Question:
- I put fresh batteries in my Fluke 1587FC and I get a "low battery" indication when I switch to the Insulation function. Why?
Answer:
This and similar questions has prompted us to test this. Three sets of new Duracell batteries were tested, in several Fluke-1587 FC's and Fluke-1587's, with the same result. Other brand of batteries may cause the same result as well. When switching directly from OFF to INSULATION function, the low batt indicator will come on.
There is a resolution for this phenomena:
By performing a high current battery test (press and keep pressed the hold button while turning the meter from OFF to the INSULATION mode) the symptom can be made to disappear. In other words, the meter will no longer display the low battery warning, when switched from OFF to INSULATION mode, subsequent to having performed the battery load test.
The above has been attributed to internal battery impedance that is added not only to the Duracell batteries but rather all "high power alkaline batteries", by design during their manufacturing process.
The added impedance is to protect the battery from leakage during storage. The added internal impedance is supposed to reduce when a load is applied to the battery. Since the 1587 does not create a high load, this higher battery impedance remains. Performing the high current battery test described above will load the battery enough to remove this added impedance.