Bow Thruster install Battery?

[PaulRainbow]

I had your situation but just added a VSR(voltage sensitive relay) between the existing cables run to the bows and the new battery. So when on shore power or with engine running the battery is charged. I never had a problem with it and the VSR's are as cheap as chips.

The VSR serves no useful purpose, you could have just wired direct, as i suggested above.

 

[Rafiki]

I had the Sidepower SE 60 installed a few years ago. I already had an electric windlass powered by the Leisure batteries in the middle of the boat ( actually it may have been the engine battery also in middle of boat, I cant remember). We fitted a new battery at front of boat for both the Windlass and thruster and utlised the existing thick cables from the middle of the boat to provide charging from both engine and shore power. Sterling Shore power battery charger had three independent outputs and engine charging went through some other Sterling Gizmo to split power three ways ( not a Battery to Battery Charger). All works well. As has been said already thruster only used when under power and ditto windlass. All batteries are lead acid, and the battery up front for the thruster/ windlass is now 8 years old, so I may change it next season.

 

[C08]

When I installed a bow thruster on my cat I was not keen on powering the BT from either of my 2 banks of leisure batteries as the BT being in the starboard bow and the 2 battery banks being in the port stern lockers would mean long cable runs and voltage drop apart from the £300 of heavy duty starter cable. Also having a main outboard engine with limited charging compared to a marine diesel alternator the assistance from the engine charge is very limited. I fitted a dedicated starter rated battery in the bows and for charging it fitted a light twin core cable leading back to the no 1 battery bank. The idea that when away from the boat or not using the thruster the connector plug is in and the BT battery is charged up by the solar, wind or engine. So the BT battery is always fully charged and ready for use. It is a cheap and cheerful solution and works well for me. The only downside is making sure not to use the thruster when the charging plug is in as the current draw would probably blow the 10A fuse in that wire. I just hang the plug with a loop over the BT joystick to remind me.

 

[IanCC]

Thanks... Yes cables are a decent size, Ive not checked size but they "normal" beefy starter cable size...
So can I connect an AGM directly to the lead acid engine start battery?

Mine, 30 footer, thruster from start battery and my cables are 70mm sq. So circa twice as big as starter cables. Might be spec'd wrong, but won't be far out.