That auction is wrong, that is a lithium battery, not lithium ion.
I feel I should clarify lest someone tthink it is a good idea to use a rechargeable LiIon cell. It would be hazardous to install a rechargeable lithium ion battery and try to trickle charge it. LiIon cells are -very- picky about the rate of charge. They may simply die quickly, or burn and destroy your MB.
What he is -really- selling is a lithium button cell with a holder and a diode in series so current can only flow out, not in.
I "turbocharged" several Amigas by installing AAA battery holders on the case with long wires to the MB. I used three-battery holders with a silicon diode, 4.5V=0.7V=3.8V, close enough to the 3.6V NiCd cells it is meant for. And I put a sticker in there specifying -only- alkaline cells and gave the owners instructions to replace the batteries every two years. I also put a 470uF 6V capacitor in parallel with the batteries to give a few minutes to change the batteries.
I'd also converted some using carbon-layer capacitors, but longer initial charging time was a complication. Now I think I'd use polyacine capacitors. No leakage ever, much longer life, no problem with charging.
