Geonics Limited EM38-MK2, Operating Manual

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The fully charged battery will read above 13 V. Recharge the battery if its voltage is below 10.5 V. 
 
The battery can be charged by attaching the battery charger to the connector on the battery pack. 
Remember to connect the charger to the battery before applying power to the charger.  
Completely charging a full discharged battery takes about 8 hours. To prevent the defective 
charger from damaging the instrument power supply PCB, do not change the battery, when the 
connected to the EM38-MK2 console. 
 
Figure 9 shows the components of the external battery pack. 
 
10.1.2  

External Battery Care

 
The external battery pack contains Pb/gel type of batteries. Pb/gel batteries work on the same 
principle a Pb/acid batteries. Gel is used in the place of acid, and the batteries are sealed. A a 
result they can be shipped by parcel post as well as by passenger and cargo aircraft (cf. IATA 
Restricted Cargo Regulations, Article 1924). 
 
The Pb/gel batteries can be fully recharged from total discharge several hundred times. If you 
typically use only a fractions of the battery capacity before recharging, the number of possible 
recharges increases. 
 
The batteries maintain full capacity regardless of the pattern of use. But their capacity will 
eventually decrease with age. 
 
From full charge, the batteries will lose 2 to 3% of their charge per month when stored at 20˚C. 
 

Deep Discharge Protection 

 
The Dryfit battery, unlike conventional lead storage batteries, is protected against excessive 
discharge. In the event that a battery remains connected to a load for an excessive period of time, 
deep discharge protection ensures that the battery can be recharged without permanent damage. 
After 30 days of deep discharge, batteries should be recharged for a period of 48 hours. A 
completely discharged battery should not be left for longer than 30 days without recharging. 
 
After re charge, it can be expected that the batteries will exhibit a loss in charge capacity, 
batteries should be run through a serial of (at least three) cycles of discharge and recharge. 
 

 
Storage Conditions 

 
It is important that the battery is stored fully charged. After use, set the battery on charge and 
keep it on till next use. If it is not possible to keep the battery continuously on charge, it should 
be stored fully charged at a mean ambient temperature of +20˚C and recharged after a maximum 
of 6 months. At higher temperatures, the period will be shorter, and at lower temperatures, will 
be extended. Since the specific gravity of the electrolyte will fall as a state of charge is reduced, 
causing the freezing point to rise, only full charged batteries should be stored at extremely low 
temperatures. Given that storage in the fully charged state discharge should not be allowed to fall 
below 50% of the charged state.