compact fridge

Thanks all for all the informative posts. Your candid assessment has convinced me I need to review my options and go in a different direction. Just not sure what direction that should/could be.

I currently have a 12v compressor fridge(second one in 4 years) that has been very problematic. The first one died outright after 3 years and now after 1 year the current one is down. At my wits end as we just cut a trip out west short by 8 weeks due to the failure. Question folks about the 12v Dometic CR1110 fridge, is it possible for a battery bank to be defective if the voltage shows good and they power everything fine including satellite tv, lights, water pump etc? I ask because the problem with the fridge is that the compressor turns off and immediately and repeatedly tries to come back on. This occurs after the compressor has run for 10 minutes or so. Sounds like it does not have enough power for the compressor to kick in. Compressor kicks off even though the fridge temp is at 45 degrees and continues to kick on and off . Any and all help appreciated . Sorta hard to explain on a forum but I can explain the symptoms over the phone better if someone would be willing to help.

I have heard negative comments about the Dometics. Consider replacing with a Truckfridge.

rexlion wrote:
I have heard negative comments about the Dometics. Consider replacing with a Truckfridge.

Not familiar with that brand, is it by Norcold?

12v compressor fridges that use the Danfoss/Secop BD35f compressor, are very intolerant of too thin of wiring from battery to compressor controller.

If one is using a chest style with a Ciggy plug connector, Bypass these horrid connectors and get the wire closer and shorter and fatter to the battery.

Danfoss BD35f spec sheet indicates to use much thicker wiring than one would assume is needed for a compressor that cannot draw more than 6.5 amps at maximum rpm, not including start up surge.

http://www.ra.danfoss.com/TechnicalInfo/Literature/Manuals/06/bd35-50f_electronic_unit_ac-dc_04-2009_ei100g402.pdf

They do not even say anything thinner than 12AWG is acceptable, no matter how short the distance might be.

The Ciggy plug cords provided with the chest style portable 12v units are 16awg perhaps 18awg on some. This is an insult to your compressor, and in direct contradiction to the Compressor manufacturer's instructions on how to wire it for power.

When I have run a 10 foot 12awg extension cord to my Vitrifrigo, and battery voltage dropped to 12.4, the compressor would not start. Only the condenser fan would kick on.

Wire them thickly, eliminate the ciggy plug. Voltage drop is the enemy. Disregard ampacity charts, and go for thick copper for minimal voltage drop.

I think Dometic is now employing Waeco's newer compressor which appears similar in design to the Danfoss/Secop bd35f.

My 1.8 cubic foot Vitrifrigo c51is performs beautifully, But I have added extra insulation to box and cabinet housing and a very well ventilated cooling unit that cannot recycle air itself has heated, as well as an interior fan.

Rare that mine consumes more than 1AH per hour or more than 24 in 24 hours

The Truckfridge TF49 and the Vitrifrigo C51is are very similar in design. The VF is assembled in Italy, the TF in China.

I spent 100$ more on a VF and am glad I did. The TF would not have allowed me to upgrade the condenser fan.

Here is a 4.2 cubic foot Truckfridge:

http://www.truckfridge.com/tf130.html

My fridge is not wired via cigarette lighter but I have speculated as well that the problem may very well be voltage drop. I have an appt Tuesday with Dometic and plan to ask them about this possibility. Do you have any other thoughts/suggestions about the possible cause/fix of this type problem.?

To check, see what the voltage at the supply side is, and then what the at the fridge end is. If there is drop, heavier wire is the answer.

It is possible for the battery bank to be able to supply normal RV low amps with no trouble, but have difficulties with high amp draws.

If the two 12s are not wired in a "balanced manner" you have an "upstream battery" taking the load first, and it will struggle with high amp draws. You also want fairly fat wires for the parallel links. I use #4 for that, some use fatter.

The Dometic cycling on and off quickly could be entirely weak undercharged sulfated batteries triggering the low voltage disconnect of the Danfoss compressor controller.

Combine that with too long and too thin wiring and the fridge might be perfectly operational, it is just the battery and the wiring from it to fridge which is severely lacking.

Most people have no idea it is bad to leave a Lead Acid battery sit in a discharged state. Many think all they have to do is drive for 15 minutes and the battery is magically restored to full charge and 100% health, when nothing can be further from the truth

I will definitely present all these potential causes to Dometic Tuesday,hopefully through the process of elimination a fix can be found.
Thanks all for the help.