UPS / Sine Wave Inverter Modifications (APC Smart-UPS 1500 UK Version) (misc)

My website link for downloads (if any are present), etc:
http://youtube.accbs.co.uk/Video.aspx?Video_Id=YRuBll8BP4c

I've discovered that I can use an old UPS as an inverter. This inverter is rated at 1kw and can deliver this for around 10 minutes before overheating. I want to modify this so that it can be used constantly.

What I've learnt up to now:
This inverter uses a 24v source - perfect.
It outputs 220-240v @ 50/60hz - perfect.
It creates a sine wave rather than a modified wave - perfect.
It can output 1kw - I could do with more!
It overheats after 10 mins - I need to stop this.

Interesting points:
The British version which I have appears to be using the same board as the US version which outputs the same wattage. What is interesting about this is that if the US version can output 1kw @ 120v, the board must be able to output 8.33a of current. 8.33a of current @ 240v is 2kw - So the AC side of the board should physically be able to cope with that load. The issue is, can the DC side cope with 80a, rather than 40a?

Видео UPS / Sine Wave Inverter Modifications (APC Smart-UPS 1500 UK Version) (misc) канала Antony Cartwright