BNC 970 Portable Multi-Channel Analyzer (MCA) - Manual (Page 6)

Model 970 Instruction Manual 3
1.2.3 Battery Compartment
1. Battery Type Selection Switch.
Recharge position : Allows NiMH batteries to be charged.
Standard position : The battery charging circuitry is disabled so that non-rechargeable
alkaline batteries can be kept in the Model 970 while it is connected to external power
1.3 Powering the Model 970
1.3.1 AC Power Supply
A 110VAC or 220VAC to 12VDC power supply is provided with the Model 970. If you need to
replace this for some reason, make sure the output is regulated 12VDC, capable of delivering at
least 1.25A continuous current. The center pin is positive. Under no circumstances allow greater
than 15VDC (or any AC voltage) into this connector, or damage to the Model 970 will likely result.
1.3.2 Charging the Internal NiMH Batteries
The 970 uses six “AA” 1800 mAh nickel metal hydride (NiMH) batteries. These are charged at
either a slow or fast rate, determined by the position of the Charge Mode Switch. Generally
speaking, it is preferable to charge these at the slow rate whenever possible. When charging for
the first time, use the Slow Charge method. This will help extend the lifetime of the NiMH
batteries. In the slow charge mode, completely drained batteries will be fully charged overnight, or
in approximately 14 hours. In Fast Charge mode, completely drained batteries will be fully
charged in three to four hours.
In order to fast charge the batteries, the Charge Mode Switch must be in the Fast position. If the
position of this switch is changed to Fast while the Model 970 is connected to external power, the
970 must be switched from the Off to the On position, or the External Power connector must be
unplugged from the 970, and plugged back in again in order to initiate the fast charging
sequence. When fast charging, the Fast Charge Indicator LED will glow green and will turn off
when the Model 970 senses that the batteries are fully charged. At the end of the fast charge
sequence, the Model 970 reverts to slow charging to maintain the charge in the batteries. Make
sure to change the Charge Mode Switch to the Slow position to prevent initiating a new fast
charge sequence on batteries that are already fully charged.
A fast charge should never be initiated when the batteries are cold. Allow them to warm up to
near-room temperature before initiating a fast charge sequence to prevent damaging the
batteries.
The NiMH batteries should power the 970 for about four hours. Note however that this figure can
change dramatically based on the current draw of the detector, High Voltage, other Hardware
Settings, ambient temperature, and age and condition of the batteries.
The expected useful lifetime of NiMH batteries under the best of circumstances is about one year.
Do not attempt to charge NiCad batteries in the Model 970. Doing so will damage the
instrument.
There is no problem with using the 970 while charging the batteries.