5 ms·

I've always known it as a battery isolator, and have purchased/installed 3 of them, and that's what I bought them as. https://en.wikipedia.org/wiki/Battery_iso

• luxpir 9y ago
  AKA a variable split relay, VSR. Use one in our campervan, still haven't made the upgrade to solar for longer stays where you don't want the engine on, but it's good to keep the leisure battery topped up.