Dual Battery System - 2006 Mobius LS

[mnichols]

I recently purchased a 2006 Mobious LS. It has the factor installed dual battery system (I don't believe it is aftermarket). I am not versed in these types of electrical systems, so please bear with me. It has a switch that allows you to either select 1, 2, 1+2 or off. The manual suggests that I should always set it to 1. However, in reading various forum posts, it seems some folks suggest that you should leave it on the 1+2 setting while cruising (therefore chargine both batteries) and set it on 1 while floating (which causes battery 1 - the starting battery - to be sensed and only run down to a certain level before being turned off).

Can someone please explain to me exactly how this system is designed to work and what settings I should use for various uses (cruising vs. floating vs. docking the boat)?

Of note, when I have it set to 1, it will not start. I have to have it set to 1+2 for the boat to start. I may be that starting battery is bad. Or it may be that I don't understand the system.

Thanks for your help!!

[sivs1]

I installed dual batteries on a switch on my Stingray and my LSV has them. I am almost always set to 1 + 2 and only switch to 1 or 2 while floating with the stereo on. I can start while on any of the three options 1, 2 or both. do you have means to check your battery 1, maybe put a charger on it?

[mnichols]

I can check it and charge it. However, my main concern is how to operate the system on a daily basis. Is it your understanding that while in 1+2 mode, it charges both batteries but also drains both batteries? So, when I stop to float and listen to the radio, should I switch to the 1 (which is the starting battery) or 2 (which is the accessory/house battery)? What is happening when I switch to either 1 or 2? Whichever one I switch to, is that the battery that gets protected from running down?

[sivs1]

When I wired it all together on the Stingray it was setup to charge both batteries while on 1+2 and drain only the battery selected while not running. 1+2 - drain both, 1 or 2 drain only the one the switch is set to. I've done quite a bit on the LSV and it is set up the same way as how I wired my Stingray. I do not know if it was factory or if the previous owner installed it.

One way to check is to switch to 1 and disconnect the negative on battery 2 and vice versa. Just play around with it to determine how yours is wired.

[REDFIVE48]

When I wired it all together on the Stingray it was setup to charge both batteries while on 1+2 and drain only the battery selected while not running. 1+2 - drain both, 1 or 2 drain only the one the switch is set to.

This is my understanding of how dual batteries work, I had mine installed last year with the same kind of switch. I have read in other forums (sorry was along time ago so don't know where I read it), that you should avoid the 1+2 setting mainly because it will continue to try and equalize the batteries which could lead to premature battery failure. Now I know people will say that you should run there to charge both batteries, but if your alternator can't put out enough amps to actually be able to charge both batteries (and I don't know if it can) then the higher charged battery will start to drain into the low battery.

[MLA]

MNichols,

If your setup consists of just the manual dual battery switch, then it is 100% manually controlled by the operator. There is nothing there that monitors draw and isolates the batteries from the loads. The switch is very basic. Which ever position the switch is on, is the battery or batteries, that will receive a charge from the alternator. Its also the battery or batteries that all the loads will draw from.

If your boat will not crank on either #1 or #2 alone, you have an issue that needs looking into. Could be as simple as a bad battery that needs replacement, a failing alternator thats leaving them undercharged, or the whole system is wired in a not so ideal way.

How you use the switch will depend on how you intend to use the boat and the battery type. If both batteries are cranking or multi-purpose batteries, then crank and run on 1+2. If you want to anchor for any length of time, switch to either 1 or 2, to isolate one battery from any draws. Again, this requires the system to be configured correctly. If you have a main cranking and a deep-cycle. Then fallow the above method, except when anchored, switch to which ever switch position is designated for the deep-cycle.

There are system that utilize a voltage sensing or auto-combining relay along with a manual switch. I do not know if Moomba was offering those in 06, but that would change how things are done, if your boat happen to have one. It may be worth some further investigating.

[blackcup]

Does your boat start if it is just on #2?

I was playing around with my factory dual battery switch the other day. Oddly enough, my boat will start on 1, 2 or 1+2. The dealer sent me the boat without the batteries connected so mine could be connected wrong.

[MLA]

Does your boat start if it is just on #2?

I was playing around with my factory dual battery switch the other day. Oddly enough, my boat will start on 1, 2 or 1+2. The dealer sent me the boat without the batteries connected so mine could be connected wrong.

It should start in all 3 positions.

[blackcup]

It should start in all 3 positions.

Ok good to know thanks.

[mnichols]

I have a little more information about my system. Attached is a picture of the switch. It is a blue Sea systems brand 901E model.

20768

[mnichols]

The boat has some aftermarket amps which are mounted in front of the battery access. I can move them somewhat, but cannot get a good view of the battery set up. However there appear to be too full size batteries and one smaller battery. However, I am unable to get specifics concerning the types of batteries at this point. I also can't tell what the set up is in relation to the switch. However, from what I can tell, the two larger batteries appear to be linked together.

[MLA]

Nothing factory about 3 batteries. But, it could be the original configuration with a 2nd house battery wired in parallel. Bu then again, could be two 6V GC's wired in series.