Wiring

[Sony2000]

I have a small question of wiring. I'm running without an alternator. Where can I attach the alternator wire, to give me a negative indication on the ammeter?

[edwardc]

I have a small question of wiring. I'm running without an alternator. Where can I attach the alternator wire, to give me a negative indication on the ammeter?

If the ammeter is in series with the battery, as shown on the diagram in post #13 of this thread, it will read both + (charging) and - (discharging). When the alternator is disconnected, it will still read the - (discharging) current.

If the ammeter is wired in series with the alternator, as shown in post #3, it can only show the + (charging) current. With the alternator disconnected it will show nothing.

So, based on your question, I'm assuming your ammeter is wired in series with the alternator. To do what you want, you should move it in series with the common terminal on the battery switch and the main 12v bus. This way all current to and from the battery (with the exception of the starter current) will be shown by the meter.

[Cool Beans]

Not to keen on #4 primary and starter wires, but please at least fuse them at the batteries. Also, I would say to dump the ammeter all together and jump a #4 wire from the alt. output to the starter lug. Your charging circuit is much simplified then and if you fuse at the battery that entire section of heavy amp circuit is protected. Also more alt. charge goes into the battery (being less wire to run through, less voltage drop).

Rely on your voltmeter for information about your alternator. Once energized, the voltage from the alt. should be 13+ (which signifies it is working), and as loads are applied the voltage will drop (which signifies power drawn). If your alt. craps out, the voltage won't increase with the engine running and you will know it is bad.

If you really want to monitor your power consumption, invest in a battery monitor. It would also replace your volt meter.

One final suggestion would be to look into getting away from the start/house battery designation and go with a Primary/Secondary battery setup.

The Primary Bank is connected to #1 and provides starting power, house loads, and takes all charging. #2 on the switch connects to the Secondary bank and is for emergencies only. You just switch to this battery every week or so to top off the charge and make sure it is functional in case something happens and you need to depend on it. You could provide some secondary trickle charging to it. . .

I'm setting up my boat like this and now seeing it, makes a lot more sense to me. It also makes the wiring easier since I'm not trying to wire both banks together for certain dynamic uses and I don't need to constantly remember to flip the switch back and forth.

Just my free 2 cents

[hanleyclifford]

Since I never know which battery is going to go south on me I have all batteries wired to the main buss bar but switched individually. I use the alternator to feed the main buss bar and whatever batteries are switched on will receive whatever charge they require. All my batteries are deep cycle flooded group 31 s so it makes no difference who does the starting and who does the house. Flexibility is complete and I like to rotate duties so each battery gets routine scrutiny. FWIW

[positron]

I had my boat surveyed last spring and the only major thing the surveyor insisted on for the electric system was a fuse at each battery positive terminal, to protect the heavy wires running to the main battery switch and the starter motor. This was not a requirement when most of our boats were built. I went with a fuse/holder combination that attaches directly to the battery post. Like most other safety items it seems like a big waste of money until you need(ed) it.