Your battery is upgraded at the following Chibi rank:

100 Battery: Rank 100,000
120 Battery: Rank 10,000
140 Battery: Rank 1,000
160 Battery: Rank 100
180 Battery: Rank 10
200 Battery: Rank 9
230 Battery: Rank 8
260 Battery: Rank 7
290 Battery: Rank 6
320 Battery: Rank 5
360 Battery: Rank 4
420 Battery: Rank 3
500 Battery: Rank 2
Unlimited Battery: Rank 1
How you like it.