Not power enough for USB 3.0

Good morning everybody,

I have a problem for the last few days that I don't find another solution than to change my laptop.

I own a Macbook (white) since Mid-2008. It has been working very well with any kind of USB drive until a few days ago. It started to don't have enough energy to hold any hard drive (perfect with pendrives, printers, scanners, etc.). Drives were recognized but after a few seconds they where lost and turned off. After a lot of trials and resets now it seems that work fine with USB 2.0 drives but now USB 3.0 drives don't turn on.

I've been trying all them with a Macbook Air from Mid-2012 with native USB 3.0 and everything works perfect.

Could be because the battery? I have done all tests with the charger conected and full battery. The battery is the original (5 years old) but still holds power for 90-100 minutes of normal use (video only about 50 minutes).

I would like to hold this laptop until new Macbook Pro retina are announced if it's possible!!!

Thanks in advance.

Best regards from Spain.