I have a 3d printer in my car powered by a bluetti eb3a. The bluetti is charged by the 12v outlet in my car while driving. I have a 24v solar panel i want to mount to the roof of the car. My bluetti has only one dc 7909 input. So got a a Y splitter to combine power from the car and panel. But when plug it into the car outlet that turns off when i turn off the car, the solar panel turns on the stereo. Thats not the case with the outlets that are always on. I am worried that i will danage the car electrical system from a 24v solar panel flowing electricity back into the car?
Good thing i asked the experts. Any i deas for a way to switch to solar power when i turn off the car? Like some form of diy relay switch
A relay switch could work. You would put the car 12V and ground across the coil connections, the 12V on the NO connection, the panel on the NC connection, and the power pack on the C connection. Make sure you get a 12VDC relay.
Are you going to have the panel installed permanently on your car?
Definitely don’t connect a 24V source directly to your cars 12V system. There’s a good chance of frying something important. A fuse would not protect from overvoltage so don’t rely on those to protect components.
You can wire the car’s 12V to a relay such that the default state (also called normally closed or NC), and when the 12V is present the relay clicks and switches the input to car power on the normally open terminal, disconnecting the solar. When 12V disappears, relay switches off and disconnects the car and reconnects the solar.
Thanks. Btw i found a DC auto transfer switch on amazon. https://a.co/d/a6pnd9B I assume i wire the car power to the “DC power source” so when it disappears it switches to “battery power” aka solar power. And the load terminal is wired to the DC in port on my bluetti
Bingo
Cool, Thank you.