Free tools › Load-shedding battery calculator
Will your security last through load-shedding?
Size the backup battery behind your cameras, recorder, alarm panel and access control for 2, 2.5 and 4 hour outages — and check it can recharge before the next one. Use the wattages on the datasheets; when you are not sure, the defaults are typical.
A 4 MP bullet is often 5–7 W at night.
Alarm panel, keypads, detectors, access controller, mag locks, router…
Sirens and strobes while sounding. 15 minutes counted.
| Outage | Battery to buy | Used per outage | Recharge |
|---|
Method: amp-hours used = load ÷ voltage × hours (+ alarm time), then divided by the usable depth of discharge (SLA 50%, lithium 80%), a temperature factor and a 20–25% end-of-life margin; lead-acid also loses capacity when emptied quickly. Rounded up to a stock battery size. These are design defaults, not a SANS or EN requirement — an alarm system's own standby rules (EN 50131-6) are a separate check. Escape-route mag locks must release when the power fails.