Alternator manual with how many cells?

alternator spec:  http://www.rdso.indianrailways.gov.in/works/uploads/File/SPEC_AC_0013(Rev%202).pdf

We are in habit of using 6 cells ( 12 V) for doing field supply manual of 25 KW alternator in AC coaches in case of RRU/ERRU failure.

Henceforth this activity should be done using tap from across 8 Cells ( thus giving 16 Volts approx). This is needed since most of the time batteries are already drained and we don’t get even 12 V from  6 Cells.

Table below relates train speed with RPM:-

Speed for Alternator output	RPM	KMPH
Cut in speed (below which no gen)	400	22
	500	30
Minimum speed for full output	930	51
	1500	82
	2500	136
	2800	156