View Full Version : Advice - Charging Rectifier/Regulator

02-12-2009, 11:03 AM

I own a 25hp 2 stroke yamaha electric start (please hold the lazy man slurs - i can pull start it if i want).

Recently i installed a minn kota 12v and made some changes to the wiring ie: main isolator, 50A breaker etc. During this process I mistakenly sent to motor the wrong polarity.

As a result I blew the fuse on the starter circuit. After replcing the fuse everything seemed back to normal.

Since then I have noticed my battery level decreasing each trip and after getting my multimeter involved it appears I am not charging. ie I cannot measure a voltage difference when running and not running. I beleive my motor is good for about 6.5A so i expect to see a voltage difference at the battery if charging.

Is it possible that the incorrect polarity has aslo affected my regulator/rectifier? I don't have any manuals or diagram for this motor so I am not exactly sure what the regultor rectifier looks like. I have followed all the wiring to what I belive is the regulator rectifier and when I try to measure resistance across it, i get an open circuit.

Hopefully your combined wealth of experience may be able to shed some light on:
1. What exactly does this regulator rectifier look like, so I know i am testing the right thing.
2. Can the wrong polarity kill it, if so what is involved to replace the regulator rectifier. I assume it is fairly striaght forward.

Many thank in advance to any assistance received.


02-12-2009, 03:13 PM
Your definetly on the right track, the rectifier is small and square with maybe around 4-6 wires coming out, there will be 2 wires exiting out from under the flywheel maybe green and one with a stipe? but they will go strait to the rectifier, then fr the rect 2 will go towards charging your battery,

being an elect start I cant tell you if they go into the loom or? good skill/luck

Jarrah Jack
02-12-2009, 10:21 PM
Depending on your unit you may be able to check the rectifier by using an ohmmeter to verify that the unit will only pass current in one direction. You can usually find the thing by following the wires from the stator under the flywheel.

Hope that helps, there are people on this site who know a lot more than me.