How to properly wire boat in regards to house and starting batteries

It really gets complicated when you get to the switches and gauges.

Just make sure to have some master on /off switches.

ABYC E10

The answer is it depends. How's the shore power wired? Charges everything or just house bank?

Usually critical loads like bilge pumps go on the cranking batteries and non critical go on house.

Eta: my general advice is start completely over. Most boats were wired by drunk thumbless idiots and are downright dangerous.

quote:

---

If you're looking for a good reference, check out Blue Sea Systems

---

Thank you. I'm going to buy a couple of their Fuse blocks and that's where some of these questions are coming from

If it means getting back to the hill its on the starting battery. If it is something you can live with until you get back to the hill it can go on anything but the starting battery. If you have fancy electronics and a fancy trolling motor they won't get along together on the same bank of batteries.

Boat Wire USA, Brunswick, Georgia, is a great source for marine wiring questions and products. Used to be a small company, I think they have been bought out but they will still answer questions.

quote:

---

Most boats were wired by drunk thumbless idiots and are downright dangerous.

---

Wish I could upvote this 1000000 times lol.

OP - I’ll try to dig up one of my wiring diagrams tomorrow for a twin engine boat. I typically do them with start batteries only powering motors and house battery powering everything else. Only exception being electronic steering. That typically goes to starting batteries. One could argue to put bilge pumps on start batteries, but I’d rather not have electronics vs not being able to start engine if pump sticks on and kills battery. Definitely wire them on the battery side and not the switch side though. You want the to have 24hr power.

I use Blue Sea dual circuit On/Off/Combine switches for each battery. I Jump the “extra” circuit of each switch to the other switches, so that you can emergency combine any battery to any of the other ones (diagram will help explain this). Basically any switch in combine is jumped to any other switch in combine.

I put on board charger leads directly to battery. ACR/VSR between each start battery and house (Port-> House & Stbd -> House). Can do this either at the battery itself or at the battery side of each switch. I like to put my ACRs on the battery side so you can use a 2 bank charger and it will charge all 3 batteries. I’ve heard people argue not to do this for various reasons, but I’ve rigged nearly every boat I’ve touched this way and none of them have had issues with on board charger. Alternatively if you have a 3 bank charger just wire ACRs on the switched side. Either way will work.

If can probably answer any other questions you have

Also, if you find yourself needing any new panels or anything I can probably help you out too. I CNC all my own panels and have been getting pretty good at it. Always looking for an excuse to cut something else. Pretty sure I have some extra starboard, luxxematte, acrylic, etc laying around here somewhere as well.

This is one I made for an American Aluminum I rigged out. It’s on a hinge so you can open it to access all the wiring behind it.

quote:

---

This is just a center console. But since I have 2 starting and one house, I mentioned off shore because I wasn't sure if bass boats were wired a little more loosely as getting back to the hill is generally not as much of a major concern.

---

You’re not wrong. It seems most bass boats and smaller boats take a slightly different approach. Atleast from what I’ve seen from MFR.

quote:

---

I'm also curious with all these new advances in battery tech, if just keeping a cheap/ small lithium for starting a motor isn't the worst idea and simplifying some of the other wiring?

---

Are you talking about basically using a lithium as a reserve/jump pack? Or using lithium to replace your starting batteries?

With 2 engines there isn’t really a need to have the “jump pack” setup. If one is low, just combine with other engine/battery. At most I’d just carry one of those portable jump packs instead of a built in one.

If you’re talking about replacing with lithium, that is a different situation. There was a post on here a few weeks ago about that. You can go read that to see how I feel about it

quote:

---

Consult a marine electrician

---

He is currently doing that.

quote:

---

Consult a marine electrician or specialized forums; wiring mistakes can be dangerous.

---

A.) This stuff isn't THAT complicated. In fact, most of it is very simple. Positive and negative and maybe a switch and fuse. Its just positive and negative and a switch and a fuse, 30 times.

B.) The marine electrician isn't going to be on the boat with me 40 miles offshore. I'm mostly trying to learn it so I also know how to diagnose issues

This is the setup I was describing. Pict is rough markup I had on my phone, so not the best quality. When switch is “on” the top terminals are connected to the bottom terminals. But the left set of posts and right set of posts are separate circuits.

When in combine, the switch basically has all 4 posts tied together

Basically right side posts in picture are only used when in combine.

quote:

---

Basically my plan this fall. I was working on my stereo and bilge pumps and now I just want to redo it all or at least clean it up. Its a 15 year old boat with at least 3 owners and I'm sure that they were as knowledgeable as me.

---

I did my stereo and some of the wiring on my new boat in 2022. I am not sure what kind of system you are doing baldona but there are some pretty tight rules with wiring amps. Meaning wire size, distance from amp to circuit breaker and what not. If you are doing multiple amps, I would suggest a amp board where you can lay things out on a bench and get the wiring done correctly. Consider the amp board as one thing and have it wired to your power from there. Including all the circuit breakers and connectors. It makes it much easier.

I have a bay boat but like someone said, it does get kind of confusing with all the different circuits and fuse panels I have and which battery they go to. Absolutely make a schematic.

For me , that sounds like a fun project. Good luck