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Old 06-08-2015, 16:15   #1
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Help me wire this, please

I have a solar panel, a solar charge controller, two batteries, a perko switch, and no real idea how I'm supposed to wire them all together.

There is no engine in this system. I would like to be able to isolate the batteries from each other if possible.

The charge controller I have can charge two banks. Should I treat each battery as a separate bank or combine them as one bank?

Could you please give me an idea about the best way to set this up?

Please feel free to doodle or mark up the attached drawing as you see fit.

Thank you in advance!!
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Old 06-08-2015, 17:44   #2
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Re: Help me wire this, please

Quote:
Originally Posted by Dexterbase View Post
I have a solar panel, a solar charge controller, two batteries, a perko switch, and no real idea how I'm supposed to wire them all together.

There is no engine in this system. I would like to be able to isolate the batteries from each other if possible.

The charge controller I have can charge two banks. Should I treat each battery as a separate bank or combine them as one bank?

Could you please give me an idea about the best way to set this up?

Please feel free to doodle or mark up the attached drawing as you see fit.

Thank you in advance!!
Why do you want to isolate the batteries from each other? These days it is agreed that it is better to have one bigger house bank rather than two small house banks.

Please post model number of the switch, solar panels and batteries. That will affect the detail of the answers.

Also please post details of what are the loads, ie what do you want to use the batteries for and how do ou plan to use the boat (dasysiling, weekending, passage making, etc and left at marina with shorepower or on a mooring without)
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Old 06-08-2015, 20:12   #3
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Re: Help me wire this, please

I can't imagine the size of the batteries affecting where to plug what into what though? I may be wrong.

This is a diagram for two 75ah batteries and a kyocera kc-120 panel. Morningstar Sunsaver Duo charge controller.

I basically need to know where to tie the charge coming out of the charge controller to the rest of the system.

This boat sits on a mooring with no access to shore power.
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Old 06-08-2015, 20:21   #4
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Re: Help me wire this, please

connect direct to each battery with a fuse at batteries.
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Old 06-08-2015, 20:32   #5
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Re: Help me wire this, please

Parallel the two batteries into one bank.

Install a Blue Sea Systems battery terminal fuse to the terminal that will feed your DC panel.

Connect the output of the charge controller to the terminal fuse.

Connect the output of the battery at the terminal fuse to the switch and the output of the switch to the DC panel.

This is the ultimate, simple basic, no frills setup. Ignores engine starting battery or any other complexities.
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Old 06-08-2015, 21:19   #6
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Re: Help me wire this, please

If you want separated batteries I believe this drawing will do the job.

I can't say I'm much of an "artist" but hopefully its readable.

I'll also point out that the manual says the Duo Charge has a common ground so you should be able to have just one ground wire to the negative buss. You also don't really need a positive buss bar in this layout.

Oh yea... there should be a negative wire from the panel to the negative buss. I kinda forgot that part.
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Old 07-08-2015, 06:20   #7
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Re: Help me wire this, please

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Originally Posted by Dexterbase View Post
I can't imagine the size of the batteries affecting where to plug what into what though? I may be wrong.
You have not said if the batteries are 12V or 6V batteries, which affects the way you connect them (series or parallel, assuming you have 12V loads of course).

The Ah or CCA rating of the batteries will affect the spec of breaker/fuse(s).
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Old 07-08-2015, 06:41   #8
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Re: Help me wire this, please

Quote:
Originally Posted by Dexterbase View Post

This is a diagram for two 75ah batteries and a kyocera kc-120 panel. Morningstar Sunsaver Duo charge controller.

I basically need to know where to tie the charge coming out of the charge controller to the rest of the system.

This boat sits on a mooring with no access to shore power.
As always, the quality of the answers you get is affected by the info you provide and whether you make assumptions beyond your knowledge. You have not said what is "the rest of the system" and this would determine the best answer.

Any way.. If the current system does not have any fuses then, as suggested by skipmac, you want to install a MRBF fuse on top of the positive terminal that is connected directly to the panel.

