Ray
If he has 3 5200ma batteries in series, they will still have 5200ma capacity.
Putting them is series will not reduce the 5200 ma capacity.
The voltage will be increased, but the ma capacity will not change.
Tom
Here is an example of batteries in series:
Series Connection
Portable equipment needing higher voltages use battery packs with two or more cells connected in series. Figure 2 shows a battery pack with four 3.6V Li-ion cells in series, also known as 4S, to produce 14.4V nominal. In comparison, a six-cell lead acid string with 2V/cell will generate 12V, and four alkaline with 1.5V/cell will give 6V.
Figure 2: Series connection of four cells (4s).
Adding cells in a string increases the voltage; the capacity remains the same. Courtesy of Cadex
Tom