create 208-vac power supplies for them for this purpose -- the 3B20 is a 48-vdc system. Now that's 25+ years ago, but most of those switches are still in service, and the 5E's made today are still based on a 3B processor.
A 1,000 port non-blocking switch runs off a 200watt power supply.
Sure. And in a "real" certificated carrier's facility, it will be a 48VDC supply.
Even modern "Internet" switching hardware, such as ATM switches and gigabit ethernet devices are available with 48-vdc supplies for installation in carrier facilities. When I was still working, deploying major network infrastructure nationwide for DSL networks, we ordered all our Cisco equipment with 48-vdc supplies.
You can, and some do, buy modern digital POTS switches with 120-vac supplies. But generally speaking, you don't find them in major carrier class-5 offices of, say, 20,000 lines or more.