2 Related Batt Wiring Questions

[wufibugs]

1. Can the alternator to house bank wire go the Positive Distribution Bloc, or is it preferable that it go straight to the House Bank? [I have an inverter/charger if that makes any difference]

2. I have a 300 amp fuse on each battery bank. On the Start Batt, should all wiring, including ammeter shunt, ACR, and boat switch be after the fuse or should any of them go directly to the battery? On the house bank, have a separate ammeter shunt, the dc fridge [Frigobot says it must be wired directly to the battery], and the alternator wire [depending on the answer to question 1]. Again, all after the fuse or any directly to battery?

 

[JK_Boston_Catalina310]

1. Can the alternator to house bank wire go the Positive Distribution Bloc, or is it preferable that it go straight to the House Bank? [I have an inverter/charger if that makes any difference]

2. I have a 300 amp fuse on each battery bank. On the Start Batt, should all wiring, including ammeter shunt, ACR, and boat switch be after the fuse or should any of them go directly to the battery? On the house bank, have a separate ammeter shunt, the dc fridge [Frigobot says it must be wired directly to the battery], and the alternator wire [depending on the answer to question 1]. Again, all after the fuse or any directly to battery?

Here's my thoughts and I am no expert but have been doing some research and upgrading on my boat.

1. I have a positive distribution block right next to my batteries that consists of 3 ANL fuse holders with a copper bar connecting the 3 on one side. Coming off of the copper bar side is the connection to the primary batter bank. For the ANL's, the other sides are connected to a) the distribution panel through a 1/2/both/off switch with a 250 amp fuse on 2/0 gauge wire, b) my alternator with a 100 amp fuse on 4 gauge wire and c) my battery charger with a 100 amp fuse on 4 gauge wire and a second 4 gauge wire connected to my ACR.

My alternator used to connect to the my starter positive lead via a 10 gauge wire and no fuse. Maine Sail has a recommendation on his website to at least upgrade this connection with a lower gauge wire but has also recommended in the past it is more efficient to have the alternator go direct to the batteries. You do need to have a service disconnect of some kind if you go this route.

2. The reason that my positive distribution block has so many fuses is that you have to fuse based on the wire size, not the load. So if you connect all your wires to the 300 amp fuse, you will very likely be over-fusing some wires. That 300 amp fuse might be good on anything you have that is 0 gauge or thicker. But anything you have that is smaller would be unprotected by that fuse. You would need to find a different way to fuse those smaller lines. I copied Maine Sail's system because it seemed to be the most straight forward approach I saw and it wasn't very expensive to do.

Good luck and fair winds,

Jesse

 

[Maine Sail]

1. Can the alternator to house bank wire go the Positive Distribution Bloc, or is it preferable that it go straight to the House Bank? [I have an inverter/charger if that makes any difference]

As long as the positive distribution block does not impart any additional voltage drop, meaning it is really too small, then this is fine.

2. I have a 300 amp fuse on each battery bank. On the Start Batt, should all wiring, including ammeter shunt, ACR, and boat switch be after the fuse or should any of them go directly to the battery?

Every wire attached to a battery positive terminal must be fuse protected. Best to put all of tehm after the initial fuse but make sure they are all sized for their own wires. You can't protect a 14GA bilge pump wire with a 300A fuse...

The ammeter shunt should be in the negative wire not positive unless this is just the small positive wire that senses voltage.

On the house bank, have a separate ammeter shunt, the dc fridge [Frigobot says it must be wired directly to the battery], and the alternator wire [depending on the answer to question 1]. Again, all after the fuse or any directly to battery?

After the main batt fuse and they can all go on the positive distribution bus...