Battery switch, how do I use it?

[peterjaw]

Good day, captains,
My Quicksilver 855 weekend comes with 2 batteries, battery 1 and battery 2.

There is a battery switch that I can select battery 1, battery 2, battery 1+2, and OFF.

My dealer tells me to alternatively use battery 1 and battery 2, which means use battery 1 this time, battery 2 next time, and so on....

For avoid messing up, I use battery 1+2 currently.

My question is, during normal operation which position should I switch to? On the user's manual, it says in emergency situation, switch to 1+2. I wonder what kind of emergency situation is it talking about?

Thanks for your help.


ps. I have no idea which battery is for house and which is for engine, neither does the dealer.

 

[sarabande]

A number of questions.

What is the engine, and size of alternator ?

Do you have a boat manual from the dealer ? Does it have a circuit diagram ? Or an "as installed" diagram ?

WHY does the dealer not know which battery does what ? That is what he is paid to know.

What are the labelled voltages and capacities (AHr), CCA, etc of each battery ?

Does the engine start if the battery switch is on 1 ONLY, or 2 ONLY ?

Do the cabin lights work on 1 ONLY, or 2 ONLY ?


Now it could be that one battery is for engine starting, and one for cabin lights etc, or it could be that both batteries are in parallel, or even in series depending on the specification. Until you can track the connections and battery cabling ( the heavy duty ones) we cannot be certain that you have a normal installation, or a modified one.


It would be normal practice for each battery to be 12v, and for one battery to be for the engine, and one for domestic lighting. When you can confirm the layout and sizes, it will be possible to give more specific advice on how to operate the battery switch to the best advantage.

In any case, whatever happens, never switch to OFF, with the engine running, as this can damage the alternator.

More info needed

 

[peterjaw]

Thank you very much, sarabande.
I am trying to answer your questions below:

What is the engine, and size of alternator ?
---- Mercury Verado 300, no alternator except the build-in one with the engine, it is 70 Amp

Do you have a boat manual from the dealer ? Does it have a circuit diagram ? Or an "as installed" diagram ?
--- Yes, I have boat manual from manufacturer. There is DC wiring schematic in the manual, but I don't know how to interpret it.

WHY does the dealer not know which battery does what ?
--- Good question, I have no idea either.

What are the labelled voltages and capacities (AHr), CCA, etc of each battery ?
Does the engine start if the battery switch is on 1 ONLY, or 2 ONLY ?
Do the cabin lights work on 1 ONLY, or 2 ONLY ?
--- I haven't had chance to find out yet, but I will check these out when next time I go to the marina.
=======================================================================================

From your questions above, it looks like each battery is dedicated to one purpose only, to start the engine or to light up the cabin, right?
Or I misunderstand your descriptions?

Here I capture the battery schematic from the manual:

 

[sarabande]

Thta's beginning to look as if the system is designed to be one battery for engine, and one for domestics (the terminal with bilge pumps and "memory").

If you leave the switch on BOTH, you are using both batteries for starting (which is not necessary except in an emergency) and both for Domestic. The risk is that if you leave a light on while you are away you may flatten both batteries.

Switch on position BOTH while running the engine does not really matter as the alternator is big enough to charge both. It would be usual to start the engine using position1 (if that is the engine battery) then change to position 2 (domestic) after a few minutes to recharge the engine battery. Do you have a single voltmeter or one for each battery ?

Without being certain that the switch is wired as I suspect, I would leave the boat with the switch on position 2 (domestic) so that the engine battery 1 is left fully charged, and the domestic battery 2 runs the pumps and "memory" while you are away. When you return to the boat, switch to position 1 to start the engine, and then leave it on 1, or switch to 2 or BOTH, depending on what the voltmeter says and how you want to manage the charging.

You need to confirm which battery does which, by confirming the cable routing.

 

[peterjaw]

Question answered

So, what are your suggestions for me?

 

[PCUK]

With your present set-up both batteries do everything, either on their own or together. This means everything works in all switch positions. Ideally you need a third battery on a totally separate switch for engine starting only and the original two batteries disconnected from the engine. This would prevent you flattening both batteries and being unable to start the engine.

