w540 UltraBay upgrades

[amaclean04]

I am a bit new to Thinkpad upgrading so apologies if this sounds uneducated, but have to start somewhere lol.

I recently bought a for parts Thinkpad w540 and fixed it up with an upgraded CPU, new FHD LCD panel, 32gb RAM, 1tb SSD, 9 cell battery, new charger, good trackpad from the w541, new backlit keyboard, and new palmrest with the CS and FR. I am waiting on an SPI programmer to arrive to libreboot it, and so far I am very happy with how it is turning out.

I saw there are hot-swappable batteries that can be added to the UltraBays of Thinkpads, but on the w540 the Fixed Serial UltraBay Slim is rather lobotomized and does not support hot swappable batteries. I was wondering if that can be replaced with the Serial UltraBay Slim, from the research I have done I've concluded it should be a similar form factor and I think I can get it to fit. Is the UltraBay replaceable on the w540 and will a Serial UltraBay Slim connect to the motherboard properly and function correctly with hot-swappable battery support? If so where can I purchase a Serial UltraBay Slim? I've only found the optical drives for sale on eBay.

[axur-delmeria]

The W540 doesn't support Ultrabay batteries, period.

Ultrabay batteries don't plug into the SATA/IDE connector on the system board; instead, there's a separate connector that looks just like the one for the external battery.

In this reference photo of a Thinkpad T400 system board, the main battery connector is on the northeast corner, at the top side . Below it, on the right side, next to the screw hole, is the Ultrabay battery connector.

In contrast, on this W540 system board, there's only the main battery connector on the top side, halfway between center and right.

[amaclean04]

Thank you for the reply and explanation, makes sense how a second battery would be impossible on the w540 board. I am not a fan of optical media and likely wouldn't get much use out of an optical drive so I figured if it was possible to replace the optical drive with even more battery it would be worth it. The 9 cell battery should be more than enough for my use case.