Regulator/rectifier question

[PaulW]

Question regarding the wiring of the rectifier for a 1984 43F - Kick start

I have a five wire rectifier, I think the following is correct:
2 white = AC in.
Black = Ground
Red = Rectified/Regulated out
Brown = Monitor/sensor wire

The wiring diagram shows the Red wire connected to the Battery and the Brown to the rest of the circuit after the main switch, so here's my question:

If you start the bike (which I can as it's a kick start),with out turning the Main switch on, you will get unregulated Voltage to the battery, (because the monitor/sensor wire is not in circuit)
Is the wiring diagram correct - as it would make more sense if the Brown wire (monitor/sensor wire), was connected to the Battery, thus controlling the Red wire supply to the rest of the circuit.

Regards

PaulW

[xtrider]

One thing that jumps out to me is you should never be able to start the bike with either the main ignition switch or the "stop" switch turned off . If you can do that you have wires hooked to where they shouldn't be . I'm not at home currently to look over the schematics for the other part of your question though.




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[PaulW]

Yes I guess your correct - but I'm building a 'tracker' and I'm rewiring it, so when I tried it - it was with a 'non standard' circuit.

It was the first start after a total engine rebuild, and to be honest I didn't think it would start quite so easily, so I was excited with the sound and wasn't really watching too closely!
After I'd noticed the battery was bulging and was red hot, I measured the voltage across the battery, 22.4 volts, so it's no wonder it was massively over charged, (now knackered). The regulated Volts came out as 14.2V, which I guess is OK for battery charging.

I've connected the Red and Brown wires, so now I'll only get Regulated Voltage into the circuit, so I'm hoping that will be OK, when I replace the Battery.

I can't quite understand why a separate monitor wire is needed anyway, why not internally connect! (I can only think that if the monitor wire was permanently connected there may be a slight drain on the battery).

Anyhow any advise gratefully received

Regards

PaulW

[thetrecker]

Hi Paul,
From a previous bike ( Aprilia)which had lousy charge voltage going from the reg. to the battery, we found the 2x55watt headlight load was taken from the reg. output ( rather than the battery) and the cable going to charge the battery went a roundabout was which resulted in poor voltage available to charge the battery, around 12.8v. After fiddling with the cable routing and not getting great results most of us went for a regulator from a goldwing and grafted it onto the bike. This one had a voltage sense cable ( connected direct to the battery pole) and my understanding of it was that the reg. can react quicker to big current draws from the battery ( eg- aux lights, heated grips) and give it more voltage to recover the drain. We found 13,8 v was available to the battery always even if a load was switched on momentarily, a good result.
The basic reg. is a shunt type, where max current is produced all the time, whatever current is needed by the bike is passed to the output and the rest is transferred to heat and dissipated through the heat sink.Because of this the reg. needs to be in the airflow and mounted to a metal base to help with heat loss or it will fry.
The newer mosfet type only produce whatever current is demanded and generally have an easier life as heat is much reduced.
Tom

[PaulW]

Hi Tom - thanks for you reply, I was trying to understand why a monitor wire is included, (bearing in mind they are electrically connected, when ignition is on)

From what I can gather the alternator sends the AC through a rectifier which then converts to DC
This DC is then fed to the Battery and lighting circuits. Two schottky diodes, which monitor the DC voltage, short the voltage down to ground if it rises above a set level, (hence producing loads of heat)

I've bought a single phase regulator/rectifier, (the type used on old British bikes), rated at 160W. Physically almost identical, same mounting holes.
Just tried it - seemed OK giving 14.6 V at the battery.
This thing only has 4 wires:
Two yellow - AC input
Red - Battery, (regulated 12V out)
Black - Ground

Ran the bike for 5 - 10 mins, Regulator gets quite hot, but not smoking.
Have not wired the rest of the bike so can't test with all lights on yet, I did test with a 60W bulb; that seemed OK.

Although I guess the big test is with no lights on, as most of the wattage would then be dumped in the regulator.

Cheers

Paul

[xtrider]

Isn't there three white or yellow wires coming out of the stator that goes to the regulator plus then the red and brown or green for the pickup gen ? The E-start bike run off the battery so they don't have the ones going to the ignition other then the pickup gens.




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[thetrecker]

Hi Paul,
I did try to discuss the voltage sense wire in the previous post, the first part of the post was to give a little background to what led us to the voltage sense wire option, maybe I didnt explain myself correctly.
With ref. to the generator, it has 3 yellow cables carrying around 60 volts AC each to the rectifier, it is referred to as a 3 phase generator. All the 3 phases are to be used ( during voltage production) so as they heat up in the same way and maintain the laminate protection etc in the windings.
You say you have a single phase rectifier/ regulator. If it has 2 yellow wires, I don't think it is single phase. If you are just using one yellow cable from the generator , you are asking one phase only to generate the requirements of the bike and you will burn out this winding quickly. Rough output from the generator of my Kawasaki KLR 650 is 14volts/ 14 amps @8000rpm across the 3 phases, I assume it is similar to the XT. So 1 phase can output less than 5 amps, around 70 watts. You will easily reach this with 55watt head and 5watt tail and a few dash lights.
Can you tell us how you have it wired?
Tom

[motorang]

Hi there,
as far as I know the brown sense line is switched by the ignition switch for not draining the battery when the engine is shut off.

5 cable three phase regulators seem to be different here and prevent the battery drain internally (e.g. Kawasaki KLX). Had one of these on my old SR500 some time, which originally has a 6 cable type regulator (extra brown sense wire).
So both regulators work well on the same engine, but if you connect brown and red on your 6 cable regulator you may kill your battery over time. I would recommend to do a measurement there (Amps drained from brown to earth with ignition off).

Andy

[PaulW]

Hi - thanks for all the replies

My bike IS single phase, with two white wires to the rectifier supplying the AC, the other coil on the alternator supplies the CDI unit to produce the sparks, (they are totally independent). In fact this bike will run happily without a battery or Rectifier ! (the CDI unit has an independent rectifier built in).
To make things simpler I bought a single phase rectifier/regulator , (two yellow - AC in, Red - +12 out, Black - Ground), I've tried this and it seems to work well, giving around 14V at the battery. The rectifier gets hot but not excessively.
Getting back to my original query, (rectifier two White - AC in, Red - +12 out, Black - Ground, Brown - monitor wire), what I've realized is that I connected the Red to battery but the Brown was open circuit, so when the bike is running the monitor wire is seeing 0V, so the Red wire will supply max voltage, as there is no monitor signal to tell it otherwise!!
So result massively overcharged battery, (now dead).

So now using a simpler rectifier, (as above), seems to have solved the problem

Thanks everybody - It's been a big help to help me understand rectifiers

Regards

PaulW