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SafeSpeed
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PostPosted: Wed Jul 18, 2007 17:28 
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hairyben wrote:
SafeSpeed wrote:
weety wrote:
how about installing proper air con for the er hot sunny weather we are expiriencing :D


Yeah, I'd love proper aircon - and I've been looking at it. Domestic air con is quite cheap, but the roof-mount campervan air cons start at about £700 - and they need around a KW to run - that's four grand's worth of solar cells, and probably considerably more than a roof-full. So they only run in practice with mains hook-up or a generator. I've got a nice little generator, but it's a bit too noisy for the places I end up working, and not really enough power for an air con.

Another technical solution to running air con is to connect a 1.5KW mains voltage alternator to the engine. For 50Hz you need a shaft speed of 3000rpm on the alternator, so maybe the engine could be persuaded to idle at 1000rpm with a 3:1 pulley/belt arrangement from the crank. In truth it's likely to be too hard and/or too expensive.


The top end merc has some sort of solar powered aircon setup, so there must be a low power solution.


I don't know what Merc have - and I'd be interested to find out - But air con is ALWAYS high power.

hairyben wrote:
Regarding mains power, an easier/more conventional way to do it would be to uprate the standard alternater & fit a high capacity/2nd battery & inverter, with solar cells could topping up the battery constantly. This would also give silent running...


I do that already. It's very cheap and easy these days. But the lowest power useful air con is about 800W, so that's about 70A at 12V - I'd be using all my 'practical' battery power in 3 hours.

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hairyben
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PostPosted: Wed Jul 18, 2007 17:42 
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SafeSpeed wrote:
I don't know what Merc have - and I'd be interested to find out - But air con is ALWAYS high power.


I do that already. It's very cheap and easy these days. But the lowest power useful air con is about 800W, so that's about 70A at 12V - I'd be using all my 'practical' battery power in 3 hours.



yeah, it's a fair old load alright, would probably want an 800AH battery or paired up batterys or something. something like ebay might turn up mis-ordered or overstock items at a nice price, as the battery dimensions are largely irrelevant.

And the merc system suprised me too, I gather it's not that powerfull more a trickle system to keep the temp down when unoccupied rather than cool it down quickly, probably works in conjunction with solar reflective glass & good insulation etc. Out of intrest, how well insulated is the campervan roof, could this have better insulation fitted, painted silver on top etc?

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SafeSpeed
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PostPosted: Wed Jul 18, 2007 19:41 
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hairyben wrote:
SafeSpeed wrote:
I don't know what Merc have - and I'd be interested to find out - But air con is ALWAYS high power.


I do that already. It's very cheap and easy these days. But the lowest power useful air con is about 800W, so that's about 70A at 12V - I'd be using all my 'practical' battery power in 3 hours.



yeah, it's a fair old load alright, would probably want an 800AH battery or paired up batterys or something. something like ebay might turn up mis-ordered or overstock items at a nice price, as the battery dimensions are largely irrelevant.


Huge battery banks are, well, huge! And space is very much at a premium. There's also the issue of what you have to do to recharge such a large battery bank. You could recharge it at about 200A - but how much does a 200A intelligent battery charger cost? And then you find you need to give the battery charger 2.5Kw, which means a bigger generator or a much longer charge time.

The real answer to all this is a low noise on board generator. They are common in American 'RVs' - and I think it's the need for air con that drives the need - but they start at about £3,000 and they are quite bulky (Nevertheless if I could afford one, I would find space for it).

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hairyben
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PostPosted: Wed Jul 18, 2007 19:55 
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SafeSpeed wrote:
hairyben wrote:
SafeSpeed wrote:
I don't know what Merc have - and I'd be interested to find out - But air con is ALWAYS high power.


I do that already. It's very cheap and easy these days. But the lowest power useful air con is about 800W, so that's about 70A at 12V - I'd be using all my 'practical' battery power in 3 hours.



yeah, it's a fair old load alright, would probably want an 800AH battery or paired up batterys or something. something like ebay might turn up mis-ordered or overstock items at a nice price, as the battery dimensions are largely irrelevant.


