Charge rate up to 40%

[Ross MacKillop]

How much faster would 110a (two 55's) be over a 75?

With three 210 Ah batteries half discharged

2 hours 47 minutes--- generator run time with 100 AMP charger or
4 hours 10 minutes-- generator run time with 75 amp charger.

100 amp Overkill? No By this article maximum charger could higher.-- from
boatus ttp://www.boatus.com/boattech/battchg.htm

If you own a small boat and
you only need battery power at dockside intermittently for things like
lights and bilge pumps, an SCR (silicone-controlled rectifier)
charger may work best for you. It varies its charge to keep your battery
at a constant 13.4 volts. The ones we carry are fully automatic and have
multiple charging capabilities.


Live-aboards and larger boats with many 12-volt accessories usually
have ferro-resonant chargers that put out 12 volts continuously
to keep up with constant power demands. Ours are fully automatic,
self-regulating,
and ruggedly built to give many years of dependable service.


Experts agree that the best way to replace the energy you consume from
your boat's batteries is through a controlled, multi-stage process.
Both conventional lead-acid (flooded) batteries and gel cells will
charge
faster and last longer if they are charged in distinct phases that
take
into account their chemical and physical complexities. The recommended
three-stage charging process works as follows:

1.
Bulk Stage: This first stage provides a constant amperage bulk charge
of 25-40% of the battery's capacity (in amp hours, Ah) up to about
14.4
volts (14.2 for gel cells). This bulk charge will restore about 75%
of the battery's total capacity. It takes less time than tapering
chargers,
like ferro-resonant and SCR chargers, because the smart charger
delivers
greater current to the batteries which can accept greater current
loads
when they are discharged.

2.
Absorption Stage: The remaining 25% of capacity is restored at a
decreasing rate. Maintaining the battery at 14.4 volts (14.2 for gel),
the amperage is steadily reduced. The battery is considered fully
charged
when it will accept only 2-4% of its amp-hour capacity at 14.4 volts.

3.
Float Phase: The charge amperage has declined to 2-4% of the battery's
capacity, and voltage drops to 13.5 (13.8 for gel cells). This
maintains
the battery without losing electrolyte from gassing.

4.
Equalization: Applies to lead-acid batteries only. This fourth,
manually triggered stage prevents lead-acid batteries from aging
prematurely
by applying a small, constant current until the battery reaches 16
volts,
which dissolves the hardened lead sulfate crystals on the battery
plates
and prolongs battery life.






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