Casella CEL CEL-278 - Manual (Page 17)

3.6 Batteries & Auxiliary Power Supplies
The CEL-278/2 is designed to operate with the set of four manganese
alkaline batteries (IEC Type LR6 (AA)) supplied with the instrument.
Depending on duty cycle, these can give up to 12 hours of operation.
Warning
Do not attempt to connect any type of charger to the Input or output
sockets of the instrument.
If rechargeable nickel cadmium cells are used, remove them from the
Instrument for recharging.
Do not use any battery with damaged insulation or sleeking.
Do not mix batteries of different types, or charge condition.
Rechargeable nickel cadmium cells may be employed, but have a shorter
operating period. Zinc carbon batteries are NOT suitable.
The end of useful battery life occurs when the output falls to approximately
3.2V, at which the' LOW BAT" message is shown on the display. If the
batteries are not replaced, approximately 30 minutes later an automatic
facility switches them OFF. This prevents them being discharged to a point
where they would cause damage if inadvertently the instrument was still left
ON.
Once the automatic switch off sequence has occurred, the instrument can be
restarted only by replacing the batteries and operating the RANGE/Off-Lo-Hi
switch. Always replace all four batteries at the same time with four of the
same type i.e. all alkaline or all NiCad cells.
As a leakage of battery fluid can cause considerable damage, remove any
leaking or unserviceable batteries as soon as they are discovered. The
batteries should also be removed when the instrument is to be stored for a
prolonged period, or is to be powered from an external source.
CEL Instruments Ltd. CEL-278/2 Handbook Page 17