# 240V habitation Air Cond. run by a generator or invertor



## 111728 (Apr 28, 2008)

We are thinking of having a 240V Domectic air con unit fitted. But should like to ask if it can be sufficiently run this by an invertor (if so, what size?) or a fitted generator (if so, what size?).

Any ideas or feedback please.


----------



## eddievanbitz (May 1, 2005)

Yes the unit can be run from genny or inverter.

The size would be dependent on the size of the AC unit, and you would only realistically use the AC on inverter when travelling as the size of the battery bank needed would just not be effective, without the alternator running.

Dometic have a DC kit to run their AC units on DC the cost of the DC Kit TWO is £508.15 this allows the invertor to share the load between the engine and leisure batteries when plenty of power is available, will not allow the engine battery to be discharged too much, at slow speeds and idle.

There is a DC Kit ONE as well which allow the inverter to be used for other things than just the AC unit

Eddie


----------



## DABurleigh (May 9, 2005)

saracen,

Under what scenarios/ context should we view your question? What you haven't said is more important than what you have, in order to avoid answering the wrong question.

Dave


----------



## ianhc (Feb 4, 2009)

This was a reply i gave to another member wanting to know if you could run the a/c whist driving, it said

I have used it whilst driving with no problems, the gasses are exited behind the vehicle.
Unfortunately most campsites abroad have limited amps available, and my own experience is that the A/C trips the hook up trip switches. I currently have a dometic A/C unit ( 240v) and also a dometic 130 generator built under the floor ( 2.6KW) , the unit can work on hook up when available ( subject to amps available ) and also on generator. The benefit is also that i can with a 100amp battery charger charge my leisure batteries up quickly (3x 110 amp units ), run the microwave, etc giving total independence. The Dometic generator uses a Honda engine so is totally reliable, uses a conventional car like exhaust sliencer system so is ultra quiet and uses very little fuel, also is transferable between motors, and because it lives next to the chassis out of the way is not obtrusive.


----------



## 111728 (Apr 28, 2008)

thanks for the info so far, really good help.

Dave

I wish to fit to a Swift Kontiki. Use whilst travelling usually, but rarely (very rarely) whilst stationary. I like the idea of the Domectic 12v two kit Eddie mentioned. I was preferring an invertor and three 110 amp batteries being charged via the alternator whilst travelling (in conjunction with the can battery).

To expand, to some more detail. I am thinking of the Domectic 2200 unit. Therefore what size of invertor should be suitable.

Really appreciate the advice...thanks


----------



## 91502 (May 1, 2005)

I used to have a domestic roof top unit and found in most countries except the uk it tripped the electric on most sites, usually on start up when it draws most power. If everything else was off and it managed to start without tripping it would usually keep running for a period before tripping out. I did try it on inverter but with 2 x 110a/h batteries both new and fully charged it slowed after about 15-20 mins and was useless after 30. If used when running the alternator was not able to keep the charge up and the batteries drained after about an hour and a half. 
James


----------



## eddievanbitz (May 1, 2005)

JP said:


> I used to have a domestic roof top unit and found in most countries except the uk it tripped the electric on most sites, usually on start up when it draws most power. If everything else was off and it managed to start without tripping it would usually keep running for a period before tripping out. I did try it on inverter but with 2 x 110a/h batteries both new and fully charged it slowed after about 15-20 mins and was useless after 30. If used when running the alternator was not able to keep the charge up and the batteries drained after about an hour and a half.
> James


Hi James this is why Dometic do the DC Kit TWO the inverter is connected to a charging block that connects the batteries together so your connected to the engine and the leisure batteries, and if installed correctly your all connected up with a miniumum of 25mm square cable.

Also the BA2200 now have soft start systems so will operate on much lower site supplies than in the past

Eddie


----------



## DABurleigh (May 9, 2005)

OK, well for predominantly use while travelling, note that a roof aircon is far less effective than dash aircon, but if you have it as well as dash aircon, you may as well arrange to be able to use it.

We then come to several barriers. The biggest is to note the load on the alternator, which is not designed for longevity under sustained high demands. 

