A solar light or other autonomously powered device assembly comprising:
- solar light pole and/or other load bearing device including,
- a rechargeable battery,
- a light and/or load electrically connected to said battery,
- photovoltaic panel for supplying a charging current to said battery, and
- a charge controller operable to sense a level of a depth of discharge (DOD) and/or a state of charge (SOC) of said battery and regulate or control a flow of charging current from the photovoltaic panel to the battery,
- a processing assembly communicating with said charge controller and operable to receive input signals representative of said sensed level of DOD and/or SOC, and to output in response thereto controller control signals for controlling the flow of said charging current, the processing assembly including memory and program instructions, wherein,
- the memory periodically receiving initial input values representative of an estimated initial battery capacity factor FB[T] for said battery, and a preselected battery target voltage VAB[T] at a selected operating temperature (TOP),
- wherein as part of a daily charging and discharge cycle the program instructions being operable whereby,
- during an initial charge period:
- A. receiving into said memory an initial bulk energy charge (AHbulk) representative of cumulative charging current over time required to charge said battery to said preselected battery target voltage (VAB)[T];
- B. calculate a target energy input (AHprojected) selected as a projected required amperage per period of time for said battery to achieve a substantially 100% state of charge, wherein said target energy input (AHprojected) is determined by the formula:
- (AHproject)=(AHbulk)(K×FB[T]×Oc %−1)
- wherein K is a constant selected at between about 1 and 2,
- FB[T] is selected at between 40% to 100%;
- and
- Oc is a maximum overcharge capacity value selected at between 100% and 120%;
- C. following the initial charging period, the processing assembly outputting control signals to said charge controller to effect a second stage charging period and regulate the flow of said charging current into said battery as a first intermittent current flow, the first intermittent current flow characterized by sequential current charging periods selected to substantially maintain said battery at said preselected battery target voltage (VAB)[T] calculating and inputting into said memory an absorption energy charge (AHAb) representative of cumulative charging energy into said battery;
- D. when the cumulative charging energy (AHAb) equals the target energy input (AHprojected), outputting control signals to said charge controller to regulate the flow of charging current to said battery as a second intermittent current flow, the second intermittent current characterized by sequential current charging periods selected to maintain said charge to said battery at a target voltage (Vfloat) selected to substantially maintain the battery at a substantially 100% state of charge.