Thanks for the reply. I would guess the CO detector is the original. I did not state that “it will not test successfully”. Maybe this is true, but my understanding is that it is working as it should, but that it is not successfully receiving the right connection that would flip it from blinking green to solid green. Do you disagree with that assessment? As to the idea that it needs replacing, I guess it s a possibility but what I find strange is that it was working perfectly until I installed the new batteries. Mere coincidence? So maybe it still IS working, and the trouble lies in something to do with either the new batteries or the connections. Yet this isn’t rocket science and the batteries are deemed good and the connections appear solid and just as before.
The original/previous batteries were two linked 6 volts. Same as these.
