Campbell CH201, Product Manual

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small relative to the current capability of the charge source, or if the battery is near full charge at
the beginning of a charge cycle.
Normally, cycle charging terminates and float charging begins when Qloss has been reduced to
zero. An exception occurs if, during cycle charging the battery, charge current is reduced to
below C/100, where C is the user-entered battery capacity. This condition indicates the charger is
trying to aggressively cycle charge a fully charged battery, perhaps because a new fully charged
battery was swapped in to replace an old battery that suffered from a significant Qloss. During
cycle charging, if the battery charge current falls below C/100, cycle charging is terminated and
Qloss is zeroed.
FIGURE 7-1. Two-step constant voltage battery charging
7.2 Maximum power point tracking
FIGURE 7-2 (p. 21) shows the current and power versus voltage for a 70 W solar panel. The graph
shows the maximum power point of operation for the solar panel. Adjusting the load on the solar
panel so it operates at this maximum power point is referred to as maximum power point
tracking (MPPT). MPPT is beneficial when insufficient power is available from the charge source,
which is the case during current limited charging. The noisy charging current and voltage
observed in
FIGURE 7-1 (p. 20) during the initial current limited charging stage is due to the
MPPT algorithm of the CH201 searching for the maximum power point of the associated solar
panel.
CH201 12V Charging Regulator 20