Subject: re: Laptop 'puters



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(983)   Sat 20 Jul 91 14:04                             
By: Tom Keller
To: Don Kulha

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Don,
 
    Be damned careful of hooking up your 'puter to a lead-acid 
battery!  A so-called "12 volt" lead-acid battery is actually 13.2 
volts at full charge, while a 12 volt ni-cad is actually 12 volts.
 
    *SOME* circuitry may find that extra 10% of EMF more than it 
can handle.  I am thinking in particular of the LCD display and its 
associated drivers.   Check this out pretty carefully before you 
fry your new toy!

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(3552)   Sun 21 Jul 91  9:40                             
By: Jim Dunmyer
To: Tom Keller

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@EID:06bf 16f54d13@
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@CHARSET: PC-8
 >  
 >     Be damned careful of hooking up your 'puter to a 
 > lead-acid battery!  A so-called "12 volt" lead-acid 
 > battery is actually 13.2 volts at full charge, while a 
 > 12 volt ni-cad is actually 12 volts. 
 > 
 >     *SOME* circuitry may find that extra 10% of EMF more 
 > than it can handle.  I am thinking in particular of the 
 > LCD display and its associated drivers.  Check this out 
 > pretty carefully before you fry your new toy! 

At least *some* laptops have a "12 volt power cord" available to 
plug into a vehicle's cigarette lighter socket. The voltage from 
that source will be from a bit over 12 volts to as high as 15 volts 
(engine running). One might assume that the laptop is capable of 
handling that variation. Matter of fact, if you measure the "AC 
adaptor" output voltage, you'll find that many aren't regulated *at 
the adaptor*, and are considerably higher than the nominal rating.
 
One caveat: If you plug a laptop into a vehicle's lighter socket, 
turn it off and unplug it while you start the engine. The inductive 
kick-back from the starter motor and solenoid can put a very 
high-voltage spike on the system, and that could be very hard on 
your laptop.

                             <<Jim>>

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