However, you can continue with your present system if you select either battery one or two and keep the other one for engine starting. This means you can always start the engine. Using both batteries together means you could flatten both using the lights etc. and then be unable to start the engine.

The emergency the dealer is talking about is this point of flattening both batteries and being unable to start.

A dedicated engine start battery as described is the optimum set-up although this would incur further costs.
Cheers, Peter

 

[Paul_S123]

Can you take and post a pic of the switch.

I had a Quicksilver 705 and it had 2 batteries too, but they were just wired together and acted as one. Looked like a house and a engine battery but they were not.

I ended up leaving them connected and adding a 3rd battery and the add a battery system posted below. I kept the new 3rd battery for engine starting only and the kit comes with an automatic changeover so it charges the engine batt first, then switches to the house batteries.

It was well worth doing.

Post a pic, you may already have some of the components.

https://www.bluesea.com/products/7650/Add-A-Battery_Kit_-_120A

 

[jfm]

Based on your diagram I would suggest you do exactly as dealer says. I would suggest you never select BOTH because you run the risk of something flattening both batteries and then you can’t start engine.

I say all that as a good rule of thumb based on the thought that you don’t have a deep understanding of DC electrics. If you know what you’re doing in some detail, it would be smart to use BOTH in some circs. But as a basic simple rule I would say your dealer is correct.

When the boat is berthed unattended select OFF

You don’t need to fit a 3rd battery in my view, if you follow the above advice.

 

[jfm]

Thta's beginning to look as if the system is designed to be one battery for engine, and one for domestics (the terminal with bilge pumps and "memory").

If you leave the switch on BOTH, you are using both batteries for starting (which is not necessary except in an emergency) and both for Domestic. The risk is that if you leave a light on while you are away you may flatten both batteries.

Switch on position BOTH while running the engine does not really matter as the alternator is big enough to charge both. It would be usual to start the engine using position1 (if that is the engine battery) then change to position 2 (domestic) after a few minutes to recharge the engine battery. Do you have a single voltmeter or one for each battery ?

Without being certain that the switch is wired as I suspect, I would leave the boat with the switch on position 2 (domestic) so that the engine battery 1 is left fully charged, and the domestic battery 2 runs the pumps and "memory" while you are away. When you return to the boat, switch to position 1 to start the engine, and then leave it on 1, or switch to 2 or BOTH, depending on what the voltmeter says and how you want to manage the charging.

You need to confirm which battery does which, by confirming the cable routing.

sarabande, your post above suggests you have not interpreted the wiring diagram correctly. Maybe take another look?

 

[Glenlivet]

I’d have thought the left hand battery in the diag should be the house battery as the neg goes to the busbar. The problem with is that if the right hand battery is turned off (either while running OR when away from the boat) the bilge pumps won’t run. In which case the right hand battery should always be on when the boat is afloat, except to start the engine.

 

[jfm]

That is totally and completely wrong, every word of it. You seem to have completely misunderstood the wiring diagram.

 

[peterjaw]

Thank you very much, captains.
Based on all your suggestions, I read through the portion of electrical system on the manual again. Here is what I found:


If I understand correctly, both battery 1 and battery 2 work as engine and domestic battery. Am I right?

========================================================================================
As regarding to the picture of the switch, since I am away from the marina so here is the drawing of the switch that I captured from the
manual.


No sure if this drawing will work, but I will take a photo when I go to marina next time.

Thank you very much for your help.

 

[PCUK]

If I understand correctly, both battery 1 and battery 2 work as engine and domestic battery. Am I right?
---------------------------

Yes, as I said in my previous post, which tells you everything you need to know!

 

[prv]

I'm puzzled at the confusion displayed on this thread (in some of the answers, not the OP). According to the diagram this is the absolutely standard traditional wiring for a 1-2-both switch. It's not a particularly good system, but it should be commonly understood.

The switch simply controls which battery (or batteries) is being used, for everything. The other is disconnected and will be neither used nor recharged.

The "normal" way to operate it is to select "Both" when the engine is running, so that both batteries get charged. Then after you stop the engine, select "2" to run the boat off battery 2 only - this ensures that even if you run it down flat with TVs and fridges and so on, battery 1 will still be nice and full to restart the engine to get home. Some people switch to "1" to start the engine before going to "both" for charging; to be honest it doesn't really matter unless battery 2 is pretty low.

