This is a really feasible diy project and you can get a ton more battery capacity for less money than buying a package deal from a reef gear company.
I have two DIY backups - a 100ah LiFePO4 battery for a vortech MP40 in my display, and a 100ah battery for a vectra return pump (pictured below). 100ah is probably overkill but will work for days on my setup. You can get a much smaller battery and still exceed the capacity of the branded backups. LiFePO4 also lets you access much more of the battery capacity than a led acid battery and will last a lot longer. A lead acid should probably be replaced every couple years while a LiFePO4 can last a decade.
To do it you’ll need:
1. The battery. It should match the input voltage of the pump you want to run or you can use a stepup transformer. My batteries are 12v. That works directly for the Vortech but I use a 12v-24v step up for the Vectra.
2. A battery maintainer. Norco makes low cost units that’ll do the trick. Just make sure it supports the battery type.
3. Cables. The battery tender will likely have ring terminals. Just connect them to the battery. You’ll need to splice together a wire with ring terminals on one end and the connector for your pump on the other. With ecotech pumps, this is really easy because they have a barrel port for backup battery. I think it’s 2.1mm but that’s going off memory so double check. You need a cable that goes from the ring terminals connected to the battery terminals and runs to the barrel plug into the pump driver.
With that setup you just plug in the battery tender, connect the cable to the pump driver and the native programming takes care of the rest. On the vectra return pump, you need to calibrate the minimum speed. Once you do that, upon a power outage, the pump will detect it’s on battery power and will automatically ramp down to the minimum speed. It keeps water flowing so you get oxygenation and the fish don’t suffocate.
I wouldn’t try to creat backup power for your lights. If the outage is long enough for that to be an issue, you’d need a generator to supply power. Unless you live somewhere extremely cold, I wouldn’t try to power heaters either. They use a ton of wattage and will deplete a battery quickly.
If you decide to try this, I can provide links to all or most of the components. Let me know.
