Another battery switch question

I'm sure this topic has been talked about plenty but I couldn't find what I was looking for. My setup is dual engines, 2 batteries, 2 alternators, and a switch for each battery. The switches are the same with the selections 1,2, all, and off. I completely understand the use of one battery for accessories and one for cranking, I'm just not clear on the battery switches. When would I want to turn the switches to 1 or 2? and do I leave both on all when I'm cruising to leth them both charge? Sorry but I'm a little confused.

Jim

Re: Another battery switch question

semo549 said:

I'm sure this topic has been talked about plenty but I couldn't find what I was looking for. My setup is dual engines, 2 batteries, 2 alternators, and a switch for each battery. The switches are the same with the selections 1,2, all, and off. I completely understand the use of one battery for accessories and one for cranking, I'm just not clear on the battery switches. When would I want to turn the switches to 1 or 2? and do I leave both on all when I'm cruising to leth them both charge? Sorry but I'm a little confused.

Jim

Click to expand...

The switch your referring to is the old traditional one. That's why I'm going with the 6011. In 1, each battery is connected to separate systems. In combine, well u get it. In your scenario, it looks like you have 2 separate and isolated system. You will have to crawl and look.

In your switch, at 1, you connect the battery to the electronics OR battery. In 2 same thing. You basically have a traditional system X2.

Re: Another battery switch question

It is so simple a "cave man can do it". (Sorry about that!) First the caviat: How you use the switch depends on how they are wired and IF one of the batteries on each engiine is somehow used as a house battery. The switch on one of the engines is probably serving as a house (accessory function) So -- IF you have just the four batteries and ignoring any other wiring peculiarities, OFF = all batteries disconnected. No power to anything, and engines will not start. BAT 1 = ONLY Battery 1 powers everything and starts the engine and is charged by the engine. BAT 2 = ONLY battery 2 powers everything and starts the engine is charged by the engine. BOTH = Both batteries power everything and both batteries start the engine and both batteries are charged by the engine. You spend as much time switching back and forth as you want and keep yourself confused, or you can think logically. The entire purpose of a battery switch is to provide isolation between two batteries so you don't get stuck with a dead starting battery. BAT 1 is normally the start battery but what you set the switch to determines that. It can be either BAT 1 or BAT 2 (or BOTH although that's sort of defeating the "protection" idea). If you spend several hours cruising, YES - set the switch to BOTH to keep both batteries up. If you make frequent starts and stops during the day you may want to set the switch to BAT 1 and just leave it there even if you are away from the boat for an hour or so with nothing running. However, if you stay in the boat while stopped and have a bunch of accessories running -- THEN you switch to BAT 2 which is normally a large deep cycle which handles deep discharge cycles better than the start battery. This action prevents sucking the life out of BAT 1 which is the starting battery. When you want to leave, switch to BAT 1 (or BOTH), start the engine(s) and go.