48v dc power

From: Lawrence Walker <lgwalker_at_look.ca>
Date: Fri Oct 13 12:29:45 2000

> At 05:54 PM 10/10/00 -0700, Chuck McManis wrote:
> >Why not buy a "dead" UPS that can over the wattage of your system and
> >install a 12V in plug on the back. Most of these use a 12V DC input
> >and provide acceptable power on the output. Its cheaper than simply
> >buying a 12V -> 120V inverter _at_600Watts or so.
> At 07:30 PM 10/10/00 -0700, Shawn T. Rutledge wrote:
> >Because it's grossly inefficient. Why convert from 12V to 120V AC
> >and then back to 12V, 5V, etc... they design some really efficient
> >DC-DC converters for laptops (to convert battery voltage to 5V) so it
> >should be possible (cheaply) for desktops also.
>
> Not only have I wondered about the most efficient way to
> power a PC inside a car, but other devices... a few months
> back I was looking for a 12 volt to 6 volt converter to
> power a Sony GV-9 video deck in the car, to no avail.
>
> All the units I found were too low in amps-out. I avoided
> the 12v -> 120v -> wall wart solution as too gross and inefficient,
> but I guess it would work.
>
> - John
>
 You'd think there'd be lots of 12v > 6v car convertors around from
the time of the change from 6v to 12v automobile systems. Might try
a large wrecker or old car-parts supplier.

 I have a couple of Tripp-lite 675W UPS. 4 sockets supply up to 6
amps, one of which I use with my main boxen. They use what
appears to me a car 12v lead-acid battery. One even has the old-
style lead terminal clamps, while the other has the screw into the
posts leads. I had always envisioned using the spare as a 120v.
supply in my (not-yet-acquired-but-soon) retirement camper or van
and simply bypassing the 120v charging cicuit on the UPS. Just
hooking the UPS battery into the vehicle charging system, thus
being able to use it for a computer, lites, TV, etc.
 It can power up even when it is disconnected from the main or
during a power failure. And since I have one, it's inexpensive.

 From this discussion I'm now concerned, and unable to discern
whether:

  A. It isn't feasable for some strange reason.
  B. There is a problem with auto power fluctuation or generation.
or
  C. It isn't the optimum in-vehicle supply for nit-pickers. (just
ignore)

 And of course many people power up their phones and laptops
using a cigarette-lighter socket. Am I missing something here ?
And no I'm not likely to travel with a mini rack.

ciao larry

Reply to:
lgwalker_at_look.ca
Received on Fri Oct 13 2000 - 12:29:45 BST