Car radio that shuts off when starting the car

[John A. Weeks III]

I have a problem where my XM radio shuts off when I start my
car. I also have a Sirius radio, but that stays running when
I start my car. The XM shutting off is kind of annoying since
it doesn't turn back on by itself after the car is running.

I was thinking of putting in a capacitor to provide power to
the XM unit to keep it live while starting the car. I was
thinking that a diode between the car power and the capacitor
would be needed to keep the cap from back-powering anything
in the car.

Anyone ever try this before? Any guesses on if it would work?
Any suggestions on how big of a capacitor would be needed?
Is there any chance the leakage of a capacitor would run down
my car battery if I let it sit for days at a time?

-john-

--
====================================================================
John A. Weeks III 952-432-2708 john@johnweeks.com
Newave Communications http://www.johnweeks.com
====================================================================

 

[Mjolinor]

"John A. Weeks III" <john@johnweeks.com> wrote in message
news:110720040141444610%john@johnweeks.com...

I have a problem where my XM radio shuts off when I start my
car. I also have a Sirius radio, but that stays running when
I start my car. The XM shutting off is kind of annoying since
it doesn't turn back on by itself after the car is running.

I would suggest that this is a sign of the battery on the car going home, as
the battery gets older the voltage drop under load gets slightly larger
until you are below the power off threshold of the radio. I would
investigate that before trying to cure the problem another way.

 

[Don Bruder]

In article <jV7Ic.295$u12.231@newsfe3-gui.ntli.net>,
"Mjolinor" <mjolinor@hotmail.com> wrote:

"John A. Weeks III" <john@johnweeks.com> wrote in message
news:110720040141444610%john@johnweeks.com...
I have a problem where my XM radio shuts off when I start my
car. I also have a Sirius radio, but that stays running when
I start my car. The XM shutting off is kind of annoying since
it doesn't turn back on by itself after the car is running.

I would suggest that this is a sign of the battery on the car going home, as
the battery gets older the voltage drop under load gets slightly larger
until you are below the power off threshold of the radio. I would
investigate that before trying to cure the problem another way.

Another concept to consider:
Try putting the XM power line to the same place as the Sirius. It may be
that the sirius is on a "more permanent" power than the XM is.

--
Don Bruder - dakidd@sonic.net - New Email policy in effect as of Feb. 21, 2004.
Short form: I'm trashing EVERY E-mail that doesn't contain a password in the
subject unless it comes from a "whitelisted" (pre-approved by me) address.
See <http://www.sonic.net/~dakidd/main/contact.html> for full details.

 

[Art]

Maybe the XM requires a permanent source of power to it, rather than a
source that is switched when powering the vehicle's systems on. There is
probable a standby that is hot constantly and a B+power feed that comes on
after the vehicle ignition's is set to either accessory or run position. Or
the voltage level of the supplied sources is dropping to such a low level
when cranking the engine that it indeed will power down. As recommended,
check what the power source is applied to the other radio and connect our XM
there also.
"Don Bruder" <dakidd@sonic.net> wrote in message
news:xW7Ic.1630$54.19888@typhoon.sonic.net...

In article <jV7Ic.295$u12.231@newsfe3-gui.ntli.net>,
"Mjolinor" <mjolinor@hotmail.com> wrote:

"John A. Weeks III" <john@johnweeks.com> wrote in message
news:110720040141444610%john@johnweeks.com...
I have a problem where my XM radio shuts off when I start my
car. I also have a Sirius radio, but that stays running when
I start my car. The XM shutting off is kind of annoying since
it doesn't turn back on by itself after the car is running.

I would suggest that this is a sign of the battery on the car going
home, as
the battery gets older the voltage drop under load gets slightly larger
until you are below the power off threshold of the radio. I would
investigate that before trying to cure the problem another way.




Another concept to consider:
Try putting the XM power line to the same place as the Sirius. It may be
that the sirius is on a "more permanent" power than the XM is.

--
Don Bruder - dakidd@sonic.net - New Email policy in effect as of Feb. 21,
2004.
Short form: I'm trashing EVERY E-mail that doesn't contain a password in
the
subject unless it comes from a "whitelisted" (pre-approved by me) address.
See <http://www.sonic.net/~dakidd/main/contact.html> for full details.

 

[JQP]

Mjolinor wrote:

"John A. Weeks III" <john@johnweeks.com> wrote in message
news:110720040141444610%john@johnweeks.com...

I have a problem where my XM radio shuts off when I start my
car. I also have a Sirius radio, but that stays running when
I start my car. The XM shutting off is kind of annoying since
it doesn't turn back on by itself after the car is running.


I would suggest that this is a sign of the battery on the car going home, as
the battery gets older the voltage drop under load gets slightly larger
until you are below the power off threshold of the radio. I would
investigate that before trying to cure the problem another way.

I had a similar problem and a new battery fixed it.

 

[Ed]

I contacted John offline to see if he ever got a solution to the XM
problem. He has not found one yet.

I think it is just a design feature that the Sirius returns to the
state it was in before the power loss, like a lamp.

The XM defaults to "off" after any blink in the power, so you need to
manually start it every darn time.

I think the only way to fix this would be a capacitor in parallel with
power for the XM so it never sees the power dip. John also mentioned
diodes to keep power from flowing back, but I am just a CHE, not a EE,
so I have little clue on how to wire this stuff.

Could you also put a battery in parallel, like a backup system? I
could see needing diodes there if you don't match voltages properly. I
would think the capacitor may not need diodes to prevent reverse flow,
but I am probably wrong.

Anyone have other ideas or methods to keep my XM on all the time, even
when starting the car?

Thanks!



John A.Weeks III wrote:

Ed,

No, I never got a solution to this problem. I have both my Sirius and
XM plugged into my
aux power outlet, which is nothing more than a cigarette lighter
socket. The Sirius radio
will stay on, but the XM shuts off when I start my car.