I see, so do you think that a 12v DC to 16V DC converter is the answer then?
Tony

Mad Dog wrote:

Yes, using a 6V battery in conjunction with some very extensive
series-parallel
connections and battery isolators you could theoretically design such a
circuit.
But lets consider the source of the interference, alternators are used
insted of generators
on car and boat engines because they are lighter and smaller but alternators
produce alternating current (A/C).
A full wave bridge rectifier consisting of trio diodes is used to convert
A/C into D/C
and a regulator governs output from 13.8 to 14.6VDC.
what a concept huh, anyway the rectifier leaks a small amount of A/C
current into
the regulated D/C.
this small amount of A/C current (700 millivolts) is infamously known as
A/C ripple.
In the D/C world you can call it dirty power because it will infect every
D/C appliance
and electronic gadget that you have turned on.
A/C ripple in a D/C circuit produces NOISE and INTERFERENCE and premature
component failure.
To compund things you are a inverter which inverts the already dirty DC
current back
into a modified square wave which resembles AC current.
****'s gittin deep over here...........
let me know if i'm going to fast 4 ya, what you need to do is condition or
filter the Dc
current before it reaches the intended circuit.
There are 3 types of electrical storage devices: condensers,capacitors and
batteries.
condensers store dc, capacitors store AC and you know what batteries do.
Gittin to the point a capacitor mounted in a DC circuit will block AC while
allowing DC
current to pass, hence we have effectively filtered the DC current.
there are also different types and sizes of capacitors, depending on it's
intended purpose.
keep in mind that DC current flows pos. to neg. thru the battery and
negative to positive thru
a circuit so what this means is grounds are just as important if not more so
than the positive wire.
Several companies make line conditioners for your purpose, but i have always
built my own using large banks of oil-filled electrolytic capacitors wired
in series to handle the demand
for heavy current draw.
Hopefully i have not confused you or gave you a headache as i now have
one..........
but instead given you some insight as to why some DC components dont
function as intended
when operated from rectified AC current.
--
Mad Dog

"TB" wrote in message ...

Would it be possible to have the house and engine batteries conected in
series to give 24v, step this down to 18v to power the laptop. Then tap
off each battery for normal 12v service. Sorry if this is a dumb
question but I need a dc supply as the inverter interferes with the ssb
radio when receiving weather faxes.
Tony