On Mon, 13 Jun 2016 18:02:10 -0500, Jon Elson
wrote:

1250 RPM sounds pretty low. Most small cars have engines that idle around
800 - 1000 RPM, and with a 3:1 pulley belt ratio, the alternator would be
spinning at least 2400 RPM at idle.

The pulley ratio is not always exactly 3:1. For example:
http://www.penntexusa.com/PulleyRatioChart.pdf
Looks like between 1.85:1 to 4.21. I would not speculate as to the
alternator RPM until the OP delivers the actual pulley ratio(s) on his
unspecified model forklift(s).

--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558