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RO# 33766

Posted - Nov 28 2017 :  14:49:47  Show Profile  Reply with Quote
Hey I have a Carver 500 CPY I am having a problem losing power if we stay on the anchor for one night. We have 3 refrigerators and a ice machine that just kills the batteries. I was looking to get enough solar power just to charge to battery that the inverter runs off of. I know my big freezer/refrigerator runs about 15 amps so I assume the other one are just below that. I am not sure how solar works - does it charge the batteries with DC or gives power to the inverter to charge AC?
I think I need about 30 or 40 amps for all refrigerators. The more the better but I think that would be the minimum?
Is my math right? Who makes a good long life solar package?

Homeport: NC


RO# 3238

Posted - Nov 28 2017 :  15:27:51  Show Profile  Reply with Quote
The solar panel(s) produce DC, which charges a battery ( often through a "charge controller. Desirable for any "large" system. You qualify ).

The refrigeration apparatus may run off of DC or AC, as some units are capable ov "dual power" operation. You need to know.

IF the refrigeration apparatus use AC, them the path is: Panel charges BigBattery -> BigBattery is the source for an Inverter -> which powers the AC load ( refrigerator(s) )

Calculating the total daily power requirement for refrigeration is difficult, bordering on impossible. Actual consumption depends on many variables, including ( but not limited to ): Ambient temp, Refrigerator efficiency, how often you open the door ( and how long ) how much ( and at what temp ) you add items to chest ...

You can guess what the "typical usage" might be, since you are nearly killing your battry bank. If you know the capacity of the battery bank, measure the time till it gives up. Divide capacity by hours to get a somewhat useable number.

BTW: You say, "I think I need about 30 or 40 amps". You may be making a common error.

You need the "rate" and the "total usage" Your power delivery system must be able to deliver at the "rate", but the "charging system" must be able to, in one day, produce greater than or equal to your expected "total usage.

Typical nomenclature can be confusing. A Type 31 deep cycle might typically have a capacity of 12V at 100A. You only want to use 50% to 70% of this capacity ( 50% gives longer service life ) SO, a type 31 can hold "50 Amps". Which is ( rpoughly, seen note ) 50 Amps delivered in one hour, or 10 Amps per hour, for 5 hours.

Note: Max battery capacity is delivered at "low rates, ie: over 20 hours ). If you discharge at a high rate, there is less capacity. ( ie: at a rate of 25A / hour, cap might be one half of the slow discharge rate )

All above is "general" and generic. All numbers are "typical". You need to know and measure to get a good result.

Have fun; it is interesting.


"No matter where you go, there you are." -- Buckaroo Bonzai
"There is nothing, absolutely nothing, half so much worth doing as simply messing about in boats." - Kenneth Grahame

Homeport: MS Gulf Coast Go to Top of Page


RO# 36

Posted - Nov 28 2017 :  16:54:42  Show Profile  Reply with Quote
We found that the ice maker used the most power. Shut off the ice maker by raising the bar (or otherwise) so that it merely keeps the ice frozen and see what happens. Ice makers run the compressor quite a bit and some have a heater to break the cubes loose when they are frozen.

Solar panels have to be sized to charge the batteries as well as keep things running.

We had two 8Ds for the house bank. We would burn 80-100 AH over nite running the inverter which powered a freezer, and we also had two DC refrigerators.

Edited by - boatbum on Nov 28 2017 16:58:57

Homeport: Go to Top of Page


RO# 33766

Posted - Nov 28 2017 :  17:12:19  Show Profile  Reply with Quote
all appliances run off of 120V since they are hooked to the inverter, but yes they also run on 12V if I was to every lose power. My inverter is 3000W. I have 4 batteries on two banks, so all 4 died within 24 to 30 hours. Could I just match the inverter? My worse fear is I am going to be stuck with what I can afford not what I need. Can you add panels at a later time to increase the wattage? Who makes good solar systems?

Thanks for all the help!

Homeport: NC Go to Top of Page


RO# 12212

Posted - Nov 28 2017 :  20:12:49  Show Profile  Reply with Quote
The typical production boat has insufficient batteries. Builders try to save a buck and a few pounds and hope they will Be on generator ornjustvdock queens

Solar won't help you if your batteries don't last a night... yeah you need sun. The moon isn't going to work.

You need to know what kind of batteries you have, otherwise it s impossible to answer your question. You need enough batteries to last overnight...

1970 Hatteras 53 MY
26' Starfish sloop
12' Westphal Catboat
16' Hobie Cat
13' Sandbarhopper

Homeport: Miami, FL Go to Top of Page


RO# 21040

Posted - Dec 18 2017 :  17:30:22  Show Profile  Reply with Quote
on my carver the batteries are dedicated and not shared in any way. 2)one per engine, 1)generator, 1)bow thrust, and 1)house. You probably have a switch for each. My refer is dual powered ac and dc.

As previously mentioned, have batteries checked, check charging of battery, check appliances, the refer pumps the heat from the inside to the outside. Does the door seal? Have you cleaned the coils? Do the coils get good airflow?

If you have a good location a wind generator may be another option.

Homeport: Go to Top of Page


RO# 7357

Posted - Dec 18 2017 :  18:17:02  Show Profile  Reply with Quote
Ok, the OP has a 50 Carver. Can we assume he has a genset? Why has no one asked why it isn't being used

Homeport: VA Go to Top of Page

Audrey II

RO# 30499

Posted - Dec 18 2017 :  20:06:40  Show Profile  Reply with Quote
Many people are afraid to run their generator over night.
I'm the cove where we spend most weekends we have two groups the genny raftup and the non genny raftup. I run my genny most of the time but I do like to give it a rest and well as my ears from time to time, frankly the less I run it the happier I am! and it is not about the fuel burn.


“Time you enjoyed wasting is not wasted time.” – T.S. Elliotcommon.

1996 440 Trojan Express

Homeport: Haverstraw, NY Go to Top of Page


RO# 7357

Posted - Dec 18 2017 :  20:42:36  Show Profile  Reply with Quote
I agree that many don't like to run the genny overnight, but the OP mentioned all of his batteries dying in 24-30 hours. Sounds like he's not running his at all, day or night.

Homeport: VA Go to Top of Page


RO# 3813

Posted - Dec 19 2017 :  10:46:08  Show Profile  Reply with Quote
Originally posted by cwms

Ok, the OP has a 50 Carver. Can we assume he has a genset? Why has no one asked why it isn't being used

Exactly, the amount of battery power he needs to run them off an inverter is crazy. Most boats his size run the generator from the time they leave the dock until they come back and plug in.

If he doesn't want to run it at night (we never run ours overnight), shut it off. So long as the refrigerators are not opened, they will stay cold.


1999 Trojan 440 Express
2005 Scout 175 Sportfish

MMSI# 338049724

Surly to bed, surly to rise...

Homeport: Haverstraw Marina, Haverstraw, NY Go to Top of Page


RO# 7357

Posted - Dec 20 2017 :  17:30:50  Show Profile  Reply with Quote
Sure would be nice to hear back from the OP on this

Homeport: VA Go to Top of Page

Bob J

RO# 181

Posted - Dec 20 2017 :  18:42:48  Show Profile  Reply with Quote
Ran my genny when anchored out over nite. Had it wired so that if CO detector measured high CO it shut genny down. Luckily never needed it.


Bob J

Homeport: Waretown, NJ Go to Top of Page
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