Yanmar Diesel Hitachi 35amp alternator - adding a Tachometer Sense (W terminal)

Need to wire an 'alternator tachometer' to a Yanmar? No W terminal on the alternator? Check this out and DIY a W terminal that looks like factory!

[@PassionateTrainer]

awesome presentation.. keep going on..

[@bjrnetveter253]

Cool Planning to cary out this modification. Where to connect the wire. To one of the spare cables on the harness and a tachmeter?

[@pardalbartz]

Connect the wire (internally) to ANY of the winding wires. there are three. On the instrument - it has to be an "alternator tachometer", usually two or three wires: negative, winding and (sometimes) positive from the key turned (ignition on).

[@bjrnetveter253]

@@pardalbartz Thanks alot for sharing this and uploading! I plan to do this mod with the stock Hitachi 35A. I am also tempted to buy an aftermarket 55A alternator and proceed with this.

[@williambrown238]

Is W terminal sometimes marked F ?

[@pardalbartz]

No. W stands for 'winding' as it comes straight from the stator windings, before passing through the rectifying diodes. F stands for 'field', which is the feed to supply power to the rotor field and by changing the voltage of this terminal, you will adjust the output voltage. Most automotive (and marine) alternator use an internal voltage regulator. For those the F terminal is internal. If you want to change the OEM regulator for a special one - like multi-stage alternator 'chargers' you will either use an existing F terminal or need to tap one, like I did for the W.

[@savagebuilds]

I’m about to do this and I just want to confirm. You solder directly to the copper windings?

[@pardalbartz]

Best place to solder is on the winding end/rectifier connection. It is a 3phase alternator and you can do in any of the 3 phases.