Hunter 37C Lithium Upgrade: Any experience?

[Rumbero]

My next task after new rudder and lower rudder bearing is to upgrade the boats electrical system. When purchased, the DC side was powered by a group 31 AGM start battery (110AH) in the starboard cockpit locker (suitable for the Yanmar 3JH3E) and a house bank made up of 4 T105s located in the bilge. Prior owner mounted positive and negative buss bars under the Galley sink, and then supplemental AC and DC distribution panels mounted on the side panel of the galley area next to the chart table. Many things I don’t like about this configuration, but I also want to go to lithium for my new house bank.

One of the thornier issues on the upgrade is locating the new batteries and supporting infrastructure. I’ve decided that the best location for the new AC/DC charger and isolation transformer will be under the chart table next to the original panel location. I can’t find any place on the port side of the boat to locate positive and negative buss bars or batteries. The location of the fuel tank under the quarterberth, and difficulty running larger grade wires through the aft cabin area are pushing me to the starboard side of the boat.

I’d like to get all batteries out of the cockpit locker just for accessibility reasons and to use that space for the myriad things that usually end up in cockpit lockers. In order to do that, the best location candidate looks like the space under the Starboard settee and aft of the starboard water tank. At a minimum, I would like to make this the location for a single 314AH Lithium battery with dimensions not much larger than a Group 31 (and it would fit). Then I‘m wrestling with keeping the start battery in the cockpit locker, and wiring the B to B charger between the two, and putting the buss bars in the space below the the top two galley drawers (losing the two bottom drawers) which are next to the engine compartment. This location was already modified by a prior owner who put a Red Dot heater in there and, in the process, cut away the liner under the drawer cabinet to run the thick inverter and alternator pos/neg wires under the stove and into the bottom of the galley sink. Battery switch would go back to the original location below the companionway.

Any H37C owners undertake this kind of upgrade? Where did you decide to place your new lithium battery(ies)? Any suggestions? Thanks in advance for your input.

 

[Tally Ho]

I don’t have a Hunter 37, but I switched to some LFP batteries last year…

My key takeaways…

1) Separate the house bank from the starter battery. I added a new battery switch and have the lead acid starter battery wired to the starter, not the original 1-2-both-off switch.

2) Get a charger for the LFP bank…that supports Lithium charge profile.

3) Find a way to charge the LFP bank… a dc-dc charger, solar, etc. My alternator is wired to my starter battery, and right niw, I can’t add power back into my LFP bank when motoring. Something I will solve at some point.

4) Paralleling Smart Batteries may be a bit of an issue. I had a hard time keeping 2) 100 Ah smart batteries “balanced “. In the end, I returned them.

5) I am now evaluating a WattCycle 314Ah Bluetooth Mini. It has a smaller footprint than the 2) 100Ah batteries I tested last year and it packs the energy of a 3rd battery in the same footprint. I really like this battery. It passed the capacity test (got 318 Ahs out of it on my bench).

Consider something like the 314Ah battery if you have space. Eliminates the need to parallel several 100 Ah batteries and saves some space.

Greg

 

[Rumbero]

Thanks Greg. We are definitely thinking along the same lines. Some components I’ve settled on:

1. I ordered the Wattcycle 314Ah mini. This will be my house bank, replacing the 4 T-105s currently in the bilge. Crazy, but got it for $369 + tax and free shipping. I’ve decided it will live in the compartment under the starboard settee and aft of the water tank. This compartment has several hoses running through it: Bilge pump hose, freshwater supply lines, and water tank fill, drain and vent. I’m going to re-route the bilge pump hose and galley freshwater supply lines to come up through the bottom of the sink cabinet.

2. Starter battery will be the AGM group 31 which came with the boat. It’s large enough (110Ah) to serve as an emergency house battery if something goes sideways with the lithium. It is a Northstar and advertised as a “dual purpose”, but with plenty of CCA and MCA for use as a start battery. Right now, I think it will stay in the starboard cockpit locker although I really would like it out of there. I just can’t find better location for it unless I go to the same space as the Lithium house battery.

3. For the AC/DC charger I went with a Pronautic 12-20P (3 bank, multiple chemistry charging options) which I’ve mounted under the chart table. No inverter or inverter/charger. Because this will be used only at the dock, I decided to get the 20 amp which is suitable for both the start battery and the house battery. It has “Global AC” capability so it can be plugged in to available shorepower world wide. I still have to purchase an isolation transformer to make that a reality beyond Mexico (where 240v is the norm).

4. Victron Orion XS 12-12 50 amp Dc/Dc charger. This will direct any alternator charging to the house battery via the start battery. 50 amps is appropriate for my 100 amp Balmar externally regulated alternator. This has a very small footprint and will either be located in the same compartment as the lithium house battery or in the space under the top two galley drawers.

5. Victron 712 battery monitor and smart shunt.

6. Blue Seas 5511e battery switch (wired as described by Greg).

I really like the modular Victron Lynx 1000 Distributor +/- buss bar system for tying everything together. The problem is where to locate it on the starboard side of the boat. It has a 12” x 7” footprint which would make it tight in the house battery compartment, so I may have to divide the buss bars for space reasons.

