I solved all of my power supply problems for $40.00
Buy one of those Jump starters from SuperCheap Spares or AutoOne, they are ony about $50.00 I think Super cheap has a special for $40.00 ATM.
They have a Gel Cell in them and will deliver up to 600amps!!!
The Gel Cell alone is worth about $120.00 if you bought it seperately.
Any way they can be plugged in and run off 240v they are great for taking to the track and can be recharged from the car on the way home. They are goood for lots of packs (I don't know how many because I mainly use it at home but I have charged up 5 packs just to see if it would work as I thought.