losing power when the sun goes down?

[Geob]

I'm using solar to power a remote security camera and wireless tranmitter. Several months passed after the inital setup before we checked for the wireless signal again. At this point we would get signal while the sun was up, but lost signal when the sun went down. Something is wrong with our power setup, but I don't know what. Could it be the 200' of 14-guage outdoor-rated cable that we are running on the ground to our loads? I described the panel location to our solar rep and he said it sounded fine.

Here is the setup:

Solar Setup:
110W, 12V Mitsubishi Module
110aH, 12V AGM Battery
25' #10/2 Cable (Panel to Solar Controller)
10A, 12V Morningstar Controller w/ LVD

Load:
200' #14/2 Cable (Solar Controller to camera and transmitter)
Infrared Security Camera , day (12hrs): 90mA=.09Amps=1.08 Amp Hrs per day
Infrared Security Camera , night (12hrs): 600mA=.6Amps=7.2 Amp Hrs per day
Wireless Video Transmitter (24hrs): 700mA=.7amps=16.8 Amp Hrs per day
Total Max Load: 1.39 Amps = 16.8 watts
Total Amp Hrs per day = 25.08

[Sunking]

Well first a ground has nothing to do with operation. What does matter is you have power from from the positive and negative from the battery termanls.. Since the system works during daylight hours and not after sunset tels me your battery circuit is at fault.

First thing i would do is check the voltage after sunset on the camera across the power input.

[Geob]

Thanks Sunking! With the panel, battery and loads all connecting to the solar controller, is it possible for the power from the panel to bypass the battery so that the camera works during the day? We have had other issues with the controllers, so even if this is not supposed to happen, maybe it is anyways.

Excuse my ingnorance, but does checking voltage "on the camera across the power input" mean checking voltage where the camera connects to the power line coming frorm the solar setup?

[Sunking]

does checking voltage "on the camera across the power input" mean checking voltage where the camera connects to the power line coming frorm the solar setup?

Yes check both the source and load device voltages.

For example at the source (battery the voltage reads 12.6 on the battery terminals, and then you read 9 volts at the camera you got a problem. You only want no more than .25 to .5 volts difference between the two. For low voltage circuit you really want to control the voltage drop to 2 to 4 % at most.

[Geob]

Okay, thanks! Is there any easy way to determine the minimum operation voltage for a device? It's not in any of the spec sheets I have. I was thinking of using a power adapter with adjustable voltage to see at what point the device shuts off. On the other hand, is there significant wear and tear on electronic devices when the voltage goes up and down too much even though it is still operating?

[Sunking]

Okay, thanks! Is there any easy way to determine the minimum operation voltage for a device?

Yes look at the equipment specs.

[Sunking]

On the other hand, is there significant wear and tear on electronic devices when the voltage goes up and down too much even though it is still operating?

No it is designed to work over a fairly broad voltage range, or at least it should. Most devices are power constant, meaning they always draw a given power or a specified voltage range. What most people fail to understand as the battery voltage goes down, the current goes up to maintain constant power input. You have got to know what is the minimum voltage and what power the device requires.

[Geob]

What most people fail to understand as the battery voltage goes down, the current goes up to maintain constant power input.

Ah, so as battery voltage goes down we accelerate to the Low Voltage Disconnect point.

You have got to know what is the minimum voltage and what power the device requires.

I can't find the minimum voltage requirements for the cameras but the transmitters specs say 12volt plus or minus 10%

[Geob]

What most people fail to understand as the battery voltage goes down, the current goes up to maintain constant power input.

Is this where the larger cables help? If you have a 10% drop in voltage at the end of the cable run, more energy is needed from the battery to run the equipment than if the voltage drop is only 2%?