Rectifier Wiring - 1986 50hp

[Ginagard]

Hi All,
I'm hoping you can help with a nagging issue. I have an '86 50hp Johnson that is not charging the battery. I'm targeting the rectifier. The replacement I have is a three wire unit and I just noticed the one I'm replacing is a four wire. I don't have a tacho on the boat. Can I just use the the 3 wire rectifier and not bother to wire the tacho?
Thanks!

 

[Bt Doctur]

if a 3 wire it will need a ground to operate correctly. yellow wires to stator, red to battery feed

 

[Vic.S]

Hi All,
I'm hoping you can help with a nagging issue. I have an '86 50hp Johnson that is not charging the battery. I'm targeting the rectifier. The replacement I have is a three wire unit and I just noticed the one I'm replacing is a four wire. I don't have a tacho on the boat. Can I just use the the 3 wire rectifier and not bother to wire the tacho?
Thanks!

You need a four wire rectifier for that engine. ( 3 yellows and a red).

The three yellow wires ( plain yellow, yellow/grey and yellow/blue ) from the stator are the AC output and connect with the corresponding wires on the rectifier ( although a replacement rectifier may have 3 plain yellow wires, in which case it does not matter which is which).
The red wire is the DC positive output and the metal case is the DC negative.

If you connect a three wire rectifier ( 2 yellows and a red) at best you will only get half the normal charging current but only if you pick the right two wires from the stator to connect it to.

 

[Ginagard]

Thanks for replies folks. I think I'll just order a for wire.
Much appreciated.

 

[Crosbyman]

3 ac inputs if for 3 phase rectifiers. normally on most rectifier the AC alternates +/- into a rectifier 2AC ====> 1 DC out

each phase is180 degrees apart ( sine wave) 2x180 =360

in a 3 phase rectifier the " rectification" process is shared as each phase is generated and.... rectified at 120 degrees intervals so you need 3 AC inputs which converger on one single +DC output (red) 3x120=360

lots of info on Internet ....high power 3 phase rectifers are no texpensive on AMAZON

High Power 100A 1600V Diode Bridge Rectifier 3-Phase Full Wave Rectifier Black Three-Phase Diode Bridge Rectifier 600~1600V : Amazon.ca: Automotive

High Power 100A 1600V Diode Bridge Rectifier 3-Phase Full Wave Rectifier Black Three-Phase Diode Bridge Rectifier 600~1600V : Amazon.ca: Automotive

www.amazon.ca