I'm in the process of restoring a Mac II with FPU and 68851 PMMU (a rare system!) The two motherboard batteries tasked with maintaining the PRAM and booting the machine died many years ago, so in order to get it booting I improvised a mechanism whereby I "jumpstart" it with a quick hit of 13V.
Of course, this isn't a suitable long-term solution, and doesn't solve several other problems I'm having with this II-- PRAM settings aren't retained, I get next to no audio volume despite system volume all the way up at 7,...-- so I'm looking to replace the flat batteries currently soldered to the motherboard.
I've seen later revision II boards with battery holders-- is this a common enough size part that I can order from e.g. DigiKey and have it be a matching fit to my earlier II board? Or was that particular battery holder a custom Apple part sized just for the II? I'd like any further mods I do to be as elegant/professional as possible, so would prefer not to jury-rig a holder that wasn't designed for the II.
Thanks applefreak but in that thread all I found were improvised solutions using either electrical tape, velcro, or battery holders that did not fit the motherboard as closely as an official Apple solution would. I'll keep these ideas in mind as a last resort but as I said, I'd prefer to go with as professional-looking a solution as possible.