danfoss vs absorption. cooling power?

[KanzKran]

Originally Posted by RossWilliams

We have 250 watts of solar that basically provides enough battery charge to keep our compressor refrigerator running indefinitely. I haven't tested it with a combination of hot weather and short days. But then there aren't many places with that combination.

My Norcold DE-0061 is an AC/DC compressor fridge/freezer of 7 cf capacity, and draws about 5A or so when it runs, which is about 40% of the time on a warm day (I timed it). That’s about 48Ah/day.

While I have 300W of solar, Coachmen didn’t connect the third solar panel (two 100W was standard, three was with the Li3 option) and for the first year it ran on just the two panels. In reasonably sunny or mixed weather, solar would just about keep up with the fridge and the many parasitic loads like the idling inverter that I’ve since learned to turn off. I thought something wasn’t right when solar power maxed out at about 10A, and after some poking about I found the leads for the third panel just laying in the electric cabinet in the overhead, not even terminated with lugs, let alone landed on the controller.

Now solar more than keeps up with the fridge/freezer, and cloudy days aren’t an issue. Freezer gets to zero, and it’s quiet. Loudest part is the thermostat clicking in and out.

The only other DC compressor fridge I’ve had was a cold plate system in my sailboat, and it worked well too. I know why absorption got so popular in RVs, but I’ve never had one and don’t intend to have one in the future unless an RV came with it already installed.

When AC is present, it will run off shore or inverter power, so I have to remember to shut off the inverter when running off the battery so save power if I’m staying for any length of time. With no shore or inverter power, it’ll go back to DC, which is the most efficient. On the inverter, there’s inverter losses, then the fridge’s converter turns it back to DC, so that’s a double whammy. Best to just let it run on DC straight from the battery.

Oh, as to venting, there are two grills - one at the top, and one at the bottom. No other venting needed, and adding insulation around it may be possible as long as that modest air flow isn’t interfered with.

I’m not trying to sell you on Norcold, by the way. It’s just what came with the van, it works very well, and I’m happy with it. One data point.

[RossWilliams]

I just unplugged the fridge from the AC so it always runs on DC whether we are on shore power and the inverter is turned on. I do wish it was quieter.

[KanzKran]

Originally Posted by RossWilliams

I just unplugged the fridge from the AC so it always runs on DC whether we are on shore power and the inverter is turned on. I do wish it was quieter.

I may try that. Looking at a photo of the breaker panel in my van, the gas cooktop and refrigerator were originally on the same breaker, but the OP had the cooktop replaced with a 2-burner induction and a new circuit was added for that in the unmarked space. So I can turn the fridge breaker off without affecting anything else.

[booster]

Originally Posted by KanzKran

I may try that. Looking at a photo of the breaker panel in my van, the gas cooktop and refrigerator were originally on the same breaker, but the OP had the cooktop replaced with a 2-burner induction and a new circuit was added for that in the unmarked space. So I can turn the fridge breaker off without affecting anything else.

Be aware that the breaker is probably not a switch duty rated one and may wear out or fail in a shorter amount of time.


Best to add switch IMO. Or just unplug it and let it run on DC like Ross and many of us do.

[KanzKran]

The plug for mine is buried inside the cabinet and is hard to get to. SWD or HID rated breakers are for switching fluorescent or high-intensity discharge lighting loads at 120V or 277V (HID rated req'd for HID lighting due to the prolonged high start current), and have heavier duty contacts since they're intended to switch under load. For the dozen times I might switch the breaker with no load on it, or the 0.4A the fridge specs show, I'm sure it'll be fine.

[Frumpster]

Hmmm...never had a problem with breakers. Usually when I'm going camping, I will have had the shore power plugged in for the day before with fridge turned on. When I leave, I just throw the isolation switch to on and run off battery power. If I park somewhere with shore power,I just leave the switch on, same when running generator. My inverter/house fusebox does the necessary switching from ac to DC. I have never had an issue.

[avanti]

A marine toggle switch panel that consolidates all DC circuit controls in a single spot makes the operation of the van SO much more understandable and convenient. The fridge certainly warrants one of these switches.
Here's mine:

Control Panel lights.JPG

I have to rethink this in the context of my van automation project, but for a van with manual controls, this approach can't be beat IMO.

[booster]

Circuit breakers are also rated in number of cycles and nowhere near what switches are. You are free to do whatever you want, but I would take a check of the temp of the breakers once in a while with an infrared temp gun (this is a good idea anyway on AC and DC stuff in a van that gets bounced down the road all the time). If the breaker is wearing out it normally would start to get warmer, but at low loads it won't be much. Back in the 1960s when I started working in factories they used to shut off almost all the breakers to the shop equipment to prevent someone from accidentally starting them during off hours. This was once a day, every day, and they did wear out after a while and make a noticeable pop when turned on sometimes. It is much more common now to require the disconnect switch at any dangerous areas in such times right at the equipment as you have to have one anyone per safety rules.

[GeorgeRa]

I used BlueSea toggle CBs as switches, this is from Blue Sea spec.: “Combines switching and circuit protection into a single device” No statistics.

[booster]

Originally Posted by GeorgeRa

I used BlueSea toggle CBs as switches, this is from Blue Sea spec.: “Combines switching and circuit protection into a single device” No statistics.

Those sound just like what would be needed in this case. Good find and looks to have switch ratings with all the major agencies.