Dual Battery system

[mvd]

Question:

How does the dual battery system works? I always use selector 1. But now battery 1 got drained. My dealers said that the accesoiry battery doesn't charge when the selector is at 1 and i always should keep it at 1+2. Only when i am not running the engine i have to put it on selector 1 to keep the battery 2 full.

Is this correct?

[JesseC]

That is the way my old Formula used to work. When we threw out the anchor and just listened to the radio, we alwasy flipped the selector to battery 1. The radio would play and possibly kill battery 1, but we always selected "both" before starting the boat up again and left it on "both" until we stopped to swim again.

Hope this helps.

[mvd]

That is the way my old Formula used to work. When we threw out the anchor and just listened to the radio, we alwasy flipped the selector to battery 1. The radio would play and possibly kill battery 1, but we always selected "both" before starting the boat up again and left it on "both" until we stopped to swim again.

Hope this helps.

But if you select 1, does the battery get charged when starting?

I thought that you always have to select 1. I case your battery got drained you always have power to start when selecting both. But battery 1 should be charged always, even when selecting 1 or both???

[zabooda]

What you have is a selector switch and whatever shows on your switch either 1, 2 or 1+2 is what is now connected to your boat electrical system. That means when the boat engine is not running the components turned on (i.e. stereo, lights ...) are draining from the battery that you selected. When the engine is running the alternator is charging the battery you selected. So you decide which battery will be your starting battery (we'll call it #1) and which battery will be your accessory battery (call it #2). When you start the engine, you use battery 1 and the switch selector should be on 1, when you get the engine started then you want both batteries charging and switch to 1+2, when your engine is off and your listening to your music, your mood lights on and have your laptop plugged in then you want to be on battery 2 so you isolate your starting battery so you can go home later at which time you will change to battery 1 to start your engine and switch to 1+2 once the engine is started to charge both batteries.

Simple huh, still more to come. When the engine is off, you should not keep the switch in the 1+2 position as it will equalize out the weak and the strong battery which can be a problem if one battery is much weaker than the other. There are devices that do all of this automatically but they are much more expensive and more prone to failure. The system you have the failure would likely be operator error in which case you ask around for someone who may have jumper cables nearby if you left the switch in 1+2 and drained both batteries. Hope that helps.

[mvd]

Hope that helps.

Thanks Zabooda, very helpfull answer.

Why did they not designed that if selected battery 1 it also get charged when the engine is running? That way you can always keep it at selection 1, but when this battery got drained you can switch to battery 2 to get home.

Is this coorcet?

Starting: Change from 0 to battery 1+2
Cruising: Leave it on 1+2
Swiming: Change to battery 1
Cruising: Change to 1+2
Docking: Change to 0

[gotmyboat]

MVD -

Docking you will want it either 1 or 2 or both. If you have it on 0 then the auto bilge won't work, and you could come back to a disaster. The only time I would turn it to 0 is if it was on the trailer with the plug pulled (no water possible in the bilge.)

Dave

[zabooda]

I made some changes to your logic. You can run one battery down and go to the next battery as you asked about but it will decrease the life of your batteries, as starting batteries are not designed for a significant power drain and then a big recharge on a regular basis so you designate one battery for starting and the other battery for accessories. The accessory battery can be a deep cycle battery designed for that purpose. People in the RV business or who own RVs can show you how it works, as the dual battery system is the basic system that is used. When I charge my RV accessory batteries after a week of camping using the engine alternator, the alternator may put out 70 amps to the batteries and the draw from the alternator actually slows down the idle from the 454 engine. Good battery management will save you $$ down the road by using the right battery for the right purpose and taking care of them when your boat is not being used for a long period of time.


[Assuming Battery 1 is the starting battery]
Starting: Battery 1
Cruising: SWITCH on 1+2
Swimming: SWITCH to battery 2 (if you plan to use accessories)
Cruising: Change to 1+2
Docking: Change to 1

I’m not familiar with the “0” position except it may disconnect both batteries from the system which is not what you want because you have components that require power for the memory systems like the clock and stereo.

[mvd]

With 0 i mean the down postition. This is the red section on the selector.
If this is selected everything is still working (bilge, blower, radio) but the engine can not be started. On selection 1 or 1+2 the engine can be started.

In my example 1 is the accessoirie battery en 2 is the starting battery.
I conclude this because batt 2 is always charged

When selecting 1 this battery in not beeing charged, when selecting 1+2 both battery's are charged.

