Electrical issues - Alternator? Rectifier?

[Grahamm]

As some of you may just remember I had some issues apparently with my battery some time ago (a lot of details follow, so some people may want to hit next message now... )

I put a new battery in and it seem to sort out the problem, but similar things seem to be happening again now, so I've looked into the matter further and I think there may be a fault with either the alternator or the rectifier.

Basically what happened is that, on Wednesday night I went to the dry ski-slope in Southampton and although it's a fast run along the motorway, when I get into town there's a lot of slow riding filtering through traffic before I get there.

The upshot of this was that when I was about to leave a couple of hours later, the bike was sluggish to turn over and it only just started at the point where I was thinking "Oh foc, I'm going to have to bump start it again".

When I got home I switched off (using the key) and then, out of interest, tried starting it again. It did start, although slightly reluctantly, but when I tried switching off and starting it once more, it turned over quite slowly and wouldn't fire and the battery was clearly getting drained.

So I charged the battery overnight on the Optimate, then this morning (just before midday) I checked the charge which was 13.18 volts. I started it, switched off and checked again, getting a reading of 12.5 volts

Following the advice in the Haynes Manual I then lifted the tank, disconnected the negative lead and checked the ammeter getting a reading of 1.5 milliamps with the alarm in service mode. This is slightly higher than standard, but it says that's to be expected with an alarm and it's not the sort of power drain that would suggest a short-circuit.

I left it for a few minutes and got a reading of 12.64 volts, so I started it again and got a reading of around 14 volts until it warmed up and then got 12.2 volts at idle.

Next I tried checking the voltage whilst revving and discovered that it would only get to about 13.8 volts at 5000 RPM and dropped to about 12.5 volts at idle.

This is more of a concern because, according to Haynes, the Regulated Voltage should be 14.1 to 14.9 volts at 5000 RPM.

I switched off, put the alarm in service mode again with a reading of 12.55 volts, started it once more, but after this it was sluggish to turn over and I couldn't get it to start any more.

I put it back on charge and about 3pm the Optimate said it was ok with a reading of 13.18 volts, but I noticed that the volts were starting to drop and a few minutes later it was 12.85 volts, but a check with the ammeter said it was still only drawing 1.5 milliamps.

I left it off the charger to see what would happen and at 16:45 it was 12.72v at 19:50 it was 12.65v and at 22:05 it was 12.63v, although when I tried to start it just before writing this, it seemed ok.

So it seems, from what Haynes says, that either the Alternator or possibly the Rectifier may be dodgy and the battery simply isn't getting the charge it needs.

Does this sound right and, if so, is there anything I can do about this or anything else I can check or do I just have to get a new Alternator or Rectfier?


Any useful suggestions would be appreciated.

[keithfzs1000]

Initially check the alternator brushes, they wear. At tick over you should get around 13V across the battery, rising towards 14V when revved. Hope this helps. Also check condition of the commutator as poles can get worn, hence not giving a good contact with the brushes. A Haynes manual should have all the tests that need to be carried out on the charging circuit. Check battery plates aren't contaminated & electrolyte is good (should be no problem with new battery though). Alt' brushes are pretty cheap, Reg/rectifiers are expensive. Check the cheap option first. 

[Fazerider]

Low volts so soon after riding definitely points to a charging issue and if the alarm and instruments are drawing 1.5mA that only means about 1AH of drain per month.


There's no commutator/brushes to worry about, it's an AC magneto.
Check the three white leads from the generator all measure about 0.3Ω to each other (remember to subtract the multimeter's lead resistance) and check there's no continuity to ground.
If the wiring and connectors are all in a good, secure condition (check the negative connection to the chassis too) then it does point to the reg/rect as the cause of the problem. Prolonged under-charging may have weakened the battery too.

[Grahamm]

I've checked the resistance on the Alternator wiring and it seems to be in the recommended range of about 0.22 to 0.34 ohms, however a) that's at 20 degrees (not about 13 as it is now) and b) my multimeter seems to be a bit screwed as when I directly touch the probes together it registers about 0.3 - 0.4 ohms instead of zero (and there's no zero adjustment!) but it only goes up to about 0.6 or 0.7 ohms which looks ok.

There doesn't seem to be any shorting to ground either.

The battery is a sealed gel-type so there's nothing I can do with that.

