Dc Auto Transfer Switch,Power Supply Controller, DC Power/Battery Switch DC 12V 24V 36V 48V 10A Power Supply Battery Controller Emergency Automatic Switch Module

Nice little relay. I needed to be able connect to three different power sources. The onboard battery, external 12v, and 120v to 12v power supply. Used two relays chained together. My wire configuration automatically starts with battery. Jumps to 12v external power, then to the 120v power supply no need for switches. Looks well made and small in size.

works great!

Worked perfect for my boats refridgerator. The built in board in my refidgerator which does exactly what this unit does stopped working with 110 power but works on 12 volt. I added a 110 to 12 volt server supply for the main source and hooked the battery to the backup side and works flawlessly. The original board for the fridge is no longer available and would cost over a hundred dollars. This board was cheap and effective. The power supply was pulled from a server which was cheap also around $20.00 from eBay.

It performs power switching without problems and its voltage range allows different types of power supply, either through batteries, solar panels, regulators or PC voltage sources. I have tested with the above mentioned and it works very well, except when you use circuits that require a constant voltage, otherwise it can reset the data. I tried a wireless sensor network that sends only data but stores the data remotely and did not reset the microcontrollers by placing a 2200uf capacitor in parallel.

Fundamentally this is just a simple relay with a cheap power monitoring circuit. Power goes in on one set of terminals. If it stops, the other set is used. Pretty simple. However, it takes bizarrely long to detect and cut over -- like an order of magnitude longer than even a mediocre implementation of something like this.That said, if you were ordering the parts to build your own one-off, it'd cost more than this, so if that behavior is what you need, its a real good deal. If your power usage is low enough and your consumer of it has enough capacitance it may keep enough power to stay running.

This is a nice compact package that is of general use in the lab - anything you need to keep powered up could benefit from one of these devices. You just need to understand what you're getting.Because you're relying on a relay to sense the loss of main voltage and then switch to alternate power, like a battery, you're going to have significant lag compared to transistorized functions. We're talking many thousands of instructions in processor time, or enough time that poor designs will see their supply voltage dip. This circuit can respond in about 70 milliseconds. So it's necessary to install plenty of capacitance on your power supply input to supply power until the supply controller can respond to the loss of main power. If your application does not involve memory or processors, and is, instead for fans or lights or something less critical, you can decide to tolerate a blink from the device as it responds.Simple design, useful in dozens of applications, cheaper than you can build it - 5 stars.

Works as described