It's a Renogy DC-DC charger. The doco says it won't turn on until is gets a signal on its' sense wire, they just skimped on the circuitry other brands use I guess.

I've been over the schematics and have found that I can get the signal from the wiper fuse as they have power when the ign key is in the 'On' spot. It's a hassle having to do this, but I guess that's why the charger was cheaper than alot of others.