In the previous paragraph I have you treating 1 as the "engine battery" and 2 as the "house" battery. In the traditional system the two batteries are identical and it doesn't matter which way round you use them; some people swap periodically to even out wear. Your boat however has some "always-on" circuits which could drain the right-hand (I am assuming number 2, since they're not labelled) battery even when it's not selected. If the two batteries are the same size, you should consider this one the "service" battery, to avoid ever being left with a flat engine battery. That's why I used the numbers the way round I did in the previous paragraph. However, next time you're at the boat, the first thing to check is whether one of the batteries (count multiples connected together as a single bigger battery for these purposes) is bigger than the other. If so, ignore the rest of this paragraph and treat the bigger one as the service battery.

Once you've established which is which, it might be a good idea to label the "1" and "2" at the switch with "engine" and "service" - especially if they are different sizes.

This is quite an old-fashioned system; there are better ways of doing things nowadays where you simply turn on one "boat master" switch when you arrive and all use and charging is automatic. But the old way is cheaper for boatbuilders to fit...

Pete

 

[peterjaw]

Thank you very much, Pete.

So, are you saying that if I switch to "1" then only battery 1 will be used and charged,
even if battery 2 are low it won't be charged unless I switch to "2" or "1+2" ?

If this is the case, then I will switch to one certain battery when in anchorage for water
activities, picnicking, snorkeling ...etc. to avoid accidentally flat out both batteries. And
when I want to go home, I switch to another battery for starting the engine. After starting
the engine, switch to the position that I can charge the other battery (or both battery).

Will this be a logical way?

 

[paultallett]

Pete has your answer, we have the same set up on our boat.

When we arrive we select a battery via the switch to power the boats systems (then click on the mains charger to keep both batteries topped up). When we want to go somewhere we turn the mains charger off, select both on the battery switch, start the engine and head off. Whilst the engine is running both batteries are being charged by the alternator.

Once we arrive at our destination and have switched the engine off we select a single battery to power systems again.

It's very straight forwards and has cause no issues in the 10 years we have owned our boat. Indeed we are still on the same batteries.

Hope that helps,


Paul.

 

[BB1]

BOTH while engine is running, either 1 or 2 when stopped for the night.
Niether battery is dedicated to domestic or engine start, whichever battery is selected is the one feeding the whole boat and the one being charged from the engine.
A very simple system.
You have the option of sending all charge to one battery if desired.

 

[peterjaw]

Thank you very much for advices, captains.

I know what to do now.

By the way, I have checked the 2 batteries yesterday. They are identical.

 

[RupertW]

The only thing that makes me uncomfortable about the advice above is the suggestion that you put the switch onto BOTH to start the engine. Although that will pretty much always be fine, it will hide a flattened Battery 1 (engine battery) which could happen through age or a connection problem draining it somehow. So you happily start up on BOTH maybe for months and are actually relying entirely on Battery 2 for all that time.

Then when you happen just once to flatten Battery 2 with inverter, lights etc etc your backup Battery 1 is not there for you. My habit when I had this setup was to (as some have said) always start on Batt 1 only, thus testing it every time. Then switch to BOTH once the voltage had got above 12.7 which was usually immediately. If it dropped low after putting it to BOTH then I'd put it to Batt 2 and allow that to rise to 12.7 before going back to BOTH.

Now I have VSR, diodes etc and independent battery switch so I don't have to do anything especially as I now have other people on board and I think the 1-2-BOTH solution is perfect for boating where just one person is doing everything and understands 12 v systems enough, but hopeless if not.

 

[peterjaw]

Hi Rupert,
Thank you very much for your advice, your solution provides an quick inspection every time I start the engine. Good idea.

I don't understand your description below:

" If it dropped low after putting it to BOTH then I'd put it to Batt 2 and allow that to rise to 12.7 before going back to BOTH."

When switching to BOTH, both batteries are charged (if needed), why do you switch to Batt 2 and wait for fully charged then
switch back to BOTH? Can't I just remain in BOTH?