AC Operation without the generator?
- Thread starter Mko8642
- Start date
- Status
chicagosam
Well-known member
- Joined
- Feb 14, 2020
- Messages
- 68
- Fluid Motion Model
- C-32 CB
- Hull Identification Number
- FMLS2426K718
- Vessel Name
- La Niña
- MMSI Number
- 338352244
Yes, although your batteries will only last 20-30 mins.
Practical answer is NO.
Practical answer is NO.
ixlr8
Well-known member
- Joined
- May 2, 2017
- Messages
- 756
- Fluid Motion Model
- R-27 (Outboard)
- Hull Identification Number
- FLMT2762C818
- Non-Fluid Motion Model
- 2018 R-27OB w/Yam 300
- Vessel Name
- Maggie
The problem is the inverter does not have enough power to handle the startup current of the AC compressor, you will just trip the breaker on the inverter. Some compressor motors can be modified with a kit that reduces the startup current and your inverter will then be able to start the compressor. Most alternators are only rated for short term current surges. I don't know what would happen if you pulled 110 amps from a 120 amp alternator for hours at a time. I don't know how many DC amps the inverter would need to pull to provide enough AC amps to drive the compressor.
BB marine
Well-known member
- Joined
- Feb 1, 2016
- Messages
- 2,916
- Fluid Motion Model
- C-26
- Non-Fluid Motion Model
- Grady White 208
- Vessel Name
- PORT-A-GEE
Dometic 12000 BTU has a max circuit breaker protection of 30 amps and a minimum of 20 amps. This is for start up. The current consumption for max cooling is 8.7 amps and for max heating is 10.9 amps.
Dometic 16000 BTU has a Max circuit breaker protection of 40 amps and minimum of 25 amps This is for start up. The current consumption for Max cooling is 10.4 amps and for max heating is 13.6 amps
12000 BTU
120 VAC 8.7 ah = 96.5 AH 12V DC.
120 VAC 10.9ah= 120.34 ah 12V DC
4 battery bank 103 ah batteries = 412 ah -50% (if AGM batteries are used 206 ah) On the hook with other 12V draws you will have batteries consumed in an hour.
4 battery bank 412ah 206 ah usable with a 110 amp alternator with a continuous output of 90 amps ( reduction due to heat resistance) with refrigerator running, engine running, electronics running, You may be able to run the air unit periodically to keep cool but I would not advise continuous. The alternator voltage regulator has a temp sensor, when it senses temperatures to high it will regulate output so you can not figure a full 90 ah capacity all the time.
Inverter size 2000W with a 4000W momentary may work but is marginal
3000W with a 6000W momentary would be the proper size.
To do this right a 600 ah battery bank with a 3000W inverter + alternator would be sufficient to operate the air unit while under way without the use of the generator.
R29 this is doable with the right equipment.
Dometic 16000 BTU has a Max circuit breaker protection of 40 amps and minimum of 25 amps This is for start up. The current consumption for Max cooling is 10.4 amps and for max heating is 13.6 amps
12000 BTU
120 VAC 8.7 ah = 96.5 AH 12V DC.
120 VAC 10.9ah= 120.34 ah 12V DC
4 battery bank 103 ah batteries = 412 ah -50% (if AGM batteries are used 206 ah) On the hook with other 12V draws you will have batteries consumed in an hour.
4 battery bank 412ah 206 ah usable with a 110 amp alternator with a continuous output of 90 amps ( reduction due to heat resistance) with refrigerator running, engine running, electronics running, You may be able to run the air unit periodically to keep cool but I would not advise continuous. The alternator voltage regulator has a temp sensor, when it senses temperatures to high it will regulate output so you can not figure a full 90 ah capacity all the time.
Inverter size 2000W with a 4000W momentary may work but is marginal
3000W with a 6000W momentary would be the proper size.
To do this right a 600 ah battery bank with a 3000W inverter + alternator would be sufficient to operate the air unit while under way without the use of the generator.
R29 this is doable with the right equipment.
Mko8642
New member
- Joined
- May 16, 2020
- Messages
- 4
- Fluid Motion Model
- C-288 C
- Hull Identification Number
- FMLT2915D414
Back to the original question. I am not well versed in electronics. How does the AC unit in my Tahoe work well enough that my wife begs me to turn it down. I live in SW Florida and the AC in my car is never short of cold.
Martin610
Well-known member
- Joined
- Feb 13, 2018
- Messages
- 532
- Fluid Motion Model
- C-28
- Vessel Name
- Venture
Apples and oranges. The car has an AC compressor turned by a fan belt connected to the engine. You have a 'condensor' for the AC just behind the engine radiator for the heat exchange. Actually pretty simple setup.
The boat has a heat pump, more like the heat pump you might find in a home in Florida. You have a water pump that runs sea water to the AC unit, two coils for heat exchange, you have to turn the compressor with electricity, and then a fan to move the cold air. All of this is completely independent of the engine and it takes a lot of electrical power. There are more details here, its more complex than a car. You do have the added benefit of reverse cycle heat.
The boat has a heat pump, more like the heat pump you might find in a home in Florida. You have a water pump that runs sea water to the AC unit, two coils for heat exchange, you have to turn the compressor with electricity, and then a fan to move the cold air. All of this is completely independent of the engine and it takes a lot of electrical power. There are more details here, its more complex than a car. You do have the added benefit of reverse cycle heat.
- Status