Replacing AA batteries of my Electrolux Ergorapido vacuum cleaner

Hi all,

Does anyone know where I can find cheap and good high discharge rechargeable batteries?

What happened is, My cordless vacuum cleaner battery is dying, to the point where it has very weak suction. I read on the internet that the vacuum cleaner uses rechargeable AA batteries packs.

http://www.lifeofandrew.com/blog/2012/4/25/electrolux-ergora…

So, I thought I would replace the batteries with Eneloop batteries since everyone seems to like Eneloop batteries on OzB. I did that and at first the vacuum cleaner won't start. I thought I might have buggered the circuit board. Next, I tried to hook it up to my car battery, since the car battery is 12v as well. The vacuum cleaner worked fine using the car battery, so I suspected one of the batteries might be faulty and not providing enough voltage. I checked all the connections using the multimeter and everything is good. Finally, I checked the voltage of the terminals when I press the on button and the voltage dropped to 5v when I try to turn the vacuum cleaner on. I am suspecting that the Eneloop batteries is not providing enough current to cause the voltage drop.

Ideas?

Thanks.