EDIT - see other thread - link is now in first post - Please help with my plan for electrical upgrades for my sailboat

[prskier17]

UPDATE 5/17/2023 - Everyone - apologies for the multiple threads. I originally posted in the marine section and then noticed the vehicle section gets a lot more action and was hoping for quick feedback. In hindsight, I shouldn't have done that and apologize. Here is a link to the other thread, I will discontinue using this one. Thanks for everyone's input on this; I'm learning a lot! https://diysolarforum.com/threads/p...l-upgrades-for-my-sailboat.62350/#post-778534

Again, sorry for creating confusion!!!


My sailboat currently has 2x 100Ah Renogy 12v lithium batteries that I've been charging from shore power. These were setup by the previous owner to provide house power as well as starting for a 9.9HP outboard. I'm going to add solar and an inverter, as well as a DC-DC MPPT charge controller that will allow me to add a separate AGM starting battery. The components I've purchased include 2x 100W 12v Renogy solar panels, Renogy 30A DC-DC MPPT Solar Charge Controller, and a 1000W Renogy Inverter. Below is my first draft at a wiring diagram, and I'd appreciate any feedback. Some questions I have include:

1. Should I use positive and negative busbars? My diagram currently assumes multiple ring terminals stacked on lugs. For a 12v system, is this better or are busbars preferred?
2. I currently have a 1, 2, 1+2, Off battery selector switch. Is there any advantage in placing the 1,2,1+2, Off Battery selector between the positive terminals of the batteries so that I can isolate one battery as well disconnect both? Should I replace that switch with a on/off battery disconnect so that the batteries can be disconnected?
3. Expanding on question 2, should I have a circuit breaker at the batteries or is the 100A fuse appropriate?

 

[wholybee]

Buss bars are usually preferred, but on simple installations not necessary. ABYC does not allow more than 4 ring connectors per terminal. The way you drew the batteries is correct, with the positive connection on one, and negative on the other.

You should have a main battery disconnect. The inverter will have a large draw to charge the capacitors even when turned off. You don't want to connect the wires to the LFP without a switch there. Your choice on the 1/2 switch. You should not parallel the LFP with the AGM however, so I would not use a switch with 1+2.

Definitely a fuse, not a breaker. A Class-T fuse, or maybe an MRBF. ANL fuses are not appropriate for the main LFP fuse, but could be used for the other fuses in the system.

The 40A and 45A fuses in this diagram need to be on the battery end of the wire, not the MPPT end.

4AWG wire is good for 100A at less than 10 feet round trip, or 5 ft for each of the positive and negative wire. That works if your inverter is very close to that LFP battery.

Consider a smaller 30A fuse for the panel. Technically not necessary with 4AWG wire, but unless the panel is rated for 100A is still needed.

 

[TimE]

Buss bars are usually preferred, but on simple installations not necessary. ABYC does not allow more than 4 ring connectors per terminal. The way you drew the batteries is correct, with the positive connection on one, and negative on the other.

You should have a main battery disconnect. The inverter will have a large draw to charge the capacitors even when turned off. You don't want to connect the wires to the LFP without a switch there. Your choice on the 1/2 switch. You should not parallel the LFP with the AGM however, so I would not use a switch with 1+2.

Definitely a fuse, not a breaker. A Class-T fuse, or maybe an MRBF. ANL fuses are not appropriate for the main LFP fuse, but could be used for the other fuses in the system.

The 40A and 45A fuses in this diagram need to be on the battery end of the wire, not the MPPT end.

4AWG wire is good for 100A at less than 10 feet round trip, or 5 ft for each of the positive and negative wire. That works if your inverter is very close to that LFP battery.

Consider a smaller 30A fuse for the panel. Technically not necessary with 4AWG wire, but unless the panel is rated for 100A is still needed.

Just a thought. We have a domestic lead bank as a back up to the lithium. We have a 1,2, both switch for ease and simplicity of switching from the lithium to lead should we have a major blackout on the lithium system. We need to switch navigation equipment, autopilot, nav light etc back on pronto. Thr lead bank is floated via a Victron B2B so spends most of its time at a voltage higher than the lithium. In the event of an accidental joining of both banks, the power from the lead bank will flow to the lithium.

 

[mikefitz]

Why are you running two discussions on the same subject? It's very confusing.

 

[TimE]

Why are you running two discussions on the same subject? It's very confusing.

Sorry didn't mean to confuse you. I will go away

 

[Ampster]

Sorry didn't mean to confuse you. I will go away

Don't go away. The OP asked question #1 about buss bars and the earlier response was about buss bars. The title was a generic design question and I assume you were commenting on a classic question of lead and lithium often found on boats, and in the OPs diagram.

 

[mikefitz]

Don't go, idealy just keep to one thread , or ask a new question with a new title.
Since this thread is running, did you follow my argument that using the Renogy DC to DC , with a low output alternator on the outboard, may not be a good idea?

Mike

 

[Ampster]

Don't go, just keep to one thread , or ask a new question with a new title.

Now I understand, you were referring to the fact that OP posted same question in two sections. Instead of doing that, my suggestion is to bump a thread so people are more likely to see original. Perhaps a simple question like, "Any input?" would get the thread bumped to the top of the What's New heading.

 

[prskier17]

Everyone - apologies for the multiple threads. I originally posted in the marine section and then noticed the vehicle section gets a lot more action and was hoping for quick feedback. In hindsight, I shouldn't have done that and apologize. Here is a link to the other thread, I will discontinue using this one. Thanks for everyone's input on this; I'm learning a lot! https://diysolarforum.com/threads/p...l-upgrades-for-my-sailboat.62350/#post-778534