I’m a great fan of the Bob Parker ESR Meter (Altronics K2574).  I do however have trouble rounding up 6 AA batteries when they need changing.  In this project I added a small Pololu 2116 (OJ7032) step-up voltage regulator so I can run the unit off 2 AA batteries.

I have found the battery life to still be very good. (I haven’t needed to change them in the 18 months since making this mod).

The partial circuit above shows the step-up regulator is installed between Q1 and the battery alarm voltage divider. This is simpler on the schematic than it is on the PCB.   The mod requires one cut two tracks, install a bridge wire and then wire the three terminal step-up regulator.  Zoom into this photo to see the detail:

Finally, I wrapped the regulator in insulation tape and tucked it in between the PCB and the from panel.