"Larry" wrote in message
...
The discharge-charge cycle is a ratio of 1:5. It takes 5 times as long
to CHARGE a lead acid battery as it does to DISCHARGE it. That ratio
hasn't changed in my lifetime. It's chemistry.....a slow chemical
reaction. The only difference is your initial charge rate will be lower.
375AH batteries CAN, but don't have to be, charged at 375 x .25 = 93A.
This bulk charge is the constant current phase and your 50A alternator
will run 50A for about twice as long. It's plenty adequate, but will
simply take longer. That small engine uses so little diesel fuel, relax!
Let everybody take a show from the hot water tank while charging, if it
has a hot water heat exchanger attached to it.

Now, discharge the battery bank down to 12.25V (at 70F). Turn off all
loads and crank The Beast. Watch the ammeter and see how long it will
hold 50A before it bumps its voltage regulator, the second phase of the
charge whereby the VOLTAGE is regulated to around 14.3VDC and the battery
sets the current load. There's the switch point between a 50A bulk
charge and the finishing phase, which is just as important, even more so
if you'd like to keep the cells from sulfating. When the current drops
to near zero, the charging is complete.....NOT when you see it start to
drop off 50A....as wishful boaters charging at 200A for 1.5 hours will
tell you theirs is charged....total nonsense.

A lead acid battery CANNOT be rushed to get a proper charge. Your 50A
alternator will never endanger your battery banks with gassing and
warping the plates from excessive heat....as long as its voltage
regulator works properly. Simply reduce your DC loads as much as is
practical during the bulk phase, then you can turn them back on during
the finishing phase when you have extra amps to spare the battery's not
using up....(c;

Larry
--
Democracy is when two wolves and a sheep vote on who's for dinner.
Liberty is when the sheep has his own gun.

My biggest load, when it's running, is the radar. All in all, if it's foggy
I'd rather just anchor out and wait, but if it comes down to it I should be
able to run the radar for a few hours straight without drawing down my bank
too much. After all, in this neck 'o it's only an hour or two to the next
anchorage or harbor anyway. And more likely than not, if it's foggy there's
no wind and to move the engine is running. No problem there.

With no refrigeration, no TV, no microwave, no electric appliances, I'm
mostly concerned with keeping enough energy to run my nav instruments and
laptop -- and the laptop has two batteries itself, running for quite some
time without needing a recharge. It's quite possible (likely, in fact) that
375 ah is overkill on Essie. But I like to stock up and feel that I have
enough to see me through hard times, and I can't see anything wrong with
stocking up on amp hours. And with your comments on charging, it's
comforting to know that I don't have to upgrade the alternator until it
actually NEEDS replacing.