Moving battery bank to galley

[Salmon Fisher]

This a great informational thread. I am seriously thinking of putting LiFePO4 in my 25 Cruiser. I would be installing 2 100 ah batteries or a single 230 ah.

What would be helpful, to me at least, is a wiring diagram that includes:

-Fuses and where they should be located
-Fuse amperage at each location
-Wire gauge for all runs
-Where DC-DC charger should be located
-Where charger/inverter should be located
-Anything else I may have forgotten

This may be available somewhere on C-Brats as someone may have already designed a "typical" system and posted their results.

Thanks in advance!

[Edward J]

I had two house and starter batteries moved to the floor at the helm seat, this really improved the drainage in the cockpit and also performance improved by getting up on plane faster. I took out the hot water tank and the switches are in the cabinet below the helm seat. I also added a Victron Multiplus charger / inverter below the front floor access panel below the helm panel. It was a lot of work but well worth it.

Ed Jonson 2008 Tomcat

[C-Wolfe]

[thataway]

[Edward J]

Stephan, when i moved the batteries forward i saw nice improvement in my Tomcat performance, up on plane much faster and cockpit able to be better at self bailing. My boat came with 5 batteries in the aft locker plus unknown to me when i purchased my Tomcat the outboards were mounted to high. I also repowered so with combined with moving batteries its a different boat from the original. Ed

[C-Wolfe]

[thataway]

If you move the start batteries, you will have to provide heavy cables which may mitigate the weight and also are expensive. It might even "pay" to go to all Li Fe PO4 batteries, Start and house weight wise. My 255 remained self bailing. But I only put the 3.5 hp outboard in the center for very slow speed trolling.

There are many ways to change the weight distribution in the TC 255. There is all of the area under the V Berth, and one side where the water tank is not present forward (unless you have 2 water tanks, which C Dory would not do when I bought mine.)

[Edward J]

Stephan I repowered with Mercury 150's with stainless steel props from 2008 honda 135's with aluminum props. Main reason i repowered the honda's were not very reliable in one motor would quit from over heating even after replacing all thermostats. So i have two house and two starter batteries under the floor at the helm seat, had to cut new opening. Ed

[C-Wolfe]

I had a couple days to think about my project and that is where I’m at, it can all change but as of now...



I will retired my start battery and use my AGM gr31 (previously use as house bank) as my start batteries, I purchased 2 LiTime 100 AH for my house bank and also 2 Victron TR smart DC/DC 12-12-18.
My start batteries and switches will be inside the hanging locker (Port Side as you enter the cabin), that will add 8-10 ft of wiring to the engines. I currently have enough 4AWG tinned wire for the whole project but I might need to get something bigger for that leg. The alternator is fuse at 90 amp but the starter is not fuse at all, I will add a terminal fuse at the battery, I have no idea what size to use, I can test load from the starter in the spring but I’d like to have it more or less figured out before then, I welcome any wisdom here.
For the house bank, I’m still debating on the location. Either behind the fridge, plenty of room for batteries and charger, only 5-6 ft between start and house bank, but I’m a bit concern about heat building up in there with both charger and fridge working simultaneously. other options are inside the galley or under the berth, that will bring the house batteries much closer to the bulk of my electrical wiring, and also more option for the main switch and breaker.
My skill at drawing electrical schematic are not very good, you guys can make fun of me all you want, but hopefully its good enough you can make sense of it. I’m still working on where to insert fuse and/or breaker, I welcome any advice on this as well as any other part of my project.
As always, I really appreciate all the wisdom that is share here, Thanks.

[WCF]

As Thataway wrote a while ago, there is no "right way" or perfect way of designing this.

I am not an EE nor do I hold any ABYC certification.

A few notes though, mostly in the form of more questions:

Why move the start batteries?

MRBF on a start battery: Most people obviously do not run fuses on the start circuit. I do think it is a good idea in theory. I would base the rating on whatever your outboard's starters are rated at + a margin of error, or the current carrying capacity of the wire, whichever is higher.

You don't show it, but MBRFs on the LiFePo4 batteries is also a good idea. I know there is some debate on this, but I use them with LiFePo4 w/ built in BMS.

You don't show any of the wire gauges, which would provide more context for what you are planning. 60A is quite light to run the entire boat, especially if you have a windlass. I believe my windlass is on a 50A breaker on it's own, but perhaps you are leaving the windlass connected to the start batteries? I also assume you have no intent of adding an inverter or inverter/charger?

Also not sure how your kicker is wired into your 1-2-both switch? I'm also not sure what your intention is with the way the switch is drawn. Might just be my misunderstanding of the drawing.

Finally, for wiring simplicity, I would personally only run one DC-DC charger, and I would put the two LiFe4Po batteries on a similar 1-2 switch so they can be isolated and disconnected (suggested by ABYC.)

[C-Wolfe]

[C-Wolfe]

Hers is my engine battery cluster switch. It might help make more sense of my drawing/explanation.

[WCF]

All makes sense, seems like you have it under control

[tsturm]

[C-Wolfe]