Ultrabay Battery prevents Bootup-Any ideas?

I am trying to figure out if I simply have a bad battery or a more serious problem

With the ultrabay secondary battery in place, my T60P won't boot on battery power. It flashes the opening screen, goes black and repeats until all batteries removed. The machine will boot on AC with the ultrabay battery installed, but shuts off when the AC is unplugged.

With the ultrabay battery removed, the machine will boot on battery power and AC power.

Problems don't occur on AC at all.

It is an older battery that only holds about 1/3 of its original charge but it seems strange that a weak secondary battery would prevent the computer from booting with a fully charged and healthy primary battery.

First line Lenovo/IBM Atlanta support was not took helpful. The women never semed to understand that I didn't purchase my ultrabay slot separately from the computer.

I will replace the battery, but I am trying to figure out if I have a bad power supply or motherboard. Has anyone experienced this?
Thanks,
Charles in Atlanta

 

if it has 1/3 its original capacity, it probably does not have enough current to power the boot, since at bootup no power saving features are enabled

you will probably just gona have to get a new battery