Dual batteries selection

[DaveM]

This question has been asked before but do most of you set your Dual battery switch to: 1, 2, or 1+2 (both) selection on dial? I use one battery at a time in order to fully charge it. I try to rotate battery selection each day we go out keeping both charged. I think I read selecting both will not fully charge either battery. Is that correct?

[Isaguel]

There's a thread on this and as I understood it, you are correct, you should not use both. The engineers explain that the only instance you use both is if both batteries are low and you need both at same time to crank the engine. Otherwise the one being used is the one getting charged, so I agree wit alternating batteries.
I garage my boat and I plug it into the onboard battery charger when I get home.

[haknslash]

I rotate mine each outing as well and was told this is preferred method by my dealer. He said only use 1+2 in the event I can't crank the engine on one battery or the other.

[parrothd]

I rotate mine each outing as well and was told this is preferred method by my dealer. He said only use 1+2 in the event I can't crank the engine on one battery or the other.

I always leave it on 1&2 so both batteries are always being charged, if we hit the party cove with the stereo I switch to 1 or 2. That way you always have both batteries charged. Using 1 & 2 with two dead batteries will not start the boat..

[sandm]

same with parrot. 3rd boat doing this and no issues.
sure mla will chime in as he's educated a few on these. I know there's different models/designs and operate differently so might depend on which one you have.

[Bch53211]

I rotate mine each outing as well and was told this is preferred method by my dealer. He said only use 1+2 in the event I can't crank the engine on one battery or the other.

This is what I do as well.

[haknslash]

I always leave it on 1&2 so both batteries are always being charged, if we hit the party cove with the stereo I switch to 1 or 2. That way you always have both batteries charged. Using 1 & 2 with two dead batteries will not start the boat..

When I'm not using the boat the onboard charger gets plugged in which keeps both batteries in good condition and topped off. When I go to the lake I'll pick 1 or 2 and use it for the day and that battery gets charged while the other acts a reserve or backup. Or you can treat one as the start battery and 2 as the house battery. There's multiple ways to skin a cat I suppose in this instance. All I know is if you use an onboard charger then it's not likely you'll need to use both batteries to be charged in the 1+2 configuration on the water so long as both batteries are wired correctly to the switch. You can do it both ways and they achieve the same idea, I just prefer to use the onboard charger as my method for charging both batteries and like the idea of a reserve or backup rather than use 1+2.

[parrothd]

I'm in a wet slip all summer so there's no plugging in the charger, that only happens in winter.

[Turbinesurgeon]

Odd days use batt 1 and even days use batt 2


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[MLA]

There is no universal method IMO. How you use the switch has a lot to do with what type of batteries are there and how you use the boat.

The 2 main functions of the 1/2/BOTH switch, is to allow for emergency starting, and isolating one bank form the other, for anchoring. If you have 2 identical batteries and your usage is mostly engine running, then alternating between banks on outings is fine, so is running on both, as it keeps both banks topped off.

If you have a cranking battery and a deep-cycle and you spend time at anchor, then you need to use the switch differently. Obviously, you would want to switch over to the house bank (deep-cycle) when you anchor, keeping the cranking in reserve. Then restart on the cranking when you are ready to move again. So now what to do with the run down house bank? Heres where I may differ from what the dealers are telling people. You can run on both, and both banks get some charge. This helps to recover the house bank while the boat is in use. Or, move past the BOTH position and go to the house bank. Now, all the alternator output is hitting the house bank.

The Blue Sea switch Moomba uses, is a make before break, so its perfectly safe to move between the 1, BOTH and 2, which engine running. Just dont go to or through OFF with engine running.

The Blue Sea Dual-Circuit-Plus switch is a whole different animal, so note my thoughts are for a 1/2/BOTH/OFF switch.

[zabooda]

Well said MLA. Motor homes charge both banks while running and then separate into the starting battery and the house batteries with the engine off. The two set of batteries are vastly different in design and function but can be using in an emergency. I didn't realize the same battery are on both sides of the switch. It sure isn't the optimal set up.

[DNIXD99]

This disscussion took place in the Autowake thread by Goose (Matt Brown with Moomba). Apparently, this is a big debate within Skiers Choice too LOL.

