Moving battery bank to galley

[C-Wolfe]

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 it’s a different boat from the original. Ed

A big reason for moving my battery is to improve the cockpit self bailing, and the reduced weight aft will help on plane also. I’ve added a kicker , about #90 much further aft, so I would like to move near twice that weight forward. I’m moving 2 group 31 AGM at -#65-70 each and I might move the 2 start group 27. That will move #240 forward. That should help with the engine trim also.
What was your previous power and what did you instal?

 

[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]

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?

For many reason but here’s a few, I have a lot of corrosion in the wiring and switches, enough to create issues so engines won’t start. I had a very similar scenario on my 22 (14 YO at the time) any wiring inside the cabin is/was still in like new condition. I’m aiming for a do it right, do it once. The marine inspector recommended to address the drip around the batteries. It’s, coming from the hatch mostly maybe a cup or two per rainy day, enough to keep things damp. I also would like to move weight forward, and increase the available storage in the cockpit.

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.

Because it will be a longer run, I would feel better if it was protected, I have not found a reliable answer on the starter draw, I can test this in the spring.

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.

It’s not very clear on my drawing but I do have MBRF on each of the LiFePo4, then to the main breaker.

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 its 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?

For the bulk of this, I will be using 4AWG, probably bigger for the leg to the engines starter. The 60A breaker will have the house load minus the windlass and line hauler. No plan to add an inverter.

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.

I will be using a BEP cluster switch. A port and starboard on/off switch and a 1/2/both/off switch. That allow me to jump start one battery with the other, have one engine charge either or both batteries. I’ll have the kicker to the common terminal, can use either battery to start it or have the kicker charge either start with or separate of the house bank. Hope that make more sense.

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.)

I really like the idea of the 1-2 switch, thanks, I will add this to my plan. The reason behind having 2 dc/dc charger is that each alternator is putting a charge on the house bank.

 

[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 8)

 

[tsturm]

With a quick search, doesn’t look like I can get those LiTime ship to Alaska. It’s too bad because they look like a very good deal right now. Bob, I’m curious to know what your test shows.
WCF, how long have you been using those? What are your thoughts on it?

Check into a FREIGHT FORWARDER?
Ship to forwarder in seattle area then barge it to the port!
Pretty reasonable. Gear shed in Homer does/did this in the past!
Give them a call? :thup

 

[C-Wolfe]

With a quick search, doesn’t look like I can get those LiTime ship to Alaska. It’s too bad because they look like a very good deal right now. Bob, I’m curious to know what your test shows.
WCF, how long have you been using those? What are your thoughts on it?

Check into a FREIGHT FORWARDER?
Ship to forwarder in seattle area then barge it to the port!
Pretty reasonable. Gear shed in Homer does/did this in the past!
Give them a call? :thup

That’s how I got my LiFePo battery, thank you for making me aware of this. Pretty easy process.

 

[C-Wolfe]

Here some follow up on this project.
I ended up placing the start batteries (2X AGM gr 31) and main switches under the aft settee of the dinette. I built a tray behind the drawer and off the floor as high as I could so I’m not really loosing any storage there and it's very easy access.



The house bank (2X Lifepo4 LiTime 100 AH) and Dc to Dc charger are located under the forward settee of the dinette behind the fridge.



The house bank switch is just outside of it for easier/quicker access.

I have one breaker for the windlass and line hauler, the other breaker is for everything else.

I still have to do a bit of tidying up with the wires and finding better cover for the start batteries post, but I was able to test most everything and it’s all working. It’s still winter here so I have not started and run the engines, I’m curious to see how well it is charging with that setup, and have not try to pull my anchor up from a deep anchorage yet. But hopefully that will happen soon.
I have a few more pictures in my album if anyone interested.

 

[C-Wolfe]

I finally had a chance to put that whole new system to the test recently. I went on 2 different trips, first one was 5 days and I was exploring a new area for shrimp pots, so I get to use my line hauler and anchor windlass several times, both of which are connected to the house bank and worked great with no issues. The second trip was a short overnight. The DC/DC charger also worked great, and on both trip a got back home with the house batteries (LiFepo4) at 98 to 100% state of charge, no need to top off at home. I’m very please with the whole system.

Only one thing puzzle me a bit, after running the engines enough to top the house bank to 100%, they go to standby mode. At this point, I’m guessing that any power draw is been supply by the charger, all good so far. Once I stop the engines, both LiFepo4 start providing power and are getting draw down at the same level, but on a few occasion, only one battery seems to wake up and supply power, the other staying on standby and at 100%. On one occasion, I had one at 80% and the other still on standby, I flip the switch to turn of discharge (thru the App on the phone) and that wake up the standby battery. the other funny thing is after turning the discharge switch back on, they do not equalize, at least not very fast. If anyone have any insight on this, I’ll be happy to hear it.

 

[ssobol]

Each battery having its own BMS can cause this issue. You want "dumb" batteries with a charge controller that feeds both as one battery source.

 

[C-Wolfe]

Each battery having its own BMS can cause this issue. You want "dumb" batteries with a charge controller that feeds both as one battery source.

Thanks, makes sense.
To clarify, they take the charge equally no problems, the issues is during discharge from 100%. Not that big of a deal but not quite as set and forget as I was hoping for.