Fans issues??

[LJM97Z]

It seems like they are drawing too much amps/volts when BOTH are on, i have one hooked to a seperate toggle (stands alone), the other is hooked up through the PCM & comes on at temp (180 low/185 high), everything seems fine with the one fan when it comes on, but if i turn the other fan on it draws the amp. guage down, & most of the time the engine rpms drop & it'll act like its developeing a slight miss like its effecting the ignition, the amp guage barely drops (but recovers) with the one fan, but drops really bad with both fans & doesn't recover, i also start hearing a slight squealing when both are on, could this be the alt. or weak battery? If i turn the toggle fan on while the engine is turned off, it sounds good, so i'm wondering if it might be in the charging system, is there a bigger amp alt. for these cars? would it benifit me too get one?? what are the amps. on the stock alt.?