Inverter to run a Dometic 2200 A/C while driving, what is the best battery to hook up to Van or Le

[Dream5]

Hi At the moment I've hooked the Inverter to the leisure batterys but they go flat while driving, I was thinking of hooking up to the van battery but worried it'll drain the battery while driving, anyone done this before?

 

[Sheddy]

This may help to achieve what you want.
Note the battery and generator requirements.
Cheers
Ed

 

[tacr2man]

You need to have about 250ah of leisure batteries , and a decent output alternator , and then the kit will connect up the inverter to both systems to maintain both at a safe level where possible.
With engine stopped , it wont run the a/c for long .

 

[TerryL]

Seems a very expensive method, not to mention the strain on the batterys or the reduced payload carrying enough battery power, to get air conditioning on the move. In fact I was surprised that such a kit was actually available.
I'm guessing that perhaps your van doesn't have the standard cab aircon?

Oh and by the way to the forum.

 

[MikeD]

Welcome to the forum

The air con on our old van took around 5 amps so that if my maths is good you want about 100amp from a 12v leisure battery.

As most leisure batteries are rated around 100amp/hour and you only get about 50% efficiency - your battery would be flat in under an hour. Probably nearer 30 mins.

Your alternator will put some back but less than you think.

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[Yorick]

Last week I had to fix the aircon on my van.

 

[Dream5]

Thanks, If i hook the inverter to the cab Battery will it flatten the battery while on the move or will the alternater 90amp hour (Sprinter 315) keep up with the lights engine etc, Ive seen on some small coaches/mini buses that they have the air con running all day seems to work for them, but who knows what there set up is?

 

[TerryL]

Ive seen on some small coaches/mini buses that they have the air con running all day seems to work for them, but who knows what there set up is?

I do. Completely different system, the compressor runs off belts from the engine crankshaft, same as the alternators (note plural, 2 sometimes 3). That's why you sometimes see coaches parked up with the engine running, they're running the aircon. Could tell you stories about thrown belts!

 

[Abacist]

Hi At the moment I've hooked the Inverter to the leisure batterys but they go flat while driving, I was thinking of hooking up to the van battery but worried it'll drain the battery while driving, anyone done this before?

Then you need a Sterling B to B Charger which with a 60 Amp hour charge rate should keep your batteries charged up whilst you are driving. You have not said what batteries and how many you have but it needs to be a decent battery bank with the batteries in good condition.

 

[Badknee]

We have an Eberspatcher retro fit a/c on our Ducato C class and a curtain across the cab behind the seats (thermal) and it works brilliantly. Save our hab a/c for when we're on ehu

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[TerryL]

@Dream5 still interested in why you need habitation aircon on the move.

None of the above will give you aircon whilst parked unless you're on a decent hookup, well not for very long and you'll kill your batteries. We've got the same unit and I've tripped 10 amp supply on compressor startup.

 

[Dream5]

Hi I dont have Cab Air Con and was hoping that the Domectic 2200 will cool the van down a little, and retro fit is about £1500, I have a CBE 522 and PC200 with 2 x110 Leisure batteries, I think this set up only gives a trickle charge while driving.
I think Abacist has the answer B to B charger I can then get a decent charge to the leisure batteries while driving which in turn should keep up with the A/C Thanks ill give it a go unless any other ideas!

 

[Richard n Ann]

That's a big extra load on the alternator.

Might not be what you want to hear but if you want A/C that much I would get rid and buy a van with cab A/C factory fitted, the ice cold vents blow on you in a way a roof mounted system in the back can never do. I think you're heading down an expensive road to disappointment.

 

[TerryL]

Sorry @Dream5 I see what you're trying to do but as Richard above says I also think you're on a loser. The B2200 system on ours is nothing like as good as the cab aircon.

But would be interested in the result if you do go ahead.

 

[EssexBoy]

I don't really know if this might work or not, but I have a Victron 125A "battery combiner" that joins my cab and hab batteries via 50mm cables (and appropriately fused), so in theory could provide the power you are looking for?

The combiner was about £40. I use this as a cheap upgrade to the standard split charge system

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[tacr2man]

That's a big extra load on the alternator.

Might not be what you want to hear but if you want A/C that much I would get rid and buy a van with cab A/C factory fitted, the ice cold vents blow on you in a way a roof mounted system in the back can never do. I think you're heading down an expensive road to disappointment.

I agree fitting a roof unit as discussed wont cut it . If you want mobile aircon then an engine driven compressor unit is pretty much the most cost effective solution . I have a engine driven rooftop Red Dot system on my defender station wagon , and it handled 46C in Australia .

 

[Hymer Life]

Why not just have engine powered air con installed? (or is that a stupid question)

 

[dabhand]

Or an endless breeze fan!

 

[tacr2man]

Or an endless breeze fan!

not got much refrigeration capability IIRC

 

[dabhand]

not got much refrigeration capability IIRC

It’ll blow the sweat out of your eyes while your driving though!

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[HandyAndy]

the dometic 2200 has a 950w draw at 220v, but at perfect efficiency (which inverters are no where near) that’s 80 amps at 12v, so in theoretical terms with a 90 amp alternator you you have 10 amps “spare” to run the vehicle electronics AND charge the batteries...
in the real world that’s not going to happen no matter how much of a battery bank you fit.
If I was dead set on getting aircon fitted I’d look into a engine driven (belt driven) retro fit aircon system fitted instead.
there are other options of course...
a second alternator,
an up rated single alternator
a 220v AC alternator

 

[DDJC]

We have an inverter dealer fitted onto our bus.

