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Scanners/ham radios that power on with ignition?

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hill

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#5
You just need to power the radios from a circuit in the car which is controlled be ignition. In my Impala have some that always powered and others turned off with the ignition.

I use both methods to power the radios, since want some to be able to powered with the key off.
 

popnokick

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#6
The problem is twofold, involving both the surge current when the vehicle is started (regardless how the radio is connected to 12VDC), and also shutting off the ignition switch if your radio is not wired to the battery.
In the latter case (not wired to the battery and with no other 12VDC supply to the radio) when you shut off the ignition switch the radio suddenly loses power before it has had a chance to write its data to the SD card or other memory. As has been noted, if you have a radio that does not need to write to an SD card or other memory before the 12VDC supply is disconnected.... then no worries. Should you worry about constantly turning the radio off without allowing it to write data to memory? Eventually, something important is not going to be saved (which may not be a big deal to you). Or... some have said that cutting the power enough times without a proper "save" / graceful shutdown first will lead to corruption of the SD card. Some reading this will probably write in and describe that they experienced SD card corruption.
The other problem... and this happens to me with my BCD536HP every time I shut off the ignition without first turning off the radio before I get out of the vehicle.... the BCD536HP spontaneously reboots due to the surge when I restart the vehicle. Again, no SD card save occurs... everything restarts. Thus far it hasn't been an issue, but I do try to remember to shut the radio off before starting the car. My BCD536HP is wired directly to the battery. So when I shut off the ignition I can still listen to the radio. And I normally remember to shut it down when I'm through. But sometimes I'm only leaving for a moment or want the 536HP to perform an "Analyze" function on a System while I'm inside the grocery store, etc. I come back out, forget to "gracefully" end the Analyze function.... and lose everything as soon as I turn the ignition switch. The BCD536HP is particularly sensitive to the surge of a vehicle startup. I don't know about other scanners. My Connect Systems CS-800D mobile radio doesn't do it, and other purpose-built mobile radios I've used do not do it.
There are surge / constant voltage devices discussed here on RR in other threads. Some of them provide only ignition start start protection, others will drop power to the radio "X" number of minutes after the ignition is turned off (which doesn't fix the graceful shutdown problem allowing the radio to write data).
 
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#7
The only caveat is that SD-card-based scanners need to have recording and Replay features turned off to prevent power off during a card write, which can cause card corruption.
 

buddrousa

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#8
My 536 powers on and off just fine with the key I do not use the record feature as stated above. Also I have not lost a card in over 18 months either.
 

ofd8001

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#9
I also haven't had any SD card corruption resulting from the power wire being on an ignition switched circuit. I just have to remember if I make any changes such as avoids, Quick Keys, etc., I have to cycle power with the On/Off switch so those changes are written to the SD card.

This is hair-splitting, but there isn't a "surge" when starting a vehicle - surge meaning more power than expected/anticipated. Rather, this is a "voltage drop" situation where so much of the battery's power is going to crank the motor. The 536 scanner doesn't like it when voltage drops, so it cycles power.

Newer Ford trucks have a big issue with this as the motor turns off for fuel economy when stopped at traffic lights, etc. There are posts on work-arounds for this issue.

Getting back to original question, I've had the following models of Uniden scanners in a mobile application where the power wire was connected to an ignition switched circuit: 536, 996XT, 996T, 796D and 780.

I suggest consideration be given to an amplified speaker when scanners are in mobile use as well as GPS devices.
 
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popnokick

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#10
Ofd8001- thanks for the correction. You are quite correct: the startup issue is voltage drop, not surge as I wrote. The voltage drop produces a restart in my 536... unless of course it is not turned on. But if it was, and you start the vehicle.... say goodbye to anything you were hoping to save during that listening or analysis session.
 
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#11
I also haven't had any SD card corruption resulting from the power wire being on an ignition switched circuit. I just have to remember if I make any changes such as avoids, Quick Keys, etc., I have to cycle power with the On/Off switch so those changes are written to the SD card.

This is hair-splitting, but there isn't a "surge" when starting a vehicle - surge meaning more power than expected/anticipated. Rather, this is a "voltage drop" situation where so much of the battery's power is going to crank the motor. The 536 scanner doesn't like it when voltage drops, so it cycles power.

Newer Ford trucks have a big issue with this as the motor turns off for fuel economy when stopped at traffic lights, etc. There are posts on work-arounds for this issue.

Getting back to original question, I've had the following models of Uniden scanners in a mobile application where the power wire was connected to an ignition switched circuit: 536, 996XT, 996T, 796D and 780.

I suggest consideration be given to an amplified speaker when scanners are in mobile use as well as GPS devices.
I had an old Bearcat 210 and it definitely did not like the spike/surge/droop of the starter system in my 1980's vintage car. It would wipe the entire memory. I don't think it was droop doing this, rather a very sharp negative polarity spike from either the starter windings or the solenoid coil.

There really is actually a potential spike when you run a starter in a vehicle, and there are specifications that manufacturers follow to simulate and test for this.

I would be far happier with my BCD536HP is I could program the dimmer wire to cause a protected soft shutdown/start up of the radio. I don't understand why with all the other firmware tweaks going on, they have not made this an option.
 
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#12
Probably because when you cut power, there isn't enough time to do a graceful shutdown before the cpu stops working.
 

N9JIG

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#13
For SD Card based scanners I have determined from scientific research that the mere presence of a spare programmed SD Card will unequivocally prevent SD Card corruption. On my 436 and both HP's I carry one taped inside the battery door, the 536 has one I keep in the glove box. Since I started doing this (as well as turning off the replay/recording options) I have not seen one failure.


Truthfully however, you can greatly reduce (but not eliminate) the possibility of SD Card corruption by turning off the Replay/Recording options. The maintenance of a spare card will provide insurance if it does get corrupted. They are cheap and easy to program.
 

popnokick

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#14
Might be coincidence since it was not in the Change Log for the latest Uniden firmware update. But my 536 no longer reboots when I start the vehicle. No new battery or any other change to the vehicle electrical system. But the 536 now “survives” an ignition start of the engine.
 
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