Taking the alternator apart requires tools I don't have and, from looking in the manual, is probably out of my comfort zone, so I think I'll have to take it to the garage

ADDENDUM - Ah, just seen Fazerider's post. When the bike's at home it's always on the Optimate, the battery was new only just over a month ago and I've only done about 800 miles since then, so I don't know if that would count as "prolonged undercharging".
 

[Fazerider]

A battery that new should (hopefully) have coped OK.
I'd try a new reg/rect, there are plenty of aftermarket ones on ebay at around £30…. probably cheaper to try one of them rather than getting a garage to diagnose the problem.

[Dead Eye]

Just a quick query; from doing some electrical work on my Gen 1 the other week, my battery was registering at around 15v even though the bike had been sat off for a several hours - I'd suggest my multi-metre is out since it is old (and analogue) but it reports correctly on other batteries (think AA or 9v batteries)

So, ignoring the multi-metre, any reason for the high voltage?

[Grahamm]

I'd suggest checking the meter against another bike or car battery or getting another meter and checking your battery first .

[schlumpf]

Mostly the batteries have a problem. And usually people hold on to the voltage they've taken and claim their battery is okay.

The reading of 15V is definitely too high and not possible with this type of battery. I would blame it to the multimeter.

A fully charged battery reads 13.8V, when connected to a charger. As soon as it rests for a while the voltage drops to somewhere between 12.5 and 12.8V. Have observed this many times when charging my battery during winter. And this is also on par with the manual. It says to wait for 30 minutes after charging for the final voltage to settle.
So far so good.

To determine the condition your only information is based on the voltage at the terminals. This does not say anything about the inner status of the 6 individual cells and their respective capacity. One weak cell is enough to cause trouble. You need to take a complete discharge measurement to make a valid statement. I guess this is beyond the capabilities of most of us.

If the battery is proven to be fine (because new) I would investigate the starter. Typically they fail bit by bit. At certain positions they might have a problem, not able to provide the initial torque. A few degrees of rotation later all appears to be fine. Assume they have 20 or so individual coils. A single one is not working properly.

Of course these are all guesses. I don't know the history of your bike.

[BIG MAC]

Isn't it worth checking the connections and performance of the starter motor and the solenoid / handlebar switch resistance?

[bigralphie]

Any sign of blackening on the stator ?

[Grahamm]

OK, a follow up to this.

I went out on the bike this evening. It started pretty much ok about 6pm, but as it was only a few miles ride to where I was going I kept the gear down and the revs up.

About an hour ago (11pm), ready to come home, I tried to start the bike, however whilst it was turning over quite acceptably, it wouldn't fire, a very similar situation to what I described in this thread (that was before I replaced the battery) not least because there was a lot of condensation on the bike seat.

After about half a dozen attempts at cranking it, unsurprisingly I ran the battery down, so I had to resort to bump starting it. When I got home I checked the voltage and got a reading of 12.71v

I've put it back on the Optimate now, but surely there has to be something screwed up somewhere if it will turn over but not fire.

Regarding the comments above:

A fully charged battery reads 13.8V, when connected to a charger. As soon as it rests for a while the voltage drops to somewhere between 12.5 and 12.8V. Have observed this many times when charging my battery during winter. And this is also on par with the manual. It says to wait for 30 minutes after charging for the final voltage to settle.

Ah, I wasn't aware of that, thanks for pointing it out.

If the battery is proven to be fine (because new) I would investigate the starter.

As I mentioned above, the starter was turning the engine over fine, but it wouldn't fire.

Regarding the Stator, I really don't feel confident about playing around with that, however I'm going to try to check the Rectifier tomorrow.

[BIG MAC]

Try something for me..does the bike start with the hazards switched on and do the revs rise and fall in time with the flashing?

[Grahamm]

Try something for me..does the bike start with the hazards switched on and do the revs rise and fall in time with the flashing?

Yes, it starts wtih the hazards on, but the revs don't seem to rise and fall noticeably in time with the flashing.

When I started it and it was warming up the revs were going roughly between 1490 and 1610, but it made no difference whether the hazards were on or off. I tried again later (after the stuff posted in the message below) when it was warmed up and idling from around 970 to about 1070 however the hazards still didn't seem to have an effect.

[unfazed]

Sounds like the regulator/rectifier, why not borrow a digital meter and check it as yours may be dodgy. There are a few foccers down your way maybe one of them has a meter which you could check it with.

[Grahamm]

I did some more looking around online and found these very useful posts: http://www.600riders.com/forum/showpost.php?p=579412&postcount=3  and http://www.600riders.com/forum/fz6-technical/52536-troubleshooting-maintenance-guide-fuel-pump-battery-charging-brake-bleeding.html and this handy video showing how to test a rectifier/ regulator (or RR for short to save me typing it every time!)

