"PeterS" wrote in news:1170197095.406328.242830
@l53g2000cwa.googlegroups.com:

Thanks for that, but I've done my calculations...

My domestic battery bank is 315Ah. 25% is about 79A, plus running
load of say 10A gives a total required charging of around 90A. 100A
would seem a good choice as it means I don't have to run the
alternator at full speed.

Regards
Peter


If you're buying, for that system, 100A alternator is plenty with room to
spare. Its starting bulk charge isn't dangerous to the plate
warping/gassing problems and leaves you plenty of overhead to pull a 10A to
30A load just fine. But, if you already have a perfectly good working 50A
charger, spending hundreds of dollars just to get 100A is nonsense.

Everyone is trying to get charged up in 30 minutes. I just don't care who
screams at me and calls me names....that isn't going to happen. The
chemical change in an old lead acid battery cannot be rushed. It LOOKS
like it charged, the voltage came up when we hit it with 250A for 30
minutes. But, do a load test and cycle it a few times and you end up with
plate sulfation and constantly dropping specific gravity, the only REAL
method of measuring the charge state of a lead acid battery...with a
temperature compensated hydrometer. Watching a bunch of meters, even like
a Link 10 AH meter (which has no facility to take into account overcharging
current rushing the chemistry, which is bogus) doesn't tell you how good it
is charged....

I can't wait until we dump all this ancient technology for:
http://www.eetimes.com/news/latest/s...leID=159907938

Check out this link page:
http://www.hobbyspace.com/Links/sciTech5.html
Buzz down the list until you hit LITHIUM and look at the various
technologies being done for the electric/hybrid car biz. Toshiba has its
own section of new items.

Your 1000AH nanotube Lithium house battery will be about the size of your
little starting battery, now. Nanotubes make them TINY. These are NOT
capacitors! They are chemical batteries, the same as your laptop and
cellphone. What's different is their PLATE SURFACE AREA, which is MASSIVE!

To charge IT, not them, your new diesel main engine will have a gear-
driven, oil-cooled alternator that can convert every HP of the engine into
DC current, not the wimpy 200A alternator boaters are dreaming of in this
thread. You will press the CHARGE button on the engine control panel. The
engine will be cranked by the charging computer in neutral. After a short
warmup to be safe for the engine to be heavily loaded, a full-load current
will be switched on the diesel by the computer which opens the throttle to
some maximum safe load. The huge conductors charging the little battery
will charge at thousands of amps, whatever the diesel can stand, for ONE
MINUTE. This will restore 80% of the battery's completely DEAD capacity.
The finishing charge will be about 60% of full load power and run for TWO
MINUTES, at which time the engine will shut itself down and a little beeper
will pleasantly beep while the CHARGED LED blinks for a minute to let you
know the house batteries are fully charged.

You'll smile as you have exactly what we've all been dreaming about since
we charged that first nasty lead acid way back in '62. The engine is now
ready for propulsion service and its transmission controls returned to
normal.

THREE MINUTES from DEAD to full charge. The technology now exists!

Consider what that means, though, to take advantage of it......

To charge a 1000AH house battery in ONE HOUR takes 1050A for an hour.
That's a hefty alternator, already! To charge a 1000AH house battery in 3
minutes takes 1050A divided by .05 (3min/60min) or 21,000A! That's going
to be hard to achieve!...(c; Reality will soon set in and quash the dream
of recharging in 3 minutes.....back to about 30 (2000A for 30 min?) or an
hour at 1000A. 2000A x 12V (about 4 cells of Lithium is 12V, but this new
technology doesn't get 3V/cell so it will probably be 5 cells if we stick
with 12V, which I hope we DON'T) 2000A x 12V = 24KW to charge it in 30
minutes. 29HP is about 21KW according to the Yanmar Saildrive website.
So, 24KW for charging it will be practical for a 35hp sailboat diesel and
up...charging the little beast in 30 minutes....VERY nice!

Nice to is Lithium-Ion batteries love float charging just as much as your
old house beasts, unlike Ni-Mh. You'll get used to the humming noise from
the 10KW charger plugged into the 100A service at the marina...(c;

The sooner the better! I'm gettin' heat for telling the truth about those
old crappers in the bilge!

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