Best option to power 15CF 120v Refrigerator for a few hours

[PenBayCruiser]

Just for getting the boat home, you might consider a solar generator. I just bought a Ugreen Power Roam 1200. 1200 AC inverter with 1028 watt hours of capacity (near 900 with inefficiencies). Will start loads up to 2400 watts. Can be charged with up to 400 watts of solar (12-48 volts). Paid $750 a week and half ago. You'll no doubt find many other uses for something like this.

 

[ranger58sb]

Boat only has two 8 D's for port and starboard starting and also act as house batteries.

I have been reluctant to chime in. I personally find it unacceptable to have two 8D’s act as starting and house Bank.

However, this being a new to OP boat, I fear that OP might not correctly understand the electrical set up.

Assuming he is correct, I wouldn’t even leave the dock without changing the set up to a starting baNk and a house bank. One 8d is more than adequate to start both engines. This would leave the seconD 8d as a house bank. In an effort to save money I would wire onE alternator to each bank.

While I wholly agree, this setup is more common than you think. My last Marine Trader was the same way with the exception of a 3rd 8D as the generator starting battery. House was still the starting 8Ds. I don't like it either and it will get a full overhaul to my liking once berthed here in Florida rather than Virginia Beach.

It's a VERY common battery architecture for U.S.-built production powerboats. In fact, I suspect it's more common than having separate start and house banks.

We're on our fourth U.S.-built production boat brand, all 4 have been set up this way.

I'm not clear whether OP means 2 8Ds per engine, or 2 8Ds total... but either way, it's pretty normal for U.S.-made sportfish, convertible, sedan bridge, motor yacht, ACMY, etc. boats to be designed that way. (Our current set-up is 2 8Ds per side, at 24VDC.)

And then these can be augmented by separate batteries for the genset (most common), or a thruster, or a windlass.

And making changes can sometimes be easy... or not. (In our cases, not.) Depending on real estate, I've found it easiest to just add capacity to each main bank if possible... or at least ensure capacity is as much as real estate will allow... and then get on with life.

Given a separate starting battery for genset, plus a typical parallel ("emergency") start switch to temporarily combine both main banks if necessary... there's not much chance of being stranded because of battery issues.

That doesn't speak to efficiency, maybe... but it's not difficult to make the most of it.

-Chris

 

[Flatswing]

It's a VERY common battery architecture for U.S.-built production powerboats. In fact, I suspect it's more common than having separate start and house banks.

We're on our fourth U.S.-built production boat brand, all 4 have been set up this way.

And then these can be augmented by separate batteries for the genset (most common), or a thruster, or a windlass.

And making changes can sometimes be easy... or not. (In our cases, not.) Depending on real estate, I've found it easiest to just add capacity to each main bank if possible... or at least ensure capacity is as much as real estate will allow... and then get on with life.

Given a separate starting battery for genset, plus a typical parallel ("emergency") start switch to temporarily combine both main banks if necessary... there's not much chance of being stranded/QUOTE]

This is my experience also with 2x12v AGM 8D’s. Before inverter use became widespread, most boats w/o generators had limited 12v dc loads, as usual the fridge being the most voracious. I recall routinely switching to “Battery 1” on odd numbered nights at anchor, preserving #2 for starting. On even numbered nights at anchor used only #2. The idea was to always leave a battery unused for house loads & even out battery usage so that both were equally dependable. We didn’t have battery monitors and the storage was only effective assuming one ran the mains each day.
Mandatory to know your battery selector switch was a “make then break” type with this strategy but it was simple, effective and safe because one was always using a single (but different each day) battery to start engines, so you could hear and see any decline in performance before it became critical. In my case, Batteries were still fine after 5 yrs when boats sold.

 

[luna]

Zeus.

If you have a handful of 8 hour passages to make, I would try this if you have 120 V AC power at your dock, as it costs virtually nothing and is done in 2 minutes. No rewiring required.

The day before you leave put a couple of 1 Gallon milk jugs and about two dozen 16 oz.+/- water bottles all almost filled with fresh water in the freezer. Turn the freezer and fridge compartment to about the coldest setting.

Just prior to departure, put one jug and half the bottles in the fridge up high, turn the freezer and fridge back down to normal, wait for the compressor to stop if it's running then remove power to the refrigerator and leave the dock.

Underway, open the fridge as little as possible and don't linger with the door open.
Put your day of passage consumables in a cooler with some ice.

Once you are back at the dock with power, your lettuce will remain crisp, the beer cold but you may have to wait an hour or so if you like your ice cream hard.

Before each 8 hour passage, rinse and repeat.

I'm on the Southwest Coast of Canada so we generally don't have the heat or humidity of Florida, but I routinely shut the Refer. off (loaded with ice) when at anchor overnight with no ill effects. It saves about 100 Ahs. from being taken from the battery bank.
The ice is in effect stored electrical power, sourced from the dock.

 

[ronobrien]

I am refitiing my GB36 which has no genset. I will have a single starting battery for both engines and a (2) 8d house bank & solar array. I am thinking of a Honda 2200W suitcase generator on deck plugged into the shore power for the times I will need a little extra. I figure I will have gas for the dinghy anyhow. This will be a cheap easy alternative to a genset. Best of luck.

 

[Zeus]

Just for getting the boat home, you might consider a solar generator. I just bought a Ugreen Power Roam 1200. 1200 AC inverter with 1028 watt hours of capacity (near 900 with inefficiencies). Will start loads up to 2400 watts. Can be charged with up to 400 watts of solar (12-48 volts). Paid $750 a week and half ago. You'll no doubt find many other uses for something like this.

I opted for this (sans solar panels). Hopefully it will be delivered in time. Its a LiFePo4 battery that should run the fridge ~6 hours. Once docked it can be recharged in 1.5 hours. Let's hope it works out. Even if you consider a power outage at home, 3 hours without opening the fridge/freezer doors is fine. I had concerns about leaning on my alternators/starting bank. These Detroits are 1980 and I don't know much about their alternators.


Thanks again everyone, good discussion.