Rectifier question??

[MichiganBrian]

Is this a normal rectifier? It wasn’t hooked up to anything?
What does it actually do?

[Dale]

Is this a normal rectifier? It wasn’t hooked up to anything?
What does it actually do?

That does not appear to be a Hodaka rectifier. Not sure if it is actually a rectifier or perhaps a voltage regulator.
A rectifier converts the AC, generated by the magneto, into DC to charge the battery and to operate the DC portion of your system.
A regulator chops the AC voltage above a specified level to protect bulbs and would be part of the AC portion of your system. Which model of bike are you working with? Prior to the Road Toads, there was not a regulator in the AC system. Some models, such as 94 Wombats are known to burn out headlamps unless you add a regulator.

[MichiganBrian]

B+ Bike with a B motor.

[MichiganBrian]

All the lights worked. Horn did not nor the switch under headlight bucket. I haven’t checked if battery is good yet.
Brian

[michael_perrett]

That unit is a bridge rectifier. It replaces the Hodaka selium rectifier. I found the bridge rectifier a much more durable unit than the Hodaka unit. Both units allow voltage to go one way only. I use them on all my Hodakas I convert from 6 volt to 12 volt. They can be tested in the same manner as shown in the Hodaka service manual. It should work well on the stock 6 volt system. I defective unit will not allow the battery to charge or will drain the battery if shorted out. I have experienced that with the stock units, but not with the bridge rectifiers.
Mike Perrett

[Al Harpster]

Excellent information from Mike perrett.

The rectifier keeps alternating current from reaching the battery. It only lets in the Direct Current pulses. If AC current gets to the battery it'll eventually cause failure. Maybe fast.

I've wondered about a modern replacement for the stock selenium rectifier.

Thanks to Mike I now know.

On the Ace B the tail light and I believe the horn work only off the battery. The Ace 100 Supplement Manual gives better information on this.

These small batteries are inexpensive. I've ordered two at a time. Seems I don't usually get more than a year out of them.

Maybe it's my rectifier?

[JPark]

I thought my rectifier was pooched because the lights were bright on AC but the [new] battery wouldn't charge. I took the ignition switch off and cleaned it so that it made a good ground. Works fine now.

It looks like the switch is a ground for the battery and also part of the magneto loop, so enough of a voltage drop could cause charging problems. Mine would charge at really high rpm but when the revs and voltage dropped it went below the threshold to charge.

If you've painted the frame it is a good idea to insure that there is enough metal to metal to ground the switch. Checking with an ohm meter is not necessarily going to indicate a potential voltage drop under load.

The rectifier in the picture appears to be a bridge rectifier which is a full wave; i.e. it pulls DC from both sides of the AC. The original selenium is a half wave which only sees one side of the AC. That's what the other two terminals would be used for. A single diode would substitute for the selenium, but can cost more than just using one side of a four diode bridge type.

Connecting up for full wave rectification is tempting, but may produce more 'juice' than the battery is capable of dissipating.

The extra 'wire to nowhere' on Wombats magnetos could be a lead to a zener diode regulator to keep the lights from blowing. Probably didn't make production further than the wiring loom.