Huge battery banks are, well, huge! And space is very much at a premium. There's also the issue of what you have to do to recharge such a large battery bank. You could recharge it at about 200A - but how much does a 200A intelligent battery charger cost? And then you find you need to give the battery charger 2.5Kw, which means a bigger generator or a much longer charge time.

The real answer to all this is a low noise on board generator. They are common in American 'RVs' - and I think it's the need for air con that drives the need - but they start at about £3,000 and they are quite bulky (Nevertheless if I could afford one, I would find space for it).


I would talk to an auto electrician or a car audio specialist about uprating the alternater- they do it all the time for huge ICE installs that need extra batteries.

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mpaton2004
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PostPosted: Wed Jul 18, 2007 20:01 
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When you're parked up, you could set up a mobile safety camera (mini-GATSO?) and power the flash from your spare power - thus detecting and punishing lethal drivers.
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Ziltro
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PostPosted: Wed Jul 18, 2007 20:16 
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mpaton2004 wrote:
When you're parked up, you could set up a mobile safety camera (mini-GATSO?) and power the flash from your spare power - thus detecting and punishing lethal drivers.

Again, I was going to suggest that. :lol:

I believe the type approval says that it has to be connected to the national grid. So generators (Like the ones they used on the M4) are out, and I would assume that includes a solar panel & battery setup.

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Steve
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PostPosted: Wed Jul 18, 2007 20:18 
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:lol:
at, not with
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botach
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PostPosted: Wed Jul 18, 2007 21:00 
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Ideas - ideas !!

One i saw some time ago for a camper involved passing the exhaust through a water tank - the heat heated up the water - was looked on as quite efficient . But on the air con idea - domestic air con eat juice - years ago in Africa we had the luxury of TWO --one in the lounge and one in the main bedroom. We got free electricity as part of the package and our bill (with both running 24/7 ) was a lot higher, and questions were asked .( Outside day temp = 40 in shade, enough to warp plastic dash on firms 4x4 )

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SafeSpeed
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PostPosted: Wed Jul 18, 2007 21:36 
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mpaton2004 wrote:
When you're parked up, you could set up a mobile safety camera (mini-GATSO?) and power the flash from your spare power - thus detecting and punishing lethal drivers.


Trolling is strongly discouraged according to forum rules.

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SafeSpeed
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PostPosted: Wed Jul 18, 2007 21:50 
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hairyben wrote:
I would talk to an auto electrician or a car audio specialist about uprating the alternater- they do it all the time for huge ICE installs that need extra batteries.


Charging batteries while driving isn't a problem; the 60A or so available from the vehicle alternator is presently sufficient.

Power when static is much more at a premium. It'd be possible to use the vehicle engine in a generator arrangement although it isn't conventional. Frankly static air con is a luxury that I won't be going for unless I have the £4k+ required for an onboard generator and roof mounted air con (and nothing better to spend it on).

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ed_m
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PostPosted: Sun Jul 22, 2007 15:10 
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botach wrote:
Ideas - ideas !!

One i saw some time ago for a camper involved passing the exhaust through a water tank - the heat heated up the water - was looked on as quite efficient .


some friends of ours have an ex AA VW van which has a small sink fitted.. and a hot water tank big enough to fill the sink, which is heated by the engine in about 20mins.
(i guess designed to provide water to wash his hands in after a job and heat it up on the journey between stops)
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ed_m
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PostPosted: Sun Jul 22, 2007 15:15 
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i was slightly inspired on my bike ride today...

how much engine wear, cold start emissions & fuel could be saved by preheating the engine ?

on our old camper it would be a bonus not to have to warm it up!

with some fairly standard automotive/12v parts you could fit a heater & secondary pump to the coolant system to keep the engine warm.

need some electronics to switch it in when there's spare power.
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