So I wanted to do something different

[Grainger49]

Ooooooo... I like that!  I kind of pulled a similar trick on my brother when I Armaralled his CD.  I used a fake label, said "Bull Semen" like Sam Tellig did.

[underdawg]

I would question how much load the meters would put on batteries when not in use, can be simply addressed with an on/off switch I would think.

[Paul Birkeland]

It kinda depends on whether they are VU meters, ammeters, or volt meters.

A VU meter or ammeter wouldn't need any switching unless there was backlighting, a voltmeter would be tricky to switch automatically, but it could tie in at the juncture where the 4K resistors go.

[corndog71]

What about using a temporary switch with a voltmeter?

[underdawg]

Sure a temp switch should work, but the key is not to have a load via the merters due to life of battery concern.

[Paul Joppa]

You can use a double-pole, 3-throw non-shorting switch to select which of the three batteries are being tested, or even a 6-throw version to test each of the 9-v separately. Each position can have its own series resistor to adjust the scale appropriately. Any meter movement up to 10mA will do; and you can calculate the resistor from a knowledge of Ohm's Law and the meter resistance. Install a push-button momentary-on switch so the meter is not used unless the button is pushed, and there will be no significant battery drain.

[corndog71]

Actually, I'm more concerned about the life of the D cells.  Of course I could just incorporate a couple of test points on the front of the box and forget the meter.

[Paul Joppa]

Direct from China, $2.99 each for a tester:

http://www.meritline.com/battery-tester-for-aa-aaa-c-d-9-volt-and-rectangular-batteries---p-40966.aspx?source=fghdac&gclid=CMmD-7SZxrUCFQThQgod8RAATg