Opportunity Charging - EnerSys Nexsys 12NXS26 Technical Manual

NexSys Technical Manual
Note: NexSys® blocs are designed to be charged with charging rates in range
0.32C5/C6 to 0.7C5/C6. Charging at rates outside this range can affect the
performance and life expectancy of the bloc. 0.2C5/C6 charging current can be used
but only in conjunction with a specific algorithm which is available in a matched
NexSys or NexSys+ charger. Contact EnerSys® before using rates outside this range.
As another example, consider a 100Ah bloc discharged by 80Ah (to 80% Depth of
Discharge), then recharged with a 0.5C5/C6 inrush current, 100% of the discharged Ah
(80Ah) will be returned after approximately 2.5h recharge. Increasing inrush current to
0.7C5/C6 reduces this to 1.8 hours recharge. The recharge process is not 100% efficient
and the bloc will achieve approximately 97% state of charge following the above recharge
procedure. A short absorption phase after recharging the 100% discharged Ah's is required
to ensure full bloc recovery. NexSys chargers are programmed to achieve such recovery
and deliver the recharge capabilities shown in Figures 2 and 3.

OPPORTUNITY CHARGING

NexSys blocs are suitable for partial state of charge operation, however the depth of
discharge must not exceed 80% of the rated C5/C6 capacity and opportunity charging must
be applied whenever the blocs are not being discharged i.e. break / lunch times, shift
handover etc.
Equipment may continue to draw low power loads when not in service, which will reduce
available bloc capacity. To counter this, EnerSys recommend that the bloc/charger remain
connected to the main power supply between equipment usage periods. EnerSys approved
chargers are designed to counter low power draw and preserve bloc state of charge.
The electrochemistry of the NexSys series allows the bloc to be recharged in a relatively
short period of time with high inrush currents with no detrimental effect. This is possible as a
result of its low internal impedance and exceptional charge acceptance.
The SOC of the NexSys bloc can be maintained at almost 100% throughout the working
day, making the equipment always available for use 24/7.
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