New Lithium setup for off grid cruising - and air conditioning

[Networker]

Hi all, recently got a new boat, a 2000 Beneteau 40 CC and one of the first things we’re doing is upgrading the electrical systems. We have plans of circumnavigating and living off the hook for a few years, and want as many of the creature comforts of home as possible.

One of the benefits of the boat is a massive engine compartment, so I’ve been monitoring the temperatures of it while running in July in Miami and it’s cool enough to keep LiFePO batteries in there. I will also build a shielded battery box in any event, but the space has room for about a dozen 300AH batteries should I go that far. The boat currently has 2 brand new 200AH AgM batteries for the house bank and 2 starter batteries. I am replacing the AGM’s with 4 300 AH Lithium batteries. After a lot of research, and looking at DIY approach vs full blown Battleborn system, decided to go somewhere in the middle and get good quality, but cheap batteries off Amazon. I ended up getting these: Ampere Time 12V 300AH https://www.amazon.com/dp/B08K7HZ6KZ/ref=cm_sw_r_cp_api_glt_fabc_K4HTMHFAFH707BWT5QDG

What gave me confidence was a review on Will Prosse’s YouTube channel, and after a tear down, he confirmed these are excellent batteries with good build quality, they just don’t have low temp cutoff protection. https://youtu.be/FQUhjDkQY5Q

Which is ok, as he then recommended a simple workaround: https://youtu.be/XpO4s6Lrrmc

Costs plus shipping was $1300 each +$200 shipping, or $1500 total. So $6000 for 1200 AH. Not the best price compared to DIY, but cheaper than Dakota or BattleBorn. It’s so cheap I might get two more, but will wait and see how this works first.

To power the lead starter batteries, I am keeping the 60AH stock alternator on my Volvo Penta MD22L connected to the lead starter batteries for now. To bridge the 2 battery banks, I got a Victron 12v DC to DC battery charger. This will allow current from the lead bank to flow to the Lithium without harming the alternator. I will upgrade the alternator in the fall, at least 160-180AH, and connect it directly to the Lithium bank via a good external regulator. I’m looking at a Mark Grasser DC alternator given how it handles temperature, as well as a serpentine belt upgrade. External regulator is TBD, looking for suggestions.

The lithium bank is being powered by 4 SunPower 170W flex solar panels and 2 370W hard panels, for 1420W of power. At 5 hours of charge time on a good day in the tropics, I should see it put about 350-450AH back into the system. I’d love more panels, but am real estate constrained. The flex panels will go on the bimini while the 2 hard panels will go on the existing solar arch. Each panel has a dedicated Victron MPPT to compensate should one panel be shaded without pulling the rest down.

I connect it all to a Victron MultiPlus 3000W charger/inverter. Shore power is selectable via 110 or 220 via a Victron Centaur charger/selector.

To monitor everything, I got a Victron Cerbo GX and touch panel, a 500AH Victron SmartShunt and a Victron Smart Battery Monitor.

Major loads on my system. I’m pulling out the propane stove and going with a Force10 electric, which should draw 60-100AH depending on how long I cook. I have a newer 16k BTU domestic AC unit for the whole boat that I will rip out and replace with a 6K BTU version just to cool just the owners cabin at night and run it off battery. Should draw about 60AH, running at night should be about 200-300ah (I’m hoping) if it’s half duty cycle. Let’s see. The rest is water heater and refrigeration, 110v electronics and all the regular 12v draws on the system. Daily draw should be about 300-600ah depending on AC, which isn’t quite enough for my solar alone.

I’m looking at a wind generator to help out, perhaps a hydro generator, and a larger alternator. Trying to stay away from a generator. Without AC, this is more than capable of powering the boat and factoring in a few sunny days, with AC I need to watch and see how it works. Will update this thread with photos as we start the installs over next few weeks, and update with consumption reports as the summer goes by. Getting this boat ready to cruise Bahamas all winter, so this summer and fall is to shake out all the electrical kinks.

[EngineerRetired]

Realistically,( average output on a daily basis) about 40% to 50% of the watt hours the solar panel manufacture tells you. KEEP them clean and cool!

