Re: Batttery Switch question
Why are these things so hard for folks to get their heads around? Consider the switch settings -- really consider them. Actually, how you use the switch depends on how it is wired. People do some really creative wiring when installing these devices so that alone can impact how it is used. However, IF (and I mean IF) every load (meaning every circuit) including the engine battery positive cable) is connected to the COM terminal on the switch, the here is how it works. How YOU use it is up to you but rather then be puzzled by the mere presence of the switch think about the batteries instead.
1) what happens when you start the engine on a boat with just a single battery? You suck a given amount of power from the one and only battery do you not? When you operate an accessory you also suck more power out of that single battery. When the engine is running, that single battery is being charged by the engine. Use too much power and you call for a tow or flag down an understanding boater.
2) So the purpose of adding the second battery and the switch is to what? If you answer "to make sure I'm not stuck with a dead starting battery you would be only half right. The correct answer is "to make sure I have ONE battery (either one or both) available to start the engine.
3) In the OFF position, it should be obvsious that both batteries are disconnected from the electrical system. Use that position when away from the boat for extended periods. That means days, weeks, or months -- not a couple hours or a few minutes.
4) In the BAT 1 position everything on the boat is powered by that battery, the engine starts from that battery and that battery is the only one being charged by the engine. BAT 2 is simply going along for the ride.
5) In the BAT 2 positon the same thing stated in step 4 applies but the second battery is doing the work. BAT 1 is simply going along for the ride.
6) Guess what happens in the BOTH position? Yes, BOTH batteries power everything and both batteries get charged by the engine and both batteries start the engine.
As I said, think about the batteries. Which one do you want to charge. Which one needs the charge? Which one do you want to use to start the engine? Is either battery nearly dead? You ran down the start battery (BAT 1) -- Now what? YOU are the brains behind (or in front) of the switch. Simply select the battery(ies) you want to do the work or you want to charge. Which ever one is the weakest is the one that should be selected when running. Which ever battery is house battery is the one that should be selected when anchored/docked and using accessories. You can use either or both to start the engine but typically it will be BAT 1 since it is generally a battery designed for starting duty. House batteries are typically deep cycle and not intended for starting duty although very many people use them as such.
