I have been looking for the optimal replacement 3V battery for benchtop multimeters for a while, and believe I have identified it.
The 3V batteries used in the HP/Agilent/Keysight typically have a shelf life of around 10 years, but as the batteries are soldered onto the PCB, it means that battery replacement is a non-trivial task – especially if you want to retain the calibration data which is kept alive by the battery on the 3478A.
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You either have to replace the battery while the DMM is powered (using a non-grounded soldering iron), or you have to connect a temporary power source (battery) while unsoldering the old battery, and soldering in the new.
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I recently discovered some attractive properties of the
Energizer Ultimate Lithium AA battery:
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Two of those batteries, placed in an AA battery holder with leads are easily fitted inside the enclosure with a couple of cable-ties.
The leads can be soldered to the existing 3V lithium battery PCB pads, after which the legs of the old battery can be cut.
Easy and low-risk replacement, and peace of mind for the next 25 years.
The most important part is to secure the battery pack