Here is what those dumb guys have to say:
5 fans - 5 lights: 2 batteries of 100Ah each.
I decided to calculate the actual load of all fans. And i was surprised by the results.
1 Pak Fan = 60W, and it used to give highest air flow.
2 Sufi fans = 95-100W each, with poor air 
1 Pak fan of 80's probably = 80W with reasonable air flow.
I calculated the impact of those idiot Sufi fans on my bills, and estimated that if i replace the fans with new Pak fan ones, they would recover their cost in maybe 2-3 years.
"Mehnga roey 1 bar, sasta roey bar bar"
Going with the calculations, I estimated that even 2 batteries of 60Ah would be sufficient, provided I discharge the batteries more. Those lead acid batteries don't last more than one year, anyways.
2 more fans connected to the system, and 85Ah ones (AGS brand) took the load of 6 fans and 8 lights with no backup problems.