Reason is that I read somewhere that the initial start drain on the EHU by an ac unit (in our case, Dometic Aventa) can trip the EHU. We've been to sites where the offered amperage is 6a.

So some guy suggested that the best way to do it was connect the inverter at your last stopping point, but leave the air con off and just use cab air con. Then when you get 10 miles from your destination, fire up the Dometic using the remote or Truma app and it will be running nicely when you arrive and connect to the EHU, with no tripping.

Does this make sense?

 

[Lenny HB]

It does make sence but check the mains fuse to your a/c if less than 6 amp it shouldn't be a problem because if it was the fuse would blow evry time you turned it on.

 

[eddie]

Hi At the moment I've hooked the Inverter to the leisure batterys but they go flat while driving, I was thinking of hooking up to the van battery but worried it'll drain the battery while driving, anyone done this before?

The correct way to do it is to use the correct Dometic AC/DC kit

In essence, a "switch" that connects to the Air Con, the inverter, the leisure batteries and the engine battery, sharing the load between the alternator/engine battery, and the leisure batteries. Should the load on the system be too much the "switch" will isolate the alternator/engine battery to ensure that the on road equipment and charging is unaffected, automatically re-instating when the situation improves.

The "switch" will turn off the Air Con if the voltage is too low, again re-instating when things improve. In essence sat in a traffic jam, on tick over, the first to be isolated would be the engine/alternator connection, then after a further period, the AC would be switched off, to avoid damaging the leisure batteries. Once the journey started again and the alternator started to produce a significant charge, the AC would be turned back on, running from the Leisure batteries, then the engine battery/alternator supply would be brought back on line.

When this is fitted the existing split charge relay has to be disconnected obviously

 

[DBK]

Hi I dont have Cab Air Con and was hoping that the Domectic 2200 will cool the van down a little, and retro fit is about £1500, I have a CBE 522 and PC200 with 2 x110 Leisure batteries, I think this set up only gives a trickle charge while driving.
I think Abacist has the answer B to B charger I can then get a decent charge to the leisure batteries while driving which in turn should keep up with the A/C Thanks ill give it a go unless any other ideas!

A 60 amp B2B charger won't be big enough I fear. A quick Google suggest the power consumption of your A/C might be around 1000W to 1200W which means from a 12 volt supply it will draw around 100 amps from the (90A!) alternator to keep up with demand. So it doesn't matter how many batteries you have they will go flat sooner or later even when driving.

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[DDJC]

It does make sence but check the mains fuse to your a/c if less than 6 amp it shouldn't be a problem because if it was the fuse would blow evry time you turned it on.

Naively, I am hoping that since it was fitted by the dealer, and is the Truma recommended inverter kit, they put the appropriate fuse in it!!

I'll log back on when I'm blocking the exit road to the Aire du Total Désastre, in 35 deg heat, with blown electrics...

 

[eddie]

All Dometic Air Con units except the Freshjet3200 (rebadged old system) have soft start relays so there is no need to expect that the start up load would trip a mains switch. The best inverter to be used for AC/DC Air Con use is an inverter/charger which will "invert" and make up the difference between whats required and what's available on start up of any device

We were on a site last weekend that had 6 amp hook up, yet we didn't trip it as the inverter/charger took care of everything even when using a 2000w hair dryer

 

[HandyAndy]

We have an inverter dealer fitted onto our bus.

Reason is that I read somewhere that the initial start drain on the EHU by an ac unit (in our case, Dometic Aventa) can trip the EHU. We've been to sites where the offered amperage is 6a.

So some guy suggested that the best way to do it was connect the inverter at your last stopping point, but leave the air con off and just use cab air con. Then when you get 10 miles from your destination, fire up the Dometic using the remote or Truma app and it will be running nicely when you arrive and connect to the EHU, with no tripping.

Does this make sense?

Makes no sense no, as the AC system cuts the compressor in and out automatically during use.

 

[tonyidle]

If you intend to run the aircon via an inverter only when travelling the simple and IMO the most sensible battery to connect it to is the starter battery. Whichever battery you intend to use you will need to replace the alternator with a higher output version. The alternator will need to be capable of at least 150A output - larger is better. Wired as I've suggested the aircon is just another load on the alternator - like, for example, the headlights. In no sense will it ever run off the battery as long as the alternator has sufficient headroom to accommodate the extra load.

 

[eddie]

If you intend to run the aircon via an inverter only when travelling the simple and IMO the most sensible battery to connect it to is the starter battery. Whichever battery you intend to use you will need to replace the alternator with a higher output version. The alternator will need to be capable of at least 150A output - larger is better. Wired as I've suggested the aircon is just another load on the alternator - like, for example, the headlights. In no sense will it ever run off the battery as long as the alternator has sufficient headroom to accommodate the extra load.

100% it’s just that most of our customers want to use the inverter all of the time and they only use the inverter a bit of the time

On road in our camper we have a 5Kw built in generator which runs the A/C very happily flat out

For Shadow, our dog lol

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