Mosfet Rectifier/Regulator

[Beam me up]

Old style regulators did rely to some extent on having a load (battery) connected. A modern voltage regulator will work without a load connected.

I don't know much specifically about the AT but assume it would have a 3 phase alternator. The output voltage is AC and will rise with engine revs. The rectifier will change this to DC and the regulator will keep the voltage across the battery to a max of 13.8 volts or thereabouts. The MOSFET is used instead of a conventional transistor because it is faster switching and has a lower on voltage drop therefore gets less hot and should be more reliable but may be sensitive to overcurrent, hence the fuse. 30A (around 400Watts) is quite a lot of current/power which would only be drawn in the event of a short circuit, knackered battery or discharged battery trying to supply a lot of accessories like headlamp, heated grips etc. all at the same time. if your bike is a reluctant starter in the winter, for example, once it has fired up it's always a good idea to give the battery a couple of minutes to recover its charge before turning on things like heated grips as this will save overtaxing the alternator/regulator.

Fit the fuse which is intended to protect the regulator. If it blows no harm will come to the alternator.

[knobbly]

The battery just wouldn't charge. Usually if a rec blows It over charges the battery (very general rule) which can knacker the battery but I cant see why a blown fuse would damage the stator.
The rec is just a set of diodes which allow the current to flow just one way. From what I understand the fuse protects the battery and possibly the CDI unit from a spike if the RR blows. Personally I would leave it in although I have never had a bike that has a fuse between the RR and the battery.

[knobbly]

I've always replaced my RR's with one from a Honda 250 superdream. They go on forever.
Had one on my 1100 Katana, never changed it again.

[Loggy]

Old style regulators did rely to some extent on having a load (battery) connected. A modern voltage regulator will work without a load connected.

I don't know much specifically about the AT but assume it would have a 3 phase alternator. The output voltage is AC and will rise with engine revs. The rectifier will change this to DC and the regulator will keep the voltage across the battery to a max of 13.8 volts or thereabouts. The MOSFET is used instead of a conventional transistor because it is faster switching and has a lower on voltage drop therefore gets less hot and should be more reliable but may be sensitive to overcurrent, hence the fuse. 30A (around 400Watts) is quite a lot of current/power which would only be drawn in the event of a short circuit, knackered battery or discharged battery trying to supply a lot of accessories like headlamp, heated grips etc. all at the same time. if your bike is a reluctant starter in the winter, for example, once it has fired up it's always a good idea to give the battery a couple of minutes to recover its charge before turning on things like heated grips as this will save overtaxing the alternator/regulator.

Fit the fuse which is intended to protect the regulator. If it blows no harm will come to the alternator.

Thanks for the plain English reply Beam Me Up!!

I'm very good with mechanical stuff, but when it comes to electrics I am worse than useless!!

You are right, the AT has a 3 phase alternator (three yellow wires from stator to OEM reg/rec) The bike starts first push of the button with no choke (these have been blanked off) even when its cold.

Thanks very much for your reply!!

[Loggy]

Thanks for all the replys guys.

I'm going to leave the fuse in. Like someone said on XRV, if there is a short that blows a 30amp fuse, then I'm in serious dodo anyway, so a blown fuse will at least stop the battery from cooking or worse, an electrical fire. I can always get another stator.

Cheers guys...

[picos mestizo]

............but anyway, who cares if current is sent or drawn...............

coming or going! sent or drawn! is all the same to some folk :silly:

[-Ralph-]

You don't want your bike to be able to draw a higher current than the components and wiring can handle. If you're drawing more than 30 amps you've got a problem and you need to know about it. The fuse is there to tell you there's a problem and to prevent wiring and components heating up and causing fires. Leave it in!

As for damaging your stator, nonsense I'm afraid. Your stator is an electromagnet and a coil of copper wire on the end of your crankshaft. If that fuse blows the reg/rec will just stop drawing any current from it. What is there to damage?

[Loggy]

You don't want your bike to be able to draw a higher current than the components and wiring can handle. If you're drawing more than 30 amps you've got a problem and you need to know about it. The fuse is there to tell you there's a problem and to prevent wiring and components heating up and causing fires. Leave it in!

As for damaging your stator, nonsense I'm afraid. Your stator is an electromagnet and a coil of copper wire on the end of your crankshaft. If that fuse blows the reg/rec will just stop drawing any current from it. What is there to damage?

Thanks for your reply Ralph,

This is why I put the question to you guys. I couldn't understand why Eastern Beaver would fit a fuse if one (according to my mate) shouldn't be fitted. As you say, 30 amps is a lot of current and it would need to be a serious problem to draw more than that. As I'm not good with electrics I thought I'd better get a second opinion.

As for damaging the Stator, I haven't got a clue why it would if the fuse went. Like you say its a mechanical item.

So say the fuse did blow and the reg/rec then stops drawing current from the stator, it would be like running the bike without a battery, yes? So if this happened would the bike be running off the battery until it depleted it and then stop running or would it just stop as soon as the fuse blew?

[bull]

it would be running off the battery, you might get maybe two hours of riding or so, maybe less, before the battery would lose to much charge and the bike would stop

[Beam me up]

Depends on the bike and battery.

I once stayed in Cologne. When I started the bike (Guzzi 1000) in the morning the charging light wouldn't go out. It was Sunday so no chance of finding spares so I decided to see how far it would go. 450 miles later we arrived home turned the bike off then tried to start her and she fired up no trouble. Didn't use the lights though, the weather was appauling through Belgium (always is), and it was dark by the time we were on the M25!