CHAPTER 8 COMPONENTS OF THE MINI-PAM
Lamp 2050-HB in combination with the Leaf-Clip Holder 2030-B is
recommended.
8.1.4 Rechargeable battery
A relatively large rechargeable lead acid battery (12 V/2 Ah) is
mounted in the bottom of the MINI-PAM housing. For recharging,
the Battery Charger MINI-PAM/L is provided which is connected to
the CHARGE-socket at the rear side of the MINI-PAM. The charger,
which operates at input voltages between 100 and 240 V AC,
features an overload protection. Full charging of an empty battery
takes approx. 5 hours. Battery voltage is displayed under menu point
34. The warning 'BAT' is given in the upper left corner of the display
when voltage drops below 11.2 V in the resting state. If in this
situation the AUTO-OFF function (menu point 10) is disabled, it will
be automatically enabled again. In addition, there is the warning Err.
3: 'LOW BATTERY' which, however, is coupled to measurements
involving START. After this error message approximately 20 further
measurements can be made and the battery should be soon recharged.
In brackets also the voltage is given which was measured during the
last saturation pulse. It is normal that voltage drops by 0.5 V during a
saturation pulse. However, if it drops below 8 V, YIELD-
measurements may become erronous, as Fm' is likely to be
underestimated. In this case, there is the warning Err. 6: 'CHECK
BATTERY'.
With a fully charged battery the displayed voltage is 12.5 - 12.9
V. In first approximation, battery voltage can be taken as a measure
of remaining battery power. The functional relationship between
capacity (Ah) and voltage of a new battery is depicted in Fig. 3. It is
apparent that battery voltage first drops steeply to about 12.3 V and
then slowly decreases to about 11.8 V, from whereon there is a steep
further drop to values below 11 V.
34
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