Tear-Down: Let's Take a Trip Inside A UPS

[Daniel Sauvageau]

That is the idea - no matter the battery is (different discharging characteristic) it has to keep the declared parameters (power capacity in this case) - it can behave differently but the total power should be the same

You are fundamentally wrong about that: look at the batteries' discharge characteristic tables or curves and you will see that the batteries' effective storage capacity changes depending on load due to internal losses, electrolyte composition, plate thickness and other design parameters. This is true even for the CSB model.

While the CSB's nominal 20-hours discharge capacity at 420mA is 7.2AH (looks like CSB is under-reporting their batteries' capacity since this should technically make it a 8.4AH one), the battery's effective rating when you increase discharge current to 14A drops to 3.5AH, which means 51% of the battery's capacity is lost internally. In the PowerSonic's case, effective capacity drops from 7AH at 350mA to 1.3AH at 14A or 81% of capacity loss. You cannot calibrate your way out of the batteries' internal losses and the PowerSonic's losses are much higher than the CSB's: after losses: the CSB has 2.5X as much usable capacity at 14A as the PowerSonic.

Unless you are telling me manufacturers are lying in their spec sheets, the usable capacity difference on a 14A discharge is very much real and cannot simply be "calibrated out."

To make things worse, UPS have to be able to provide constant POWER and as noted in the battery page, this would make things much worse for the PowerSonic batteries since the current draw on them would get progressively worse much faster than the other two batteries, further reducing their effective capacity.