Battries and battery switches

[Mr.Stuart]

This is probably going to sound like a complete nu-be question, but here it goes anyway.

My starcraft has 2 12 volt batteries and a battery switch, the switch reads 1, 2, all, and off.

When I'm running the boat, I always have the switch in the "all" position, but is that necessary?

Why the need for two batteries? And what the proper way to operate that switch? It would be my guess that one battery would be an auxiliary battery to run accessories or what ever, maybe nav lights? How should I be using the batteries and battery switch? Should I have the switch in the "all" position? Or only run off one of the batteries, 1, or 2?

 

[QC]

Re: Battries and battery switches

The reason for two batteries is so you can isolate one to run accessories and then still have a back up to start the boat. Also, sometimes you may need both if you need more power for something.

What I do is I run "both" for the first start of the morning and then if I remember I switch to one or the other after the first stop. This insures a good charge on both. I use the odd/even day of the month to determine which battery I use that day. In this way if a kid leaves something on, or I run the stereo forever, or I leave a light on, I have another battery ready to go . . . Off is for . . . uh . . . off

 

[Barnacle_Bill]

Re: Battries and battery switches

When I had a setup like that I did it the way QC does. That way you always have a fresh back up.

 

[Mr.Stuart]

Re: Battries and battery switches

that sounds like a good solid plan, I'll start doing that way, thanks

 

[reelfishin]

Re: Battries and battery switches

On both of my boats that have factory installed battery switches, the engine and engine controls are wired to battery #1, and all other accessories are on Battery #2. If I was to run on only #1, I'd have no accessory function, (no fish finder, gps, radio, etc.), It will not run on only #2, with that disconnected, there is no dash, no controls, no start power. The motor charges both batteries in "ALL", #1 and #2, but will only draw off both in "ALL", if one battery failed, switching to "ALL" will start the motor off the power from the other good battery, but switching to only #1 or #2, would leave me without either engine or the accessories. The only time I can switch one off is if I am docked or anchored with the engine off for an extended period and don't want to run down both batteries. In that case I switch to #2 only, then back to "All" when I resume travel.
I've considered switching over to an automatic isolator, thus eliminating the need to manually switch off the starting battery. On both boats, #1 is a Marine starting battery, and #2 is a deep cycle battery.

 

[Mr.Stuart]

Re: Battries and battery switches

I have no idea how mine is wired, I know the two batteries and battery switch was an after thought, the boat didn't come set up like that, I'll have to do some checking to see how it's wired before I can figure out how I should be using the two batteries and switch I guess. I've always used in the "all" position, and always switch it to the "off" position when I'm done with the boat, so I'll have to see what works and what doesn't between position "1" and "2"

Having two batteries seems like a good idea to me, especially if I'm going to be doing any camping in the boat, or running lights and accessories with the engine off, plus I want to equip it with some radio gear, I've already got the radios I just haven't installed them yet, but thought I'd ad a stereo, a marine radio, a CB, and a 2 meter amateur ham radio.

 

[Silvertip]

Re: Battries and battery switches

Having a battery switch with the various loads hooked directly to the batteries defeats the purpose of the switch. Loads should be connected to the COM (common) terminal on the switch. Automatic bilge pumps should be connected directly to the battery however. Therefore when the battery switch is OFF, everything is OFF even though you didn't turn the device(s) off with the switch on that device(s). That also allows all accessories and systems to function normally regardless of switch setting. You then start the boat on BAT 1, BAT 2 or BOTH and switch to BOTH underway. When you are beached or docked and want to run the accessories, switch to BAT 1 or BAT 2 so you are guaranteed the other battery is good when you get ready to leave again. There is nothing inherently wrong with having various loads connected to the batteries but it does limit the versatility of the switch.

 

[Mr.Stuart]

Re: Battries and battery switches

The battery switch on mine is right next to a circuit panel the previous owner had installed, I'll trace out the wiring and see what's hooked to what, and kind of take it from there, I've always run it in the "all" position, even when staying on the boat over night, but can see why I'd want to use "1" or "2" and save myself a fully charged battery.

I know when turn the battery switch to "off" it kills everything on the boat, the guy was pretty good about "doing it right" so I'm going to guess that all the electrical is running through the switch to one battery, while the other battery is set up for starting only, that would be my guess, and if I was going to set it up, that's how I'd do it, and with the circuit panel right next to the switch, it should be pretty easy to swap wires around to get a setup like that.

 

[Mr.Stuart]

Re: Battries and battery switches

My next question would be, if your running the boat off of (as an example) say, switch position "1" assuming that all the electrical is wired through that position, is the alternator on the outboard still going to charge the second battery? (The battery connected to position "2"?) Or is the only way to get both batteries charging simultaneously is to have it in the "all" position with the engine running?

 

[Silvertip]

Re: Battries and battery switches

If the alternator output is connected to the COM terminal as it should be, it will charge BAT 1 only when the switch is set to BAT 1. It will charge only BAT 2 when set to BAT 2. It will charge both when set to BOTH. That's why ALL of the loads should also be connected to the COM terminal, not the batteries. That configuration gives you the most flexibility. You run everything from BAT 1, BAT 2 or BOTH depending on what position you have the switch in. Let's assume you ran down BAT 2. You want to get BAT 2 fully charged as soon as possible so you start on BAT 1, switch to BAT 2 so the full alternator output goes to that battery. If you set to BOTH, some of the output goes to BAT 1 which delays topping off BAT 2. If both batteries are fairly well charged, run on BOTH to top both of them off. Think of both batteries as buckets of water. If one is empty and one is full, the alternator (the water pump in this example) doesn't need to pump water into bucket #1 so let it fill up bucket #2.

 

[Mr.Stuart]

Re: Battries and battery switches

ok, makes sense to me, I'll take a look at the wiring and see how it's put together and go from there

 

[reelfishin]

Re: Battries and battery switches

The only thing wired which bypasses the switch on my boats is the automatic bilge pump. That can not be turned off. (There is a second manual only bilge pump and a manual mode to the automatic pump as well that are wired to run only off of the second battery).
On mine all other wires are wired to the "Com" terminal. There is however a bold warning on the switch face, "Do Not Turn Switch with Engine Running" It looks to have been added by the manufacturer. That switch looks just like the Perko battery switches only this one is all gray with no name, only the positions molding into the plastic.

I am currently setting up another boat for next season, I plan to use an electronic battery isolator with a switch on the dash to engage the second battery. I may still ad a manual switch that can shut down all power, but that will only be for storage or service. With the Delcotron Battery isolator, it will charge both batteries all the time, but the accessories will only draw off the alternate battery. The dash switch will connect the second battery only in the case the the main battery is dead or too weak to start the motor.