[PUP] PPM Electrical generation & storage

[2elnav at netbistro.com]

> Gentlemen, can we carry on with the PPM discussion, please?
> John "Seahorse"
>
>
>
> I still love the PPM discussion, too. Here's a potentially arousing
> thread:
> How are we going to generate and store electrical power on the PPM?

> In the past, Arild has advocated (persuasively, to me) using a DC genset
> and maybe making that big enough to serve as a good wing engine.
> That advice seems even more persuasive when we consider that new Thin
Plate > Pure Lead ("TPPL") battery technology claims to be able to
charge the
> battery with considerably more speed than an ordinary AGM unit.
> A good starter question then, might be: how fast can a big TPPL bank be
> charged from how deep a discharge? And does the answer to that mean we
> could have some truly BIG alternators on that wing engine to do the job?
> Regards, Bob Frenier


REPLY
If I might add a little something to the discussion. The cost of lead has
escalated in recent times. In addition, light weight has proven to be a
desirable aspect of cruising boat design. Especially in power cats but
also in other boats.
It begs the question; does it really make sense to lug around a ton or two
of lead batteries in order to never go below about 25% depth of discharge?
So far conventional wisdom has suggested that avoiding severe depth of
discharge promotes long life in the house batteries. By doing this we end
up buying a huge bank of lead acid batteries, suffer the penalty of
powering this large mass around with our propulsion engine and on occasion
 suffering a premature failure due to some miscalculation or other or
omission in maintenance.

Have we reached a point where the cost involved means it is cheaper to go
for deeper depth of discharge and live with only four years of battery
life but save on fuel burn by reducing the run time on the genset. And
since each change out of the battery bank involves less mass it cost
correspondingly less.
I'm thinking  we need to consider total life cycle costs over five years
or more rather than just the initial cost of acquisition.

regards
Arild