Good idea to go with independent controllers for each panel.

The need for a soft start on the AC is almost mandatory.

Run heavier wire than called for, I like welding cable. (Very fine strands, better ampacity)

[Adelie]

Your solar panels will be good for about 450Ahr/d.
Count on the AC using more power.
I would get a larger inverter, like 4kW or 4.5kW. If you cook and are running the AC at the same time your will need that extra capacity.
I would make sure it is producing a real sine wave too.
The Force 10 looks nice but it's still resistive heating elements. I would consider getting an induction cooktop instead which is way more efficient with power and a counter top convection oven which will also use less power for cooking.
Insulate the walls of the master cabin which dramatically help with energy required for cooling.

[LoudMusic]

I don't think every panel needs its own controller, but it doesn't hurt! I have six panels on three controllers because they're basically in pairs on the boat anyway. There's a balance to be found in performance and physical space for the equipment/wiring. Also, more solar more better - I'd pack it on everywhere it's reasonable to do so.

I up-sized the AC cable from my inverter and found I got much improved efficiency, especially when running high load items like the air-conditioner, microwave, hair drier, cloths drier, etc.

On a monohull I think a wind generator is probably a good idea. I'm not sure how useful hydrogenators are, but you have to be in motion to make use of it, and you're probably not running the aircon when you're underway

Bigger alternator(s) on the main engine I think are the key here. There are now complex products for doing this, but it can realistically be DIY installed. Your engine should have no problem turning a big alternator for charging your house bank - just make sure you've got everything regulated and monitored correctly. Lithium batteries can draw so much power that they will burn up an alternator if it's not being closely observed and adjusted.

But my utmost recommendation is to spend time on the boat before dumping tens of thousands of dollars into it. Make sure this is the lifestyle you really want. What you're talking about doing is spending nearly as much on upgrades as you have on the boat. And what it will be in the end is not something very many people will want so you'd have a hard time getting your money back out of it if it's not the life you thought it would be.

[EngineerRetired]

Originally Posted by Adelie

an induction cooktop instead which is way more efficient with power and a counter top convection oven which will also use less power for cooking.
Insulate the walls of the master cabin which dramatically help with energy required for cooling.

Agree 100%. I don't even like the built in induction cook tops, too expensive. You can buy a good portable one on Amazon for under $100 and as a BIG bonus, move it to the cock pit and keep the heat out of the boat, when convenient.

[LoudMusic]

Originally Posted by Adelie

Your solar panels will be good for about 450Ahr/d.
Count on the AC using more power.
I would get a larger inverter, like 4kW or 4.5kW. If you cook and are running the AC at the same time your will need that extra capacity.
I would make sure it is producing a real sine wave too.
The Force 10 looks nice but it's still resistive heating elements. I would consider getting an induction cooktop instead which is way more efficient with power and a counter top convection oven which will also use less power for cooking.
Insulate the walls of the master cabin which dramatically help with energy required for cooling.

I had a 2800W Magnum for a couple years and added a 3000W Victron to my system because I thought we would need the extra power when I installed an electric oven and induction cooktop. But honestly, I think you could get by with a single 3000W.

Obviously you'd have to very closely manage consumption. Turning of aircon before cooking dinner, etc. would be a necessity, but once you're the one responsible for MAKING the power, managing how it's used becomes second nature

That said, being able to willy-nilly use our appliances has been kind of nice

I'd like the replace my Magnum inverter with a matching Victron but the damn thing is going strong like the day it was made.

[Wilyum]

This is the setup I am aiming for specifically to have AC in the owners cabin. Run the engine or a genny during the initial half hour to cool to cabin to desired temperature, once there, it wouldn’t draw much off your Lithiums to keep it cool all night. Insulating was a great idea. Id keep the 16k AC unit installed just for resale value and install the smaller unit around it somehow.

[GreenWave]

Love the plans. No watermaker needed?

[CarlF]

Things to consider:

- How will you protect the alternator diodes from surge in case the BMS shuts down when the engine is running? Stirling Alternator protection device and/or relay to parallel lead acid start batteries

- Will you install a Class T fuse?

