Measuring Power Input Voltage on the A119 or A119S Camera with GPS

5Cowbells

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Dash Cam
FW A119 V4.01, FW A119S_180919_V4.0
Edited: The A119 and A119S dashcams seem to have an appetite for power more so than most dashcams that have been used up to now. There are power limitations in the typical power supply circuitry consisting of a 12 to 5 volt converter with long 3.5 to 4 meter long USB cables for powering the A119/S dashcams. There doesn't seem to be much difference in power consumption between the A119 and A119S. The power supply circuit converter and USB cables supplied with the cameras are just adequate to supply sufficient power to the A119 to maintain proper operation.

Power cycling is a commonly reported problem with the A119/A119S, seeming more so than other cameras, and is usually symptomatic of marginal or insufficient power available to the camera. I think this is due to the voltage at the camera input being drawn down due to problems in the power supply circuit to the point where the camera thinks power has been removed and shuts down. Then with the load removed, the power supply voltage rises again and the camera senses that power has been restored and turns on again. This may repeat causing the power to cycle on and off.

The current troubleshooting technique is just to recognized the symptoms and by trial and error find the right combination of power supply circuit parts (usually first try the Viofo supplied or recommended converter and cables) to make the camera function properly, and all the while not even being sure that power is the problem. There have been cases reported where the microSD card turned out to be the problem.

I suggest that there is an easy inexpensive way to accurately measure the critical parameter indicative of this problem - voltage at the input of the camera. The problem of measuring voltage at the input is the tiny mini USB connectors used at the power input to the camera. To measure voltage at the input under load (camera powered) in-line requires a custom made in-line USB breakout card (I couldn't find a commercial one), or an in-line USB volt/amp meter, along with appropriate adapters on either or both ends of the device. These devices unless are somewhat cumbersome and unless carefully constructed usually just add resistive losses to the circuit and affect the result. In addition, multiple added connections in the circuit cause intermittent variations in readings if the connections are wiggled, making it more difficult to find a consistent result.

My proposal is to buy an inexpensive and available {edit: ??} mini USB breakout card and connect it to the GPS port and measure voltage there with the circuit under load (camera connected and powered up). You can use a Radio Shack like hobby voltmeter that many folks already have. You could also reverse the connections, inputting power to the GPS connector and measuring voltage at camera side input. The relatively high resistance of the voltmeter is much less likely to affect circuit than an in-line device with adapters. You would then be able to more accurately measure the combined effects of the 12 to 5 volt DC converter, the USB cable, and the GPS mount on the voltage input to the camera under load (while powered). Once a nominal minimum voltage for proper operation is established, this simple measurement could tell you if the power supply circuit components are OK or not.
 
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IIRC this was already done by a member here who did not find an exceptional power draw, yet all the empirical evidence points the other way :rolleyes: I'm not sure why the A119 cams need a strong power source but I am sure that they need it :cool:

Phil
 
give them 5V at a steady 1 amp and there's no problem, the problem is a lot of aftermarket power supplies fall short regardless of what the manufacturers may print on them
 
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I put a USB volt/ammeter on my A119S for one of my commutes, to see what its power consumption was like.

The average consumption was pretty close to 0.5A, however from one moment to the next, consumption jumped all over the place-- lowest that I saw was about 230mA, highest was about 800mA.
 
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I put a USB volt/ammeter on my A119S for one of my commutes, to see what its power consumption was like.

The average consumption was pretty close to 0.5A, however from one moment to the next, consumption jumped all over the place-- lowest that I saw was about 230mA, highest was about 800mA.
I’m a bit older than you folks and I can remember when we had ampere gauges in our cars.
When you revved the engine up the ampere gauge would show charging and when the car was idling the gauge showed discharging.
 
in-line requires a custom made in-line USB breakout card (I couldn't find a commercial one)

This is something I have laying around somewhere. Haven't tested it on any dashcams and haven't touched it in years. I think I had to solder the two ends too. I gotta look for it.

https://www.adafruit.com/product/1549

1549-00.jpg


 
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This video demonstrates the Power Requirements for the A119 A119S Dashcam using an inline USB Tester and Power Bank.
The TackLife MUT01 USB Tester monitors Voltage, load current Amps and battery drain or charge in mAh milliAmp hours.
 
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