Bypass batteries in devices that have a built-in chargers.

I guess mobile phones and ipods are examples of this.

So, you have a device that has a removable rechargeable battery that you can usually charge directly in the device. Sometimes, (like in laptops) you can plug in to the mains and run the device without the battery at all -- bypassing the battery, so to speak. You can't do this with phones or ipods though. If you remove the battery, the device won't run.

Is there some guide/hack that would show me how I could get round this?