ChrisRR: OK, that screwgun 12v battery test with the board worked out pretty well, actually.
Shot a couple of quick videos below showing the test results.

Turns out the one Ryobi battery can manage all 4 phones for bells, buzzers, intercom, the works, with no wall AC needed. The little PowerDsine ring gen rang all 4 phone's bells pretty well, even though I think it's a 3 REN device (?).

Video #1: 4 x 1a2 phones + KSU powered by a Ryobi screwgun's 12V batt battery.

Video #2: Volt meter showing the battery's output voltage running 4 x 1a2 phones

Some extra details:

  • The battery's output voltage did sag a few 10ths of a volt at the end of each bells/buzz/intercom test, so I'm not sure how long one can sustain this type of use on a single battery charge before the lamps get dim and the DTMF dialing and CPU power stops working. For instance, in the 2nd video, the meter starts out showing 11.76v when the KSU is idle, and after a run of tests and return to idle, the batt is down to 11.72v.
  • The single batt used in this video had already run several tests before I made the video, and it started with a full charge showing about 11.82 or so.
  • The two batts for my Ryobi are about 3 years old, and gets a lot of use, so they're by no means new batts. But I do always keep the spare on the charger.



Last edited by Greg Ercolano; 04/15/19 07:10 PM. Reason: Video #2's url description was being truncated