valve regulated lead acid batt question

[Brett Dikeman]

Any battery experts out there?

I've got a Valve regulated lead acid battery(ie, looks like a gel
cell) that I'm trying to charge.  I've got it on a 1.5A slow charger,
and it's a 20AH battery- going by the 20% rule for regular lead-acid
batteries, that's a max current of 4A- well under the 1.4-1.5A it's
currently taking.

However, as the battery approached 13.3V, I started hearing very
quiet(ie, gotta be within a foot of the battery to hear it) slightly
bubbling/gurgling noises.  It's currently at 14v- I think it's
entered its absorbtion phase- and the noises are more frequent.  The
battery is rated between 14.5 and 14.9v peak voltage, 13.3-13.8
constant-standby(ie, the float voltage.)  There has been no
noticeable rise in the temperature of the battery, probably at most
60 degrees.

Valve regulated/AGM batteries, from what I understand, use some
interesting chemistry to reconvert the hydrogen+oxygen the battery
gasses out back to water again- but there's a valve that opens "in
the event of charger system failure", and there's no mention of how
much gassing is too much for the battery to handle reconverting back
to water.

All the numbers point to me safely charging the battery, but the
noises make me nervous(I'd rather there was no gassing, especially
with a sealed battery), and the famous Lead Acid Battery FAQ is
rather silent about VRLA's, AGM's, etc- except to say that they
really don't like getting hot and can go into thermal runaway above
110-120 degrees("Cap'tain, she canna take much morea this!")-
certainly not a problem in this case.

B
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