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Lead Acid Battery BLAM!

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JeffVolp:
While this isn't X10 related, I wanted to share this to alert others to use caution around lead acid batteries.

Some of you may know that we have a large UPS that powers a 15A "electronics circuit" in our home.  That circuit is isolated by a big 20A X10 filter, and it powers our computers and most other potential noise generators and signal suckers.  The UPS uses a bank of four large deep-cycle marine lead-acid batteries to carry a typical load for several hours.

Recently the UPS started giving an intermittent a low battery warning.  The electrolyte level in all batteries was fine.  Voltage measurements uncovered no shorted cells, so I was not sure what the problem could be.  I transferred that circuit back to utility power to bypass the UPS, and started to unplug the UPS to investigate the problem further.  As I unplugged the UPS, one of the batteries went BLAM, bounced both caps off the ceiling, and sprayed electrolyte from one cell that had cracked open.

Unplugging the UPS (the outlet is about 6 feet away from the battery) caused the UPS to switch on, and at that instant the battery blew.  Obviously, hydrogen gas in the battery had exploded, but I still don't understand why.  The vent caps were on all batteries.  They were not undergoing any fast charge at that point that might produce hydrogen.  My only guess is that particular cell was failing, and perhaps a spark was generated internally when the UPS switched on..

I since have replaced that one battery, and there have been no low battery warnings since then.  So clearly something was going wrong with that battery.

I had read warnings about being careful attaching jumper cables to a battery to avoid sparks near the battery to avoid a possible explosion.  In this case there was no spark near the battery, just a sudden increase in current draw.  It is just something to consider when working around lead acid batteries in the future.

Jeff

Brian H:
I had one blow up in one of my cars.
Was a supposed to be maintenance free type. Though it had a way to access the top of the cells.
Well it was low on electrolyte.
When I tied to start the car. A big BANG.  My thoughts a spark inside a cell ignited the hydrogen gasses.
Top and one side was split.
Car want dead as there was no +12 volts.
Electrolyte sprayed all over the inside of the hood.
Car paint is not made to have electrolyte on it. The paint on the inside of the hood came off. Cleaned it off before the primer was also gone.

Auto parts store indicated they had seen many exploded car batteries and my experience was not rare.  B:(

dave w:
Dang!
I think I will be sure to don safety googles anytime I need to touch a car battery.

JeffVolp:
I was sitting at the computer answering email during lunch yesterday, and heard a terrific crash.  I thought maybe one of the ceiling fixtures fell, but no.  Then I checked the pantry, but I couldn't find anything that had fallen there.  When I returned to the computer I found it was finishing booting up.  Ah ha...  So I headed downstairs and found the top of another lead acid battery had blown off, and acid was spreading across the floor.  After a quick run to the local grocery store for a big box of baking soda, I spent much of the afternoon cleaning up the mess.

Except for the cells that drained, the three good cells still had water covering the plates, so the water level wasn't low.  The battery was over 4 years old - dated 3/14 - but another one is dated 6/13.  The three good batteries read about 13.3V, and even the one blown apart still reads 12.6V.  So all were fine before the blast.  (In the past I had to replace batteries when a cell shorted.)

The UPS does an automatic self-test every two weeks to check battery capacity.  When it does that it transfers the load over to the battery.  Since power to the computer was interrupted, I suspect that is when the battery blew.

Jeff

Brian H:
I got an indication on my APC a few days ago.
Self test passed. I noticed the LCD battery level display dropped to about 3/4 as soon as the test was run. Powering about 200 Watts of the rated 600 watts. Put a 400 watt bulb load on it and unplugged it. Battery level dropped to the about to shut down warning in maybe a minute. New one is here just warming back up from being outside.
Mine is a sealed lead acid battery with no filler type caps.

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