scott wrote:
>>> This explains why on old cars the radio switches off momentarily as 
>>> you start your car.
>>
>> What do you mean "old cars"?
> 
> On most new cars the entertainment system must function correctly for 
> supply voltages over a very wide range, like down to 6 or even 4 volts, 
> and up to 16 or 18 volts.  This means that the radio (and all the other 
> stuff like satnav, climate control display etc) won't turn off while you 
> start the car.
> 
> In the past the radio wasn't specced this high, and it was ok to only 
> work down to say 10 volts.  Of course this meant that when you started 
> the engine, the voltage dropped down to 6 or so volts and the radio 
> turned off.

Interesting. I've never seen any car where turning the ignition 
*doesn't* disable all the other electrics in the system [including the 
headlights].

As I understand it, turning the starter motor requires a massive amount 
of current, and is essentially the *only* reason a car has such a 
whopping great battery in the first place. (Certainly it's not necessary 
just to run the spark plugs... or even the headlights...)

-- 
http://blog.orphi.me.uk/
http://www.zazzle.com/MathematicalOrchid*

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