[Miata] Battery Mythology

[John Freas]

Previously on Battery Mythology, Jim T <entropycat at verizon.net> said...

   I have noted several threads over the past year or two concerning what I
> can only term "battery mythology".   I suppose that I will have to shove
> my
> oar in and try to shed a little scientific light on the subject...


Thanks for the extremely detailed explanation Jim.  I've archived it for
future reference.

Now, my issue is that despite the logic of the explanation given, empirical
evidence has shown that the AGM batteries we use in Miatæ appear to require
the 2Amp/24Hr charge in order to recover from depletion.  I'm wondering why
that is since the science indicates that it should not be so.  It is likely
that in most cases where a Panasonic/Westco, etc. is in need of a charge, it
has been depleted below 10.8 volts, would the amount or type of damage from
discharge to these batteries be sufficiently different from a standard wet
cell that it would cause them to fail completely after one occurrence?  That
wouldn't explain a battery that is deeply discharged, heats but does not
gain a useful charge at a normal charge rate but recovers sufficiently to
function reliably after a 2/24 charge.  This has been seen to happen.  Might
the AGM sulfate differently and that cause it to behave differently?

I'd really like to understand the reason for the difference between theory
and reality in this case since I've given up on the AGM batteries due to the
nuisance of having to slow charge them when they get low, and having to do
so repeatedly as they age.

    -John
------------------------------
John Freas <%20john7690 at comcast.net>
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