Rectifier PN Yamaha 8 2 stroke

[mitch184]

I'm not a electrical guy, so the whole rectifier charging system is kind of muddy to me. I've got a 2006 8MSH as a kicker motor and I'd like to power my fishfinder when *****ing long days. So I'm really only looking for 2amps, since I know these engines don't put out much.

As is, I looked at the schematics and I have the 2 green wires, both with female connectors, coming off the Lighting Coil Assy. When checked with a volt meter, in DC, the readings are all over the map. There are also several wires coming off the charge coil and pulser coil but they are not open connections.

Can anyone give me the quick run down on which wires I need to tap into and/or if I need an additional rectifier? I don't see a rectifier in the "Optional Equipment". I found a "common" wire color code for Yamaha engines but it talks about High Speed and Low Speed Charge Coils and the green wires seem to be Lightning Coil Leads.

Thanks
Sean

[boscoe99]

The two green wires are the output for the system that charges a battery or operates lights. The voltage is AC, for alternating current. You would put your multi-meter on the AC setting to measure the output voltage. Do that to ensure that the two wires have a voltage output that varies as the motor RPM increases or decreases.

A device referred to as a rectifier is used to convert AC voltage to DC voltage. So that the DC voltage can be used to charge a battery or power a light or two.

Now there is also a device referred to as a rectifier/regulator. It first converts AC voltage to DC voltage and then controls the DC voltage to some value. Say 14/15/16 volts.

Given the low output of a 8 HP two stroke Yamaha I suspect that all you need is the rectifier.

http://www.boats.net/parts/detail/ya...970-01-00.html

[mitch184]

Thanks. that appears to be what I need. I kind of doubt it will over voltage especially since its a *****ing motor. If I do end up needing a rectifier/regulator, is there a yamaha part number offered? Do any of the T9 4 stroke kickers use a rectifier/regulator?

[boscoe99]

Yes, there are many F9.9 and T9.9 models that use a rectifier/regulator. For instance http://www.boats.net/parts/detail/ya...960-00-00.html

[mitch184]

Thanks for the response. There seem to be a few rectifier/regulators. Mine is a 2006, it seemed like the 6G8-81960-A1-00 was the part number for the 2006 4 stroke 9.9. Do you think either would work?

[boscoe99]

The same lighting coil (P/N 6E7-81303-A0-00) that is used on your motor http://www.boats.net/parts/search/Ya...TOR/parts.html

was also used on a 9.9ELHT http://www.boats.net/parts/search/Ya...TOR/parts.html

A P/N 664-81970-61-00 rectifier was provided with the 9.9ELHT http://www.boats.net/parts/search/Ya...EH)/parts.html

Given that it is known that a 664-81970-61-00 rectifier will work with a P/N 6E7-81303-A0-00 lighting coil I might be inclined to use that one. More than likely almost any small rectifier will work with your lighting coil but the one installed on the 9.9ELHT is known to work. It probably will be plug and play whereas with a non-Yamaha rectifier you might have to do some modifications.

[boscoe99]

Here is a link to a diagram that depicts how the rectifier is installed and wired to a fused harness.

http://www.boats.net/parts/search/Ya...0ER/parts.html

[mitch184]

Just to follow up, bought the 68T-81960-00-00 rectifier/regulator. It came with 2 male green plugs, a female green plug, a red power wire and ground wire with a ring terminal. Plugged in both green wires from the lightning coil into the male connectors and left the female green connector, from the assembly, empty.

From there, I snipped the ground wire and ran both the red power wire and ground wire directly to the postive/negative busses. With the battery switch OFF, I can get upwards of 30 volts out of the motor. This would be basically no accessories on and no load what so ever. With the battery switch on, it regulates it to 15.5 volts at WOT. As accessories are turned on, that voltage drops down closer to 14. I didn't ground the block because I try and always limit stray current and running the ground directly to the bus and then battery, should reduce it.

I assuming that since I didn't ground the recifier/regulator to the block, it doesn't actually regulate until the battery is connected. I guess I just need to make sure I never turn any of the accessories on if the battery switch is off.

I just wanted to double check that nothing needs to be plugged into that female green connector from the regulator/rectifier.