32 Volt System on a Motor Yacht

Thom Price said:

From what I've heard from other Hatteras owners, it isn't worth it to try to rewire the whole boat. Not only is it a huge expense in coper and new parts, but you pretty much have to dismantle the whole boat. It's one of those quirky things about owning an old Hatt, kind of like the Whitworth wrenches you need if you have an old MG. Also, the original wiring is known to be top quality. Messing with it would definitely not increase the value of the boat.
The alternators and starters are also 32V. Sometimes an OEM starter is hard to find and it gets replaced with a 24V starter, which will work for a while, but they can burn up fairly easily. I would consider replacing the alternators and starters with 24V and have dedicated batteries for them, but for the rest of the boat, I want to keep the 32V system.

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Yeah I'm 100% not suggesting that you rewire your boat . I wouldn't do it.

For heating/cooling, I think unless you have a ton of solar and a massive battery bank (for overnight), you're better off using a diesel heater or run the generator. My 38ft boat takes ~800W continuous to heat, and my battery is 8kWh. I could heat the boat (and use nothing else) for 10h before running out of power, and it'd take me 3 days to recharge the battery. A 53' boat probably need a lot more than 800W to keep warm. I'm using a resistive type of heater and my boat isn't really insulated, it might work better if you heat using a marine AC in reverse cycle, and maybe the Hatteras have been built with isolation? I don't know.

You have a genset so I'd count on it for the heating/cooling. Unless you have a pretty big solar install and a bank big enough to last through the night. That would really be the ideal, but it gets expensive. Alternatives for the heating is to do it per-cabin, and to use heating pads at night (no need to heat the whole boat when you just need a warm bunk). I haven't done this yet, because it's not high on my priority list, but that's probably the strategy I would adopt for heating. For cooling, I'd make sure my installation allows me to cool down individual cabins independently.

Btw 1500kWh per month is 50kWh per day. That's really a lot! What do they do to use so much power on a boat?

I just realized Hatteras 53 are powerboats, that changes things. I'm on a sailboat. You probably have a much larger power budget than I do, and more unshaded surfaces to put solar.

aybabtme said:

Btw 1500kWh per month is 50kWh per day. That's really a lot! What do they do to use so much power on a boat?

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I know! It's twice as much as what we use in our house, so I'm curious to find out why it is so high, but I've seen their utility bills, and that's what they use. They probably run space heaters in the winter to supplement the reverse cycle AC units and blast the AC in the summer. I want to see if there aren't more efficient reverse cycle ACs I can put in. If it is anything like in residential, a new unit should be about twice as efficient as what was being installed 20 years ago.
I'll definitely be working on improving efficiency as much as possible before installing the PV.

Thom Price said:

I'll definitely be working on improving efficiency as much as possible before installing the PV.

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Yup... the lowest cost energy is the energy you don't have to buy/produce/store!

aybabtme said:

You have a genset so I'd count on it for the heating/cooling.

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@$3/Gal for diesel we'd spend $0.50/kWh to run the genset. I think the diesel heater might cost less than the reverse cycle heaters on shore power at very low outdoor temp, but I'll be curious to see.

Check out 12vmonster.com, they have led bulbs thet work perfectly with 32 volt. My Tug is also 32volt with a converter in the wheelhouse for radios etc. I use an outback inverter charger - yes they make them for 32 volt systems. What I am looking for is a boost mppt controller that will work with my 32 volt system. That would make adding solar easy! All I find are for 36 volt.

Thom Price said:

... looking forward to being a part of this forum and sharing my project as it progresses...

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Hey Thom!

Welcome to the forums and I can't wait to see what you do with it.

Tugster said:

Check out 12vmonster.com, they have led bulbs thet work perfectly with 32 volt. My Tug is also 32volt with a converter in the wheelhouse for radios etc. I use an outback inverter charger - yes they make them for 32 volt systems. What I am looking for is a boost mppt controller that will work with my 32 volt system. That would make adding solar easy! All I find are for 36 volt.

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Thanks for that resource!

svetz said:

Hey Thom!

Welcome to the forums and I can't wait to see what you do with it.

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You and me both! We've been held up by the pandemic, but should take possession by the middle of July. Then the fun begins.

You may want to consider an on demand propane water heater, they work great and require little fuel.

Maybe consider a 36v starting / bow thruster solution and convert the rest of the boat to 12v.