Stock motorcycle regulator/rectifier check out

I'd charged the battery overnight on the Optimate again and got 12.83v at 3pm.

I then checked the RR with the Diode tester as per the video above and got three zero readings and three 540 readings, then three 550 readings followed by three zero readings so that suggests it is rectifying ok.

I started it with the hazards on as Big Mac asked above and it ran fine, so I let things settle down for a while as it warmed up and then found I was getting a reading of 12.15v from the RR output at tickover and 14.12 at 5000 rpm. According to the manual, the output should be between 14.1v and 14.9v so that seems to be low as it's the very bottom of the range.

Next I tried checking the AC output from the Alternator by reading the values from the white wires leading into the RR. At tickover I was getting 10.2v but it stayed at that level even when I revved to 5000rpm (one of the readings on one of the pairs of wires actually dropped slightly to 9.8v)

According to the link above, I should be getting "1300 RPM ~ 15 - 20vAC, 2500 RPM ~ 40 - 50vAC, 5000 RPM ~ 80 - 90vAC" but I was getting nothing like that, so I'm wondering if that means that the alternator is shot? But, if so, why was I getting 14.12v output with only 10.12v going in?? The only difference was that I hadn't unplugged the lead from the alternator, but surely the volts shouldn't change with the load, only the current draw should change, shouldn't it?

This is all very strange...!

PS @unfazed, I am using a digital meter although I haven't checked it against another one.

[schlumpf]

(Please take care to have your multimeter set to the right position: AC for the white leads, DC for the battery voltages.)

Under load the voltage on the white wires can be below 12V. Because the voltages from all 3 wires are added up (in some kind, it's a star configuration, similar to your electric oven at home). So that's not a worry in general.

Sounds to me as your RR is okay.

Also keep in mind that your battery is partly drained after each start. If the current from the RR is primarily needed to replace the charge in the battery who might get a low reading near 12V. It takes several minutes (maybe 5 .. 10 minutes, depending on battery conditon and revs) to reach steady conditions again.

[unfazed]

I just replaced the regulator on my sons 2003 Foxeye 600 and everything had tested ok,  but  it was failing under load and the only real indication was a faltering at around 7 to 8000 revs when riding aggressively.
I discovered it was charging eratically at high revs which led me to believe it was causing the faltering and since I replaced it bike is running cleanly again.

Check as Schlumpf said that the meter was set to AC when checking the white wires, however a faulty Regulator/Rectifier would effect the readings.

I would be inclined to change the regulator/rectifier first as there are plenty of spares and  it is a Shindengen SH719AA. I have not heard of many FZ600 stators or for that matter Regulator/rectifiers failing

[chris.biker]

How long has the present battery been in the bike, and what make is. I found that I was replacing cheaper replacement batteries after a year. So fitted a YUASA  I have replaced it this week after four years, it did not let me down every time but the new replacement spins the starter motor much faster. My bike is a Hornet and on their forum advice is constantly given to replace rectifiers I often wonder how often it is just an aging battery problem.

[Fazerider]

... why was I getting 14.12v output with only 10.12v going in??

That's thanks to the way AC is measured. The meter will be telling you the r.m.s value of the AC waveform which is the equivalent voltage for power delivery... the peak voltage of the waveform is higher than that. A 10.1v r.m.s sine wave will have a peak voltage of 14.3v, a spikier waveform will have an even higher peak. The top bit of the waveform (i.e. above whatever the battery voltage is) is where the diode goes into conduction and starts delivering useful current to the battery.

[Grahamm]

(Please take care to have your multimeter set to the right position: AC for the white leads, DC for the battery voltages.)

Oh I am. I already blew the 250mA fuse when I forgot to change the setting from Amps to Volts and touched the probes to the battery terminals!(Oops)

But it was definitely on the 200v AC setting when I was reading the white wires.

Under load the voltage on the white wires can be below 12V.

Yes, I've just seen Fazerider's post, it's been a very long time since I learned about RMS voltages... The question is: Are those values that that other post mentions (90v!) correct? If I disconnected the plug from the stator to the rectifier and measured that, without load, rather than the input to the RR, would I get them then?

I just replaced the regulator on my sons 2003 Foxeye 600 and everything had tested ok,  but  it was failing under load and the only real indication was a faltering at around 7 to 8000 revs when riding aggressively.

