650 watts is like 45 to 50 amps of current draw.

Equal to the main beams, cabin heater and a small stereo and other bits and bobs, the rear demister is a killer with 30 amps of current drive, the cooling fan is another 25 amperes, break lights take a good deal of power as well.

so the 70 amp alternator output is conservative IMHO for the 900.

I have peak current draw of 220 amperes from my amplifiers before i even use anything of the cars own electrical system, the fuel pump and coil use very little power TBO.

I have been looking at Volvo and BMW alternators made by bosch, close fitting almost perfect, but there only rated at 90.

There simply is not enough room for 2 alternators so one high power unit is a must.

I have two Bosch calcium deep cycle batteries rated at 74ah, this gives me a good foundation for large current dumping, but as we know batteries dont make power only store it, so i get alot of voltage drop once the current draw becomes larger than 150 amps, after 5 seconds the voltage drops from 14.2 to 13.5 another 3 seconds and I am down to 12.8 and then 2 more seconds am down to 11.8 then 10.5 volts.

I would like to be able to hold the voltage at 13.0 voltas for 30 seconds or more, so i really need a 150 ampere rated alternator.

thank goodness for the twin V belts as the alternator can get very stiff making this amount of power.

Are you guys sure the 9-5s alternator would fit with just a pully change?

is it self regulated?

This chirping is driving me mad;oops: