Li Ion run time

[Bob H]

I am in the process of spec'ing my new boat and have zeroed in on either the R27 or C288. I was dead set on a generator but now and second guessing that need but need s bit more convincing. Now that the Li Ion package is standard do you have any solid data on AC run time while underway and on the hook? Assume for underway using only the required accessories like chart plotter, radio, both refrigerators. No grills or other items. For on the hook assume dinner prep using microwave a small amount and minimum cabin lights. I know the C288 is new but will it be much different with twin alternators running?

 

[knotflying]

I can't give you any stats, but from cruising experience, if you plan on using your air-conditioner while anchored, using a generator at night is not courteous. Using the air-conditioner without a generator will most likely drain those batteries pretty well after 12 hours. I know the lithium can be discharges considerably without damage though. Having cruised quite a bit in Florida I found air-conditioning from November to March was not really needed when anchored. At a slip it was used many times, but then you have shore power. Summer cruising is a different story. I did not have a generator on my R-27. I never missed it. I initially carried a Honda 2000 and took it off because of lack of use. Everyone will have differing opinions.

 

[trailertrawlerkismet]

Bob: You’re discussing the Dakota Lithium “Iron” battery option? If so I was told that they’d run for 12 hours with the AC on. I’ve never run my ac that long at anchor, hardly ever at all but that’s me.The point is thou that they have a lot of capacity to do so. I have a couple page explanation of the Dakota Lithium batteries. PM me your email and I’ll send you a copy….if you’d like. We have a soon to be delivered R25OB with the Lithium option and anxious to see how they work first hand.

Jim F

 

[philbyrd]

From the materials my dealer provided as to my R-25 with this option. 600 amp hours. This is with no other load.

• How long can I run the Air Conditioning when I am not connected to shore power?
o Like anything, this all depends on your power management. Traditional batteries whether that is
lead acid or AGM do not like to be run below 50% power. The main issue with lead acid and AGM batteries is once you have a high load against them, they will decrease voltage which in turn increases the amp draw on the device you are running. The numbers I will provide you below would be with the AC running and no other draw on the batteries.
o With the Lithium Iron Package, you will be able to discharge these batteries to a much lower state of charge allowing for more power consumption. If you figure in a 90% discharge, this would leave you with approximately 540AH of use. With our air conditioning systems, they can draw between 65-75 amps per hour. With the higher output AC unit, this would allow you right around 7 hours of run time before your batteries were discharged. Keep in mind, this would be with no other charging coming into the boat such as solar power or running the engine.
o Now, if you are running the engine, the alternator output will be anywhere between 35-50 amps. If you figure the incoming charge with the numbers above, this would give you anywhere between 13-21 hours while under way before you would discharge your batteries.

 

[philbyrd]

FYI, my experience is that the solar panel gets me at best 8 amps per hour and the alternator on my 250 gets 60.

 

[Submariner]

If you're running air conditioning, I have to assume there's lots of sun where you boat.

If I needed A/C, I'd go with the LiFEPO4 option, and once I took delivery, I'd figure a way to to get a couple of Sunpower 270 watt solar panels mounted up top with a Victron MPPT 100/50 controller. With 540 watts of solar, I would guess in a warm/sunny climate such as Florida, would see 3,000 watt-hours a day (about 250 amp-hours), maybe more.

The 540Ah battery bank (usable capacity) would get you through the night. Solar would help recharge during the day and would help eliminate the drain on the batteries while running the AC during the day out cruising.

I have 400 watts of solar (2x200 watt panels) in the Pacific Northwest and it's not uncommon for me to see 20-25 amps coming in from solar between 10am and 4pm during the summer. If I had 570 watts of solar, maybe that becomes 30-35 amps, plus the amps from the engine while out cruising, and there's the 65 amps needed to run the air conditioner.

The R27-OB has a single Yamaha F300. The C288 has twin Yamaha F250's. So there should be two 70amp alternators. They don't output at 70amps... but they do output about 45amps. With two of them, that should be 90amps usable coming off the twins.

With the wider beam of the C288, maybe it'd be possible to go bigger than 570 watts of solar. Maybe (3) 225 watt panels would fit up top for 675 watts of solar. That'd bring in, I'd think, at least 4 hours a day of free air conditioning. Probably more.

You asked about solid data. On my RT27-OB, it will go through 50 amps a day without us onboard. When we're underway, chartplotter on, radar, vhf radio... it pulls about 10-12 amps. I have a complete spreadsheet that itemizes what everything onboard my boat consumes, in watts. I use it for power management to better understand what I can expect.

For folks with air conditioning and the LiFEPO4 option, I recommend taking that 540ah usable number, subtract 100ah a day from it for the boat (refrigerators and such) and passengers onboard. That leaves 440ah usable for air conditioning, plus whatever you add back into the system via engine charging, solar, or a generator.

If I went the generator option instead of solar, I'd be looking at what the max charge rate for the LiFEPO4 batteries were. I'd upgrade my battery charger to match that such that it's big enough to recharge the batteries quick so I can shut off the generator. The generator would also need to be sized big enough to feed the charger and the air conditioner.

 

[Rangas]

I have a generator but we mostly do day trips so my boating is not like a lot of you who spend many days on the hook. But still things to consider are maintenance, winterizing, and the biggest negative is the space it takes up. If you can get by with the setup Submariner suggested that would be a big win in my opinion. Good luck with your new boat.

 

[Martin610]

As Rangas says, it's all about the use case.

I have a generator on my C-28 and I'm glad I have it. It came with the boat and at first, I was thinking I wouldn't use it.

However, the way I use my boat, it's a good thing. I often stay on the hook for a couple of days. This fall we had a couple of good super moon evenings, there were spectacular. So we hung out. It was nice to run the heat cycle of the HVAC as it got chilly at night. I like to have coffee and flap jacks in the morning (electric stove). My wife uses a hair dryer. And if you want to have hot water after day one, the power consumption for the hot water heater is high. Afternoons I'm running around in the dingy, exploring, fishing, beach combing. The fridge is cranking away. While I have solar, I don't have enough for more than one day. Of course, I have only a 200 aH bank, 100 useable.

You have a lot more power in the bank spec'd for your boat but possibly not enough to do everything. And you have to have sun. Mother nature doesn't always cooperate.

It all depends on your usage. I'm my case, I'm retired. If we're having fun, I'm in no hurry to get back and the generator provides flexibility. For other people time is really tight and even finding time for one night isn't easy.

-martin610