Real Sword 56-2 battery question

[Ivanatom]

Hello!
I wont to apologize, if my question was answered before, but I haven't find right topic.
I planning to buy RS 56-2 soon enough, but not quite sure what battery should I purchase? As far as I understand, the space is really limited, so some will fit, some not. And, of course, brand. It is hard to know for sure, which brand is good, and which is not. On every positive battery review post, there will be a negative one.
Please, can someone help me? Would be very thankful...

[Ale]

8.4v or 9.6v AK Stick batteries. All the cells run in a straight line.

Fixing the "tight fit" is really more a matter of not having wires sticking out too far on the side of the battery. It's a circumference issue, not an issue with the depth of the battery pocket.

I run both Firefox and Intellect in mine.

[Ivanatom]

Thanks, Ale. What capacity is enough? 1800?

[Ale]

Higher the better really. It's voltage that turns the crank, Mah ratings determine run time.

They aren't terribly hard to swap batteries on if you had to do it in the field.