Portable Airconditioner and power inverter

[Malomoto]

So I got this portable airconditioner and a massive power inverter 5000w continuous and 10000w peak. I plan to only use the ac while my van (1978 chevy) is running. The thing works intermittently. I have an Optima deepcell and my charging system reads 12.5-14v while in use.  What are most folk using to run a window unit in their rigs?

 

[ckelly78z]

Does this A/C unit actually work for long periods of time without draining the battery (even while it is being charged from a running van ) ?

Have you tried this already, and are you satisfied with the results ?

 

[highdesertranger]

I see a lot of potential issues,

why such a big inverter?
how much power does the inverter consume while in standby?
one battery is not going to cut it even with the engine running?
what is the output of the alternator? what is the real life output?
how much energy does the AC consume?
is the AC it a vented portable?
what size cables feed that inverter? they must be massive.

highdesertranger

 

[Malomoto]

The big inverter was to run the ac and s couple of lights. I have 2awg wires running to the inverter. I have no idea what the "real life output" (I mean I don't know what your asking). The engine will run the ac temporarily but it does cut out. I was really hoping to find out what other people use to run window units.

 

[mjbeam64]

I have three 12 volt 100 amp hour AGM batteries in parallel, 700 watts of solar panels, and a 1200 watt inverter to run a 5000 BTU window AC in my van.

I suspect you will probably ruin your battery and probably alternator quickly with that setup.

 

[tx2sturgis]

 I was really hoping to find out what other people use to run window units.

 
You have questions, we have answers!

What other people use to power a window A/C unit:

Shore power, or a 1000w to 2000w portable generator, or a really large solar array, usually 1000 PV watts or more and usually 4 or more large batteries feeding a large inverter and even that sometimes is marginal. 

In some situations they use a combination of these sources depending on what is available.

 

[Trebor English]

Presuming that while using the air conditioner you are parked.  The engine is probably idling.  Idle engine speed is the slowest normal running speed.  That causes the lowest alternator RPM.  The lowest alternator RPM causes the lowest alternator fan speed and the lowest alternator fan air motion.  This will lead to high alternator temperature. 

While parked there is no 45 MPH wind blowing through the engine compartment.  The air being blown through the alternator will be hotter while parked than at highway speed. 

The 1978 vintage implies that the alternator contains its own regulator rather than having the engine control computer dictating the alternator field current.  Due to the heavy electrical load the battery voltage will be low so the alternator's regulator will increase the field current to generate more electricity to meet the demand.  The high field current and resulting high output current will cause high power dissipation inside the alternator windings and diodes.  The high heat production and low cooling will cause maximum alternator temperature. 

Alternator current ratings are usually combined with a corresponding alternator shaft speed.  That is usually quite high to get a good current number to advertise.  There are often duty cycle or time limits in the fine print.

It sometimes happens that people connect huge deeply depleted battery banks to vehicle alternators and fry the alternator due to the continuous high current.  In this case it is an inverter load rather than a discharged battery bank.  Alternator regulators intended for marine use often have alternator temperature sensors and some even have power limit algorithms to protect drive belts.

 

[Malomoto]

Yuck So what I'm hearing is there is no way to run it (the ac) off the engine even with an additional battery?

 

[JerryJ]

Yuck So what I'm hearing is there is no way to run it (the ac) off the engine even with an additional battery?

Correct.  You will need a generator or large solar system in order to run an AC.

 

[highdesertranger]

ok,

real world alternator ratings is what the alternator actually puts out in real life, i.e. bolted to a hot engine in a hot engine compartment at a relatively slow speed(idle). not what it puts out in some manufacturer test lab where they will do whatever it takes to inflate the numbers.

BTW this is true for solar panels too. you will never see what the panel is rated for.

using a V-8 engine and an automotive alternator as a generator is the most inefficient way to get power. but don't get me wrong it is good to have the alternator as part of the total recharge package.

so back to your question as to what do you need to do?

1. drive to where you don't need AC
2. use shore power
3. use a portable generator
4. have a big old honkin solar array and lots of batteries

my preferred method is number 1.

highdesertranger

 

[Malamute]

I dont have the choice to go where its not too hot, so this was my way to have a window AC for the dog when the vehicle wasnt running.









 It works to run the gen on eco mode when you get a $12 hard start capacitor and plug it onto the AC unit.

 I keep mine set at 66 deg and the dog snoozes in comfort when i have to go in somewhere. Everything inside the 4runner feels cold. Its perfect.

 

[Malomoto]

Well not what I hoped but thanks for the help. Maybe I will look into an ac system from one of the local pick a parts.

 

[highdesertranger]

"Maybe I will look into an ac system from one of the local pick a parts."

I don't understand how that will help. you need a electrical system to run the AC first.

highdesertranger