JamesO
Member
Hope you have fused the feed to the battery properly. Probably a 1-2 Amp fuse might be good enough, you would need to check with a Ampmeter and see what kind of draw the scanner and battery might present.
Hard reboot when vehicle is turned on.
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JamesO
Member
I would not want to rely on a diode to be a fuse.
Fuses are usually put into protect the wiring!!!
Usually you look at the max Amperage draw + 25% to fuse properly as long as the wire is not undersized.
I would prefer to have a fuse in case the SLA battery starts to have problems.
Fuses are usually put into protect the wiring!!!
Usually you look at the max Amperage draw + 25% to fuse properly as long as the wire is not undersized.
I would prefer to have a fuse in case the SLA battery starts to have problems.
Maybe something like this would also be an option for anyone who wants to leave things turned on for a little while after shutting off the vehicle:
Watchdog-B60 60A Battery Saver Discharge Timer by D&R - Fleet Safety
This unit shuts off power x minutes after you turn the vehicle off. You set how long it stays on. It also monitors voltage, and cuts the power if it falls below 11.5v, especially if you have set a long delay time. There are probably other similar units available.
Watchdog-B60 60A Battery Saver Discharge Timer by D&R - Fleet Safety
This unit shuts off power x minutes after you turn the vehicle off. You set how long it stays on. It also monitors voltage, and cuts the power if it falls below 11.5v, especially if you have set a long delay time. There are probably other similar units available.
Flywheel17
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Mean Well SD-50A-12
The best solution that I found after a lot of research and at the suggestion of another member on here (sorry - can't remember who...) is a DC-DC Converter.
It can be found here:
SD-50A-12: Mean Well : DC/DC Power Supply Single Output 12 Volt 4.2A 50.4W 5-Pin : Power Supplies & Wall Adapters
It is very easy to hook up and will keep constant voltage to your scanner when starting or even low voltage. I have mine switched so that I can shut it down completely and hidden behind the dash out of site.
None of the other solutions are as simple or elegant. I looked at the isolated / switched batteries and the other devices used in emergency vehicles for other reasons and nothing was as simple as this.
With this - you can leave your scanner on all the time and not worry about the reboot during starting or even low voltage (to a point). As you can tell - I have been very happy with the performance.
The best solution that I found after a lot of research and at the suggestion of another member on here (sorry - can't remember who...) is a DC-DC Converter.
It can be found here:
SD-50A-12: Mean Well : DC/DC Power Supply Single Output 12 Volt 4.2A 50.4W 5-Pin : Power Supplies & Wall Adapters
It is very easy to hook up and will keep constant voltage to your scanner when starting or even low voltage. I have mine switched so that I can shut it down completely and hidden behind the dash out of site.
None of the other solutions are as simple or elegant. I looked at the isolated / switched batteries and the other devices used in emergency vehicles for other reasons and nothing was as simple as this.
With this - you can leave your scanner on all the time and not worry about the reboot during starting or even low voltage (to a point). As you can tell - I have been very happy with the performance.
That is exactly what I was talking about. And with the amperage it's rated for will also allow you to use a HAM or LMR/DMR radio that's software based and not worry about restarts.
I have a HP1, Kenwood D710, and Yaesu FTM400 and the only thing that doesn't reboot when I start my truck is the HP1.
JamesO
Member
In theory, this should be able to do the job as well? HOWEVER, if the input Voltage drops below 10 Volts, the output may drop to 10 Volts as well? I guess it would be a vehicle specific issue to see how it worked?
https://www.amazon.com/Geeetech-Con...3201756&sr=8-8&keywords=12+DC+to+DC+converter
Any takers?
https://www.amazon.com/Geeetech-Con...3201756&sr=8-8&keywords=12+DC+to+DC+converter
Any takers?
Please re-read posts 7 and 20 from this thread. If your cranking voltage drops below 10v, your 536 will reboot. A blocking diode and small gel cell battery fixed my problem for less than $15. A diode alone or a battery alone will not work; you need both. This solution has been working for a month now.
teknishun
Member
I got around this problem by wiring the scanner power cable directly to the battery terminals,
thus bypassing the rest of the car's electrical system and anything that is controlled by the
ignition key. Both my 2 meter FM and the scanner are direct wired this way and I have no
problems when the vehicle is started. Of course it is always a good idea to turn electronics
off when the engine is cranking. And of course both units have a fuse in the cable very
close to the battery terminal.
