Alpha Technologies FXM2000 Specifications download pdf (Page 50)

017-230-B0 Rev 0810

Figure 24 — UPS Maintenance: Inverter screen

An accurate battery runtime estimation requires the following parameter to be adjusted:

• Peukert Number: Refer to the appendix for information about how to calculate the Peukert number to be

entered here.

• Battery Capacity: This is the rated capacity (Ah) of the battery shown on the battery data sheet. Do not con-

fuse 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 series, this num-

ber must be multiplied by four.

The "Battery Runtime Remaining" algorithm attempts to calculate the health of the battery to get a more accurate

prediction of the remaining battery runtime. An accurate estimate of the battery health requires that at least one

battery discharge 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 connected to the unit. Each dis-

charge 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 battery. 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 runtime.

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.

Inverter

Is used to turn the inverter on or off to start or stop backup battery power to the load.

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Alpha Technologies FXM2000 Specifications Page 50