This post is to document how to properly wire a three battery system in conjunction with a Blue Sea Add A Battery combo (http://bluesea.com/category/2/productline/overview/329) and a ProSport20 Dual Bank onboard battery charger (http://www.pmariner.com/productFeatu...oductNum=42020). Hopefully, this will give someone the confidence to do the install themselves. I thought it would be helpful to show the wiring diagram in three stages as it can get pretty confusing. This is the set up I have which I ran the past two summers without a hitch. I wil post some pics of my install later this week when I finish my current rewiring project.
So below is step 1, which is wiring the switch and the batteries. Note that stereo batteries 1 and 2 are wired together (in parallel) so they act like one, big 12 volt battery. Also note that the 4 pole Dual Circuit Plus Switch is very different that the three pole Perko switch that is commonly installed on our boats. The Dual Circuit Plus is like two separate switches in one housing and does not have a common post like the Perko does.
The idea is to wire all the stereo related stuff to the stereo battery bank via one side of the switch, and the starter and the helm buss to the starting battery via the other side of the switch. When the switch is in the ON position, both sides of the switch are closed, and are separate. In the OFF position, both sides of the switch are open so everything is dead. In the COMBINE position, both sides of the switch are closed and connected together so both batteries are feeding all the electrical loads.
Note that I show suggested wire sizes but I do not show any fuses but they must be installed as specified by the equipment manufacturers.
Step 2 is shown below, in which the Blue Sea ACR is added. Note that a jumper is added between the neg post of stereo battery 1 and the neg post of the starting battery.
The ACR automates the switching process so that you just set it to ON and forget it. When the ACR senses that either battery is receiving a charge from the alternator (in this case, the starting battery), the relay closes so that the charging current is also sent to the stereo battery bank. It does this once it senses 13.0 Volts for more than 2 minutes. So essentially, the relay closes two minutes after the engine is started. Once the engine is off and you are cranking your stereo, once the ACR senses that the batteries combined voltage has fallen below 12.75 Volts for 30 seconds, the relay opens, isolating the batteries. So now your stereo is only draining the stereo bank and you won't accidentally drain your starting battery.
Note that the ACR will not close if either battery bank is less than 10.8 volts. Doing so would cause the batteries to equalize, which means you now have two discharged batteries instead of one.
Step 3 is shown below, which shows the addition of the onboard dual bank smart charger. The ProSport20 is a 20A dual bank smart charger and can send up to 20A to the bank that needs it most. However, since the ACR will detect the charge and it's relay will close, both banks will receive the charging voltage equally and in essence, defeats the purpose of the smart charger. So it's important that a 100A resettable circuit breaker is installed between the ACR and each battery so that the breaker can be opened during onboard charging operation to disable the ACR.
Sorry if this is too much information. I think it will help once you see the pics of my actual install.
Results 1 to 10 of 21
05-03-2011, 04:13 AM #1
Wiring Diagram for Blue Sea Add A Battery (Switch + ACR Combo)Al
2006 Mobius LSV
05-03-2011, 09:20 AM #2
Holy crap, Al! That is fantastic, but I'm sure glad I'm looking at this in the morning with a cup of coffee vs in the evening with a few beers!Drew
New ride: 2012 Mojo
Old ride: 2008 OBV
05-03-2011, 12:23 PM #3
05-03-2011, 12:26 PM #4
David at Earmark,
I know you have done tons of these installs so could you please do us a favor and (1) review my wiring diagram and let us know if you see any errors and (2) let us know if there is a different way to wire this up that would result in operational improvements, and what those improvements are.
Thanks in advance.
2006 Mobius LSV
05-03-2011, 01:21 PM #5
Al, bad question on my part but what does it do? blue sea stuffHey, Its Moomba time
13 Mobius LSV
08 Mobius LSV-sold
03 Mobius LSV-sold
life is about finding the balance between being a responsible adult and staying young at heart
05-03-2011, 02:21 PM #6
Please see step 2 in my original post above but in simple terms, the ACR automatically isolates the starting and stereo batteries when the engine is not running so that if you are playing your stereo, it is only draining the stereo battery. And when you start up the engine, its only using the starting battery. After your engine has been running for about two minutes, the ACR will combine both batteries so that both batteries are getting charged by the alternator. So all you have to do is set the switch to ON and forget it.
Without an ACR, you have to do this manually by switching the Perko switch to battery 2 when the engine is off, to 1 when you are getting ready to start the engine, and to Both after the engine is running. If you forget to switch it to 2 and you are hanging out at party cove for an extended period of time cranking your stereo, you could drain both batteries and not be able to start the engine.
Hope that helps.
2006 Mobius LSV
05-03-2011, 02:31 PM #7
Pertaining to the Blue Sea equipment, you have it wired the way that the manufacturer suggests. This is a complex category. Our approach to this category uses different equipment (same switch but different voltage sensing relay) and our scheme will change according to the boat type (whether the stereo is dependent on the helm buss for touch screen controls or can be wired totally independent), the amount of current draw from the audio equipment and the amount of reserve time for the stereo batteries. One of the largest problems with ACR/VSRs is they don't combine after a long period at rest with a large stereo so the stereo bank isn't brought on line with the alternator as expected. Not a problem if you are going straight home but a definite concern if its a long weekend with no AC access. So we have schemes to confront the problems of systems becoming too large and exceeding the functional limits for which the ACR/VSRs were originally intended. This category should not be generalized with a one scheme fits all approach.
Contact me via email so I can learn more about what equipment you have or will have, your total battery reserves and how you will use the system and boat most weekends. At that time I can make some suggestions that will be specific to only your sysyem. Give me a little time as its crazy this time of year.