Agilent Technologies e4418b, e4419b manual A8 Rechargeable Battery Assembly

Theory of Operation

A8 Rechargeable Battery Assembly

A8 Rechargeable Battery Assembly

The A8 Rechargeable Battery Assembly allows the EPM power meter with option 001 fitted to operate when no AC power input is available. The battery pack contains a health monitoring circuit which the A2 processor assembly can interrogate. The A8 battery assembly connects to the A2 processor assembly and the PSU/battery charger circuit via the A5 Daughter Assembly.

There are three connections from the rechargeable battery assembly to the A1 psu/charger assembly, +12V, 0V, and Signal 1. The Signal 1 line is an indicator line which signals when the battery is below a threshold limit. When this line goes low, indicating there is insufficient charge left in the Battery Assembly to continue operating the power meter, it will cause the A1 psu/charger assembly to shut down.

There is one connection, the communications line, from the A8 Battery Module to the A2 processor assembly. This line provides serial communications with the processor assembly on battery pack status information, such as amount of charge remaining. When there is less than 10 minutes run time charge remaining in the battery an error message "Battery Power Low’" is displayed on the power meter front panel display.

The battery assembly can only be recharged when fitted to a power meter with the battery option fitted. The charge current from the charging circuit is controlled by a module contained within the Battery assembly. When the ac power is connected the battery assembly regulates the charging current based on the discharge state of the battery.

The battery should fully charge from empty within 2 hours. At 25 degrees C this will give the meter 2 hours operational time. The A8 Battery module has a lifetime of approximately 450 charge/discharge cycles after which the battery can still be used, but will only have approximately 70% of its original capacity. The battery capacity may be reduced whilst charging at temperatures above 35 degrees C.

Note:- partially discharging and recharging the battery module will reduce its lifetime. It is advised that periodically the battery assembly should have its charge fully cycled i.e. fully discharged and then fully recharged.

4-12 Agilent E4418B/E4419B Service Guide