- Is you insurance company OK with Lithium? Some aren't. Others require that that lithium banks be installed by an ABYC electrician.

Excellent piece by Rod Collins - one of the best marine electricians in the country that covers all of the above points:
https://marinehowto.com/lifepo4-batteries-on-boats/

[Networker]

Originally Posted by GreenWave

Love the plans. No watermaker needed?

Watermaker is definitely in the plans, but not until I go full time. For now, I can’t spend more than a few weeks at a time on the boat, so I was worried about storage of the water maker until I use it more by cruising full time.

[Networker]

Originally Posted by Adelie

Your solar panels will be good for about 450Ahr/d.
Count on the AC using more power.
I would get a larger inverter, like 4kW or 4.5kW. If you cook and are running the AC at the same time your will need that extra capacity.
I would make sure it is producing a real sine wave too.
The Force 10 looks nice but it's still resistive heating elements. I would consider getting an induction cooktop instead which is way more efficient with power and a counter top convection oven which will also use less power for cooking.
Insulate the walls of the master cabin which dramatically help with energy required for cooling.

Great suggestions. I haven’t made the purchase yet and have also looked at a induction stove top that I can add fiddles and gimballs to. And a breville smart convection oven.

[Networker]

Originally Posted by CarlF

Things to consider:

- How will you protect the alternator diodes from surge in case the BMS shuts down when the engine is running? Stirling Alternator protection device and/or relay to parallel lead acid start batteries

- Will you install a Class T fuse?

- Is you insurance company OK with Lithium? Some aren't. Others require that that lithium banks be installed by an ABYC electrician.

Excellent piece by Rod Collins - one of the best marine electricians in the country that covers all of the above points:
https://marinehowto.com/lifepo4-batteries-on-boats/

Yes, will have a 400A T class fuse ( I believe that’s what I need).

Not sure how to protect alternator if BMS does, what should I be looking for?

[roland stockham]

Lots of people report problems getting these very high power alternators to work well. Main issues are either overheating or low output at low engine speeds. Often a 160a+ alternator does not seem to produce significantly more amps when the engine is at 1500rpm or less than a stock one. Hove you considered going to twin alternators, 2 120a alternators are likely to produce close to twice the output of a single 200a at slow speeds. Not to complex to fit by ether getting custom mounts made or using a kit just need to make sure the regulation will take twins.

But if I was looking at that much power draw I would likely look at a genset. A small DC generator is very efficient and quieter than using the main engine. Whats you reason for not wanting one?

[CarlF]

See Rod's piece. There are several ways to protect against BMS shutdown damage. The best is to have the battery BMS send a signal to the alternator before shutdown - but most drop-in batteries don't have this. An alternative is to install both of these (or similar):

https://shop.marinehowto.com/product...tection-device

https://shop.marinehowto.com/product...ction-solenoid

Also, install an alternator regulator (Like the Balmar 614) that monitors a temperature sensor on the alternator to keep the alternator from getting too hot and destroying itself trying to charge the lithium batteries.

Be sure all charge sources are set to the battery manufacturer's spec including the right absorption time (which for some batteries is zero). Turn off temperature compensation. Never exceed the battery maker's recommended charge voltage. If the BMS is regularly turning off - something is wrong with your setup.

[Hermia II]

I've installed a 800Ah/24v bank of Victron LiFePo4 batteries. My alternator, a Mastervolt 24/75A unit, was charging 60A and I thought that would be o'kay. After 2 hours the alternator temp was 130°C (270°F), clearly not an option. Talking to Balmar they advised me that the only option that would do was their large frame 98-series 24v/220A with forced cooling and the MC-624 regulator, which also keeps track of alternator temperature. I write this just to exemplify the enormous absorption from the Lithium batteries and the impact it has on the charging infrastructure.
The Victron MultiPlus 24/3000/75 is part of the set-up and the BMS-system is integrated to it, a very sensible solution.
Consider a 75A rated alternator getting overheated at 60A. The continuous output should probably be 1/3 less the rated output, or even less for safety. Consider also the cooling and plan for using a fan.