Refrigeration

[Ken Brown]

How do I find out how much current a refrigeration unite will consume,and how long will the battery last before I have to recharge.I am buying a new Hunter 310 and I need to know what type of refrigeration would be best for me.The boat will be used for costal cruiseing

 

[Michael Cohn]

Not an easy question...

The best data in this situation is empirical data - there are too many variables to give a good answer to your question. Some of these include ambient temperature, quality of the box insulation, number of times the box is opened, temperature you wish to achieve in the box, amount of stuff in the box, type of battery, condition of the refrigeration unit, quality of box lid seals, etc.The best thing to do is to run the box and measure its current requirements over time under a variety of likely conditions. This will give you a better (although not complete) set of answers to your questions.My own experience has been that the box insulation in Hunters is generally inadequate and needs to be upgraded, and that under the best of conditions most refrigeration units draw a very substantial amount of amps over time - on my boat, with an A/B Supercoldmachine, about 70 AH per day when cruising.MC

 

[Phil Williams]

Calculations

To find the answers to your questions you need the following information.1. The cubic footage of the box.2. The type and thickness of insulation on all six sides of the box.3. The division of the box, 40% freezer - 60% refrigerator.4. The size of the battery on the boat.5. The size of the charging system on the boat.6. The average ambient temperature of where the compressor will be located on the boat.With the above information you can determine how long the refrigeration system will operate, how much amperage the unit will draw and how often you will need to charge the batteries.The formula for find the heat leak of a particular size box is too long to publish here. So you can go to www.kenyonmarine.com/boxtable.htm and locate your size box with the insulation thickness you have and it will tell you how many BTU's per 24 hours it will take to maintain the box at refrigerator and freezing temperature.The ColdMachine can provide up to 300 BTU's per hour of heat removal. Take the total box heat load (from the tables) and divide that number by 300 and you have the amount of running time the system will need each day. The ColdMachine will take approximately 5 amps per hour of running.As for the battery charging take the size of your battery and divide by 1/2 and that will give you the amount of amp hours you can take out safely. Now take the charging rate of your system and divide that into the amount of amps used for the refrigeration system.I hope this all makes sense to you.

 

[Wayne Estabrooks]

Simpler Answer

I have a 1997 340 so my refrigeration needs are probably similar to yours on a 310. I have the Adler Barbour Cold Machine (Air Cooled) which is the standard basic system that was installed by Hunter. I am in a little cooler climate than you and this makes some difference although we have several days in July and August with continuous 90 degree days and humid. I installed 2 group 27 deep cycle batteries for my house battery which gives me a couple of nights at anchor before having to recharge batteries. I have been very happy with the Hunter installed refrigeration system. I sometimes use the boat for long weekends and I leave the reefer off while I am away from the boat so it takes a few hours to get the reefer down to temp to keep the beer cold unless it is in February. I bring a cooler to the boat and transfer already cold items to the refrigerator. Somtimes I cruise for a week or 2 with 50% to 70% of the nights at anchor and the rest of the overnight in Marinas and if this is the typical kind of cruising that you would be doing, then the standard factory installed system would work for you. It sure beats messing with ice! Feel free to ask any questions about my system.