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Old 10-02-2021, 06:15   #1
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Where to cconnect MPPT output?

Hello all,


I am installing a Victron MPPT 30 with one LG 375 Panel, I am not sure where to connect the output of the controller into my boats DC system, please comment or make a suggestion as to the idea input.



At first I was thinking to connect to the Common of the house Battery switch but I am not 100% sure.


Welcome all comments....
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Old 10-02-2021, 06:38   #2
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Re: Where to cconnect MPPT output?

Look up pacific yacht systems on youtube. Jeff Cote is god when it comes to this stuff. I would bet he would say that it needs to be fused and directly to the battery. An acr or combiner to charge the other bank. He dislikes connection to switches because if you turn it off without covering the panel you will blow a diode.
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Old 10-02-2021, 06:46   #3
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Re: Where to cconnect MPPT output?

Connect the positive (fused) to the house battery, connect the negative to the battery monitor shunt if you have one. Battery negative ,if not.


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Old 10-02-2021, 06:58   #4
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Re: Where to cconnect MPPT output?

OK, but the positive of House battery 1 or 2?.....that's where I am unsure..
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Old 10-02-2021, 07:02   #5
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Re: Where to cconnect MPPT output?

Use a charge splitter diode , and connect to both.


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Old 10-02-2021, 07:25   #6
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Re: Where to cconnect MPPT output?

So much of this really depends on the physical layout, where you have to run wires, and how happy you are with the current operations.

You could hook it up to the common of the switch in the same position as the inverter/charger and alternator. If you run mostly in "all", or you're fine with the current charging setup from the alternator and inverter/charger, then why not add another charging source there? Simple, but if you switch between 1 and 2 regularly then you'll have to manage the charging (same as you would have to with the alternator and inverter/charger).

Or you could connect the positive to the input of the isolator shown at the alternator output. That would also then charge the start batteries (if that is desirable).

Or you could connect to output 1 of the isolator (if that is close by), which is essentially the same as the common of the 1-2-All switch.

All of those though, mean that the solar panel will be disconnected if the switch is "off". If you switch off when leaving the boat, and if you want the solar panel to keep things topped up when gone....
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Old 10-02-2021, 07:41   #7
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Re: Where to cconnect MPPT output?

OK,, Only time I have ever turned the House battery switch off is when I had to do some kind of maintenance, so its normally always in the all position.


Here is a picture of the house battery bank, switch and the main DC panel to the left.


Thanks...
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Old 10-02-2021, 08:42   #8
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Re: Where to cconnect MPPT output?

Quote:
Originally Posted by Drew- View Post
Look up pacific yacht systems on youtube. Jeff Cote is god when it comes to this stuff. I would bet he would say that it needs to be fused and directly to the battery. An acr or combiner to charge the other bank. He dislikes connection to switches because if you turn it off without covering the panel you will blow a diode.
Interesting. I have my panels wired to a breaker before the controller on both of my boats. I have switched them off many times for one reason or another and never had any issues with the diodes.
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Old 10-02-2021, 08:47   #9
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Re: Where to cconnect MPPT output?

If you connect controller output to the common of the switch then you have to keep switch in ALL position if you want both batteries to be charged all the time and it kind of defeats the purpose of the switch. Also if switch is left in OFF position then batteries won't be charged at all.
It is better to connect the controller output to terminal 1 or 2 and add ACR between 1 and 2. And you need( or rather must) to fuse the wire at the at the switch not at the controller. Fuse at the controller is optional.
In general it is recommended that MPPT connected directly to the battery but sometime it is difficult and costly to do.
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Old 10-02-2021, 09:02   #10
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Re: Where to cconnect MPPT output?

Quote:
Originally Posted by Drew- View Post
Look up pacific yacht systems on youtube. Jeff Cote is god when it comes to this stuff. I would bet he would say that it needs to be fused and directly to the battery. An acr or combiner to charge the other bank. He dislikes connection to switches because if you turn it off without covering the panel you will blow a diode.
Wait... Say what? I think you misunderstood something that your god said. What "diode" are you talking about?

Are you saying that a solar panel will blow a diode if it is in the sun and not connected to anything? That is not true.

Maybe you saying that a Victron MPPT will blow an internal diode if its output in not connected to the battery and the panels are in the sun? That is not true.
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Old 10-02-2021, 09:42   #11
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Re: Where to cconnect MPPT output?

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Originally Posted by manitu View Post
Use a charge splitter diode , and connect to both.


.manitu
charge splitting diodes are generally a bad idea. If you do use diodes in this manner your charge voltage settings need to be adjusted to compensate for the voltage drop across the diodes.

I suggest connecting your panel directly to one of your house banks. Then that bank will always get charged and when your battery switch is in the all position all the batteries will be charged.
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Old 10-02-2021, 09:48   #12
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Re: Where to cconnect MPPT output?

Well I have one bank, (other than the start battery),, consisting of 2 8D batteries, which are only connected in parallel when the battery switch is in the All position..

its the factory wiring setup i having to deal with..Connecting the mppt output to just one of the two doesn't seem right....am I wrong?
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Old 10-02-2021, 10:08   #13
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Where to cconnect MPPT output?

I have two batteries set up as one bank, both connected to the common bus bar before going to appliances or electric panel.
I connected my MPPT to the bus bar, so as to ensure both batteries are charged. So in effect it is the same as your main switch put on 1+2. Negative is after the shunt so the monitor takes the charge into account for the state of charge of the bank.
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Old 10-02-2021, 12:28   #14
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Re: Where to cconnect MPPT output?

Quote:
Originally Posted by jefndeb View Post
OK, but the positive of House battery 1 or 2?.....that's where I am unsure..
You should have 1 house bank, not 2 separate batteries. I would parallel the 2 8D batteries and run all loads off of them except for engine starting. They are easy to paralles as they are side by side. An ACR between the now combined house bank and the start battery finishes the system.
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Old 10-02-2021, 12:31   #15
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Re: Where to cconnect MPPT output?

Because you have 2 house banks which is no longer done. There is not a proper answer. The most correct awnswer would be 2 panels and 2 controllers. 1 to each house battery..., Yiu do not want it on the common of the switch. Because when you turn the house switch off. Now the solar panel is direct powering the panel.

You need to choose 1 battery to connect to, likly does not matter which. I would choose the one with the bilge pump. If the switch is in all. Both will charge. If the switch is off. 1, or 2. Only 1 will charge.

Or combine both batteries into 1 bank. And just feed both to #1 on the switch. Now you have off and 1. (Or change the switch to an on/off. And connect solar to the single house bank.
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