Alpha Technologies FXM350_Micro350 UPS - Manual (Page 58)

017-241-B0 Rev B 56
An accurate battery runtime estimation requires adjustment of the following parameter:
• Peukert Number: Refer to Appendix A for calculation of the Peukert number to enter here.
• Battery Capacity: This is the rated capacity (Ah) of the battery shown on the battery data sheet. Do not
confuse the battery capacity with the Peukert capacity.
• Battery Open Circuit Voltage: This number is obtained from the battery data sheet. The battery data
sheet shows the value for a single battery, so for a 48 V system where 4 batteries are connected in se-
ries, this number must be multiplied by four.
The Battery Runtime Remaining algorithm attempts to calculate the health of the battery to get a more ac-
curate prediction of the remaining battery runtime. An accurate estimate of the battery health requires that at
least one battery discharge cycle greater than 20% depth of discharge has taken place since the unit was
switched on. When the unit is powered up from an off state, the algorithm assumes that a new battery is con-
nected to the unit. Each discharge of greater than 20% will result in a new calculation for the relative battery
health. This value is then used in the Battery Runtime Prediction algorithm to compensate for an aging bat-
tery. We recommend that the user set up a periodic (every 6 months) battery test with a depth of discharge of
at least 20%.
The Battery Runtime Remaining algorithm relies heavily on the battery voltage to predict the remaining run-
time. This results in a less accurate predicted runtime during periods when the battery voltage is changing
rapidly. The battery voltage typically changes rapidly during the first few minutes of discharge when the unit
switches from charging to discharging while the unit is in the Inverter mode. The battery voltage may also
change rapidly during the last 20% of the discharge time when the battery is almost drained.
7.3.4.4 UPS Maintenance > Battery: Allows adjustments of battery string voltage, charging
parameters, low battery warning setting, periodic self test time, and starts the self test.
Figure 38 — UPS Maintenance: Battery screen
CAUTION!
The battery runtime is only an estimation and must not be relied on for critical applica-
tions. The battery runtime remaining is applicable only in inverter/backup mode.