ethandicks/KA630-TOY-Battery-Replacement-Board

A modern Lithium ion battery replacement board for the KA630 CPU

KA630-TOY-Battery-Replacement-Board

A modern Lithium ion battery replacement board for the KA630 CPU of a MicroVAX II.

The original KA630 CPU has a NiCad battery on its FUNCT SEL/SLU module. It allows the KA630 clock (a MC146818 chip) to keep the time for up to 240 hours unpowered.

This board allows you to get rid of the old 3.6V NiCad battery in favor of a modern 14500-type Lithium ion battery.

To use: plug the board directly into an existing FUNCT SEL/SLU board, using its 20-pin connector. Connect the KA630's 20-pin flat cable to this board, insert the battery, and you're done. You don't need to connect anything else.

The circuit takes care of battery charging and protects it from over-discharge.

Not fully tested for performance, but a typical 900mAh battery should keep the time for up to two years. Testing of actual charge trigger/start/stop yet to be completed.

DO NOT use a standard 1.5V alkaline battery in this board. The size is similar to a 14500, but it will end in tears.

Note to Other (ie not MicroVAX II) users:

This board includes a couple of features to make it work as a generic NiCad battery replacement, on older workstations/PCs that used a NiCad battery to keep the time and store BIOS setup parameters).

Typically (on a PC) use the 4-pin Molex connector to power the board, and wire the "battery" connector (marked "Battery Out") directly to where the old battery would have been connected on the motherboard.

This set-up has not been tested, but there is no reason it should not work.