When converting an LED engine that involves a separate driver and LED wired together, the conversion kit interrupts the low voltage line between the driver and the load. The emergency control gear simply allows the dimmable driver to power the load at its chosen level without getting involved.
At the point of an interruption of the mains power, the emergency pack’s relay switches over and allows the battery to power the load at its pre-determined brightness. The level at which it was previously dimmed, does not play any part in this. For example, if you had a 10W LED downlight that was dimmed to 10 percent and the power was cut, the average emergency pack would then increase the light level to around 25 percent.
There are however many chips on board (COB) or mains input downlights where there is no way of accessing the low voltage flow between the driver and the load. This poses more of a challenge.
There are emergency packs that can power these loads, but your emergency lighting control gear manufacturer would need to test the downlight you are looking to operate in an emergency.
In some cases, the emergency control gear will power the primary of the dimmed driver which is set at a reduced output and therefore not meet the light levels to which it was designed or specified. Some emergency packs will allow for this, however my advice is, when using mains voltage, dimmable downlights, ensure that you have your chosen fitting tested first.