JamesO
Member
A lot of newer vehicles have an "unloader" relay that drops power to specific circuits when the engine is cranking to do the following:
1. Have maximum power available for starter when cranking the engine
2. Have maximum power for critical loads when cranking the engine
3. Protect specific circuits and modules from Voltage drops and spikes when cranking the engine.
So connecting directly to the battery may bypass the "unloader" on an accessory circuit and/or reduce the Voltage drop/variations the scanner sees.
Best to have a way to stabilize the power to the scanner, it may work fine for a while, but you may run into problems over time as the scanner sees constant Voltage variations when starting.
1. Have maximum power available for starter when cranking the engine
2. Have maximum power for critical loads when cranking the engine
3. Protect specific circuits and modules from Voltage drops and spikes when cranking the engine.
So connecting directly to the battery may bypass the "unloader" on an accessory circuit and/or reduce the Voltage drop/variations the scanner sees.
Best to have a way to stabilize the power to the scanner, it may work fine for a while, but you may run into problems over time as the scanner sees constant Voltage variations when starting.
HummerMike
Member
I'll throw in my two cents worth. From reading the specs on the late model Uniden scanners, 11 volts is the minimum to operate properly. That's not much of a margin to play with.
(A) A super capacitor with a diode between the capacitor and battery may work. Yes, there would be a .6 volt drop across the diode. I would use a minimum of a 5 amp rated diode. Reason being, the in-rush current to charge the capacitor will wary depending on how low the voltage drops. The diode acts just like a check valve for voltage. It will pass voltage going from the battery to the capacitor / scanner, but block voltage from going back from the capacitor to the battery. I would definitely have a 1 amp fuse between the capacitor to the scanner.
(B) The voltage regulators are a good choice, but have draw backs. Some will work as low as 9 volts which is good. The only draw back, is that you would most likely have to install a switch in front of the regulator to battery. The regulator will draw a minute amount of current just to stay active at 12.5 volts. This might draw a battery down over a day or two.
(C) The best option is the second battery. Can get expensive. If you installed a small 12 volt nicad style battery, one would need to regulate the charge to the smaller battery. The car alternator is looking at the main battery and will charge that battery accordingly. A small battery in line, would not last long without a charge regulator for it.
I run a lot of equipment in my vehicle. I do have a second battery. Both the cranking battery and the second battery are AGM battery's of the same specs. The second battery is disconnected from the main battery while the car is off. After the car is started and the main battery sees 13.8 volts or higher, a voltage sensitive relay pulls in and the second battery is charged. Both batterys charge while the engine is running. When the car is turned off and the voltage drops below 13.8 volts, the relay falls out. This is the best in my opinion. But costs upwards of $200 ~ $250.
(A) A super capacitor with a diode between the capacitor and battery may work. Yes, there would be a .6 volt drop across the diode. I would use a minimum of a 5 amp rated diode. Reason being, the in-rush current to charge the capacitor will wary depending on how low the voltage drops. The diode acts just like a check valve for voltage. It will pass voltage going from the battery to the capacitor / scanner, but block voltage from going back from the capacitor to the battery. I would definitely have a 1 amp fuse between the capacitor to the scanner.
(B) The voltage regulators are a good choice, but have draw backs. Some will work as low as 9 volts which is good. The only draw back, is that you would most likely have to install a switch in front of the regulator to battery. The regulator will draw a minute amount of current just to stay active at 12.5 volts. This might draw a battery down over a day or two.
(C) The best option is the second battery. Can get expensive. If you installed a small 12 volt nicad style battery, one would need to regulate the charge to the smaller battery. The car alternator is looking at the main battery and will charge that battery accordingly. A small battery in line, would not last long without a charge regulator for it.
I run a lot of equipment in my vehicle. I do have a second battery. Both the cranking battery and the second battery are AGM battery's of the same specs. The second battery is disconnected from the main battery while the car is off. After the car is started and the main battery sees 13.8 volts or higher, a voltage sensitive relay pulls in and the second battery is charged. Both batterys charge while the engine is running. When the car is turned off and the voltage drops below 13.8 volts, the relay falls out. This is the best in my opinion. But costs upwards of $200 ~ $250.
marshall58
Member
I use a DROK Waterproof 60W Automatic Step Up/Down Voltage Regulator Stabilizer 10V-36V to 12V 5A High Conversion Efficiency Buck Boost Power Converter and had no reboots on my 536 or issues for less than 30 dollars
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