Charon said, ".... The charging current causes the water to dissociate, that is, break down into its component hydrogen and oxygen. These gases are what escapes. ...."

I can verify this with practical experience.  I had been working on a Fiat that had a starter problem, and needed a tune up.  The battery was pretty new, and had started off fully charged, but during this work session, had been used repeatedly.  When I finally got the thing started, it was being charged a lot,... you could hear the alternator singing.  While the motor was running, I got out the timing light and was about to check the timing when the top of the battery blew off.  The timing light (one of the 110v versions) had gotten too close to the battery that (as Charon would testify) was apparently giving off a lot of hydrogen as a result of the high charging current.  I was a lucky boy that day since I was several feet from the battery when it exploded.  It made quite a bang, and scattered little drops of acid all over the place.

justin_o_guy2 wrote on 11/20/12 at 07:12:18:


Yes, a very lucky lad.

Hydrogen gas is extremely ignitable,.. and apparently there was some sort of an arc inside that timing light.

Maybe this will be on thread.....maybe not.

One day my wife came home and started putting these little plastic pieces into the wall sockets that we weren't using by having and electrial appliance plugged into them.  They were little white plastic pieces with two prongs that went into the plug slots.....and a round white cap.  I asked "What are those for?"....and she told me that "They will save use energy!".  I refrained from laughing......but began to tell her that electricity cannot leak out of a wall plug.....and that they weren't going to do anything.  She responed that they were to keep the cold air from flowing out of the holes in our not so well insulated old house.........seems I was the one that was uninformed.

Update...so far so good.  Only screwed up a little....my charger has both 12A and 2A currents, I figures bigger is better.  A couple of hours later when the battery was bubbling like crazy and pretty dang hot, I learned from the internet that using a 12A current to charge a motorcycle battery is a no-no.  Regardless, the battery does now have a charge and starts the bike, but I guess I won't be surprised if I'm replacing the battery in the near future.

Incidentally, what changed in my life was that I used to live on the Oregon Coast where 95% of my rides were less than 15 minutes in temps less than 55 degrees, and would sometimes go weeks without riding due to the rain.  Now we live in Arizona, where my nearly daily rides are typically at least 30 minutes in warm temperatures and my weekly mileage has increased significantly.  So I understand why I was surprised by my battery suddenly not behaving like it did in the past.  

Perhaps the more frequent, longer rides are contributing to overcharging, I'll check it out as soon as I find someone who sells a fuse for my voltmeter.  Incidentally, what type of voltage should I be reading with the engine running?  14V?

Thanks everyone!