View Single Post
  #76   Report Post  
posted to rec.boats.cruising,rec.boats.building
Geoff Schultz Geoff Schultz is offline
external usenet poster
 
First recorded activity by BoatBanter: Oct 2006
Posts: 454
Default Amps, etc.

Wayne.B wrote in
:

On Thu, 26 Jul 2007 01:51:23 -0000, 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. But if we don't put in the charge,
eventually the biggest battery bank will be flat, even if nothing is
drawn from it, out of normal charge dissapation (flooded = ?%/
month)...


To recharge 750 AH in a reasonable length of time you need a 3 stage
charging source of 150 to 200 amps (25% of capacity). Don't let Larry
tell you anything different. Wiring of appropriate size is also
required of course.

If you had a generator you could do that the way we do - use the
charger half of a high powered inverter/charger. Since you don't, you
will need a seriously high powered alternator with an external
regulator. An alternator of 200 amp capacity will typically be a
large frame Leece-Neville, require two drive belts, and quite possibly
some custom work on your engine drive sheaves and alternator mount.
All of this is not cheap of course, and it will take some shopping
around just to find someone qualified to do the work. Nothing less is
going to get the job done however.


And don't forget cooling. A 200A alternator is going to generate a lot
of heat and will need to be cooled. You just can't throw it into an
enclosed engine space and expect it to crank out 200A without burning
up. You need to have a 3 stage controller with a thermocouple on the
alternator and you need to pipe air into the engine space.


-- Geoff