Hmm, that's interesting. A few times I've thought I've felt a slight "twitch" when I was riding, but I'd put it down to either my imagination or maybe a bump in the road.

But does that mean that, when the bike is running, it's actually getting power from the RR rather than the battery? 

I would be inclined to change the regulator/rectifier first as there are plenty of spares and  it is a Shindengen SH719AA

It's also £60 which I don't want to spend if I don't have to if it isn't that which is causing the problem :-/

How long has the present battery been in the bike, and what make is.

The battery is only about a month old this is the one I bought to replace the old one when I first started having these problems.

Initially it seemed to have sorted the problem, but now it's come back which suggests that the battery may not have been at fault (or, at least, not entirely).

[BIG MAC]

The reason I ask Graham is that my mk1 had a dodgy battery and putting the hazards on somehow foxed the charging circuit into giving just enough for the engine to run. I managed to ride the thing from Chelmsford to Portsmouth in the dark with nothing but hazards...even braking would make it cut out because of the brake lights!

[schlumpf]

Yes, I've just seen Fazerider's post, it's been a very long time since I learned about RMS voltages... The question is: Are those values that that other post mentions (90v!) correct? If I disconnected the plug from the stator to the rectifier and measured that, without load, rather than the input to the RR, would I get them then?

Right, the white wires alone should give a very high reading. 90V AC might be possible. On my FZS1000 it was about 40V (if I remember correctly ..). The absolute value is not important as long as all 3 readings are similar and in the range 30V or up.

Even if all measurements are fine this is no absolute proof that the RR behaves the same while riding.

To narrow down the bug you could still do some more experiments:
- Charge the battery fully up. Unplug the RR completely. If possible switch off all lights (by pulling the respective fuses if no switch is present). This should give you enough power for maybe 30 minutes. Go for some test rides.

- And/or connect your multimeter directly to the battery terminals. Tape it to the tank, or wherever, to be able to observe it while riding.
This should give you a indication whether a voltage drop occurs at the battery.

Any sudden voltage drop at the battery will be caused by a short circuit somewhere in the system. Sometimes it's only a damaged cable insulation, making contact due to engine vibration.

Avoid focusing only to the positive lead. Ground is as important.

In case you decide to swap your RR you can go for almost any other type. They all (not only Yamaha's) work the same way. The only difference is power rating. All modern bikes use Mosfet type RRs. FH012AA is a very popular and reliable replacement.
Only trouble is to find one with matching connector. Maybe unclipping and re-using the old connector housing does the job. 

[Fazerider]

... Are those values that that other post mentions (90v!) correct? If I disconnected the plug from the stator to the rectifier and measured that, without load, rather than the input to the RR, would I get them then?

Yes. That webpage has me slightly puzzled, it states that the AC voltages should be that high on-load which is possible with certain methods of regulation, but not the one that they show as being used by the FZ6.
Shunt regulation simply loads the magneto heavily when the battery voltage gets to the 14.5v region so the AC voltage shouldn't be anywhere near the figures quoted.
Off load, i.e. with the white leads not connected to the R/R, the voltages will increase pretty much in line with engine revs. If you try that measurement I'd keep the revs below 5000rpm as I'm not sure what the insulation is rated at… and be careful, the voltages are potentially lethal since they're coming from a low impedance source.
I still feel that a cheap aftermarket or second-hand regulator/rectifier is the simplest way to diagnose the problem.

[chris.biker]

How long has the present battery been in the bike, and what make is.

The battery is only about a month old this is the one I bought to replace the old one when I first started having these problems.Initially it seemed to have sorted the problem, but now it's come back which suggests that the battery may not have been at fault (or, at least, not entirely).

One of the first things taught on any of the training courses I go to is '' just because you have swapped it for a new component it is not 100% that the new one is good.''  I would try changing it under warranty.

[unfazed]

In reply to some of you questions

Yes you can check the alternator in a no load condition, but be extremely careful for the reasons fazerrider has stated.

To do this, ensure you have a fully charged battery.
Disconnect the regulator/rectifier and then start the bike
Check the AC voltage on all three phases (white wires). All three phases should be around 20V AC and it should climb to as you rev the engine and as fazerrider states don't rev it over 5000.
If all three phase rise and fall (within a few volts of each other with the engine revs then the alternator is is doing what it is supposed to be.


In my case the regulator was causing slight over charging occasionally and may have caused the CDI to drop out due to over voltage protection.