Blackman battery charging system

[Wa Mei]

Guys,

I am a little foggy with how Blackman wires the alternator
to the 2 battery banks...sorry to be long winded, but I can
use you info.

The battery box has 4 group 24 batteries all Interstate deep cycle...almost exact fit. 2 are for house and 2 for starting.

1.From my research on this board, Blackman doesn't have battery switch, just isolators so when the boat is running, it charges both batteries, but all the electrical uses the house banks correct?

2. What is that switch located near the battery box?

I replaced 2 of the 4 which I believe are house batteries (#1) but it's not doing too well for the amount of time I sit on the hook with the bait pump, lights and electronics running. I can't go 6v (works great on the Skippy) without going to a different box so I am thinking about adding 1 more to the house side and go with 1 group 24 starting battery....1k cranking, 800 cold. my questions are...

1. Is 1k/800 cold enough to crank the Volvo 41?
2. What happen if the starter battery die? Is there a switch to put all the batteries to the starter? Besides
jumper cable...
3. Does not having exact size (total load) batteries for house and starting affect or fool the alternator...like thinking the batteries are charged when in-fact, only the starting is charged?

Thank you in advance for any info guys...

[Knot Now]

IIRC.
The solenoid that connects the house and starting batteries is in the power panel "box" and is controlled by the voltage regulator / Alternator output.

I raised the lid of my battery box with 1"x2" wood and metal straps and this allowed me to install 2 6volt golf cart batteries from Costco. I also removed my inverter. The house batteries have not given me any problems. When I am on the hook for a extended time, I run my Honda E2000 generator for cooking and ??? then the house batteries at night.

[NoSlack]

Here it a crude drawing of how Blackman charges the house batteries. The Cole Hersse solenoid is energized only when the key is on. If your house battery voltage doesn't match the engine battery voltage when the engine is running, you need to replace the solenoid. It should be behind the 12V panel. Disconnect the battery + before you do the work,

[yellowfin1]

Nice drawing Mike. On tenacious it looks just like that except add another house battery (2 starting and 2 house). I haven't had any problems on the hook when over-nighting as long as the batteries are fresh. I've run the bait tank late into the night but, I usually turn it off before going to sleep and either dump my bait or transfer the bait to a floating bait container and tie it off on the aft cleat. As long as the current isn't too strong it works fine. Having said this I do plan to to convert my anchor, deck, and running lights to LED just for fun.

[Wa Mei]

Thanks for the information guys...I am leaning toward having 3 group 24 batteries and 1 group 24 starting
battery. I sometimes stay on the hook for up to 12 hours
and may only move 3-4 miles at a time and the motor
need to stay off.

I am still trying to find out how much cranking power the
motor need so I can buy the correct battery.