Battery immediately drops from 100 to 90% when discharging

[Anonymous user]

Hi,

I've bought a brand new Back-UPS BX950UI and I'm experiencing this issue: the UPS has battery level at 100% but, when the power goes off, it immediately (in a matter of 5-6 seconds, as reported by Powerchute) drops to 90%. After this sudden drop, it start discharging with a normal rate.

I'd like to ask: is this a sign of a defective battery?

Thanks,

Alessandro

[MarkC_apc · Accepted solution]

My experience has been that the "Smart UPS" lines of SU/SUA/SUM (no LCD) will drop the first LED very quickly.  When monitering with a NMC, the % drop initially is usually quite large also.  The SMX line with the LCD seems to be more accurate (?) in that similar loads seem to drop the battery % much more linear.  The ultimate test of your battery array is to compare to the load curves of your unit (run times before battery depletion vrs load).