AC Adaptor in Parallel With Battery?

Paul · Apr 16, 2008

We plan on placing a +12VDC AC adaptor (110-220AC, which
will plug into
an outlet) in parallel with a battery connector using a "Y" connector,
so that the user can operate our device using either a battery, or the
wall adaptor. ONLY EITHER the battery or the wall adaptor will
be hooked up at any time.

Here is the adaptor we will use:

http://www.cui.com/pdffiles/DPS120100UPS-P5P-SZ.pdf

However, will the impedance of the AC adaptor (when it's
not plugged in) be sufficiently
high enough to make the current draw on the battery insignificant?

Because if the adaptor looks anything like the following:

http://www.coilws.com/images/Switch Mode/1R5W_ckt.gif

Then I'm not worried about the half-wave rectifying diode, but rather
the shunt Zener diode which is only 8.2V.

I'm hoping that the current draw going into the adaptor
will
be insignificant, so that i can wire it in parallel to the battery
connector,
without having to hassle with putting a relay or switch in there.

Maybe i can just solder in a series diode in-line with the
AC adaptor....

a7yvm109gf5d1@netzero.com · Apr 16, 2008

We plan on placing a +12VDC AC adaptor (110-220AC, which
will plug into
an outlet) in parallel with a battery connector using a "Y" connector,
so that the user can operate our device using either a battery, or the
wall adaptor. ONLY EITHER the battery or the wall adaptor will
be hooked up at any time.

Here is the adaptor we will use:

http://www.cui.com/pdffiles/DPS120100UPS-P5P-SZ.pdf

However, will the impedance of the AC adaptor (when it's
not plugged in) be sufficiently
high enough to make the current draw on the battery insignificant?

Because if the adaptor looks anything like the following:

http://www.coilws.com/images/Switch Mode/1R5W_ckt.gif

Then I'm not worried about the half-wave rectifying diode, but rather
the shunt Zener diode which is only 8.2V.

I'm hoping that the current draw going into the adaptor
will
be insignificant, so that i can wire it in parallel to the battery
connector,
without having to hassle with putting a relay or switch in there.

Maybe i can just solder in a series diode in-line with the
AC adaptor....

You could have done that in less time than it took to write that post.
So what do you think the answer is?

Phil Allison · Apr 16, 2008

Paul said:
We plan on placing a +12VDC AC adaptor (110-220AC, which
will plug into
an outlet) in parallel with a battery connector using a "Y" connector,
so that the user can operate our device using either a battery, or the
wall adaptor. ONLY EITHER the battery or the wall adaptor will
be hooked up at any time.

Here is the adaptor we will use:

http://www.cui.com/pdffiles/DPS120100UPS-P5P-SZ.pdf

However, will the impedance of the AC adaptor (when it's
not plugged in) be sufficiently
high enough to make the current draw on the battery insignificant?

** No !!

Not only will the output circuit of the adaptor draw current from the 12
volt battery - but it may in fact place a dead short across it !!!

This switching PSU is stated to have over-voltage protection that shuts down
the output ( in case of internal failure) - so very likely it has a SCR
" crow-bar "

circuit. This will trigger at some voltage a little above the nominal 12
volt level and hard short the output PLUS any connected battery supply.

Use a series diode after the adaptor, for god's sake.

....... Phil

Paul · Apr 16, 2008

You could have done that in less time than it took to write that post.
So what do you think the answer is?- Hide quoted text -

- Show quoted text -

Don't ask advice from a numbskull...

Paul · Apr 16, 2008

"Paul" <[email protected]>

** No ï¿½!!

Not only will the output circuit of the adaptor draw current from the 12
volt battery - ï¿½but it may in fact place a dead short across it ï¿½!!!

How "in fact" do you know this?

This switching PSU is stated to have over-voltage protection that shuts down
the output ï¿½( in case of internal failure) ï¿½ - ï¿½sovery likely it has a SCR
" crow-bar "

INCORRECT. This is just a wall AC adaptor.
It's just a linear regulator.

And the crow-bar would limit the current FROM
the unit, not limit current INTO the adaptor.

ï¿½circuit. ï¿½This will trigger at some voltage a little above the nominal 12
volt level and hard short the output PLUS any connected battery supply.

What the hell are you talking about??

The over-voltage circuit is separate from
the over-current protection, and a short-circuit
protection will do anything BUT short out the output!

Why would you have a SHORT-circuit protection
SHORT out the output???!!?

Use a series diode after the adaptor, ï¿½ for god's sake.

I probably will, but certainly
NOT from anything you have typed!

Phil Allison · Apr 16, 2008

"Paul"
"Phil Allison"

** No ?!!

Not only will the output circuit of the adaptor draw current from the 12
volt battery - ?but it may in fact place a dead short across it ?!!!

How "in fact" do you know this?

** Read on - fool.

This switching PSU is stated to have over-voltage protection that shuts
down
the output ?( in case of internal failure) ? - ?so very likely it has a
SCR
" crow-bar "

INCORRECT. This is just a wall AC adaptor.
It's just a linear regulator.

** Read the damn URL you supplied - asshole !!

It **IS ** a " switch- mode power supply " !!!!!

Says so right on the back of the damn unit !!!!!
------------------------------------------------------------

And the crow-bar would limit the current FROM
the unit, not limit current INTO the adaptor.