For me, I use BOTH (1&2), UNLESS Im parked with the stereo on, then I put it on 1 or 2.

I also always have my tinder plugged in when its stored, and use my boat often, so it really doesnt matter what I do. THIS was the biggest deciding factor when the debate went down. If you dont use a tinder frequently, then youll need to have some kind of rotation for maintaining the batteries. Rather you rotate usage, or use both at the same time.

[MLA]

This disscussion took place in the Autowake thread by Goose (Matt Brown with Moomba). Apparently, this is a big debate within Skiers Choice too LOL.

I recall this discussion as it related to voltage issues or stereo pops/resets and running all the ballast pumps. Supra's (Skiers Choice in the end) position was to run on the BOTH position. On a 12V boat system, it cant be a fix for one model and a no-no on another model. It just cant.

[TXSurf4]

I posted this in another recent thread as well but here is a discussion about the battery switch that happened in 2017 on the "Autowake Questions" thread. It begins on page 9 and ends on page 11 if anyone wants to go look at it. This isn't where they were talking about the issues with the speakers as that was on a different more recent thread. This battery conversation came up here as they were discussing ballast timer settings and such.....



I am curious, do either of you have dual batteries in your boat and if so, where do you run your switch? Also, do you recharge your batteries often? I personally always run my switch in the "both" position and we keep the R&D boats batteries charged fairly often. Even if filling with engine off (which you can't do in 2018 ), it gives me a little extra battery bank to hold a slightly higher voltage.


This is interesting, as my dealer specifically advised never to run on both, always choose 1 or 2.

Edit: My bags seem to fill fine at the preset times. I always fill with boat on, idling forward.


Well, the battery switch and recommended switch location has been a point of controversy over the years and internally we probably all don't see it the same way. The most conservative approach is to recommend the consumer leave the switch in the 1 or 2 position. IF you do that, and IF you charge your batteries often, then IF you were to be sitting on the lake all day listening to the stereo and the battery went dead, then you could theoretically switch it to the other battery, start your engine and go merrily on your way.

However, what I have found is most consumers do NOT charge their batteries often. And many consumers leave the switch in 1 position forever, never turning it off. If you leave the switch in the 1 position, then you would never be charging the 2nd battery as the alternator is completely separated from the 2nd battery. If you left it that all way all season without charging it, it is likely that if you ever did need the 2nd battery, it might be dead. In addition to that, running the engine and all accessories off 1 battery only will draw that battery down very quickly. Then discharging and charging that one battery often will then make that battery fail prematurely. Worst case is you end up having 1 battery that dies premature or doesn't hold a change very long, only to find out the other battery is also dead from not being charged.

That is why I personally always run my battery switch in both and charge often. One of the highest premature failures of deep cycle batteries is not charging them often enough or leaving them in a lower voltage situation for long times. In addition to that as I said before, if you are in the both position, then you have a true dual battery bank and it will not draw down your voltage near as quick when running ballast or stereo. In addition to that, the alternator will always be charging BOTH batteries when switch is in both. Granted, it can charge one battery at a time faster than 2, but I currently trailer my boat and I almost always end up having a decent run back to the dock at the end of the day when I am finished. Running the boat at a higher RPM increases the alternator output and seems to do a decent job of recharging the batteries. And like I said, we try and plug up the R&D boats very regularly which again tops off the charge to the batteries.

As a side note, I personally think some of the low voltage codes seen in some of the newer boats are also because most people are running the battery switch in 1 position and not charging the batteries enough. If you were to fill the ballast for 15 minutes, while listening to the stereo with key off, I could definitely see the one battery getting into the 11 volts or less range. That is when we start seeing "low voltage" and this amplifies the possibility of seeing the O2 sensor codes when you start back up. That is another reason we changed the 2018 ballast to only filling when the engine is running. While some people may not like it, with the 6 pumps running, it can drain the battery fairly quickly, especially with the battery in 1 position and key off. IF you do decide to run with the battery switch in "both" but want to sit and listen to the stereo for long times, then you can still move the switch to 1 battery only while you are sitting there. If you did that, then you would probably have a good backup battery if you run the 1 battery dead. Just remember to switch it back to both after you get started and then recharge the battery when you get home.

