The lithium battery is able to charge at much higher rates than the lead acid battery but most of the applications using these 12v 7Ah batteries, like gate motors or alarm systems do not have strong chargers built in. They typically have 0.4 to 1A chargers. Thus, depending on the charger output it can take between 15 hours to 6 hours to fully charge the battery if completely depleted (depends on the current output of charger).

You can check the manual for your specific model to see what the maximum current of the charger is. Charge time guidelines for a fully depleted 12.8v 75Wh lithium battery : 0.5A = 12 hours, 1A = 6 hours, 2A = 3 hours, 3A = 2hours

Normally the charger output and typical usage of a device makes sense to keep a battery charged for occasional outages. But you could find that with very frequent loadshedding, that the battery drains more than it is able to recover in the periods there is electricity. This is not a restriction of the battery (our lithium batteries can handle charging currents of 6A to 100A), but a restriction of the charger. This should only be a problem if a gate or garage door is used a lot, and load shedding takes place a few times in a day. In this case an extra or stronger charging circuitry might be required so the battery can be recharged in a short period of time. Alarm companies supply extra battery backup power supply that can charge at 3.2 Amp for example. Speak to you device supplier if this is identified as a problem in your case.