Car radio that shuts off when starting the car

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-

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John A. Weeks III            952-432-2708         john@johnweeks.com
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John A. Weeks III
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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.

Reply to
Mjolinor

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.

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Don Bruder

home, as

2004.

the

Reply to
Art

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

Reply to
JQP

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:

XM plugged into my

socket. The Sirius radio

Reply to
Ed

Wait, I just found a solution on google. A bit more complex than I would like, and it requires a switched power source.

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I don't have switched power, but I think I could rewire my system so that it would witch, and $30 seems reasonable...

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Ed

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