My gut feeling is that you'll need to consume a huge amount of power all of the time to make it work.

The reason I say that is if you think about how much work a compressor fridge like a Waeco has to do to keep a small, sealed, well-insulated box cool, and then try to scale that up to keep a large, leaky, poorly-insulated van cool.

The reason engine driven systems work well is that the engine itself has massive power reserves - trying to replicate that with a 12V compressor system is just going to be very very hard work, and you will need top quality components just to get any sort of reliability. I doubt it would be physically possible to make it small, because you will need a heat exchanger of significant size just to be able to dump the heat outside the van.

Last time I looked, there were commercially available systems that dropped into the space under the rear seat, and these always seemed a better idea than the roof-mounted systems (because the roof mounted systems put a lot of heavy components too high on the vehicle). But they (necessarily) take up a lot of space and consume a lot of power - the latter not a problem if you're on 240V hookup.

Probably the best, most environmentally friendly solution (if you care about things like that) is not to go to hot places if you don't like the heat!

 

That compressor uses over 1kw of power. Using a typical 110Ah leisure battery you'd have around 45mins use. How many leisure batteries are you packing and what's your plan to recharge them?

 

I did a ***-packet estimation and I reckon if you used every bit of space you could get 1kW of solar panels on the roof of a LWB T5.1. this would just about run a small AC, and of course you'd only need it if the sun was blazing.

 

Hi,
Sorry for the delay in replying, the Australian company still hasn't come back.
But I've been having a few more thoughts and research, as there are retro fit systems out there for classic cars etc.

Regarding the power situation.
It should consume about 88 Amps at 12v for a 1kw ish system, I'm not sure how much our Alternators kick out ? Prob about 130A ?? I also don't know what power are vans use as a base line, stereo, DLR lights, blower, fridge etc. So I suspect a bigger alternator is required.

Then in regards to being parked up connected to 240v at a campsites. 1kw equates to 4 amps at 240v, I seem to remember most campsites do 6amps on electric hook up.

So my battery charger is 7amps I think (at 240v)?? Or you could connect up to a AC to DC transformer. You would have to switch it off for cooking etc as the draw would be too big, but really it would be used for traveling and sleeping at night with only the Aircon and fridge pulling a load.

This is all very rough thinking and please tell me if I'm miles off, but it feels do able.
There was also a retro system that had intelligent circuitry to reduce out put to the Aircon system of the van, if it was pulling too much current else where, not ideal but a protection system.

Adam

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Looks like the original alternator is quite a bit smaller but it could built bigger. Or how about fitting a 2nd alternator ? Where the Aircon compressor would have fitted if it was fitted originally.
Not sure how this would work ? In regards to load on the engine, does it just load up as required ?
I know the Aircon compressor has a clutch which engages when active and puts a load on the engine and therefore uses more mpg etc. Does an alternator work in a similar way ? What happens to the spare electricity produced if it's not consumed ? I'm sure there is a far cleverer person on here that could explain the down floors of such a situation ?

When I get more time, I'll also ask Google [emoji1787][emoji1787]

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What happens to the spare electricity produced if it's not consumed ?

[emoji1787][emoji1787]

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It only produces what's required up to it's maximum output. In you OP you mentioned about EV's having a heatpump for heating & cooling, I think that runs off the traction batteries not the 12v battery.

 

As Roger says, an alternator doesn't produce power that's not needed - the load that it places on the engine increases as you put more electrical load on it.

But one thing to bear in mind about an alternator: it will be rated according to a "duty cycle", which is an assumption about how much of the time it will be fully loaded. If you take an alternator that's rated at 100A, it will not be capable of providing 100A all of the time. No conventional automotive use will load an alternator in that way, and if you try to, you are likely to break it fairly quickly.

