Starting 13.5 ac on inverter/charger then switching to gen ??

[20052]

I have a new travel trailer with a brisk air ii 13.5 and 2-225 AH 6 volt deep cycle batteries in series. There is a WFCO power center with converter/charger OEM. I want to use a new inverter/charger to take the start up load of the ac and then plug in a running small 2000 watt generator to the shore power and let it run the ac for the rest of the day. Dometic told me those high start up loads are only from the very first start up and it cycles at a much lower watt rating, under 2000. Thank you

 

[mel s]

I have a new travel trailer with a brisk air ii 13.5 and 2-225 AH 6 volt deep cycle batteries in series. There is a WFCO power center with converter/charger OEM. I want to use a new inverter/charger to take the start up load of the ac and then plug in a running small 2000 watt generator to the shore power and let it run the ac for the rest of the day. Dometic told me those high start up loads are only from the very first start up and it cycles at a much lower watt rating, under 2000. Thank you

20052
I could be wrong but I believe a "high start up load" occurs each and every time the A/C compressor in a Brisk Air II "cycles on".

 

[Chakara]

One way to do this would be with the newer Inverter/Converter combo units like those from Victron.  I haven't done this myself, but my understanding is that they can be setup to "supplement" the AC power with Inverter power to do basically what you are looking for.

https://www.victronenergy.com/

 

[Frank B]

A much easier solution is to reduce the start up load with a device like I am linking here below

http://www.rvforum.net/SMF_forum/index.php?topic=115568.new;topicseen#new

A device like that will allow you to start and run your air conditioner from a single 2000 watt generator.

 

[20052]

Thank you for your replies, I looked into the micro air 364 and the dometic smart start. from the reviews I read (other than the sponsored ones) there is only a slight chance that it would work in 100 degree + desert conditions. the inverter/chargers that offer "power share" are very expensive. I think I have looked into every possibility, a hard wired inverter only, with ac pass through (even when off) and auto switching from aims for $400 would be fine if my idea will work (i have the charger converter already). I dont know if my batteries will be able to handle 300 amps at start up? I even considered using a "stacking" inverter with the inverter generator as a parallel set up and just turning off the inverter once it starts.

 

[Frank B]

From what I know of air conditioners and the Microair device, I'm afraid I don't understand what ambient temperature would have to do with startup surge. I can see where CONTINOUS running in high temperatures would up the overall load on the generator (you would use more gas), but not the startup load.  Isn't that a function of the motor specs?

If you are concerned about heat buildup in the micro air device itself, I mounted mine in the cool air flow side of the air conditioner. It stays cool because the air conditioner is running.

Anyway, I've been happy with mine.

 

[John From Detroit]

Can it be done: YES. but it is not that easy.

I think the company is Victron but I may very well be wrong on that.
They make an inverter expressly designed for this task... and it will work
Standard inverters will not.  Solar.... Might (I do not know)

But the one I am speaking of is specifically designed to handle the high peak load of an air conditioenr when running off a generator.

I see someone else came up with the same device.  ONly 1100 and change.

The very device I'm talking about

 

[20052]

temp may not effect start up amps, I dont know, coleman web site

Cool/Heat Capacity: 13,500
Electric Heat Element Capacity: 5,600
Electrical Rating: 115 VAC, 60HZ
Cooling Amps-High: 13.1
Running Watts Standard: 1400
Running Watts Desert: 1695
Running Watts Heat Strip: 1800
Locked Rotor Amps: 50.5
CFM: 320
Weight (Lbs.): 79.5

 

[20052]

thanks, the soft start device is a no brainier, it would help no matter what. its not the heat build up on the device but the lack of real world testing on the soft start devices. most reviews i looked at (many) were paid for. I did not find any testing done when it was hot outside and they use different generators. it seems there is a big difference in output, breakers and inverters in the different generators that make the soft start device a hit or miss proposition when the numbers are so close.

the honda 2200 seems to have been the one that had a slower acting breaker and a truer output. many of the gen seem to reset under different load conditions and dont put out what they claim. thanks

 

[Frank B]

Got it!


Those figures appear to support what I suggested. Locked rotor current, or startup surge, is only quoted once. However, power consumption goes up to 1695 watts in high temperatures. That is to be expected. The air conditioner will have to work harder when it is hotter. But I see no change in the start-up surge in hot weather or cooler.


The micro air unit will reduce the startup Surge from in excess of 50 amps, to somewhere in the neighborhood of 20 to 25 apps.


1695 watts is on the upper end of what a 2000 watt generator can put out continuously. In other words, a 2000 watt generator will probably be maxed out in hundred degree temperatures trying to run that air conditioner. I would think that a bigger issue might be: Can the generator do that in that kind of ambient temperature without the generator itself having cooling problems?


