Marinette Boat Forum

It's not the size of the inverter that counts, it's the amount of battery power available. Our old boat would run the 120 volt "apartment size" fridge all afternoon and night on two deep cycle batteries (along with a TV, a VCR and lights). I needed another battery to make my coffee in the morning, however.

That said, a block of ice added to the 'fridge before you leave the slip will keep the contents cool by itself for several hours. In addition, we used a cooler with ice in it to keep beverages cool and avoid opening the 'fridge.

Jeff

We used a Xantrex 1000W inverter.
http://www.ase-supply.com/Xantrex_806_1 ... 6-1010.htm
It supplies plenty of affordable AC to the fridge (ours draws 74 watts when running). You'd need to check your fridge's current draw + normal run time as it cycles on/off to figure the amount of current pulled en total. Run that against the available current from the battery used to supply the inverter to see how long a fully charged battery would keep the fridge/freezer running.
Couple of good things on the Xantrex:
1. The display is detachable (remote cord's supplied) so you can mount it where you can easily see the display / check on battery.
2. There'r are programmable alarms, such as low voltage.
3. You can disable the display to save juice, though in normal operation this is minimal.

Bill

Remember standard Frig like the GE's on newer Marinette's have a defrost circuit that is a Heater with a timer that drains batteries fast. Consider disabling that feature.

I have a tripp lite 450 watt inverter. It is powered by two group 27 deep cycle batteries. I start the generator about every 6 hours to replenish charge. Tripp Lite also makes a APS750, which is an automatic power switching inverter that can provide up to 750 watts. When the 120 vac circuit is live, it will charge batteries at 20 amps. It will be my next inverter. Just plug the fridge into it and forget it -- no moving the plug from 120 ac outlet to inverter manually.

I put a larger refrigerator in where the hanging clothes locker was across the aisle form the galley. I cruise for weeks at a time between reliable and easy (to get to) groceries so a real freezer was desired. It draws 6 amps as measured on the DC monitor on the house bank batteries. 600 amp hours practical capacity on the house bank. I am running the refrigerator on AC but monitor power usage/charge on the DC side of the inverter. Low amp draw, but if I put a lot of warm things in there it can take over a day to come down to temp and stop running continuously. If I am underway for four hours a day I do not need to run the generator to charge the house bank. 12 volt from the alternator goes directly to the batteries through a battery isolator (the starting battery charges first) and then through a resistor to keep the continuous load on the alternator below what burns it out. I don't have to worry about switching anything when going from engine to shore or genny power. The inverter (Xantrex Freedom HF) switches power source from house bank to AC whenever reliable AC is available to it.

Darn clever approach! Never thought of that. What did you place in the old refrigerator spot?

Jeff

The inverter does 1800 watt AC, which is enough for a microwave, coffee maker or the things first mates use for their hair. The 70 watts the refrigerator uses is insignificant as far as the inverter goes, also computer, phone charger, WiFi and lights. Normally the amp draw on the house bank stays under 8 amps. On average it's more like 5 amps. For bigger loads; making a pizza, hot water, Air Conditioning, the generator runs. While running the generator the inverter charges the house bank at 40 amps. I think the standard advice for choosing charging capacity is to stay under 10% of the amp-hour capacity. While out at anchor the generator runs two hours a day or so, using less than 5 gal of gas in a week.

As for "stress" on the house batteries, the are damaged if drawn below 50% which is at 12.0 volts. I will manage them to stay between 50% and 75% while I am away from the dock. Above 75% to 80% charge, they will not accept 40 amps and running the gen to charge them isn't so economical. When I get to a dock and pay big bucks for the services I will let the inverter charge the batteries all the way up and condition them. If I am motoring any considerable distance I don't need the generator much. The current house batteries have several hundred of these cycles on them and I have not noticed any drop in capacity.

Where the old refrigerator was I put a microwave/convection oven under the counter. It's a much better location than up high as far as not spilling hot stuff all over you. Below that I put in two sliding open drawers for cooking utensils.

very robust and thoughtful electrical config.

Outstanding work! Now, where do you hang your clothes?

Leff