You don't seem to have addressed one thing yet: how are you going to arrange for the internal and external heat exchangers to be mounted, and where? It seems obvious that you could replicate the cab aircon system, adding most of the components of the factory aircon system (at probably around the same cost as the factory aircon system) but devising you own custom controller to run the compressor and drive the fans. That of course would centre the aircon around the cab. Or you could place all of those parts further back, which would place the circulation of the system more centrally in the van but would of course mean cutting largish holes in the van to vent the heat outside.

If you choose the latter, bear in mind that the factory system (which is really only designed to cool the cab) has roughly half a square metre of external heat exchanger, and this, or something like it, will have to be accommodated somewhere...

 

Thank you very much for the discussion, I've been having a good look around at various parts and work involved and removing the factory heater matrix seems a big pain in the ass.
A thought would be to put a standard condensor in front of the rad ( but unsure if it's big enough, as the system needs to be bigger than standard as it's cooling the whole van, but then again it's the same condenser as the caravelle I think ?).

Then I could buy either 1 large off the shelf evaporator (off a big car, Landover maybe)
Then build a box from aluminium to fit it in and fit a fan to it. This box could be mounted under the van (under the chassis), in line with driver's seat as there is a space there. Then it can be vented to the cab, just behind handbrake and to the rear in another location.

Or I could build 2 boxes, 1 for the front and 1 for the rear.

Alot of the retro systems I've seen have a thermostatic cut off at 3 degrees in the evaporator box which cuts the power of to the A/c clutch (in this case the electric compressor). What I don't know is if it would be possible to control the compressor speed to vary it's output, dependant on demand. But I don't know if this is possible ?

Food for thought.

PS I found lots of bits on a website called carbuilder solutions

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Yep, shedloads of work. I don't think you'll fit anything big enough under the van. It probably looks possible until you add in mounting brackets, insulation, protection from stones coming up off the road, enough free space on both sides for sensible airflow and a big fan - but with all that it'll be scraping on the ground, I would think.

Of the two, I would rate messing about with the factory heater matrix - which obviously has enough space next to it for the factory fitted evaporator, and obviously already has a nice big fan alongside - as much less of a pain in the ass, but then I haven't tried to do either.

 

Yeh fair enough, I couldn't find a specific YouTube clip on heater out of T5. But other vehicles it is dash out...

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Just a thought that may help you figure out what size system.

I have a/c in my house and yes, it is possible to run it hard and reduce the house temperature to 23 degrees when it’s 33 outside, but I don’t. Typically, I run the system on the lowest fan setting and let it take a few degrees off. It this point, it is probably running at a lot less than 25%. It is a 2kw system that puts out 6-7kw of cooling. The whole house runs on two. So 4kw max consumption for 1100 sq ft. at max cool and less than 1kw the way I run it. Obviously it is 240v. Do bear in mind that domestic systems recirculate.

 

EV compressors run at 200v DC and are networked. 12v compressors would draw as much power as a starter motor so you would quickly drain the battery. Alternators cant produce 130A at idle, you need to spin it at 3000rpm to get that sort of output.

Small 240v domestic ac units could be run off an inverter but the smallest units that have a compressor are around 300watts at 240v. Power = volts x amps so youd be looking at drawing 30 amps which would quickly kill your leisure battery.

The simplest way to get AC for camping is to use the hook up.

To get AC for driving, retrofit AC from another vehicle.

For reference I'm about to do this to a T4. The brackets and parts are a straight swap from a Golf mk3. The tricky part is the in vehicle evaporator which is a dash out job.

 

I design AC systems for EVs and hybrids. As mentioned above, theres no way you can design a system within the confines of an existing vehicle to work both driving and stationary. Best to fit an under bench RV style system. Maybe then you could fit a secondary high power alternator to generate the 240v to drive it. I think Antares make such systems for ambulances. I have seen a 12v ac compressor but it's only capable of cooling a sports car, not a camper van.

 

There you go Put it on the passenger seat and blow the hot vent out of the passenger window. If it works then build it under the bench and blow the hot air into the floor

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