You mentioned that you had seen reports of people suggesting that the micro air unit would not work in hot weather. Just out of curiosity, are those people that had actually tried this, or so-called armchair experts that only thought that it could not do that? In pretty much any online Forum, there is no exam that you have to pass to gain entrance. All you have to have is an opinion.


Full disclosure: This is not my area of expertise, so to some extent I too am an armchair expert in this area. Hopefully, someone else with more knowledge than myself will add to this discussion and correct me if I'm wrong.


In addition, a single 15 amp receptacle is not rated to give that kind of power continuously. In some cases I have seen reports here of people that have paralleled the outputs from a 2000 watt generator over two plugs to get around that problem. Otherwise, you run the risk of melting the plug on a single 15 amp extension cord.

 

[Frank B]

thanks, the soft start device is a no brainier, it would help no matter what. its not the heat build up on the device but the lack of real world testing on the soft start devices. most reviews i looked at (many) were paid for. I did not find any testing done when it was hot outside and they use different generators. it seems there is a big difference in output, breakers and inverters in the different generators that make the soft start device a hit or miss proposition when the numbers are so close.

the honda 2200 seems to have been the one that had a slower acting breaker and a truer output. many of the gen seem to reset under different load conditions and dont put out what they claim. thanks

OK, that makes sense. However, I think we are dealing with two different things here. Start-up current, and the ability of a 2000 watt generator to even continously power the air conditioner in high temperatures. This is now outside of my experience. I'm a Canadian living in Calgary, and we seldom see temperatures like that up here. When we travel to the states, it's usually cooler than that where we go.


Someone else needs to step in here, someone that has real experience, and let you know if a 2000 watt Honda generator can power a 1350 watt Coleman air conditioner continuously in 100-plus degree temperatures. I am somewhat doubtful if it is up to that task.


Remember to get someone with real experience, not just someone with an opinion.

 

[John From Detroit]

Speaking of SOFT STARTS.
I'd like to add one to my Coleman or better yet my advent air. That sucker really starts "hard".
Can someone post a "Before" and "After" schematic who has done it?

I"m not sure how this thing is supposed to work.

 

[Frank B]

Speaking of SOFT STARTS.
I'd like to add one to my Coleman or better yet my advent air. That sucker really starts "hard".
Can someone post a "Before" and "After" schematic who has done it?

I"m not sure how this thing is supposed to work.

The unit comes with its own schematic, and I think you can see a how to video on the micro AIR website. Because of its proprietary nature, however, it is a black box device.


If I understand the device correctly, it plays with the phase going to the induction motor and/or start winding so that it spins it up more slowly. This reduces the shock load on the system.  If I remember correctly, at least one lead of the device is in series with the start winding. We are away from home in Arizona for a few months, and, unfortunately, I don't have the schematic with me.

 

[Utclmjmpr]

I would be concerned about the voltage drop causing a high rise in amperage that can damage motors quickly.>>>Dan

 

[Gary RV_Wizard]

Check to see if you already have the hard start capacitor in place. The Coleman Mach heat pumps on my former coach had them right from the factory.

It seems to me the start-up surge problem got worse with inverter-generators.  They all have electronic load management and most seem to simulate a "fast blow" breaker or fuse, no doubt to protect the expensive inverter circuitry.  Mechanical generators that use an alternator to produce 120vac were mostly slow-blow, relying on a breaker to trip. That gave them the few seconds needed for the compressor to get going.

 

[20052]

do you think my 2 - 6 volt 225 AH batteries in series  can handle a momentary load into an inverter of say 300 amps?

 

[Back2PA]

do you think my 2 - 6 volt 225 AH batteries in series  can handle a momentary load into an inverter of say 300 amps?

I would guess the inverter will trip for low voltage

 

[Utclmjmpr]

Where do you expect to get 300 AMPS???>>>Dan  ( I think you are confusing AMPS with WATTS.)

 

[Lou Schneider]

Where do you expect to get 300 AMPS???>>>Dan  ( I think you are confusing AMPS with WATTS.)

The air conditioner starting surge.  If the surge draws 3600 watts (3 times the running current) that's 300 Amps at 12 volts.

do you think my 2 - 6 volt 225 AH batteries in series  can handle a momentary load into an inverter of say 300 amps?

Not likely.  As a comparison, that's more than a starter draws while cranking a large V-8.  A single set of golf cart batteries will drop voltage under this large of a load just like your headlights dim while cranking the main engine.

 

[Utclmjmpr]

Thats part of my response Lou, 6 volt deeps don't give high surges like a start battery would.>>>Dan