Maintenance
EGM-4 Operator's Manual – Version 4.19
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Slide the new battery into the battery compartment, connect the charger leads correctly (Red
= Positive, Black = Negative) and refit the enclosure.
12V NiMH Battery
Some EGM-4’s are supplied with a 12V NiMH, rechargeable battery and it should last for
several years as long as it is properly maintained. It should be checked periodically to ensure
that it takes up charge. Measuring the voltage across the terminals of the battery after it has
been charged overnight can assess this.
If the battery is not fully charged after 12 hours, first check that the 1A fuse is ok. This fuse
protects the charging circuit and if blown, the internal battery will not take a charge.
Please Note. When storing the instrument for long periods, the internal 12V NiMH battery will
slowly discharge over time regardless of the state of charge. Therefore you must ensure that
you charge the instrument fully prior to next use.
12V NiMH Battery Specification
Nominal Capacity
@ 20 hr.rate (Ah)
13cm L x 8.5cm W x 1.5cm D
Removing The 12V NiMH Battery
When removing the battery, first ensure that the power to the EGM-4 is turned off. With the
enclosure and back panel removed, simply pull out the battery pack as shown below and
locate the three terminal connections. The front panel may need to be removed to slide the
battery out of its compartment if it is stuck.
Next, remove the red, yellow and black terminal connections from the internal leads and
remove the battery pack. To replace, simply slide in the replacement battery pack and
connect up the three leads appropriately.
Terminal
Connections