I need the explanation on a DMM instruction manual

Question

It's HIOKI DT4211 digital MM
In Electrical Characteristics section it states:

Rated power voltage: 1.5 v DC x2, use LR6 AA Alkaline battery 2x 1.5v

But then...
in Accuracy Table section, it states:

Accuracy warranty period: 1 year

Regulated Power Supply range: 2.4 V +- 0.15 v or more until Bat lights up

What'd 'Regulated power supply range' specification mean?

Does it mean the DMM can also use 2x 1.2 v AA battery supply as long as it doesn't complain warning Bat low ?

And what is 'Accuracy warranty period 1 year' supposed to mean?

Does DMM maker think it'll be likely degraded quickly to lower quality after a year so he may not give a damn anything to be responsible?

Anyone who would sincerely help me, of course I'm so much thankful

Answer 1

I would interpret the Regulated Power Supply specification to mean that the DMM is guaranteed to work with a battery voltage of 2.4 + .15 or 2.55 volts and maybe down to 2.4 - .15 or 2.25 volts. In any case, operation is not guaranteed if the BAT indicator lights up. Thus, to answer your question, it might work with a voltage of 2.4 but it is not guaranteed. The Accuracy warranty period of 1 year simply means that the DMM is guaranteed to meet its accuracy specifications for a period of 1 year (presumably starting from when it was manufactured). AFter that, the manufacturer will not guarantee that the effects of component drifts have not caused the DMM to fail one or more accuracy specifications. It does not mean that something happens after exactly 1 year. This is a perfectly normal specification for most electronic measuring devices. The time period might vary depending on the initial accuracy specifications and the quality of the components.