Hybrid refrigeration system ??

[Miguelso]

Our new to us boat came with an Seafrost engine driven refrigeration system that works fine. We are planning this sabbatical year off with the family in the Caribbean and I see ourselves at anchor for several days, and I don't want to turn on the engine twice a day to maintain the refrigerator. So I was planning to add a 12v system (with adequate batteries/solar and wind) together with the engine driven system. I was thinking this two systems might complement each other storing in the holding plate while motoring and using solar and wind while at anchor. In my previous boat I would keep water bottles frozen to avoid temp fluctuations and I was thinking the holding plates would act in a similar way.
Does this make any sense or should I just remove the old Seafrost?

Thanks

[a64pilot]

Unless mistaken, I believe what your contemplating has been done, and with good results.
What I do not know is was there separate holding plates, or one plate with two separate refrigerant lines?
Only downside I see to dual plates is loss of room?

I would leave what is there and working, alone. Although running the engine twice daily is not ideal, if your DC system broke at least you would have a back up

[StuM]

My freezer has both a fairly bulky engine driven eutectic holding plate on one wall and a thin Frigoboat 12V plate around the top half of the other 3 walls.

The thin plate doesn't take up very much room and I have the best of both worlds.

Solar/battery powered most of the time so generally no need to run the engine for refrigeration, but if I am getting a bit low on available AH the engine will pull the freezer back down at the same time as it is putting "juice" back into the batteries.

[MooGroc]

I did exactly this last spring. I had a 25 year old Seafrost engine driven system that worked well and I added a Seafrost 12v system that plumbed into the same holding block. Everything works great. It's amazing to see how quickly the engine driven system can cool the block compared to the 12v system.

Now I just need to improve the insulation of the box. Cleave at Seafrost was very helpful with the install.

[Miguelso]

Thank you for the feedback, I'll go ahead and install the 12v system together with the engine driven system, I also like the idea of having redundancy.

[a64pilot]

I was also thinking having excess cooling capacity would be nice for those times when you put a significant amount of meat or fish in the freezer and want it frozen quick, just start up the motor and run both systems for awhile

[Richard Kollmann]

I have designed maybe 100 hybrid boat refrigeration systems most of these were engine driven and electric. In the 1980s most hybrid systems with electric systems had added 110 or 220 volt compressors but later designs were able to benefit from improved onboard DC 12/24 volt compressors and alternative energy sources. As early as 1984 I tried to convince boaters when I made them custom holding plates to add a second $35 coil inside their plates.

There are several ways to change an engine driven single evaporator coil holding plate system without disturbing existing engine drive unit. When adding a standard 12/24 volt icebox conversion unit evaporator coil in the same box with a holding plate already there best results are achieved by creating thermo heat conduction between 12 volt evaporator and holding plate. The object of absorbing heat direct from holding plate by convection into 12 volt evaporator is not to freeze holding plate solution but lower holding plates unfrozen solution to its eutectic freeze point. Sliding 12 volt thin plate evaporator behind holding plate and using thermo conducting paste as used in icemakers has produced good results converting single coil holding plates over to hybrid plates.

Any live aboard boater planning on cruising lifestyle in tropics needs engine driven and hybrid duel energy on his boat.

[Miguelso]

Originally Posted by Richard Kollmann

I have designed maybe 100 hybrid boat refrigeration systems most of these were engine driven and electric. In the 1980s most hybrid systems with electric systems had added 110 or 220 volt compressors but later designs were able to benefit from improved onboard DC 12/24 volt compressors and alternative energy sources. As early as 1984 I tried to convince boaters when I made them custom holding plates to add a second $35 coil inside their plates.

There are several ways to change an engine driven single evaporator coil holding plate system without disturbing existing engine drive unit. When adding a standard 12/24 volt icebox conversion unit evaporator coil in the same box with a holding plate already there best results are achieved by creating thermo heat conduction between 12 volt evaporator and holding plate. The object of absorbing heat direct from holding plate by convection into 12 volt evaporator is not to freeze holding plate solution but lower holding plates unfrozen solution to its eutectic freeze point. Sliding 12 volt thin plate evaporator behind holding plate and using thermo conducting paste as used in icemakers has produced good results converting single coil holding plates over to hybrid plates.

Any live aboard boater planning on cruising lifestyle in tropics needs engine driven and hybrid duel energy on his boat.

Thanks for the tip. I'll try to fix the new evaporator to the holding plate, not sure if possible though. I don't think it would be a good idea to drill holes on the holding plate

[wsmurdoch]

Originally Posted by Richard Kollmann

I have designed maybe 100 hybrid boat refrigeration systems most of these were engine driven and electric. In the 1980s most hybrid systems with electric systems had added 110 or 220 volt compressors...

I have one of the 1980s hybrid refrigeration systems. The plate says, "Kollmann Marine Products". There is a single cold plate with two internal coils in the freezer and with spillover to the fridge. The compressor on the engine will keep the cold plate frozen with an hour of run time per day unless the temperature gets in the upper 90s (F), then two 45 min sessions will do it. We make ice and keep meat frozen. At the dock we run the 125v compressor to keep the cold plate frozen. Without the daily swings in temperature, everything in freezer stays rock hard. If the engine driven system were to quit, we could run the 125v system off the inverter as a short term backup. The refrigeration system is old, but still works. With Richard's advice and his books we have kept it running without any serious problems. The best thing about the Kollmann system is that all the parts are standard automotive or refrigeration items and are readily available.