>
> On Feb 29, 2008, at 3:54 PM, Apptech wrote:
>
>> I want to build the following invention for a client.
>> There is no
>> NDA.  A air mover of some sort forces air up a tube and
>> out some jets
>> on the windshield/windscreen of a car/truck.  The air is
>> heated via
>> compression and possibly an electric heater.  The hot air
>> defrosts
>> the WS and melts thin coatings of ice.
>
>
> You really want an energy source other than auxiliary
> battery for the heat if engine heat is not available. This
> could be eg propane (catalytic heater could be almost safe)
> or a real burner. I understand that some US cars have had
> gas (petrol) field heaters to allow cabin heating with
> engine off, so there is a precedent and possibly a parts
> source. Regulatory provisions and sanity may have changed
> since these were used?

R.  Great ideas about heat generation from fuel.  Would diesel be  
better ?  I was intending to have a duplicate of the main battery at  
12V ( which would be perhaps 100AH ).  Being nice to the battery and  
demanding 30AH would lead to ---> 1KW of power could be supplied for  
( 30AH x 12V ) / 1000 = .36 hrs  which seems like plenty of time.     
I followed Rustles example to create these figgers.  All mistakes are  
my own.
cc

> Even a largish SLA brick at 12V 7AH gives only about 80
> Watt.hour of energy. At a first guesstimate I'd suspect that
> 1 kW of power would be needed so you SLA would supply this
> for rather less than 80 x 3600 seconds / 1000 =  288
> seconds. Given the reaction of a 7AH SLA to an 80A+ load the
> actual Wattage achievable would be rather lower and the
> duration  much much lower due to low efficiency at high
> loads. Even a say 100W load has a << 1 hour duration -
> possibly in the 20 minute range.
>
> You could consider using the main battery with generous
> protection on reserve left when you stop using it.
>
> Catalytic heat generation from petrol can produce the
> desired amount of energy out with no flame but 'a lot of
> glowing'.
>
>
>
>         Russell
>


-- 
http://www.piclist.com PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist


-- 
http://www.piclist.com PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist