EXFO FTB-2 - Manual (Page 270)

Maintenance
260 FTB-2 and FTB-2 Pro
Replacing Batteries
Replacing Batteries
Your unit can be powered either by batteries or from an appropriate power
outlet when used with the provided AC adapter/charger.
For more information on the available power sources for your unit, as well
as their characteristics, see Technical Specifications on page 315.
Before you go out in the field, make sure you install batteries in the unit
unless you have an adequate and reliable power source.
W
ARNING
Do not throw batteries into fire or water and do not short-circuit
the battery electrical contacts. Do not disassemble.
C
AUTION
Your unit uses smart lithium-ion (Li-Ion) batteries with built-in
protection that have been especially designed for EXFO. For this
reason, you can only replace them with batteries of the same type
and model.
The use of other batteries may damage your unit and compromise
your safety.