You also may need a bigger alternator to drive the aircon you want, to have the effect you want, in the volume you have. If you want to be able to recharge leisure batteries while driving, this presents an even greater alternator demand.

The inverter you use should be big enough not just to cope with the sustained power consumption, but with the bigger startup current demand.

The inverter may need to be a sine-wave one to cope with inductive loads.

That said, I do it with a Dometic B1500S from a Victron 1.6kW sine-wave inverter/charger and can maintain a positive energy budget other than at tickover.

Dave


----------



## ianhc (Feb 4, 2009)

Be aware that when running the engine with inverter switched on you must ensure that the cable between the alternator and batteries is of good diameter due to the fact that the inverter will draw as much power as possible, which means the batteries will try and " suck" power from the alternator. 
Simply replacing with a larger alternator will not sort the problem, it may well cause more problems due to the wiring loom and the core diameter, being suited to the alternator fitted.

Also, when the engine is started most motorhome charging systems will connect the starter battery to the leisure batteries for charging.
This would also drag down the starter battery. The system disconnects the starter battery when the ignition is switched off.

As far as i can see, from previous threads, the longevity of any leisure battery inverter/combination to power an aircon will be measured in a few hours not days. This would leave you totally power drained.
The generator/aircon combination gives much more flexibility, it can be used whilst travelling, it can be used where there is no hook up, it can be used where the site gives limited amps ( most continental), it can be used to give 240v power wherever you are, it can be used to power your battery bank, any time, anywhere. Total independence, thats what we are all striving for with motorhoming.


----------



## teemyob (Nov 22, 2005)

*Alternator*

here you go......

Min Alternator (absolute min -due to fact your alternator may be running your fridge and all the other appliances) is 90amps.

Coolauto Link<Click

As suggested, you will need decent cables!

Trev.


----------



## eddievanbitz (May 1, 2005)

ianhc said:


> Be aware that when running the engine with inverter switched on you must ensure that the cable between the alternator and batteries is of good diameter due to the fact that the inverter will draw as much power as possible, which means the batteries will try and " suck" power from the alternator.
> Simply replacing with a larger alternator will not sort the problem, it may well cause more problems due to the wiring loom and the core diameter, being suited to the alternator fitted.
> 
> Also, when the engine is started most motorhome charging systems will connect the starter battery to the leisure batteries for charging.
> ...


No one is arguing that a generator is superior to an inverter. It also costs a lot more, weighs a lot more and take up a lot of space! is noisy and winds up loads of people and splits opinion!

Installed correctly, the DC Kit TWO allows the Air conditioning to be used whilst travelling, in a controlled measured way, the voltage sensing element of the DC kit TWO ensures that you do not arrive with depleted batteries.

No one is suggesting that you can run it for days on batteries, I don't know anyone who drives their motorhome for "days" without stopping at all.

Also, don't forget that the unit simply switches to normal mains operation when your plugged in.

Some of your suggestions are a bit optimistic however, you say that "most continental sites have limited amps" which isn't the case, although to be fair this may be your personal experience, I don't know the quality of sights you stay on. Even so, you suggest that you can run your genny on a site to power your air conditioning, again, most decent sites would stop you from doing this out of respect for other campers trying to relax.

Generators are fine I have one, I also have a Phenix self tracking solar panel and I have a chuffing great inverter, and the inverter is the most use most of the time.

Eddie


----------



## teemyob (Nov 22, 2005)

*Sites Amps*

I would agree with Eddie on the AMPS/Hook-Ups.

Many of the sites we stay at on the continent do have 15amp hook-ups. Okay some sites are limited to 6 amps, but then you would just have to be careful what else you are using electrical wise.

Many of the sites along the beach front of the Cote D'Azur for example include 6amps, with the option to upgrade for a small cost.

Sites slightly inland Naiades 10 mins walk to beach, do have 15amps.

Trev


----------



## Vennwood (Feb 4, 2007)

Our neighbours have just got back from Cote D'Azure (tuggers) and are telling the tale of electricity cost. Seems they had their aircon on during the day (pretty much all day from what I can gather) and when they went to square up ready for home they were faced with a bill of over £50 for units of electricity over and above their quota.

We once had this in winter in Antibes but first I have heard in summer...


----------

