360SS Electrical Upgrade

[Alanna Mo Cree]

Source of the post I don't have a lot of experience with gas engines, but from all my research about my Cummins diesels, the alternator drive system on a 370HP 6BTA will not support driving an alternator output above about 60-70 AMP’s at 700 Idle RPM, or much above 180- 200 AMP at 1500 RPM.

Again, I realize this is for my diesels, and gassers are a whole different animal, but it seems wild that they could drive a 7KW alternator.

We settled on 9KW alternators. These are still about 180 amps, but they are 48 volts. While it sounds cool to say 9KW, the reality is I expect they will more often be outputting about 4KW given our typical cruise at about 1750 RPM. This would give the alternators about 3500RPM which is around 100 amps according to their power curve.

We're in the yard starting March 17. The estimated time for all of the work we are having done is about 3 weeks.

[KyleR]

Gotcha! I missed/forgot the 48V configuration!

[Alanna Mo Cree]

Refit has begun!

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After quite an adventure getting the boat from Sanford to St. Augustine, she is now out of the water and getting an extensive list of projects done. Most are regular maintenance items, a couple of corrective actions, and of course the exciting bit being the electrical upgrades. Until this trip we had mostly only gone a few hours at most. We discovered that neither alternator has been charging along with other electrical issues. I am glad we are doing an extensive upgrade rather than trying to change things out one at a time.

We came up about 20NM short of St. Augustine when the engines started alarming for low power. The Yacht Rigger East sent someone out to meet us where we docked so they could switch out the start batteries for the rest of the trip. When looking at the wiring on the batteries, the electrician's quote was "there is a whole lotta what the hell going on in here."

After walking through the "final" plan (are any plans ever really final) this is the work list for the system.
48v generator replacement system

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• 2x Arco 48v 9kw alternators with Zeus external regulation replacing...
  
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• Custom built enclosure with blower system for cooling and slight positive pressure to allow install in gasoline engine room
• Blower suction will come from a vent that looks like the existing galley/head exhaust and located just forward or aft of that vent (the white vent by the steps to go forward)
  
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• Blower exhaust will go to a vent that looks like above on the starboard side
• 4x 24v 200Ah LiFePO4 batteries (~16kWh usable capacity)
• Victron Multiplus II for 110v loads and 48v charging from shore power
• 48v system charges existing 12v AGM house bank (until that bank needs to be replaced and then I can go LiFePO4 by changing the charge profile)
• 2x Cerbo GX (one for 48v system and one for 12v house bank)
• 2x Touch GX 70 (one for 48v system and one for 12v house bank)
• 9k BTU Mabru variable speed air/heat for staterooms
• 17k BTU Mabru variable speed air/heat for the salon
• 2x hardwired shore power changed to 2x SmartPlug receptacles with one 25' 30A cord and one 50' 30A cord
• Gobius tank monitors for the two fuel tanks, fresh water tank, and holding tank

The 12v GX70 will be located forward salon on the starboard side below the air conditioning control panel. The 48v GX70 will be just inside the aft slider above the light switches and will be the main monitoring station. This GX70 will also include the tank monitors.

Everything will be tied in to both my NMEA2000 network and my wifi network. This will allow monitoring from the helm underway (NMEA2000) as well as from home (wifi).

The installation will be featured in promotional material for Victron and The Yacht Rigger, so some promotional considerations have been provided. Everyone here on Carver Yacht Owners will be getting some behind the scenes info as well as the thought process that has gone into this project. Please let me know what details are most interesting and I will be happy to provide whatever information I can.

Why both a 25' and a 50' 30A cord instead of two cords of the same length?
It turns out that we will normally only need to use a single 30A shore power with the new system. My home dock only needs the 25' cord. My plan is to use the 25' cord most of the time, but have the 50' available when needed. The shore power was going to need to be rerouted to the new system, so I'm taking the opportunity to change from the shore power cords being hardwired all the way to the panel to using a SmartPlug system.

Why Gobius tank monitoring?
I was originally intending to go with Maretron, but there were a few reasons we decided to switch to Gobius:

• Maretron monitors require a Maretron display for configuration which adds to the cost.
• Gobius monitors integrate with the Cerbo GX so the tanks can be monitored without having the NMEA2000 network powered up.
• Gobius uses micro radar technology instead of sonar, which is supposed to be faster reading with less lag.

[Alanna Mo Cree]

Source of the post I think it’s totally feasible but I’m still struggling to understand just how much battery capacity it really takes to run 1 or all three of the ac units all night. Can you tell me what usage you calculated for just the aircon units? Do the new dc or variable units really reduce that number enough to make switching worth the $$?

I just realized I never addressed this question on air conditioning usage.

The Mabru 9k BTU for the staterooms is rated at 5.2A @ 115V = ~600W. The current 12k BTU stateroom air conditioner draws 8A @ 120V = 960W.

The Mabru 17k BTU for the salon is rated at 9A @ 115V = ~1,000W. The current 16k BTU salon air conditioner draws 12A @ 120V = 1,440W.

Total for both new air conditioners is 1,600W, down from about 2,400W, and we have specified about 16KWh of storage to 80% depth of discharge. If my math is correct, we should have a worst case of 10 hours running both air conditioners at 100%. Practical usage has the goal at about 3 days. I think the real result is going to be somewhere in the middle, which is fine.

[Carverlvr2]

Wow, roughly 30% reduction if the actual cooling capability is equal. There’s a YouTube series called In Too Deep. He just converted his 70’ to a similar hybrid 48v system with 8-100ah, 48v epoch batteries and a charger inverter tied to his existing gen. Says he can run everything except the air for something like 72 hours or everything with the air for 14hrs. So I figure a similar system in a much smaller and more efficient boat could yield 2-3 full days on battery only.

