DIY Rectifier Regulator

[Daibheid]

I'm on my third Yamaha F100 - an engine which I'm prone to sing its praises for reliability, quietness and economy. However, the RR went up in smoke recently and it turns out it is a weak spot on these engines. In fact Yamaha have upgraded it from the original engines although whether it's improved the situation or not I can't tell.
Anyway, blown RR units are quite common on outboards as any interruption to the battery circuit -e.g. a flaky isolator switch or accidental switching or even bad connections mean near instant death. So that and the price of the Yamaha replacement got me looking at schematics etc hoping to come up with a universal approach to replacing RRs.
After looking at putting a regulator and a zener diode together on a chunk of aluminium I got a bit more sophisticated and eventually tracked down a motorcycle unit that has the grunt required. The plan was to wire it up, fit it and report on here with construction/source details after reliability had been established. But I could use some help on the DC output side with what I think is a sense wire....
So here's the old Yamaha RR - and you won't get a lot of change out of £300 for a new one. Mercury Mariner versions are not cheap either!
There are 3 AC input wires as it's a 3 phase alternator and they're all green but individually colour coded and keyed via the plug pictured.
On the DC side there's a conventionally coloured Red Positive and Negative black.
There's also a green wire which is capped off and shown as such on the F100 wiring diagram. I took it to be an optional tacho signal similar to some Mariner/Mercury engines I've owned.

[Daibheid]

Here's my proposed replacement - subject to a bit of cutting and splicing of connectors, it's 35A rated and will fit the same mounting points on the engine. It will also fit a very large number of Mercury Mariner mounting points - 65mm pitch holes. Most importantly it has a much better heatsink than the OE item - being bigger and finned on top and bottom sides. Physical fit is one thing, clearance around the area is also something that needs to be checked for your application but it's tight on my Yamaha.
The wiring is almost effortless with three yellow wires for the AC input to pair with the 3 AC green on the Yamaha plug. There's no sequencing issue as it's all AC 3 phase so no problem that the yellow wires are identical.
On the DC output the red wire is positive but here's where it starts to get a little confusing, the green wire is the DC negative - not what I expected. Bike wiring is not known for being logically coloured! The black wire you can also see is considerably lighter guage than the red or green wires and this is the one that's catching me right now as I'd assumed it would be the DC negative when I bought it. I think I can just insulate it and all will be fine as it's probably meant to be switched via the ignition to prevent the RR being live permanently and draining the battery - not an issue with isolator switches but I think it could also be a sense wire which sets the voltage regulation level and so needs to connect to the battery positive.
The first three pics show the OEM vs the proposed replacement side by side to show the better heatsink and common mounting pitch slots.
Input appreciated!

[Daibheid]

This is a wiring diagram I tracked down showing a similar 6 wire RR in a bike circuit. Suggestions welcome about handling the black wire as the replacement I bought is on eBay for £30 - a fraction of the price of a replacement OEM RR from Yamaha or indeed Mercury Mariner units and no doubt most other Outboard brands.

I also think it will be more reliable being much better cooled. I've read of engine fires from these particular OEM items on the fourstroke yamahas. As there's little air movement under the Outboard cowl, the RR is mounted very close to the air intake to maximize cooling but that's not so good if the RR is quietly frying itself and any fuel is backfired or dripped into the air intakes and they're lowermost when the engine is trimmed up......

The other mod I'm considering to my proposed replacement is to open the starboard end mounting slot as the starboard mounting bolt on the F100 really can't be removed without getting the intake manifolds out of the way.

[Peter_C]

I couldn't find much information in RR's when I wanted to put a charging system into my 40hp 2 stroke. A little research and a $16 shipped motorcycle part off of Ebay had me fixed right up. I grounded the black wire solid and used one bolt to the motor close to the location the factory rectifier was supposed to go. I wanted a regulator too since I have an AGM battery. I don't put a ton of hours on my boat, but it has been reliable the last couple of years.

[Nos4r2]

That's a Superdream unit Dabheid.

Check your stats for the AC voltage of the outboard alternator. If it's over 25v, don't use it-Honda Superdream rec/reg units don't like it. the Superdream was around 25v max from the alternator.

