I have been doing some tests with the new 20 amp/hr lithium batteries.

I discharged the battery until it cut out (9.6 VDC), it took about 18 hours before it shut down. My concern was when I switched the grid power back on. The battery was drawing 2.6 amps DC, I decided to shut down the test because the device (looks like a MOV of sorts) just after the battery plug on the PC board got to 200 degrees C, so I decided to rather shut down the grid power, removed the battery and rather used the Victron charger to recharge the battery. The battery was drawing 10 amps DC from the 10 amp lithium charger.

The lithium battery spec sheet indicates that the charge current should be less than 5 amp.

So much for drop in lithium batteries, I contacted the company who supplies the power supply and was told "DO NOT CONNECT A LITHIUM BATTERY" to their power supply it is not designed for lithium batteries, which could explain the 200 degrees on the electronic components.

Just imagine if I had sold this to a customer without doing the tests first

I would be very cautious of offering lithium batteries as a drop for lead acid on security systems and gates. Not only will you be stuck with a warranty claim from the power supply, but you could burn down someone's houses or building.