If you insist in not combining the two batteries into a single bank then you will need two MRBF fuses. Also make sure DIP switch 3 is set to 50/50. Yeti´s drawing will help you but you need to add the two MRBF fuses. You also need to add a 30A or so fuse close to the battery end of the red wire that connects controller to battery. This addition fuse will let you work on the controller without disconnecting all loads, and will make sure the controller is protected regardless of what the rating of the MRBF fuse (driven by variables that you have not provided)is

Make sure that this red wire between battery and controller is actually connected to the MRBF fuse, not the nattery terminal, to make sure you get the high interrupting capacity of the MRBF fuse to protect the blade fuse.

If you combine the two batteries (provided the two batteries are close) you only need one fuse of each type, but make sure that the bridge wire that connects both battery positive terminal is located between the fuse and the battery.
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Old 07-08-2015, 08:16   #9
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Re: Help me wire this, please

Quote:
Originally Posted by svlamorocha View Post
As always, the quality of the answers you get is affected by the info you provide and whether you make assumptions beyond your knowledge. You have not said what is "the rest of the system" and this would determine the best answer.

Any way.. If the current system does not have any fuses then, as suggested by skipmac, you want to install a MRBF fuse on top of the positive terminal that is connected directly to the panel.

If you insist in not combining the two batteries into a single bank then you will need two MRBF fuses. Also make sure DIP switch 3 is set to 50/50. Yeti´s drawing will help you but you need to add the two MRBF fuses. You also need to add a 30A or so fuse close to the battery end of the red wire that connects controller to battery. This addition fuse will let you work on the controller without disconnecting all loads, and will make sure the controller is protected regardless of what the rating of the MRBF fuse (driven by variables that you have not provided)is

Make sure that this red wire between battery and controller is actually connected to the MRBF fuse, not the nattery terminal, to make sure you get the high interrupting capacity of the MRBF fuse to protect the blade fuse.

If you combine the two batteries (provided the two batteries are close) you only need one fuse of each type, but make sure that the bridge wire that connects both battery positive terminal is located between the fuse and the battery.
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Old 07-08-2015, 08:20   #10
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Re: Help me wire this, please

You all are amazing.

You are correct, the batteries are 12v 75ah batteries and they're sitting end to end in the battery box. So the consensus is that they're best combined into a single bank rather than treated as separate batteries?
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Old 07-08-2015, 08:31   #11
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Re: Help me wire this, please

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You all are amazing.

(snip) So the consensus is that they're best combined into a single bank rather than treated as separate batteries?
You have not told us what are the loads that will be fed by those batteries...

.. but under most possible scenarios the common wisdom these days is that you prefer to run all batteries in parallel as a single bank. This will extend battery life (shallower discharges) and save energy (Peukert effect).

The only common exception to that is if you have an engine that you want to be able to start even if you "kill" one bank with a load such as a fridge that is left on without a low voltage disconnect. I believe Maine Sail will not even grant that exception and I like his logic. If I was wiring my boat from scratch I would merge house and engine banks into one.

Even if you do not have an engine, if you have a fridge make sure the low voltage disconnect is set to a proper (higher than default) value and the wires that feed the fridge are fat enough to make drop negligible. Your batteries will thank you for that.
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Old 07-08-2015, 08:36   #12
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Re: Help me wire this, please

Quote:
Originally Posted by Dexterbase View Post
You all are amazing.

You are correct, the batteries are 12v 75ah batteries and they're sitting end to end in the battery box.
Make sure you connect them in a way that equalized voltage drop for both batteries, ie the positive wire that feeds the panel starts from one battery and the negative wire that goes to the panel starts from the other battery. See drawing from Trojan:



Of course, given that the batteries are placed "end to end" you will need longer wires.

**
Note that the gauge of the wires and rating of the fuses/breakers will depend on the panel and loads you have or will have..
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Old 07-08-2015, 08:52   #13
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Re: Help me wire this, please

Quote:
Originally Posted by svlamorocha View Post
You have not told us what are the loads that will be fed by those batteries...