So my logic would be:

1: accessoirie bat
2: starting bat

Starting: 1 or 1+2
Cruising: 1+2
Swiming and relaxing: switch to 1
Cruising: 1+2
Docking: 0

I assume that al Moomba's are wirred the same way.
I also thing its wierd that selection 0 does not cut all the power exept for the bilge.

My best future option would be:

0= cut all power exept bilge
1= Accessoirie battery who get charged when enigine is running
1+ 2 =Starting battery who get charged when engine is running

Does this make sence?

[Buttafewcoe]

Ah, another mystery solved
.
B

[zabooda]

Everything looks good except:

2: starting bat

Starting: 1 or 1+2

Change to:
2: starting bat

Starting: 2

#2 is your starting battery so start the engine with #2 only since battery #1, the accessory battery, may be discharged and be more of a power load than a power source.

[mvd]

Everything looks good except:

2: starting bat

Starting: 1 or 1+2

Change to:
2: starting bat

Starting: 2

#2 is your starting battery so start the engine with #2 only since battery #1, the accessory battery, may be discharged and be more of a power load than a power source.

I have on the factory installed selector

0 (down) 1 (left) and 1+2(up) 2 (right)

I now notiched the selection 2 :oops:

So last question, when draining the battery in selection 1+2, will it be possible to start when changing to selection 2?

Why is this so difficult :lol:

[tazz3069]

I just got mine installed this past week. Mine says #1, #2, both, and off. When running the boat, I keep it on both. When running the stereo, lights, and accesories, I keep it on #2. When I am ready to start the engine, I set it to both. When the boat is in storage, I set it to off. When the switch is in the both position, it charges both batteries. When #1 or #2 is selected, it only charges that battery. I hope this helps.

[moomba_armada]

For what I have read:

-Both batteries while running,charging mode.
-One battery kept only to start the engine.
-Other battery while accesories are working with the engine off.
-At the dock both batteries off.



Is that right,seems logical...

[mvd]

this dual thing is difficult. the manual isn't verry helpful how to opperate. there also isn,t a controle light on th selector like the manual says.
maybe SC should rewrite this part?

[moomba_armada]

Dual Battery Option Hookup
The dual battery option is designed to give you extra
battery power to run accessories, but at the same time
give you a safety feature not commonly found in a dual
battery setup. The Moomba Dual battery option features
a Voltage Sensitive relay which always monitors the
engine starting battery so that your engine will always
restart.
We recommend that the selector switch always be set
to “1”. In the “1” position, the Voltage Sensitive Relay
monitors the engine starting battery, which will ensure
that you have a fully charged battery to start your boat.
The “House” or Accessory” battery may become drained
during a high discharge cycle since it does not get
charged until the Starting battery is fully charged.
In position “1” when the Sensed battery (engine starting
battery) reaches 13.7 volts, the relay closes and parallels
both batteries. When this happens the LED light on
Voltage Sensitive Relay comes on.
In position “2” the sensed battery is the accessory
battery. We do not recommend using this position since
it can cause the starting battery to drain, which would
not allow the engine battery to have enough power to
restart your boat.
In position “both”, the batteries are paralleled and in a
high discharge cycle, both batteries can become
drained, which would not allow the engine battery to
have enough power to restart your boat.
NOTE: It is recommended that you fully recharge
your batteries using a battery charger periodically
or after a session of high discharge (lots of
accessories running for an extended period).
NOTE: It is possible with this system for accessories
to shut down when the engine is running due to
the accessory battery draining down. This is a
safety feature. This system monitors the starting
battery and will sacrifice the accessory battery so
that you are not stranded on the water with a weak
starting battery.
NOTE: We highly recommend using high quality
“Dual-Purpose Batteries” in both the starting and
house position.

[mvd]

I read this part in the manual.

I left it on 1 for a week and even running the engine it got drained (accessorie batt) The starting battery (2) was fully charged. When i switched to 1+2 the accessorie battery got charged (tested it with an multimeter).

There is noLED light on Voltage Sensitive Relay on the selector.
I think that they used an older version in the manual. My dealer said to put it always on 1+2 when the engine is running. That way both battery's are charged.

It would be nice if an moomba enginer would give his opinion on this matter because i think there are to much different options how this works

[zabooda]

When in doubt, trace the wiring and draw a schematic. There is no assurances that the device was wired correctly and when you go through the system you will get familiar to how the switch works. When you go from describing switches to adding relay(s) in the mix then you have changed the process to how the "switch" works. Find the manufacterer of the switch and contact them and if the switch is connected correctly then they should be able to explain the different steps needed to keep the system running correctly.