Use MBP at full CPU capacity without battery? Third-party batteries?

[oYx]

My 2007 17" MBP's battery has bulged again, causing my trackpad button to be mushy. I don't feel like spending on yet another battery from Apple.

Since it is always being used as a desktop replacement these days, is there a way to 'trick' it into thinking that a battery is connected?

Else, has anyone tried buying replacement batteries from third parties? Any issues with those?

 

[GGJstudios]

Since it is always being used as a desktop replacement these days, is there a way to 'trick' it into thinking that a battery is connected?

No, there isn't. The CPU will be throttled if the battery isn't installed.

Else, has anyone tried buying replacement batteries from third parties? Any issues with those?

I wouldn't trust or recommend any non-Apple battery, due to the number of problems reported with "knockoff" batteries. Also, there is no assurance that knockoff batteries have the same charging technology that Apple uses, involving the battery, the MagSafe adapter and the Mac's logic board.

Battery Replacement
Replacing the built-in battery in your MacBook Pro
Replacing the Battery in your MacBook Air
Intel-based Apple Portables: How to replace or service a built-in battery

This should answer most, if not all, of your battery questions:

Apple Notebook Battery FAQ​

 

[Stetrain]

Since it is always being used as a desktop replacement these days, is there a way to 'trick' it into thinking that a battery is connected?

Even if you could do this, it would be a bad idea. Your Macbook is capable of using more power at peak usage than the charger can provide, so without the battery buffer it could have to do a hard shut down because of insufficient power.