refridgerators

C

caw

New member
For those of you that have refridgerators on your boats I am interested in knowing how many of you leave it running off of battery power when you are towing and when you are anchored w/o shore power. If you do so, how long do you think it is safe to do so w/o draining the battery too low. This is an issue I have not resolved because I don't want to drain the battery, but hate having to move food from the fridge to a cooler.
CW on My Lee
 
We run our refrigerator while towing and at anchor. This year I added a Victron V600 battery monitor. We have a 115 amp hour house battery and base on a 50% discharge Max we could go without power for 4 days approximately. We love having the Victron as it takes the guessing out of it. Kind of like a fuel gauge.
 
The length of time you can run a refrigerator depends of many factors--including the battery capacity. I am surprised that you can get 4 days before you get the 50% discharge level on a 115 amp hour battery (that would be the use of about 57 amps.) The refrigerator generally are rated at about 3 amps per hour. This means that in 4 days the refer runs about 19 hours out of 96 hours or about 20% of the time. Realistically I have found that refers run about 5 amps and run about 30 to 50% of the time.

Factors include ambient temperature, and insulation. We have to either charge the battery via the engine, or run a charger every day to keep the batteries up (of course that includes some lights a night and the Wallas stove for heating and cooking, even in the cool of the PNW.

The solution for trailering is to charge the house battery off of the tow vehicle. I do this on both our RV and we did it with the Ford Excursion. We put a 30 amp fused circuit (you will not be running 30 amps, but that allows some safety factory on both ends) off the tow vehicle's battery, with either a separate plug, or one of the pins of a 6 or 7 pin connector. There is a cable of #10 wire from the trailer hitch, going in thru the hawse pipe, with a connector in the anchor locker, and then a second cable going into the back of the console (fused) where it feeds into the house battery circuit. This way the house battery is kept topped off. If you wish you can put a diode in the circuit and that will prevent back feeding into the vehicle. We unplug the connection at night when "camping" in the boat.
 
I have a type 24 size house battery. I filled the refrigerator and let it run a day with the boat hooked to the house power. I then "unplugged" and measured the house battery at 12.8 volts. It took 30 hours to pull the house battery down to 11.8 volts and the 'frig was still running.

I made a long extension cord of 30 feet of 10 gauge wire from my pickup's camper electrical outlet to the boat house battery. With that I've gone two days on the road and the house battery was still "up" at 12.8 volts when we arrived. We lived on the boat those days on the road and used stuff from the fridge several times a day. We are presently planning a 2 month road/ boating trip using that system. Check with me in December and I'll tell you how it worked.

Chuck
 
I used to get 3-4 days to 50% discharge on my 22 with the fridge running off the battery. It helps being up here in the PacNW where temps don't get too hot. However, rarely was I ever more than 1 day without shore power. When I have the boat out, I'm either trolling (engine running all day) or at a dock (on shore power with a charger). When the boat's at home, it's hooked to shore power. I love having a fridge since it's always stocked, cold and ready to go.
 
Battery voltages are best measured at rest, with no load. Most consider a battery 50% discharged at 12.2 volts. A battery at 11.8 volts is for all intensive purposes discharged. The refrigerator may not have a voltage cut off until point lower than that. But If you routinely discharge batteries to 11.8 volts it will significantly shorten their life.

The water temperature is important as well as the ambient air temp. If you are in AK (Juneau is reported as 47 degrees F today)--or N. BC, the water temp may be much lower than at Lake Powell (82 degrees F today).
 
rogerbum":1dld4shv said:
I love having a fridge since it's always stocked, cold and ready to go.
Click to expand...

I agree - wouldn't have the boat without the refridge.

Before we leave on vacation or while we are on shore power in a marina, we always turn the refrigerator to Max cold. Then on battery we turn to middle cold and that might help w/battery usage.
 
I'm a little more pessimistic than Bob, but my numbers are similar.

First of all, Journey On has a 2.7 cu ft Norcold refridg, from the factory. Once we leave the house, the refridg is running and doesn't get turned off until we get home. So it's been running about 10 weeks now, full time. At night, whilst listening to the darn thing run, I'd estimate the duty cycle is 50% and doesn't seem to vary much with the external temp. I'll admit that it hasn't been very warm this year in the Pacific NW, but 50% is still a reasonable duty cycle.

I also estimate the darn thing draws 4 amps, though the mfg says 3 max. I'd bet that's at full voltage at the refridg, which it doesn't see.

That amounts to 4x0.5x24= 48 amp hrs/day. I would bet this is a good number to use for a lot of refrigerators.

Journey On has 2 ea set of golph cart batteries, which provide 200 amp-hrs of capacity. Doing the arithmetic, we can safely go 2+ days to reach ~50%. For a 115 A-H battery, that's 1 day for 50%. AND NOTHING ELSE, such as cabin lights.

However, we usually recharge the batteries once/day. If we're driving, we stop at night and hook up to electricity. If we're anchored for a couple of days, I'll run the Honda generator once a day. We stop comfort's sake and I take advantage to recharge so as to not ruin the batteries. Those suckers run $120 ea, though they last for 6 years (as recharged per above.) That's worked well for years.

Trying to run 2 days on a small 115 AH (Grp 29) or even 130 AH (Grp 31) is possible but just reduces battery life. Your call.

Boris
 
We also made an adapter cable to run from the tow vehicle to the boat batteries. Our fridge is on any time we are traveling with the boat, on water or on the trailer. It is no issue, since we rarely sit in one place for days at a time. With 2 Grp-27 house batteries, we get two days at most of fridge use before the batteries get low. If necessary, we will charge the batteries with an automotive charger run off the Honda 2000 generator (faster recharge time than the "trickle" type charge of the factory supplied Guest charger. Running the engine daily does a better job of keeping everything charged up.

Having a refrigerator onboard is part of our cruising "necessities." We've done the "hunt for ice" on previous boats, and don't care for the mess and fuss. With the small freezer compartment, we can make enough ice cubes for evening beverages. Nothing gets soaked like in the bottom of a cooler. It's just part of the easy-living amenities that make the boat more home-like... and easier to spend more time onboard.

That said, we do often have a large cooler in the cockpit when we cruise - it is just dry storage (not cold). It has a padded top, so offers additional seating or as a footrest. I don't think we've ever had ice in it. 8) Love the fridge.

Best wishes,
Jim B.
 
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