Hi Alan/George,
Both the 3 secs and 15 secs are battery capacity tests operatong on different power source (dc and ac respectively). If the test proved that it takes longer than the specified time, the battery is expected to be changed. This is stated in the service manual. But since defibrillator is a life saving kit, we normally replaced the battery way ahead every 2 years. We believe prevention is better than cure.
In the older days, battery capacity test was tested quite stringently for its battery condition. Successive charges and discharges at full energy (360 joules) capacity to simulate loading the battery and towards the end of the 10 cycles of charge and discharge, the time taken for the defibrillator to attain full energy on the capacitor was taken. If the time taken exceeds 10 secs, the battery needs replacement. But with today's technology we do not need to perform these successive test again. Hope this is useful.
Regards
