[sdiy] Typical load for 9V alkaline batteries?

[Grant Richter]

Just because the subject has come up...

I had problems making a precision voltage source (less than 1 mv. shift)
with a 9V alkaline, because of the battery internal impedance.

Switching a 10ma load produces voltage shifts, the 9V behaves like it has a
4 ohm resistor in series (for a SPICE model with perfect voltage sources,
use a 9.26 volt source in series with 4 ohms).

> They key battery parameter is capacity.  Looking at the datasheet for the
> Energizer 9V, the capacity is 625 mA-hours at 25 mA continuous drain.  Lacking
> any specific drain or duty information, that translates to 25 hours of
> continuous use at 25 mA.  As you know, YMMV due to the various conditions you
> listed.