90% of the
work in these projects is the up front planning.
Speaking with BattleBorn, they say the 300Ah bank will support the windlass/bow-thruster operation, especially if the
engine is running.
I keep coming back to this as removing the
battery up front and moving the 300Ah house
battery bank from the stern locker to amidships seems to make sense, weight & balance wise. One less battery to install/maintain. More than likely a 4th 100Ah battery will be added in a year.
Using
this calculator assuming 14 ft cable run from the LI house
batteries ("LIHB") amidships at 13V to the 370A windlass/bow-thruster, 4/0 cable would yield a 4% drop to 12.5V.
The
windlass draw is 120A but would be for as long as 1-2 minutes.
Again, in both cases, the
engine would be running, so the LIHB would be
charging.
It appears this would
work. I would also feel better about the
windlass operation from the house bank, as that draw is lower but more deep cycle in nature.
Decided to keep the engine start battery, as the LIHB needs somewhere for the
Alternator to keep a load when the BMS shuts off
charging to the LIHB.
Now the question about charging the LIHB from the
Alternator and LA starter battery.
Upgrading to a 170A
Balmar alternator (
XT-DF-170-J10-KIT) that comes with a MC-614 external voltage
regulator, which should be able to put out 150A continuous. Tried to call
Balmar to discuss but they are closed until 1/4/21. Spoke to Peter Kennedy at
PKYS about it. I can't recommend him enough. He steered me away from a 200A alternator. Sent him pictures of the engine compartment and he thinks there would be
cooling issues, so 170A it is (ordered from him). He also recommended using 3
Victron DC-DC 30A chargers in parallel to charge the LIHB.
The distance from the engine/alternator/starter-battery to the LIHB would be 18 feet.
As recommended will use 3
Victron Orion-Tr Smart 12/12-30A (360W) Non-isolated DC-DC chargers in parallel, which comes to 90A continuous to the LI house
batteries.
The spec sheet recommends 6 AWG on each DC-DC
charger, so three 6 AWG positive cable runs from the DC-DC
charger to the LI house batteries. The ground would be the 4/0 cable running from the bow to the engine. The output voltage of the DC-DC chargers can be increased to 15V so a 2.84% drop would yield 14.6V at the LI house batteries.