Hope that makes sense. Sorry about change in topic, but thought it might be helpful as some of you might want to try running the battery in the "both" switch and I hope that everyone will try and charge the batteries more often. Trust me, it will help!


Goose - not to completely hijack this AutoWake thread (which is awesome BTW) but I think maybe now you can see why there is some confusion on the battery setting. If I'm following along correctly, you have said you personally use the battery "1 + 2" setting all the time on the R&D boats and that is what you recommend. That being said, it contradicts what we are told in the Owner's Manual (quoted in the other thread).

Is the Owner's Manual being overly cautious in advising that the "1+2" setting only be used in emergency situations? What about the ground differentiation mentioned in respect to sensitive electronics onboard?

TIA for any clarification!


That is a good question and I will try to answer it as best as I can....

The guy that wrote that sits in the office next to mine. His job is customer service. As many of you know, they deal with problems all day because most of you happy customers never call him to tell him how much you love your boat. Because of that, they sometimes come across a little on the conservative side and especially conservative when we have prior issues with items. As the boats have gotten more electronically advanced, we have had issues with sensitive electronics. Some of that is our fault, some has been vendor issues, but truth is we have also had some issues that could have been avoided IF people would have used a little more common sense to start with. Again, that is when we really get overly conservative on the owners manual side. It reminds me of the warning on the coffee cup that says the liquid inside is hot. Granted, that was probably because of a stupid lawsuit, but I think you get my point.

Anyways, IF you use 2 different style batteries that have different voltages, then you could absolutely get ground differentiation. And having ground differentiation can cause ground loops and other issues. So, part of that statement is true. However, the way it currently reads, it sounds like it will definitely happen all the time and that part is not true. As I and others have said, we highly recommend you use 2 of the exact same style batteries that are sized appropriately and keep them properly charged. If you do that, then you should not have ground differentiation and in fact running them on the both switch location would probably help keep them from having ground differentiation to start with.

Hope that helps clear up the confusion. We are actually planning to change how we word that for the 2018 owners manuals.


It doesn't look like they changed the wording in my 2019 manual and I can't see the 2020 manual online so not sure about it there.

I have always run mine on "1+2" and if my boat is not on the water then the charger is plugged in. I guess it is just a good habit that I started from my fishing boat.

[Branden967]

I thought I read somewhere it was bad to run both 1+2 constantly, something about the excess load on the alternator. Personally I rotate between 1 or 2, and Ive only used 1+2 in an emergency need to the extra crack on the motor mode. Sounds like there isnt a wright or wrong...

[MLA]

something about the excess load on the alternator.

Load on the alternator is relative to the electrical loads and the state of charge of the battery(s). 10 fully charged batteries is less load then one deeply discharged battery.

In another scenario, say you have a single battery boat and carry a jump box. At anchor, you run the battery down, then have to use the jump box to restart that dead battery. Now say you have a dual bank setup and run the house bank down, turn switch to main, start engine, then turn back to 1+2. In both setups, you have one dead battery thats a load to the alternator.

[parrothd]

Also by switching from 1 to 2 you may have a voltage difference between the batteries, ie one full and one empty. When you switch to 1&2 the batteries have to equalize which isn't good for them. The batteries will last longer if they're always equally charged and always being charged so 1&2 is the only option. Unless you like buying replacement batteries. :)

[Branden967]

Awesome info makes sense. Thanks guys.

[Isaguel]

Sheesh!!! why does electrical stuff have to be so D*** complicated... FML.

I'll just stick to what I've been doing. Run on 1 or 2 and plugging in to on board charger at end of day. Clean and simple.

[MLA]

If you have a cranking battery on one bank and a deep-cycle house battery on the other bank, they will NEVER be discharged and charged equally. So this has little to do with how long they last doing their job, compared to each others lifespan.

Its not complicated, it just comes down to what batteries you have, and how you use the boat. Someone else's plan, may not be wrong, but may not be best for you, due to the difference in use and battery type.

I have no issues with running in BOTH or 1+2 even with different type or size batteries with the engine running. With the alternator pumping in and active loads drawing off them no measurable or detrimental equalization will take place.