[Alanna Mo Cree]

It's been about a month so I owe an update, especially since the original estimate was three weeks. As with most boat things, once we got started on some of the work that needed to be done before we load in the new power station there were some additional items to be addressed. For example, the centerline tab was so badly corroded there were holes through it. A new one was fabricated and installed.

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The generator has been removed and the through hulls for the generator have been glassed over.

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If it weren't for the space in the pin stripe no one would know there was a generator exhaust here.

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The smart plug receptacles have been mounted, but it looks like the wiring is still to be done.

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Hopefully some serious progress can be made starting this week and we'll see if this upgrade was worth it.

[Alanna Mo Cree]

Looks like I'm going to be posting monthly updates instead of a completed story. As the work on the 12v system got started there was a lot of corrosion discovered. This required quite a bit of remediation. All of that is behind us. We are doing final system testing and tweaks with a little more to do. Unfortunately my next opportunity for final certification and bringing her home is June 14, so I probably won't post another update until after that.

In the mean time, the system is installed and I have some preliminary data to share.

This is where the two GX Touch 70s are installed. They have since been labeled. Top is for the 12v "buffer bank" system. Bottom is for the 48v system.

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With just the two air conditioners on and the rear slider open on a 90F day outside it is consuming about 1430W. In normal anchoring configuration we see about 1500W consumption. This is a little less than what I predicted, which is good. With 20KWh of battery storage available, this would give 13 hours. This is a bit of a worst case scenario because consumption should be much less overnight when it isn't so hot. We are also going to take bud37's suggestion about changing the window cover.

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A lot of the equipment ended up in the "man cave" behind the refrigerator. The blue ductwork is for the positive pressure and ventilation system for the power station box that replaced the generator. The disconnected black duct is the head and stove exhaust. With that system in place we haven't seen battery temps get more than about 2-3F above ambient. I'm checking the system now from my house and see the batteries are charging at 2476W and 91F.

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This is how the system looks when on both shore power cords. The automatic transfer switch that was used for the generator has been repurposed to allow shore power 2 to feed the air conditioners directly when available. This gives shore power 1 the ability to carry minimal loads and send the rest of the available power to charge the 48v batteries.

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I should have taken a closer pic or zoomed in to show the intake and exhaust grills. They are oriented vertically by the top step up to the side deck.

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We tested the alternators, but the Zeus regulator settings need to be adjusted. Both worked and started powering the system from idle (700rpm) to about 1000rpm by the engine tachs. How much power is unknown until the settings are corrected.

So far I am happy with the early results. Normal operation is pretty simple. The system instantly switches between the three different power sources (shore power, batteries, alternators) automatically without even a blink. My Verizon 5G and Orbi onboard internet/wifi didn't even notice, and I know my home Orbi is very susceptible to power blinks. It is very weird to be on "ship's power" without any noise. You have to look at a screen to know whether you are on shore power or the batteries. The run time on batteries alone is sufficient for our weekending needs. If we were full time cruising with multiple days away from power I would have to think about battery capacity. On the current profile, charging from a little under 50% to 90% takes about three hours on shore power. I wouldn't want to have to run the engine(s) that long unless we were moving the boat, but we should be able to get a lot more power from the alternators than we do from shore power. Shore power is limited to about 46A charging. The BMS limit is 400A, so there is quite a bit of room for faster charging.

The downside is the components take up more space than I was anticipating. The power station box is larger than the generator it replaced, and we have another box in the lazarette aft of the freshwater tank for the Zeus regulators. This takes up a lot of the storage space I used for extra lines and fenders. As shown in the picture above, there are some additional components taking up a little bit of the inside storage too.

Next update in June. Please let me know if there are any questions I can try to answer.

[Midnightsun]

Shore power is limited to about 46A charging

Why is this? I know that my system which is far from your elaborate one however I easily get 100+ amps from genny or shore power. The combination of 80a shore power charger and dual DC to DC chargers does the work for me in our case.

[Alanna Mo Cree]

Source of the post I easily get 100+ amps from genny or shore power. The combination of 80a shore power charger and dual DC to DC chargers does the work for me in our case.

Shore power 1 is used for charging and the shore power 1 house loads. We have the total grid draw set to 24A at 120v (80% of 30A). After the house loads are accounted for, there are about 46A left over for charging at a little over 53v (2400W). This would be roughly 100A on a 24v system or 200A on a 12v system.

[Alanna Mo Cree]

Finally on our way back home! Ran from St. Augustine to Green Cove Springs today. The alternators are complete beasts! They never even broke a sweat because the batteries weren't depleted at all when we left St. Augustine. All electrical loads ran off the alternators, including both air conditioners, microwave, and stove to cook lunch. I never saw temps get above about 70C and at one point we were generating about 6kw across both alternators. If the batteries also needed charging we could theoretically get double or more power. The power curves are customized based on how we use the boat, maximizing alternator output around 1700rpm and dropping as we throttle up to make as much power available from the engines as possible. That will take some getting used to.

At Green Cove Springs we are having to test another feature of the system. The shore power voltage is too low for the Victron system to use it, but the boat is rigged so that shore power 2 can offload the air conditioners from the batteries and inverter. We plugged in to shore power 2 and still have air conditioning while the other house loads are on battery. This configuration gives us about 34 hours of battery run time.

Another day or two to get back home, then hope to get things cleaned up for some pictures.