Risk of using 90 Amp instead of 120 Amp replacement alternator?

[wmgo...@juno.com]

I have a cold temperature bearing squeal in my 120 amp altenator, 1988
Plymouth Sundance, with fog lights. Service manual states that 90 amp
are standard EXCEPT if the car has fog lights, then a 120 amp is used.
I presume that the halogen lights are big current suckers, so to keep
the battery up to par, they put in the 120 amp alternator.

90 Amp specs
Current rating 40/90 Amp
Current output 87 Amp minimum

120 Amp specs
Current rating 50/120
Current output 98 Amp minimum

Current output is measured at 1250 engine RPM and 15 volts at the
alternator. Voltage output is controlled by the engine electronics.

I have air conditioning and the only power option is door locks.

What are the risks if I replace the 120 amp alternator with a 90 amp?
Rebuilds are $150 - forget that - I have 100K on the car.
I can get a used which was rebuilt in Jan 95 for $35 plus $10 core
charge. Any electrical wizards out there care to give me an opinion?
Wade Goldman
wgol...@draper.com

[Michael E. Mitchell]

If the two alternators are of the same external dimensions it can be
used as a "crutch" if need be. However, don't think you can operate
all your electical accessories at once for an extended period of time
and expect to get trouble free starting the next morning. The scenario
plays out when you drive in bad weather at night-- wipers,defroster,
lights, all take alot of current. This time of year, depending on your
local climate is hard on the battery too. Have your jumper cables
ready. Mike.