You can get batteries designed for that type of use, guaranteed to last 12 years. They are used in backup power supplied (emergency lighting, for instance)

What's that model? Emergency lights that use lead acid sold in consumer market typically fail by itself within 2 years plugged in 24/7..


Btw I got my test capacitor, where I should put the capacitor?

 

Ye

240kuF

Sure, 0.7V drop * ~0.5A = 350mW, but that's only during the relay delay <1second.
Diodes are the most typical way of making load sharing systems, however they are power consuming but in this case it has no meaning since the relay is the primary switch carrying most of the energy.

Okay! Thank you so much. Will try it some. I just bought test capacitor. Where I should put my capacitor in my circuit?

I tried to put capacitor on output, didn't work. It seems like the capacitor is trying to get its charge back to 12V source...
My powerbank blinking (that's not normal) and the led remains off :/

I tried to put my adaptor 12v to battery input port, the adapter light lights up itself.

 

Pardon my bad editing, I put the capacitor between relay and router. Positive to com, negative is on GND cable (drawn as black line).

Is this correct?

 

What's that model?

http://www.hazebattery.com/date/HZB 6 12V.pdf
But it's only going to manage 12 years if you stick to the charging voltage spec: 2.27 to 2.30 Volts per cell minus 3mV/°C

 

View attachment 247101Pardon my bad editing, I put the capacitor between relay and router. Positive to com, negative is on GND cable (drawn as black line).

Is this correct?

Sure, that's the way with cap.

 

Sure, that's the way with cap.

Looks like I have to redesign a bit, because capacitor placed in that place, it somehow also powers my relay (my relay is paralel with power source line). So it delays the switching even further more...