B&W 801 series 80 batteries?

I just got some of these to. Do you need to replace the batteries at all? Mine are dead also but they sound fine. Hope you can get an answer and if I find out I will let you know. Tom.

Here's how they work.First thing - series 80's are not a APOC as used in later 801's and other B&W's. The 80's protection circuit is powered by the battery.If you beat the guts out of this speaker ( with a 9V battery installed) - the speaker will disconnect from the amp (no sound) and the red LED will light up. Turn the volume down and hit the button that has the slash thru the lightbulb and the red LED goes out and the speaker comes back on.The button with simply a lightbulb icon on it apparently is a test button - press it and the red LED lights and the speaker disconnects from the amp. Again -reset by pressing the ligtbulb with slash thru it button.
Later APOC circuits charged a capacitor when you entered the idiot range and disconnected the speaker from the amp and lit a LED so that those truly impaired might notice another symptom beyond the lack of sound.No button needed to reset - just turn down the deafness control and they come right back on.
I'm not sure how great the old relays in these protection circuits sound ( maybe ever sounded?) - but most of the APOC equipped speakers are getting tough to source replacement drive units for - so removing the APOC circuit is something you probably would want to at least think about a bit before hauling out the soldering iron?

Based on Stonedeaf's info that the APOC circuit uses relays, a battery with one quarter the current spec of the original battery may not trip the relays, or trip just a few times then go dead.
This is just a hunch, so you may want to try the lithium batteries and see how long they last in actual usage.
If they are pin & size compatible, any battery is better than no battery.
Good luck