Physically Connecting Multiple Charging Sources To Battery Banks and Locating Fuses

[Tom_F]

The boat is a 2004 Jeanneau Sun Odyssey 40.3 (40 feet monohull) with a Yanmar 4JH3E diesel and an 80-amp Yanmar alternator. The boat 3 battery banks, all with new-ish (June, 2019) AGM batteries. The battery banks, all 12v, are a house bank (3 AGM group 31s) and a dedicated starter battery (single AGM group 24) all co-located near the engine compartment and a battery (also single AGM group 24) forward under the V-berth for a bow thruster. The house and starter batteries are charged via the alternator and a Xantrex ProSine 2.0 charger/inverter under the nav station. The thruster battery is charged only by shore power using a Cristic 40 amp battery charger located forward near the battery. It does not appear the thruster battery is charged by the alternator, which I must change.

Right now, in addition to cut-off switches on the positive side of each battery, the boat also has a switch that disconnects the negative circuit.

Rather than replace the alternator or have it modified to fit an external regulator, I have decided to install a Sterling Power Pro Alt C alternator-to-battery charger and a Sterling Power Pro Split R. The Pro Alt C will be used to charge the house bank and the Pro Split R. The Pro Split R will, in turn, charge the starter battery and the thruster battery. I also hope to add both solar and, perhaps, wind in the future. I have not decided on the watts of solar I can accommodate or definitively committed to add a wind generator, so I have not selected a controller for those. However, I want to properly construct the charging system now so it can accommodate the future charging sources assuming I add them.

So, setting aside electrical theory and the debate over whether multiple controllers can work well together, how does one physically connect multiple charging sources to a battery bank? Should I simply connect the charging source positive to the positive terminal on the relevant battery or should I install a positive bus for each battery bank and connect all charging sources to that? I see Maine Sail shows a bus in his wiring diagram, but I have not seen anyone else mention using one. Maybe it’s just so basic people assume you use one, so be gentle in your comments.

Also, Sterling Recommends an appropriate fuse at the battery for the wires from the Pro Alt C and Pro Split R. I assume an MPPT solar controller and a wind controller will make a similar suggestion, but I have not looked into that yet. Where would those fuses go? Terminal-mount fuses (such as https://tinyurl.com/sc6g628) on the bus bar connected to each charging source? Multiple terminal-mount fuses, one for each charging source, on each battery terminal? Surface mount high capacity fuses (such as https://tinyurl.com/u6mwgem) for each battery as close to each battery as I can get them?

Assuming I use a bus and fuse the wires from the charging source as they connect to the bus, do I need an additional fuse at the battery on the wire it connects to the bus with? Seems unnecessary to me, but I want to make sure.

Finally, should I be making sure the battery switches are connected in a certain location in the wiring for each battery bank? I assume a switch should be between the battery and the bus to which the charging sources are connected, assuming there is one, but is that right?

Sorry if these seem to be very basic questions, Thanks for all of your insight.

Tom

[CarlF]

Use a bus because you shouldn’t connect too many wires to any single terminal

The battery terminal fuses are an inexpensive and good solution that puts the fuse right at the battery. The bigger one will even handle the starter draw from the start bank on your engine.

Remember fuses should be sized to protect the wire gauge that comes next. Most times when you step down to a smaller wire size you need another fuse to protect the smaller wire.

You will blow your alternator diodes if it is disconnected from the battery while running by a switch being accidently thrown. There are a variety of ways to avoid this.

But you are doing some pretty major changes here and are pretty new at it. I’d have an experienced guy come to the boat and go over your plans even if it cost you a few hundred bucks.

Have any larger cables custom made. If you don’t have someone good local, I’ve had good luck here:
http://www.genuinedealz.com/custom-cables

[c.spots]

If you want to charge your thruster battery, you will need long cable for the high amp, long wire run. Especially if that battery is 12 volt.
Consider simply wiring (or plugging) your shore power charger to your inverter circuit.