Topic: Regulator/Rectifier woe

[MauiK3]

When I put my 1973 K3 750 together a few years ago I decided to put in a modern combined rectifier/regulator.
Not so sure about that decision now.
I went to start it yesterday, dim lights on the dash, no start.
Tried to jump it with my little jump box, it started after a few tries.
It would not idle, had to keep it at 3000 rpm.
I started checking things.
Battery is not quite 1 year old.
Disconnected battery voltage was just over 12.
Running voltage at 3000 rpm was just over 6 volts.
When not running, I heard a funny squealing sound from the regulator/rectifier, weird.
I also noticed a toasty wire, see photo.
I'm going to order a new unit, anyone have any suggestions for a reliable one? This one came from Yamiya.
It seems to be the culprit.

[MauiK3]

Oops, forgot to mention, it's a lead/acid battery

[Deltarider]

When was the last time your battery was charged? A battery that reads 12V is about 90% depleted. During hibernation a lead acid battery needs a refresh charge every 5-6 weeks.

[maxheadflow]

You need to make sure that the battery  is good.  The toastie wire is likely due to corroded connector contact. Since the connector on the viewed side appears new, the corrosion is likely on the other side.  On the OEM stuff, if you lose connection one of alternator output wires you can blow the rectifier. Don't know if the new stuff is more robust. If you haven't checked recently, it's also worth while to check the alternator connections for the alternator under the sprocket cover.

[MauiK3]

I keep the battery on a Tender.
I'll have to do some more troubleshooting.

[jamracing]

I replaced all the block connectors to avoid the old corroded pins. 4into1 has all sorts of connector kits if you find that as the culprit.


Sent from my iPhone using Tapatalk Pro

[Deltarider]

I keep the battery on a Tender.
I'll have to do some more troubleshooting.

Personally I don't trust tenders. All tests should be done with a well charged battery. A well charged battery is a battery that, when left unconnected for a couple of hours, will read 12,6 V minimum.

[maxheadflow]

I keep the battery on a Tender.
I'll have to do some more troubleshooting.

Personally I don't trust tenders. All tests should be done with a well charged battery. A well charged battery is a battery that, when left unconnected for a couple of hours, will read 12,6 V minimum.

I agree with this. I really don't use them very much as I ride year round. The bike might sit for a month but when ridden, it will typically get 100 miles. Low side is about 35 miles.  Friends that live in cooler climates, prefer a tender that is at least 2 amps. They do a better job of guaranteeing that battery will get a full charge.  My personal experience with tenders showed that about 0.25 amps could not maintain a marine battery for a generator. About 1 1/2 amp keeps it up.  MC batteries are smaller but if the bike is ridden only short distances, the tender may not be able to fully charge the battery.