It works basicly by using a 12volt dc battery maintainer that maintains a fully charged AGM maintenance free deep cycle battery. Then it uses an old 12v dc power supply I found laying around the house to hold a normally closed relay open and tranfers power over when power is lost, directly to a dc y cable hooked in to pump and normal power.
How much did the battery run you? I thought about going DIY until I priced a battery.. I ended up buying some ice caps because the batteries I priced were shockingly expensive. I am currently using a battery back up air pump for my quarantine tank and wouldn't mind building something if it's not more than buying pre made.
Hey Leggman, I have been obsessing a bit over this topic lately. Looking for some way to power one power head (AC), my HOB overflow box and return pump from the sump in the event of a power outage, something that will automatically activate for when I am asleep or not at home. Just want emergency stuff taken care of, not necessarily the heater but if that could be included that would be great.
Will your set-up get me headed in the right direction?
Yea it would but your going to need to create an auto ac tranfer switch and have power split from an inverter and regular wall power. Also if you don't have an understanding of things like resistance, amperage, voltage and and good wiring skills I don't recommend doing a project like this as it can be a huge fire hazard and potentially life threatening if you do something wrong. My backround is a proffessional auto mechanic that is going to to school for electrical engineering. And even I made a mistake by adding a dc power supply that was too large for the dc relay and it had to me replaced, do to it heating the relay coil to much. I had to replace it with a dc power supply that was eqivalent to aprox 150mA. As this was more appropriate for an average relay amperage draw.
Now that said, the project is relatively simple electrically and can be quite fun, but does require safe disipline as all electrical projects do. And I encourage my warning not to scare you just to realize what you may be getting into. I just ordered my 300watt inverter for my heater and and internet router. I'll be adding them also. I'll post more photos when I get parts and finish further.
Now that I think about it you may be able to just have the same set up as what I have for the transfer switch but you'll need a cord the has two ac power inputs and one output. Running power parallel from wall outlet and inverter just set the inverter to come on with the normally closed dc relay with power loss. But again I'm not sure how this would effect the inverter. With power sitting at the output side with it off.
If someone knows please chime in.