Having problems getting a project to work. Here's a brief overview. I'm open to all ideas.

I'm building a wildlife monitoring camera station. It's a remote location and needs to run for 4 days at a time. It is a difficult hike and carrying heavy lead acid batteries back there isn't an option.

I have the camera and DVR hooked up to a digital timer. The timer is set to run the gear for 5 hours a day. The power supply is a couple of Anker Astro 3 (2nd gen) 20000 mAh external batteries. They are lipo and give me the 12v the gear needs.

The problem is that the Anker power supplies go to sleep and don't wake up until they sense a draw - however when the digital timer turns on - it needs to sense power otherwise it won't turn on and the Ankers just don't wake up quick enough to satisfy the timers. Bottom line the timer won't pass power through.

A couple ideas I had:
1. Keep the Ankers on all the time - the minimum current needed is 100 mA to keep it awake. I built a 5 (20 mA) LED diode device I can plug into the USB to keep it awake and that solves the problem, but it's inelegant and wasteful.

2. Maybe I can put a capacitor on the timer so it has enough juice for the initial start-up giving time for the power supplies to wake up?

Thanks for reading. I'm frustrated with all the "smart" gear.

 

This might be worth a try, if the timer can respond to a 8.3V supply.
Operation: When the timer switches on, it sees the PP3 voltage and wakes up the Anker, which then takes over and back-biases D1 so that the PP3 then no longer supplies current.
If a PP3 alone won't cut the mustard you could add an AA cell in series.
D2 may be unnecessary if the Anker doesn't object to having 9V or more on its output pin when asleep.

 

This might be worth a try, if the timer can respond to a 8.3V supply.
Operation: When the timer switches on, the it sees the PP3 voltage and wakes up the Anker, which then takes over and back-biases D1 so that the PP3 then no longer supplies current.
If a PP3 alone won't cut the mustard you could add an AA cell in series.
D2 may be unnecessary if the Anker doesn't object to having 9V or more on its output pin when asleep.
View attachment 77042

Thank you Alec, I really appreciate it. I will give this a shot.

Looks like I'm pulling 200-300 mA total @12v (Camera 50-150 mAh & DVR 150 mAh). Any suggestions for diodes? I'm not exactly sure about how these are rated. Looks like I have couple 1N4001. I also have some 1N4148. I also have a bunch of Zeners.

 

The 1N4001 is rated for 1A, so try that. The 1N4148 rating is only 200mA.