New 12 volt compressor refrigerators

This is sort of a long read but interesting partly because of the location:

https://www.exploroz.com/members/145028.75/1/2009/queensland_adventures_winter_2008.aspx?p=%2fblogs%2fdefault.aspx

fj12ryder wrote:
From what I've been seeing, as the 12V compressor fridges proliferate, so do the numbers of people with issues with them.

12V refrigeration has been available for 5-10 years now. Unfortunately, not one brand has shown to be "head and shoulders" above the rest in quality. Worse, the cheap ones are hitting the market.

If you have the space, a good residential refrigerator and an inverter is a REASONABLE ALTERNATIVE!

12v is old school in the boat world, so not a new technology.

We happen to have gotten one in our current unit. They do have pros & cons.

Pros:
- The cool much quicker.
- No need for external vents which can lead to leaks in the roof.
- Better control of temp.
- For the same size space in the trailer, you get around 50% more interior space.

Cons:
- For off grid, you do need more battery/charging capability.

Ours came with a single 100amp 12v battery and a 50w solar panel. It draws around 50w when running. So assuming a 50% duty cycle, you will need around 600w-hr of usable power.
- By itself, the 50w solar panel will generate around 200-250w-hr per day, so it's not going to handle it.
- A 100amp-hr lead-acid battery holds around 600w-hr of usable power (rated power is near double but regularly dragging it down below 50% will result in a short life for the battery). So for a single overnight, it's doable but multiple days of boondocking are not going to work.

Our solution:
- Buy 2nd 100amp-hr battery giving us 2 days of usable battery power.
- In the morning run the generator for an hour. With a 50amp converter, that's around 500amp-hr in. Then the solar tops it up over the rest of the day.
- Check in the evening and if not above 90%, give it another hour on the generator.

We already have the generator for other purposes and only boondock occasionally. If not, we would pick up another 100-200w of solar, so the solar system could handle it all.

By using uber efficient Danfoss dc compressor’s, these are NOT your Father’s refer..insulation is also superior to help minimize duty cycle:

https://www.danfoss.com/en-us/service-and-support/case-stories/dcs/direct-current-compressors/

3 tons

valhalla360 wrote:
... So for a single overnight, it's doable but multiple days of boondocking are not going to work.

Our solution:
........
- In the morning run the generator for an hour. With a 50amp converter, that's around 500amp-hr in.

Typo? A generator running for an hour with a 50 amp converter with provide 50 AH of power to the battery. If you are lucky. Many converters drop down in amps when the to maintain an absorption voltage of 14.3.

JimK-NY wrote:

valhalla360 wrote:
... So for a single overnight, it's doable but multiple days of boondocking are not going to work.

Our solution:
........
- In the morning run the generator for an hour. With a 50amp converter, that's around 500amp-hr in.

Typo? A generator running for an hour with a 50 amp converter with provide 50 AH of power to the battery. If you are lucky. Many converters drop down in amps when the to maintain an absorption voltage of 14.3.

Opps, meant 500w-hr.

50ah ~ 600w-hr (I downgraded it to 500w-hr)

If it's dropping down, that means the battery is getting to upwards of 80-90%...then the small solar panel can make up the difference slowly over several hours.

If we boondocked a lot, we would look to upgrade the solar to take the generator out of the mix but with only occasional off grid, generator makes more sense to do the bulk charging.