On Fri, 02 Dec 2005 00:19:28 -0500, Larry wrote:

Bil wrote in news:3ebvo1lujj9hblfr8iu9g5aefpolvle9ea@
4ax.com:

250 Amps of nominal 14VDC

What Ampere-Hour batteries are you charging with this much current, and
not boiling them? Will the boat float that much battery weight?

Battery charging is not the only use for electrical energy, Larry. But
I figure you knew that.

250 A at 14VDC is the theoretical maximum output from the genset, with
the diesel set at max rpm. When I specified the battery bank and
genset, I wanted to take advantage of the ability of AGM batts to
absorb charge fast. And the 500 Ah bank of AGMs does (although
efficiency has dropped - they're 5 years old now). I think the biggest
current I've seen when just battery charging is about half of the
theoretical max.

Bil wrote in news:eu70p1dt8ckcbgsi7ouhgqtdtb73nle372@
4ax.com:

ability of AGM batts to
absorb charge fast.

Another AGM myth. An AGM battery is exactly the same as any lead-acid
wetcell. It consists of the same plates, the same acid, the same
chemistry, the same physics as the cheapest car battery you can buy.
It's difference is the acid, instead of being a free liquid that can cool
the cell, self-healing, adjustable in gravity and measurable in that
gravity...it's soaked into a fiberglass mat that looks like really thin
gauze and the plates, soft lead that will tolerate being rolled up
tightly, is, in fact rolled up and stuffed into a plastic tube.

Being rolled up tightly in fiberglass, the AGM lacks the wetcell's plate
distortion problems of suspended soft lead, somewhat, and will tolerate a
little higher core temperature, which it must do as there is no cooling
circulation. But, when the red starting AGM in my stepvan tore itself
apart and melted the red plastic case, the results were the same.

Hard charging an AGM produces the same surface charge of lead plating as
hard charging any lead-acid battery without the deeper plating of slow
charging over hours at low current. AGM is not chemical magic or voodoo
as the sales hype tries to justify the awful price.