patzfan4eva
Veteran Member
- Joined
- Jul 18, 2010
- Messages
- 88
If I have an invertor, is there any value to having a AC/DC Fridge or will AC work just fine. Amp hours always confuse me.....
If I have an invertor, is there any value to having a AC/DC Fridge or will AC work just fine. Amp hours always confuse me.....
I been reading about AC fridges and they seem to use less amp then DC fridges, but I'm not sure how much the invertor uses to convert. The primary reason for this question is my Norcold is dead and If I can function properly with a $150 fridge as opposed to $900 unit I want to go that route.
Rather than do the costly replacement of the auto-switch, the advice I got from 2 marine refrigeration techs was to direct-connect the fridge to the house battery bank buss (with appropriate fusing & cable sizes of course) to be sure to get the full 13+ volts to the fridge.
Also add solar panels to your system to feed the batteries, via a good regulator. Your batteries will love you for it and live longer in better shape.180watts of panels gives enough charge run a 12v fridge on a sunny day with batteries staying full. BruceKI asked my mechanic who said that in his opinion, with the money I'll save on an AC unit, I can purchase additional batteries to help power it thru the invertor.
They seem to use less amps than a DC refrigerator because you're looking at the current (amps) draw at 120 volts for the AC refrigerator and at 12 volts for the DC refrigerator. Multiply the current draw of the AC reprigerator by ten, then add ten percent to that and you'll have the current drawn from your batteries by the inverter to run the refrigerator.I been reading about AC fridges and they seem to use less amp then DC fridges, but I'm not sure how much the invertor uses to convert. The primary reason for this question is my Norcold is dead and If I can function properly with a $150 fridge as opposed to $900 unit I want to go that route.
A lot depends on what is running on AC and or the inverter. If its just the refrigerator and a couple of items not problem. But if you have a lot of AC stuff, like heaters/water heater/batter chargers etc then they have to be turned off and on so only the refrigerator is running.
....... standard domestic fridges are much cheaper than 12v models. Often they are better insulated and more energy-efficient too..........
You know....you guys are supposed to help me by making it easy to buy a AC fridge!!! Thanks a lot!
I'll check into this further with some of the electrical engineers here at work and get there opinion as well. But $1300 (Nova Kool) $1150 (Norcold) etc versus $170 is hard to swallow without a significant argument for them.
Ron,
All very good points, I'm just being cheap. LOL! I'll find out what my invertor is rated for before any decisions are made. Someone has to explain to me why the same size fridge differs by over $1000 from "Dorm" to "Marine" use!!
Ask yourself this question - If a 120 volt AC "dorm" refrigerator powered by an inverter from 12 volt batteries was a reasonable and less expensive alternative than a "real" AC/DC refrigerator, wouldn't the entry level boat manufacturers like Bayliner and Glastron do this instead of installing an AC/DC refrigerator in their boats?
You didn't bother to post the capacity of your inverter, how it was installed, or your battery bank capacity. Is the inverter rated for continuous duty?
Remember, an AC/DC refrigerator runs and draws power until the thermostat determines that it's cold enough, then it shuts off. An inverter would have to run 24/7 to provide power even when the thermostat is satisfied.
Unless your electrical engineers are boaters and experienced with boat electrical systems, their advice is more apt to lead you astray than to set you straight.
BTW: You have what appears to be a pretty nice boat. Why screw it up with a dorm refrigerator? You'll have to put a real one in when it comes time to sell the boat anyway. Think of it as an investment.
"When we're using the boat we switch the Norcold over to DC which means we don't have to have the inverter going in addition to the refrigerator."
No, but there is no saving in amperes drawn while the fridge is cycled on, as it runs off of an AC compressor, with its own built-in inverter, so when you are away from a source of AC power (whether the shore power cord or your ship's inverter), its own inverter kicks in, making that DC into AC, and increasing the amperage draw from 2.7 (for the Danfoss DC only fridge) to 9 amps. The only type of fridge worse than this is the AC only, for which your ship's inverter would need to run all of the time, anticipating the fridge coming on.