Have a chat to Electrex-they'll be able to send you the right unit for the job-or alternatively the XJ900 Yam one will do nicely-I've been running one on my ancient GS850 for 15 years and the alternator chucks out 75v on that before the rec/reg.

You'll need to check the wiring codes on it though as the 3 AC wires on the XJ unit have different colour codes for no apparent reason. Red and black are obvious though-no green earth wire.

[IanH]

Originally Posted by Daibheid

Anyway, blown RR units are quite common on outboards as any interruption to the battery circuit -e.g. a flaky isolator switch or accidental switching or even bad connections mean near instant death.

Im interested in this comment. I have a 4-stroke Mariner with AC power takeoff and, having no experience of this, I was thinking of fitting an rectifier/regulator and terminate so that I could fit say a power/cigarette lighter socket for the occasional powering or charging of devices - phone, handheld VHF etc

If I understand your comment correctly, do I take it that if there is no load then a rectifier/regulator would fail?

[Nos4r2]

Originally Posted by IanH

Im interested in this comment. I have a 4-stroke Mariner with AC power takeoff and, having no experience of this, I was thinking of fitting an rectifier/regulator and terminate so that I could fit say a power/cigarette lighter socket for the occasional powering or charging of devices - phone, handheld VHF etc

If I understand your comment correctly, do I take it that if there is no load then a rectifier/regulator would fail?

You have to have a battery in the circuit or it'll kill the rec/reg unit.

If you don't have a battery in the circuit and try to 'load' it by attaching a device to it you may find anything you've got attached to an accessory plug will fry or pop fuses.


On bikes it's been known for people to use a huge capacitor instead, but given that one big enough will cost many times more than a small sealed lead acid battery, it's a no-brainer.

[9D280]

Or, go to an outboard breaker's anf get someone else's reg / rect.

I went through all this about a year ago on the Merc. Ended up with one off a Honda 30bolted to the outside of my intake Air box. theory being the cold air past the wall underneath would help keep it cool. That and my cowl leaks like a sieve!

[simsy]

A modest sized Electrolytic capacitor permanently connected directly to the RR’s output may help. The size would be sufficient to smooth out any surges caused by flaky isolator switch etc., but not so big as to hold significant charge that could start a fire or be considered a battery. Maybe around 3300uF and 35 volt. (£5) This will help in stopping RR failures.

[Daibheid]

Originally Posted by IanH

If I understand your comment correctly, do I take it that if there is no load then a rectifier/regulator would fail?

affirmative but if you set it up so you can unplug it from the AC supply you won't have the problem or as Nos said ensure you put a battery in the circuit

Originally Posted by Nos4r2

That's a Superdream unit Dabheid.

Check your stats for the AC voltage of the outboard alternator. If it's over 25v, don't use it-Honda Superdream rec/reg units don't like it. the Superdream was around 25v max from the alternator.

Have a chat to Electrex-they'll be able to send you the right unit for the job-or alternatively the XJ900 Yam one will do nicely-I've been running one on my ancient GS850 for 15 years and the alternator chucks out 75v on that before the rec/reg.

You'll need to check the wiring codes on it though as the 3 AC wires on the XJ unit have different colour codes for no apparent reason. Red and black are obvious though-no green earth wire.

close Nos but no cigar it's actaully a CM450 unit - the beefiest one I could find although the Superdream one was in second place. The pictured one is 35A rated - I think the SD one is under 30 but would have done OK too I'm sure. The circuit is fused at 30A so I wanted to ensure the fuse would go before the RR melted (again!)
Thanks for the headsup on the AC peak V. Yamaha rate the output at 18V at 3,500rpm although mine measured about 20 so I think still OK for this unit.
Ellectrex look great but your Electrex 7wire XJ unit would beat me to wire with an additional brown wire in the mix - I'm still figuring out the black wire on my 6 wire unit!

Regarding the wiring of the AC - I tried to get across that it doesn't matter even though it took a while to figure it out. Yamaha and Mercury all colour code their AC wires and/or key their connection to the RR. The only reason I've found that might make this a good idea is to avoid having a defective RR short a stator coil and then get plugged into a different coil and kill that too. I can see or find no electrical reason to differentiate them and yes I did do coloured Sine wave drawings to try get my head round it!

