Battery discharge and preservation while anchored

[Pilot]

Curious how others preserve their battery life while spending several hours out on the hook. I have 2 banks of 2 batteries and I'm always worried about draining them. (And I have many times, at least the starboard bank).
I've gotten to the point of turning off the fridge and any other non-essential items. Then running the generator or starting the engines occassionally to recharge say, every 2 hours.
My issue is Running the generator all the time makes for a noisy and uncomfortable outing, especially with guests on the outside of the boat or swimming.
Thx

 

[Boater420]

Are your batteries weak? Are they deep cycle? Are they old? Is the water level in the battery ok?

I'm able to run my 12v items all night without killing my batteries. I have a 2 battery house bank comprised of dual purpose deep cycle batteries. I run the fridge, TV, lights, and stereo all day and most of the night without ever having an issue starting in the morning.

I've replaced my cabin fridge with a Vitrifrigo, which has a newer Danfoss compressor which is supposed to use very little electricity. I've also changed out the old halogen bulbs with new LED's. Other than that the rest of the boat is stock.

 

[RollerCoastr]

I've spent days on the hook running the genny only a few hours per day. (coffee in morning, stove in the evening...)

Fridge tips:

- don't let it cycle off while on AC power - let it get as cold as possible, then back it down while on batt
- open as seldom as possible
- load it with cold, dense items. (cans/bottles, ice and dense frozen food in the freezer)

 

[Little Ducky]

If you are worried I would start with the health of your batteries. If they are close to 5 years old they are pushing their life expediency. I changed my flooded (one leaking) batteries out earlier this year with AGM deep cycle batteries and the boat is loving them.

I see some folks out on the water over night and they have their boats lit up like a landing strip.

Keep unessential lights off and you should be good to go for at least 24 hours even with the frig on.

 

[Pilot]

Thanks for the reply, Yes, I'm replacing batteries which are midway thru 3rd year. I normally replace on the beginning of season 4 as a precaution. I ran deep cycles this last time and now the dealer is recommending Dual Purpose Group 31's. These have a 205 minute reserve capacity, 700 CCA 850 MCA.
I think the frig is the main culprit followed by stereo/amp and lights. We run the stereo a lot.
The LCD TV doesn't work unless the gen is on, so I don't worry about that.

 

[Little Ducky]

https://www.batteriesplus.com/battery/marine-and-boat/deep-cycle/bci-group-31m/sli31dtmagmdc

I went with these. They were a good upgrade from my lead acid group 24 batteries that the previous owner had in the boat.

Plus BatteriesPlus had 3 of them in stock locally on a Sunday....10% off and a rebate.

 

[Wylie_Tunes]

I would designate one as the primary house bank, then build it bigger with more battery amp hours. Just make sure you have an on-board charger that can accommodate the extra capacity.

 

[insfnds]

I had similar issues. I added a 3rd battery to the port bank which also runs the house loads. I'm also a firm believer in deep cycle batteries in boats, AGM even better.

 

[sbw1]

Our fridge has a cold plate that recharges anytime the engines are running so at anchor it will go for hours and not run. We have never run our house batteries down as the boat is pretty energy efficient. Should that happen, the genny has its own isolated, starting battery which is charged any time the genny is running so we can start it up, run the battery charger and get house batteries charged up again.

 

[northern]

Little Ducky
Are your new batteries made in the US
Pilot
We have 2 group 27 deep cycle batteries that run all the 12 volt system including refrigerator. We get 2 days before they need charging.

 

[M Prod]

My house (port) bank are two group 31 AGM batteries new this season. We never have an issue and have never run them below 60% capacity after any given night. We have switched all bulbs to LED’s, but the fridges are stock, we usually watch tv for an hour or two before bed, and we run a nightlight/noisemaker for my son all night every night. Generator is usually run in the morning for coffee and cooking, and at night for an hour or so for the same (minus coffee). We’ve stayed out for days like this with no issue. I would check your battery health and don’t trust the voltage meters on your ac/dc panels. Install a proper battery monitor if you’re worried and don’t already have one. If you have flooded batteries, you can check the health with a hydrometer. That’s really the only way for flooded to see where exactly your batteries are in their life cycle. If it’s time to replace, I highly recommend AGM’s.

 

[importmonkey]

the biggest draws i've seen when on the hook are:

lights - keep them turned off (i'll be swapping to LEDs this season)
fridge/freezer - open as seldom as possible
satellite tv system - dear goodness does this thing draw some power!
heads and water pump - if it's yellow, let it mellow; if it's brown, flush it down
stereo - if you've upgraded it to a larger amp, then definitely yes (consider a bluetooth speaker if you are worried)

you really shouldn't have a problem draining your bank over night (especially since most of that is off). start looking at your amperage meter at the breaker panel and see what spikes the needle.

 

[Loyd Dinneen]

I have kind of a unconventional setup on my 1977 240 Sundancer SDA. This boat didn't come with a generator as there is no room as it has twin 470 mercruisers. I have done some upgrades I installed a three place battery charger for the two group 65 deep cycle engine batteries and the two group 65 deep cycle house batteries. I have also installed a 4000 watt inverter to run the fridge which is 120 volt model and my little coffee pot. I charge the house batteries with a 50amp solar charger when I need too. When the boat is in the slip(only 3 weeks out of 9 months) I put the solar charger on one of the engine batteries put the switch on both and keep them topped off to run the bilge pump, I only use the fridge when using the boat(haven't been able to do that yet still working on getting her ship shape)and then will hookup to the solar charger, lots of sun in Las Vegas. I still have too change out all the bulbs to LEDs, no tv or microwave to worry about. I have tried to keep things simple electrical wise and concentrated on the mechanical side of this boat as it has had alot of things wrong with it, it has spent more time in front of my house than on the water. I would love to figure out whats wrong with the horn lol. I'm sure theres lots of you out there that have had the same situation.
I have tested the fridge with the inverter and one battery and on a low setting kept the fridge at 40 degrees and lasted for two days and the battery was down to 12.3 volts.
Also since putting in all the new batteries I also replaced the rectifier charging system on both engines with the alternater conversions.