** If the output is shorted by an SCR - so will anything attached to the
output, like your battery. Read the damn URL you supplied.

It says:

" Over voltage protection 15 -18 V dc max. ( output shut down) "

Unlike the "Short circuit protection", it is not self restarting and that
is how an SCR crow-bar circuit behaves.

?circuit. ?This will trigger at some voltage a little above the nominal 12
volt level and hard short the output PLUS any connected battery supply.

What the hell are you talking about??

** Listen, pal -

YOU need to learn some basic power supply stuff.

Cos YOU fucking don't know ANY yet.

The over-voltage circuit is separate from
the over-current protection, and a short-circuit
protection will do anything BUT short out the output!

** I said the " over voltage protection " would short the output - because
that is what the maker's specs suggest.

Use a series diode after the adaptor, ? for god's sake.

I probably will, but certainly
NOT from anything you have typed!

** Try learning to read - asshole.

Then get some better manners.

Cos you have FUCKING TERRIBLE ones now.

....... Phil

Paul · Apr 16, 2008

"Paul"
ï¿½"Phil Allison"

ï¿½ How "in fact" do you know this?

ï¿½ ï¿½** Read on - ï¿½fool.

INCORRECT. This is just a wall AC adaptor.
It's just a linear regulator.

** Read the damn ï¿½URL ï¿½you supplied - ï¿½ asshole ï¿½!!

It ï¿½**IS ** ï¿½a ï¿½" switch- mode power supply " ï¿½ !!!!!

Says so right on the back of the damn unit ï¿½ !!!!!
------------------------------------------------------------

** If the output is shorted by an SCR - ï¿½so will anything attachedto the
output, like your battery. ï¿½Read the damn ï¿½URL ï¿½you supplied.

It says:

" Over voltage protection ï¿½15 -18 V dc max. ( output shut down) ï¿½"

Unlike the ï¿½"Short circuit protection", it is not self restarting and that
is how an SCR crow-bar circuit behaves.

ï¿½ ï¿½What the hell are you talking about??

** Listen, ï¿½pal ï¿½-

ï¿½YOU ï¿½need to learn some basic power supply stuff.

ï¿½Cos YOU fucking don't know ANY yet.

The over-voltage circuit is separate from
the over-current protection, and a short-circuit
protection will do anything BUT short out the output!

** I said the " over voltage protection " would short the output ï¿½- ï¿½because
that is what the maker's specs suggest.

You don't know SHIT, Aussie-Holiday Faggot!

Why the hell would an over-voltage protection
short out the fucking output? If anything, it would
open a SERIES MOSFET.

I probably will, but certainly
NOT from anything you have typed!

** Try learning to read ï¿½- ï¿½asshole.

ï¿½Then get some better manners.

ï¿½Cos you have FUCKING TERRIBLE ones now.

...... ï¿½Phil

Look in the mirror, Crocodile Dund-Fuckin'-Dee!

All your "!!" are extremely bad manners, so i
give them back to you, Shit-wit!

Paul · Apr 16, 2008

What's ONLY EITHER mean? ï¿½I thought I knew but then you
mentioned a diode, which wouldn't be necessary if only
either but not both would be simultaneously hooked up.

But even if only the battery is hooked up, the
AC adaptor may still have a not-so-high impedance
looking into it. In which case, a reverse-biased
diode will certainly help things.

How about a power input jack that switches one off (out of
circuit) when the other is plugged in? ï¿½We don't know enough
about the device, usage, and power consumption. ï¿½Depending
on these another option might be a relay flips when AC-DC
adapter is present.

Yes, but we'd like to avoid this if possible.

As Phil not so gently put it, that is a switching PSU. ï¿½May
or may not hav ea crowbard, some of this small size are
fairly crude and yet still probably sufficient, unless you
were running an analog amp.

You'd have to pop 'er open and reverse engineer a bit to
know this, so while some would turn their nose up at a
series diode because of the fraction of a volt power loss
(from an efficiency standpoint), it is a cheap, quick,
reasonable ï¿½solution.

Yeah, i'm also gonna use an external power
supply, and measure the current going into the adaptor
when it's unplugged, and see what the current is.

That should tell me if I'll need the series
diode or not.

It might be a bit more elaborate, different than that, but
you shouldn't leave the adaptor and battery in parallel.

Another option that hasn't been covered would be if the
adapter were behind the battery as a charger with a peak
voltage under the maximum tolerable by the powered device,
but without an expressed need for this, the series diode
would be the more reasonable solution, or the relay.

I suppose it depends on what you consider a hassle, a relay
isn't all that complex but there's something to be said for
altering only the cheap little AC-DC supply internally with
a diode.

Yeah, but a relay would draw current, which i can't
do if i want the batteries to last. And even just a simple
manual switch (SPDT) would be a bit bulky, which is what
i'm trying to avoid.

Thanks for your input.

Phil Allison · Apr 16, 2008

"Paul"

** This retarded VILE PIG is a FUCKING MORON.

Killfile the **** now !!

....... Phil

Phil Allison · Apr 16, 2008

"Paul" <[email protected]>

** This retarded VILE PIG is a FUCKING MORON.

Killfile the **** now !!

....... Phil

Phil Allison · Apr 16, 2008