Turning a 110 Volt AC Back Up Power Supply Into a Solar Charged Power Supply

I had a good friend to send me a commercial emergency back power supply and surge protector with a new 12 volt 9amp battery.
The manual states that it would power a desktop and LCD screen for approximately 1 hour.
It has 4 surge and noise protected outlets that operate continuously and 4 outlets that provide backup power along with surge and noise protection.
It is designed to only charge the battery when plugged in an AC outlet and the power pack turned "on".

So I connected 2 wires to both terminals on the batteries and ran the wires through some vent holes.
Using wire splice connectors, I connected an existing 12 volt cigarette lighter terminal to the wires running from the battery.
I used the wire splice clips to keep the plugs that I had already had wired to the cigarette lighter terminal.

Using a 2 ended 12 volt plug teminal, I have one end plugged into the terminal to the new power pack and the other end plug into my existing 12 power pack that is charged from my 15 watt solar panel.
This method will charge the battery in the new back up power supply continuously without it being pluged into an 110 AC outlet with  the unit being turned "on"
The power pack can be used in any position, as long as there is proper ventilation at the vents.
The read out can even be rotated to any position.