Wall Light Solar power adapter

I bought the Wall Light Solar & find that it just CAN'T keep its batteries charged even though it is in VERY DIRECT Sunlight most of the day. I took it down & FULLY charged the 18650 batteries using an Ultrafire 18650 charger. But, I noticed that it has a barrel plug adapter socket on the back & clear routing for the cord to be used. So... I found THIS " Indoor/Outdoor Power Adapter Barrel Plug for Ring Stick Up Cam Plug-In - White" on Amazon which appears to be just what I need to hardwire it. Anyone tried this or can answer if this adapter works for the "Wall Light Solar"?? (Especially since the "solar" part is pretty much a lost cause. I can't take the light down every day for an 8 hour charge OR keep a pair of batteries around to swap out as I'd still be taking the unit down every couple of days or so. I DO NOT keep the light on all the time & I disable motion detection from Dawn to Dusk.