UPS backup time calculator
Will your UPS last through load-shedding?
Know what stays on. Know for how long. LoadReserve shows your real backup: not what the box says, but what is left once your battery has gone through a few days of cuts and short recharges.
See my backupYour real daily backup
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Load-shedding UPS cut-off
What stays on
What fixes it
Common questions
How long will a 200 Ah battery last on a 1 kVA UPS?
From full, about 5.1 h at 300 W. During daily load-shedding it often starts each cut far from full: with cuts of 6 h a day, 1 h every 4 h, a typical home gets about 47 min per cut. See the backup time chart for other battery sizes and loads.
Why does my UPS backup get shorter after a few days of load-shedding?
The grid is not on long enough between cuts for the UPS charger to refill the battery, so each cut starts a little emptier until it settles low. Read why your UPS backup keeps getting shorter.
Will a bigger battery give more backup?
From full, yes. With frequent cuts, often not: in the example above a bigger battery still gives 47 min per cut, because it refills no faster. Adding 1 kW of solar panels gives 3.1 h per cut, and a lithium battery 3.8 h.
How much can a 1 kVA UPS run?
About 800 W at once: a UPS supplies roughly 0.8 W for each VA. How long it lasts depends on the battery; see how long will my UPS last?
Is it free, and does it work offline?
Yes to both. After one visit the planner works without a connection, and your plan stays on your phone.