Originally Posted by simsy

A modest sized Electrolytic capacitor permanently connected directly to the RR’s output may help. The size would be sufficient to smooth out any surges caused by flaky isolator switch etc., but not so big as to hold significant charge that could start a fire or be considered a battery. Maybe around 3300uF and 35 volt. (£5) This will help in stopping RR failures.

Make sure you wire it right way round though
I think this is similar to the protected battery selector switches - bought one after someone accidentally knocked off the isolator and killed my mariner RR a couple of years back - never tested it though one replacement was enough! My current set-up is to use battery quick connects - one less switch to go wrong

[Nos4r2]

The black wire on the one you've got is a Honda oddity. Connect it to the red-it's an 'auxiliary power' wire and is +12v. If you're not comfortable doing that just tape it off.

Alternatively, just give Electrex a bell-the unit you need is a standard unit and they'll supply off the shelf. It's just a 12v Rec/reg unit for a 3 phase alternator.

[Peter_C]

Originally Posted by Nos4r2

The black wire on the one you've got is a Honda oddity. Connect it to the red-it's an 'auxiliary power' wire and is +12v. If you're not comfortable doing that just tape it off.

According to the wiring diagram he posted black is definitely a ground. It is also a ground on the motorcycle unit I installed on my outboard, which is exactly what I did. Am I missing something?

[Nos4r2]

Originally Posted by Peter_C

According to the wiring diagram he posted black is definitely a ground.

No it's not-look at it again.The black in that wiring diagramme is a positive. The green is negative.

Originally Posted by Peter_C

It is also a ground on the motorcycle unit I installed on my outboard, which is exactly what I did. Am I missing something?

Probably not. Honda motorcyles use green as earth. I'll guess yours isn't a Honda rec/reg unit. They are the only ones that do it.

[Peter_C]

Originally Posted by Nos4r2

No it's not-look at it again.The black in that wiring diagramme is a positive. The green is negative. Probably not. Honda motorcyles use green as earth. I'll guess yours isn't a Honda rec/reg unit. They are the only ones that do it.

Upon closer inspection you are correct, the green is the ground and black is positive. I just saw it go around the diagram and assumed, which is the first mistake. Must be a European thing...In the USA it is either black or brown for ground. Mine is a Kawasaki regulator.

[m chappelow]

old Kawasaki motorcycle rectifier that I used on an old Yamaha 9.5 outboard for charging a battery this one has the red / black battery wires ( put a switch on one )for the battery and 3 white wires 2 in use from the coil the other ( redundant / not used for the outboard taped back ).

[Nos4r2]

Originally Posted by Peter_C

Must be a European thing...

No, it's a Honda thing. Honda in the USA are the same.

[Daibheid]

Originally Posted by Nos4r2

The black wire on the one you've got is a Honda oddity. Connect it to the red-it's an 'auxiliary power' wire and is +12v. If you're not comfortable doing that just tape it off.

It's used on some cars too - I've pretty well figured out it's meant to be positive switched on with the ignition and is there to cut off the few mA the RR will otherwise draw. Not an issue on the original unit or for my use as I always isolate batteries if leaving the boat overnight etc. I've been poring over the Yamaha schematic to try find a switched live to do it perfectly if possible but I believe that black wire does have to be 12v+ or the RR won't switch on so might just jump it on to the red wire. Hopefully when I get round to doing it, unlike electing a pope, there'll be no smoke

[Daibheid]

FYI and to whomever messaged me the rectifier has worked fine all Summer with a lot of miles going up on the boat. It keeps pushing 14.2V so I often use it with the running lights on to burn off a little power. I ran it with a temperature probe on the first trip and it got up to 80-90C which seemed OK to me relative to the engine itself. So I went off on a few long trips since with no problem. You can find similar RRs on eBay.
Satisfying!

[serkan80]

@Daibheid, Thank you for this information. This might've actually saved someone from spending around $300 and who knows, that person might be me. However, you mentioned that after a bit of cutting and fitting in your second post we can fit this in, can you tell us how much do we have to cute and whether or not filing instead of cutting and fitting will be a better option. Also, colour codes are generally not followed by all the companies because they are not that universal. In case of rectifiers and filters where you have multiple inputs and outputs, they use their own specified colours as specified in service books. Thank you again for the information.