.. but under most possible scenarios the common wisdom these days is that you prefer to run all batteries in parallel as a single bank. This will extend battery life (shallower discharges) and save energy (Peukert effect).

The only common exception to that is if you have an engine that you want to be able to start even if you "kill" one bank with a load such as a fridge that is left on without a low voltage disconnect. I believe Maine Sail will not even grant that exception and I like his logic. If I was wiring my boat from scratch I would merge house and engine banks into one.

Even if you do not have an engine, if you have a fridge make sure the low voltage disconnect is set to a proper (higher than default) value and the wires that feed the fridge are fat enough to make drop negligible. Your batteries will thank you for that.
I'm totally on the same page with all this except merging house and engine banks. Maybe coastal cruising this would work but I've been stranded in the middle of nowhere 2-3 times (yes it was operator error, failure to monitor batteries and switches, etc but hey, I'm not yet perfect ) without juice to start the engine so I want a separate, isolated, protected, dedicated start battery.
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Old 07-08-2015, 10:26   #14
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Re: Help me wire this, please

Whats the rated output of the panel? whats the rated Amp/hr of the batteries in each bank. what is the stimated daily amp/hr usage. What latitude are you normally in?

Say I have 60 amp/hr usage, one banks amp/hr rating should be 3x that and my solar out put should be at least 2x the usage. which will screw you on a week of cloudy days you'll need some other source of temporary charging. ok I'm around the 25th parallel so 400 watts of solar will give me an average of about 120 amp/hrs a day. I have 15 ft of actual run to the charge controller. I'll need a pos, neg and ground of 8 gauge wire or equivalent, to the controller I'll need the same to the batteries two bank controller, two banks. run pos & neg from bank 1 on controller to pos & neg on bank i do same with bank 2. your not cranking engines so #4 or even #6 wire would work to the batt switch. I'd use #4. run pos of each bank to the perspective terminal on batt switch run same size wire from common on switch to pos busbar. run same size wires from neg terminal on batt bank to neg busbar.

unless you charge controller states otherwise do not run its neg to the common neg. your controller will decide which bank needs the most charge.

Run the ground from the panel to the engine block or other path to earth. not through the neg side of your circuitry. any ground circuit should always be as close, in the electrical path, as it can get to earth. not in the beginning,not in the middle, but at the end as close as you can reasonably get to earth. the water your floating is earth.

hope this will help you. there is a book by Don Casey "sailboat Electrics simplified" It will answer all your previous questions plus all the ones you didn't know you needed to ask. and all the terminology is based on a high school level. So, easily understood. Hell I know a housewife that excelled through it and now fixes her own stuff.
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Old 07-08-2015, 10:59   #15
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Re: Help me wire this, please

Quote:
Originally Posted by Yeti View Post
If you want separated batteries I believe this drawing will do the job.

I can't say I'm much of an "artist" but hopefully its readable.

I'll also point out that the manual says the Duo Charge has a common ground so you should be able to have just one ground wire to the negative buss. You also don't really need a positive buss bar in this layout.

Oh yea... there should be a negative wire from the panel to the negative buss. I kinda forgot that part.
I agree with this solution. Although the drawing leaves something to be desired.

In short, connect the charge controller pos and neg for each "bank" to each battery. Yes, in this case each battery is a bank of one. You might double check that the charge controller isolates the banks...but thats the fundamental function of having a 2 bank controller, so I would be surprised if it didn't.

An alternative would be to connect the pos and neg of the charge controller to the common pos and neg of the selector switch. This would allow you to select which battery is charged via the switch. However, it would also have the unexpected affect of providing power to the panel even when the switch is off...so I would not go this route. Its preferred to be able to charge the batteries all the time, even with the switch off...which is why the charge controller should go directly to the batteries.

Also, time to read some 12volt books and learn more about electricity. Its not complicated or difficult. Just one more skill its handy to have on your boat.
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