Overnight without generator

daddyox

Member
Apr 1, 2007
244
Connecticut River
Boat Info
Sundancer 320 2004
Engines
260 5.0 B III's
I’ve never anchored overnight on the hook. Always at marinas. No generator. What are the best practices in terms of the batteries? Should i shut down refrigerator? Start the boat before bed to charge? Am I worried about nothing?

thanks for the input. I want a generator...next boat. Please no generator debates lol!
 
Tells us how many and what type of batteries you have
Two group 27 deep cycle will run refrigerator, anchor light, enough 12 volt lights to play cards and run your potable water pump for 48 hours
If you are worried get a 12 volt portable booster battery for about $100 at NAPA
 
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you will be fine as long as your batteries are in good shape - your fridge and other house loads will run off the dual bank - if you run them down too far. you can always cross over the isolated start battery with the switch on the helm
 
Thanks to both of you. 3 good (1 new) group 27 deep cycle batteries. I could probably turn down or “off” the beer fridge if needed. I appreciate the input.
 
One option might be a large cooler so you can leave the fridge off if it's just overnight
 
If the batteries are good and you don't run lights all night you will be fine overnight. I don't have a generator, so I replaced my port/house batteries with twin 6v golf cart (USB 2200's) batteries in series. Gives plenty of capacity for 3 days with fridge and basic lighting (I did replace all with LED bulbs though). I also installed an inverter so I can run 110v stuff from the batteries. My other battery bank is 2 group 27s, so I am not worried about running the 6v down. Emergency button has me covered. I get by fine without a generator. Can't run the AC of course, but in Southern Ontario its not critical.
 
Thanks to both of you. 3 good (1 new) group 27 deep cycle batteries. I could probably turn down or “off” the beer fridge if needed. I appreciate the input.
No chance, you absolutely cannot turn the beer fridge off. That could end in catastrophe failure of all systems.
 
very valid point that has me concerned. Better to take my chances with a dead battery. I can have a beer while I wait for seatow! Thanks!

See, you're a problem solver!
 
I once ran 3 nights and days on one Group 27 deep cycle battery. Ran the fridge the whole time, anchor light at night, cockpit and interior lights as needed, some stereo. Ran the engine for a total of about an hour that whole time (to the area to see fireworks and back). Still had plenty of juice to start the engine on the last day. You'll be fine.
 
I get about a day out of a battery and can combine them for one more day. I've got LED's as well and watch the voltage. I installed a USB 12v meter so I can charge phones and see the voltage any time I need to. It lets me gauge how well I'm doing. I have had group 31's but couldn't find them last year, so I went with group 29's and noticed immediately a diminished capacity. I'll throw those in the travel trailer and get Group 31's this year. That additional capacity helps immensely too! Just keep an eye and use the crossover emergency start if you have too. Don't let them drop too low and you'll be fine.
 
When reading your voltmeter gauge on the hook. When do you know when your batteries are at 50% and when they are running low?
What voltage should it be at?
 
12.6 is fully charged. 11.2 is dead

BUT these readings need to be taken with an accurate meter at the battery with it disconnected from all loads.

example: You have a discharged battery down to say, 10% and it reads 11.4 OCV (open circuit voltage). Hook it back up with some small loads active and you could read 10 volts.

example: You have a fully charged battery, 12.6 OCV and you have 2 refrigerators running, stereo, some lights on, and the water pump running. You’ll likely see voltage closer to 12V
 
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Did this for 6 years when we were at the lake with no gen. Our MO would be run the fridge at night. Get up and cook breakfast then go out in the morning for a nice long cruise around the lake and charge everything back up and do it all over again that night.
 
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We used to overnight a lot with just batteries and never had problems using the following practices. Always maintained our batteries and replaced them when the first signs of failure occurred. We did not run lights unless needed. Turned them on for whatever reason requiring lights and then switched them off when done. Always had a small cooler with ice in it to keep drinks cold. Switched the fridge down to lowest setting for the evening and used the cooler for cold food and drink. Switched the battery switch to run on one bank of batteries, saving the other one for starting in the morning. When we bought a boat with a genny we followed the same routine except did not do anything with the fridge because it had a cold holding plate, and did not switch the batteries around because of improved battery technology. We would also keep the genny running for heat or AC and charger until bed time and the turned everything off while sleeping.
 
Thanks for all the replies thus far. Very helpful. My approach is always conservative, in fact too conservative at times. Off topic, I think I was more brave when I was younger, single engine smaller boat, less experience, and no radar.
 
LEDs for all lights, including the anchor light. That will save a lot. LEDs in the cabin won't contribute to heat in the cabin.
 
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LEDs for all lights, including the anchor light. That will save a lot. LEDs in the cabin won't contribute to heat in the cabin.
Hi Guys,
I have the 34EC an old girl, just curious on what voltage gauge you would recommend I buy? Going to switch to LCD too.
Cheers Rob
 
I thought 11.2 was empty? If it's 12.2, I've been killing batteries for years and that might explain why I only get 3 or 4 years on a set of batteries?
 

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