I was given a really old video conference computer. From like early 1990s. I tried booting it, it starts, but the CMOS battery has failed. It's some odd ball battery says TL 5186 on it. I thought ok 3 volt battery, i'll just pull it and insert input from a 2 AAA battery pack. It doesn't help. Some reason even changing it and then it reloading while still on clears the bios, so i can't boot from CD due to defaults being wrong. I noticed that the battery is actually odd, and it's 3.6V. I don't want to buy a new one, so thought maybe feed in 4.5 V from a 3 cell pack. But what would i need for a resistor to make ~3.6 V?