I hope to share the final placement/solutions and photos once I get things wired up.

 

[Rumbero]

Update. I changed direction and found a pretty elegant (for me) solution to relocating both house and start batteries on my 1984 Hunter 37C. But, it came at the expense of an oven.

I had an Origo 6000 stove/oven combination I was going to use in my Hunter 37C. During the electrical thought process, the best I could figure out was to keep the start battery in the cockpit locker, place the Wattcycle 314 Ah Mini in the space aft of the Starboard water tank, with the distribution somewhere between them. Then one day the light came on: look at that perfect space meant for the oven!

Part of what makes it possible is that I have a new in box Origo 3000 stove with gimbals. I’ve come to appreciate the simplicity and safety of Origo stoves over the years. Several YouTube channels (Sailing Wisdom and Calico Skies) have used them on some pretty long cruises as well. As long as I go with that cooktop (I have an above deck “slim”propane tank that mounts to my solar arch and can be used for my barbecue), I can use that space for both batteries and the distribution system.

The space fits both batteries (on through bolted trays with ratchet strap tie downs), a Victron Lynx Power In distributor (1000 amp +/- buss bar which I’ve modified to accept mega fuses). I discovered the Artek Shim Plate to allow the class T fuse holder, Victron 712 shunt, and a safety “on/off” switch between the class T and positive “always on” buss on the Lynx, to be mounted such that they all connect without wires between them. Compact footprint and allows mounting the Victron DC-DC charger in the same space.

I’m still building this out and will add photos when finished. There will be a removable shelf under the Origo stove and above the batteries, as well as a removable front panel, to protect the batteries and distribution system underneath. When completed it should solve all my issues with getting the house batteries out of the bilge, start battery out of the cockpit locker, and having everything pretty accessible for maintenance and further electrical additions for solar, windlass, etc.

But, giving up a proper oven is the price—one I’m willing to pay.

 

[Rumbero]

I thought I would provide an update about how I decided to upgrade to lithium on my 1984 Hunter 37C. [NOTE: I tried to add photos but it says they are “too big.” If someone can share how to make them small enough to attach i will add them]. My choices likely won’t be shared by others, but thsee are my choices based on my priorities. My priorities were:

1. Get the batteries out of the bilge
2. Upgrade to lithium
3. Provide best possible access to the batteries

As mentioned in an earlier post, I ultimately decided to lose the oven in the galley. I trialed an Origo 6000 alcohol stove/oven for a month long trip around Vancouver Island a couple of years ago. I wanted to get rid of propane inside the boat. I ended up liking the Origo a lot. So I decided to replace the propane stove/oven in favor of an Origo 3000 stove, which is gimbaled and has potholders.

I tore out everything that supported the original propane stove and set about designing a space underneath which (1) could hold the batteries and distribution system, (2) be closed off from the stove above, but (3) easily accessed by removing a few panels.

I went with one (highly rated) Wattcycle 314 Ah lithium “mini” for the house bank and a group 31 AGM for my start battery. The alternator charges the AGM, regulated by a Balmar 614 regulator. The AGM then charges the lithium house via a Victron Orion XS 50 amp charger. Charger goes to the positive buss of the Victron Lynx Distributor, as does the AC/DC charger. I’ll be adding solar with charge controllers to also charge the house bank via the Lynx.

Keeping the batteries secure and in place was key, and I found aluminum battery trays to fit both batteries. These are bolted through the thick (and 3/4” cored) shelf which is part of the liner underneath the stove. The batteries are also held in place with ratchet straps.

Part of what made everything fit together nicely was the Artek mounting plate for the switch off the battery, the class T fuse holder, the Victron smart shunt, and the Lynx Distributor. The mounting plate allows all those components to be directly bolted together without running separate wires between them—which saves a little space in the compartment under the stove.

To separate the upper stove area from the bottom battery compartment I used aluminum “U” channel into which epoxy coated plywood panels can slide in and out to access the bottom compartment. The vertical panel prevents the horizontal panel under the stove from sliding out.

To make wiring access better to the main switch (under the companionway) I went through the bottom drawer space in the galley. A prior owner had already removed it to put in a red dot heater, so I simply got rid of the red dot heater and ran wires through there into the cockpit locker and up to the switch. I also added some busses and overcurrent protection there as well. The price for this was to cut off the back half of the icebox. Because I use a low draw Engel fridge/freezer which is portable, I had no qualms about doing that. I also would rather have more storage in cockpit locker than have the back half of the icebox box.

Overall, I’m happy with the outcome and everything works. Again, if anyone can help with how to attach photos which satisfy the size requirement I will add those. Thanks.

 

[Stu Jackson]

if anyone can help with how to attach photos which satisfy the size requirement I will add those.

Nice description, thanks.
Google IMAGE RESIZER if you use Windows. It's a simple utility accessed with a right click on your mouse. I'm sure there must be something similar for Macs.