Adding an elapsed time condition to a calculation

Trying to add an indicator (LED) to a dash for when the hybrid is available on the RF2 BTCC cars. I can get it to work but I need to add a condition that stops the hybrid showing as being available if it has been used for 15+ per lap.

ChatGPT (sorry!) tells me I need to add a custom variable but the code/calc it gives me seems to be load of bobbins. 

Any guidance or help would be appreciated!