On Sat, Dec 17, 2011 at 11:32:03AM -0800, Carter Quillen wrote:
>
>
> My statement was based on anecdotal evidence, second hand at that and I don't
> know the particulars of the brand of AGM batteries that you have but the story
> from my friend was that he was operating the voltage regulator at 14.4V from
> the alternator on his diesel after switching from lead acid batteries and it
> toasted his brand new AGMs in EXTREMELY short order. The guy where he got the
> battery said it should never be set to charge above 13.5V, it was his fault,
> and wouldn't make good on the batteries so he had some very expensive ballast.
Sounds like a transparent excuse on the part of the guy not wanting to
make good on defective batteries that he sold. AGMs are still lead-acid
batteries; however, they're sealed (valved), so gassing them with
overvoltage would leave holes in the thickened electrolyte that they
use. Gassing, however, does not normally occur until you get to ~15V -
and with 14.6V as a limit, it shouldn't happen at all. 13.5V would only
charge them to 12.3V at rest, or about 40%.
> Perhaps his voltmetering was off or there was some other anomoly in the system.
It could be. Given the "social factor" in the story, though - a salesman who
was financially interested in the outcome - I wouldn't place much value
on its accuracy as useful data. ;)
> Maybe you're suppose to make adjustments for the output on some alternators, I
> don't know but the warning I was offering was simply that very expensive
> batteries can get ruined quickly when everythng isn't just right.
I appreciate that, thanks. In my case, however, I'm not getting anywhere
near the point of overcharging - my problem is undercharging, or at
least what looks like greatly diminished battery capacity - which I
can't quite figure out how to confirm with my charging configuration.
Maybe I'll go buy a "stupid" 50A car charger and just push amps into
them (watching the voltage, of course.) Seriously annoying, this,
especially given the price of the batteries and the reputability of the
manufacturer.
--
Ben Okopnik
-=-=-=-=-=-
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