Initial And/Or Freshening Charge - EnerSys PowerSafe mP Series Battery Safety, Installation, Storage, Operating And Maintenance Manual

16.0 INITIAL and/or FRESHENING CHARGE

Batteries lose some initial charge during shipment and storage. Depending on storage time,
a battery may require a freshening charge. See Section 4.0 for battery storage times.
Constant voltage is the ONLY charging method allowed. Confirm that your charger bus is a
constant voltage type. (Most modern chargers are the constant voltage type.)
If all cells OCV's are above 2.11 vpc, no initial or freshening charge is required. However, an
initial or freshening charge will reduce the time required for the battery strings' individual cell
voltages to balance with each other.
1. Determine the maximum voltage that may be applied to the system equipment (or
maximum charger voltage if load is not yet connected). Refer to the recommendations of
the manufacturer/supplier of system equipment connected to DC bus.
2. Divide the maximum total system voltage by the number of cells (not units) connected in
series. This is the maximum volts per cell that may be used for the initial charge.
Do NOT exceed 2.35 volts per cell.
Table 16.1 lists recommended initial charge voltages per cell and charge time for the initial
charge. Select the HIGHEST voltage the system allows for the initial charge without exceeding
2.35 volts per cell.
CELL VOLTS
Initial Charge
2.27
2.30
2.32
2.35
3. Connect battery positive (+) terminal to charger bus positive (+) terminal.
4. Connect battery negative (-) terminal to charger bus negative (-) terminal.
5. Raise the voltage to the maximum value permitted by the equipment as shown in
Table 16.1. Do NOT exceed 2.35 volts under any conditions.
6. When charging current has decreased and stabilized (i.e., no further reduction for three hours),
charge for the hours shown in Table 16.1, or until the lowest cell voltage ceases to rise.
Monitor the battery temperature during the charge. If the cell/battery temperature
exceeds 105˚F (40˚C) stop the charge immediately and allow the temperature to
decrease below 90˚F (32˚C). Failure to follow this warning may result in severe
CAUTION overcharge and damage to the cell/battery.
Publication No. US-MP-OM-001
March 2017
TABLE 16.1
TIME (Hours)
Temp. 60˚-90˚F
(16˚-32˚C)
60
48
24
12
www.enersys.com
TIME (Hours)
TIME (Hours)
Temp. 40˚-59˚F
Temp. < 39˚F
(5˚-15˚C)
120
96
48
24
(<4˚C)
240
192
96
48
29