Someone may have already mentioned it...but 10S lifepo cells is 32 volts. Just saying... May be able to diy or have someone customer make a BMS for that.

danphillips said:

You may want to consider an on demand propane water heater, they work great and require little fuel.

Maybe consider a 36v starting / bow thruster solution and convert the rest of the boat to 12v.

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Thanks. Propane can be a good solution in some circumstances but I'd rather not have it on board. I'd probably consider an on-demand diesel water heater, though. But since I can fit 4KW of solar on the roof, a water heater can be a good place to store extra energy. Also, I'll be connected to shore power 99% of the time, I'm just trying to minimize having to use it as much as possible. Rewiring the entire boat for 12v is far beyond the amount of work that I would like to undertake. 12V systems require much larger conductors than 32V systems.

danphillips said:

You may want to consider an on demand propane water heater, they work great and require little fuel.

Maybe consider a 36v starting / bow thruster solution and convert the rest of the boat to 12v.

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Thanks. Propane can be a good solution in some circumstances but I'd rather not have it on board. I'd probably consider an on-demand diesel water heater, though. But since I can fit 4KW of solar on the roof, a water heater can be a good place to store extra energy. Also, I'll be connected to shore power 99% of the time, I'm just trying to minimize having to use it as much as possible. Rewiring the entire boat for 12v is far beyond the amount of work that I would like to undertake. 12V systems require much larger conductors than 32V systems.

CoryBaker said:

Someone may have already mentioned it...but 10S lifepo cells is 32 volts. Just saying... May be able to diy or have someone customer make a BMS for that.

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Yes, that's true, but then I'd have to keep them topped up all of the time for my appliances to have the proper voltage. I'd rather add an extra cell and be able to discharge farther.

Thom Price said:

Yes, that's true, but then I'd have to keep them topped up all of the time for my appliances to have the proper voltage. I'd rather add an extra cell and be able to discharge farther.

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Yeah, I have no idea of your inverter specs. Just a thought. If you were thinking a lithium setup in the future already. A custom BMS sounds easier and cheaper than a rewire and swapping everything else out.

aybabtme said:

The existing 32V battery bank will also operate within a range of voltage: as such, it can probably be assumed that the 12S LFP setup should work fine, voltage-wise.

But I'd still go for a more standard voltage house bank. Smaller wires at 32V is cool but the small wires matter more with regard to heavy loads, and OP is going to have a hard time getting the heavy load items like windlass/bow thrusters/watermaker/AC/etc, in 32V. As such I'd really consider a 24V battery, or even 48V before 32V.

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I totally agree. Once you replace all the incandescent bulbs with leds, your power requirements will be much lower, so the current wiring will be fine.
For the heavier load stuff, you will end up converting it to something that's easy and affordable to replace, so new wiring, ir additional wiring, will be well worth it.

Both your heating and cooling loads will be higher than the boat in San Francisco, especially in summer.

I am working on the same issue, I have a 58 LRC with a 32v system. Did you make any progress? Very interested in what you plan to do. How will you handle the bms dropping out, in effect leaving no battery to act as resistance in the electrical panel and possibly having the charging source send voltage right to the consumers. I would like to keep the fla starting batteries but how can I mix the two chemistries together?

Dconte said:

I would like to keep the fla starting batteries but how can I mix the two chemistries together?

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You could used a programmable DC to DC converter to charge the Lithium from the output of the 32 volt alternator. What major loads do you plan on running off the 32 volt Lithium system?

Dconte said:

I am working on the same issue, I have a 58 LRC with a 32v system. Did you make any progress? Very interested in what you plan to do. How will you handle the bms dropping out, in effect leaving no battery to act as resistance in the electrical panel and possibly having the charging source send voltage right to the consumers. I would like to keep the fla starting batteries but how can I mix the two chemistries together?

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I'll take possession of the boat in a few weeks (COVID has delayed things a bit). It will probably be a few months before I get started on upgrading the electrical systems. I, too, am thinking that I should keep the FLA starting batteries. Let me know if you have any ideas, and I'll also keep my progress posted here.
Good Luck!

Ampster said:

You could used a programmable DC to DC converter to charge the Lithium from the output of the 32 volt alternator. What major loads do you plan on running off the 32 volt Lithium system?

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Mainly the house loads through a 3000 watt inverter. Around 500 watts for a refrigerator and two freezers, some led lighting, TVs, computers and other light draw stuff. Also DC pumps that are high draw but short duration.