On Jul 25, 10:39 pm, Lew Hodgett wrote:
Skip Gundlach wrote:

We've already got massive batteries. The issue is properly keeping
them charged. At 750 nominal (less aging) AH, we can go for a long
time with no charge input.

A 750AH bank will require an alternator that can put out about
110A-115A at engine idle to properly recharge them.

This will require a dual belt drive such as is required to drive a
Leece-Neville machine.

If you don't need a dual belt drive with your present alternator, you
have the wrong alternator.

If you discharge this bank by 40%, you have consumed 300AH which must
be replaced with 1.25*300 = 375 AH.

To replace 375 AH you will require 375/115 = 3.3 hours of engine time.

It ain't rocket science.

Nobody said wet cell batteries were efficient, but they are mobile.

Yes I must confess.

In my misspent youth, worked on the engineering team that designed the
great-great-great-great-grandfather of the L/N 4800.

Lew

Hi, Lew, and thanks for the expansion.

We have as a target of never letting our batteries get below 75% - and
only rarely below 90%. Recent excitement aside, we've succeeded in
that. Our original tests of relying solely on solar and wind (last
year, on the hard), for 6 months, went very well. Of course, we
didn't have the same wind as normally seen in the water, and also
didn't run instruments, offsetting that.

Our solar and wind were calculated to provide somewhere between 150
low and 300 high AH/Day on average. Continuously cloudy (well,
raining - it was completely overcast here at 5 and we were still
getting 12A from the solar), windless days will throw that off, of
course. However, we watch that meter like a hawk, and having had a
bit of training about the interface of volts and amps as to what's
happening in there, believe we'll be better managers than before.

If we were dependent on our engine alternator entirely for recharging,
we'd prolly do something different. However, as backup, but aboard
for our use of power tools in strange countries, as well as our hookah
rig, we have a 2000w Honda much bruited about here on other
occasions. Were it necessary while on the hook, likely we'd start
that before the diesel, solely for charging.

However, of course, having just slain the dragon of no effective
alternator power (and shore charging, too, but we expect that to be so
infrequent as to be unworthy of mention other than as powered by a
Honda if needed), we have no track record to fall back on. Stay tuned
as we live on the hook and under way in the next few weeks...


L8R

Skip

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