i'm asking this more from curiosity than anything else, but i haven't found anything in the FAQ or forum yet that explains the details of what...
Apple Macintosh 128k/512k/FatMac/Plus clock battery For Sale
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Apple Macintosh 128k/512k/FatMac/Plus clock battery: $5
Selling replacement for non longer produced Energizer battery that was used to keep the date and clock in Original Mac 128K/512K/Plus. It has slightly lower voltage (3.6v) than original battery (4.5v), but it doesnt affect computer function, keeps clock and date perfectly! Made in France, not some NO NAME Chinese product.