Rectifier replacement?

[aaron7]

I remember reading on some other 6v Honda forum something about replacing the old-tech rectifier with some new parts from Radio Shack.

Anyone know anything about this? Anything that can improve this electrical system is definately needed!

[aaron7]

Thoughts on this one?

http://www.electrexworld.co.uk/rr1-regulator-rectifier-universal-6v-single-phase-electrical-parts-for-motorcycles-electrex-world-8237-0.html

[onchiman]

Yes, you can replace the old Selenium rectifier with a new tech silicon rectifier. Radio Shack part http://www.radioshack.com/product/index.jsp?productId=2062584. You should also add a small heat sink http://www.radioshack.com/product/index.jsp?productId=2102856. You can just attach the heat sink with a small bolt and nut through the rectifier. Remove the old rectifier from inside the frame and look at the wire attachments. Disconnect / cut the wires strip off a little insulation from the ends and crimp on a new female spade connector to each. You can also solder the connections directly onto the rectifier if you prefer.
The wiring is simple with only four connections to make. All terminals are marked on the rectifier. There are two "AC" terminals. Brown and yellow wires from the dynamo go one to each "AC" terminal. The red or white with red stripe wire goes to the "+" terminal and then you need to connect the "-" terminal by an added wire to the battery "-" or a good ground on the frame somewhere. Done ;)

[aaron7]

Awesome! Just what I was hoping to read.

Now that one you linked is the exact one I need for this 6v system? And what are the benefits of running this one? As in, what improvments might I see?

And to mount it, can I just mount it to the frame with the hole in the center? As in, use the frame for a heatsink?

[onchiman]

It doesn't matter if it's for a 6 or 12 or 24 volt system since the unit only rectifies the ac output from the dynamo, meaning it turns the ac voltage into dc voltage to charge the battery. It's a more efficient rectifier than the original selenium unit so it should provide a tad more dc voltage to the battery at all engine speeds. Can make all the difference at idle especially if you run with your headlight on. I never thought about using the frame itself as a heatsink. I suppose it could work if you could mount it to a smooth flat area somewhere. Try it and see :rolleyes:

[aaron7]

What about one of these?

http://www.norbsa02.freeuk.com/goffyelectrex.htm

The "SOLID STATE VOLTAGE REGULATOR/RECTIFIER" type?

What is the difference between one of those, and the one from Radio Shack?

[onchiman]

There is no need for a regulator on the CA95. It's electric system was designed without one. The system as created is really to maintain an already fully charged battery. You cannot put a discharged battery in the bike and expect it to be charged.
If you run the bike at idle with the headlight on the battery will die. There's just not enough capacity in the dynamo to generate sufficient output. If you look at the wiring diagram for the bike you'll notice that when the headlight is switched on, an extra coil in the dynamo is switched in to compensate for the increased current draw. It's a balanced system that requires you to fully charge the battery before installing it in the bike. At best it will only maintain that full charge when you operate the bike at speed. If you ride around town idling and stop and go, your battery will discharge, requiring you to use a charger to charge it up again. You might want to visit this forum for lots of information concerning the mechanics of the old Hondas http://www.honda305.com/forum/. It's mostly for the Honda 305's but also contains a section for the 150 twins and lots of information pertaining to both.

[aaron7]

I never knew any of that, thanks for the input!

I just ordered a 6v charger that has a trickle setting with an auto shutoff so I can hook it up whenever the bike is parked.

Also, would a weak battery hurt spark on the bike? Or is that separate?

[onchiman]

Also, would a weak battery hurt spark on the bike? Or is that separate?

You MUST have a fully charged battery and a functioning charging system for this bike to run right.

[aaron7]

That could most definately be my problem then! Here we are kicking it over and over and over and just not having it start!

[Missourimike]

Keep in mind that the COIL fires the spark plugs and you need a good battery to fire the coil. Definately can't use the electric start with a weak battery, as it will draw most all the voltage, leaving little for the coil to fire plugs.

[brookville]

I think this is some of the best info I have seen posted. I know everyone has wondered why the electric starter doesn't seem to want to work after sitting around for a while. I thought I may have a bad starter but it looks like I need to charge the battery more often. Thanks Norm

[Missourimike]

I think this is some of the best info I have seen posted. I know everyone has wondered why the electric starter doesn't seem to want to work after sitting around for a while. I thought I may have a bad starter but it looks like I need to charge the battery more often. Thanks Norm
One other thing that might drain your battery. A component(device)that is "on", drawing juice but not showing itself to be on. A "short" in the wiring that is grounding out and zapping the battery, for instance. To tell if that is the problem, with all devices, key, lights, etc, in the "off" mode...disconnect a battery terminal, then barely touch the wire to the post. See any spark? If so, the vehicle is drawing power from the battery. On a vehicle with a number of circuits and a row of fuses, use the same method on the fuses, disconnecting at the fuse. Spark at the fuse? Then that circuit is "on". A tech person would do the same tests using a voltage meter or test light.

[ByTheLake]

I've used this fellow as a source for silicon rectifiers for several restoration projects:

http://www.oregonmotorcycleparts.com/rectifiers.html

He includes a little instruction sheet with the package. I replace the original selenium rectifiers every time I encounter one, given how inexpensive the silicon replacements are.

[Smithers]

Oh nice! That takes all of the guesswork out of the upgrade. Very nice thanks.