Topic: Electrical nonsense on my Sanglas bike (update aug 2nd)

[Raul CB750K1]

The electrical system of my Sanglas bike got me puzzled. You know, these spanish bikes had a Yamaha XS400 engine. The Sanglas bikes always had a reputation of having a weak electrical system, that is, that the battery discharged quite easily.

I have first-hand experience on this. Running with parking liights the battery gets fully loaded, but running with low beam -mandatory even at daytime-, the battery gets discharged. Problem is that you only notice it when you stop at a stoplight, when the bike suddenly dies and the battery is so empty that you can't even kickstart it, because it has no juice to feed the stator coil. So you need to carry your jumper cables all the time just in case.

I thought to myself: no worries. It must be because of the spanish-made regulator. Let's use the original Yamaha XS400 regulator. But I had to do some modifications to the wiring loom: the original regulator -electronic, spanish made- regulates the "positive" of the stator coil, and the other end of the coil goes to ground. With the XS400 regulator, it regulates the "negative", and the other end of the coils goes to +12V. No problem. Stator coils shows 5 ohm or so.

So I connect an ammeter to the battery. With the ignition on, it is discharging at 2A. No lights, no nothing, so it must be the stator coil drawing 2 amps, makes sense. Start the bike, and it shows charge at 2A or so, but as soon as the low beam is connected, it is discharging at a rate of 4A. Rev the bike, and above 4K rpm the battery charges at 1A rate with the low beam on. With the beam off, the battery charges at 6A or so. Thus, it seems that as long as you keep the RPM's above 4K, it will always charge even with low beam.

So I get the bike this morning for a club rally. First it gets a 20 min ride up to the meeting point, with no beam. The battery gets a little charge. From then, 200 km of low-beam riding. In a couple of coffee stops, the bike starts with the starting motor, like if the battery was charged. Looks good to me. But when I arrive home, stop the bike, try to start it with the starter motor, and the battery is weak.


So what's going on? It has been a fast ride. The ammeter showed charge about 4K, but the fact is that it is not charging. The rectifier was good, the six diodes, and there was voltage -dependent on the engine RPM- in the three alternator wires. The alternator is rated at 210W, so it should have enough juice to power the headlight, ignition and charge the battery.


I just hope some of you could give me any idea of where the missing current is going to.

[DarkRider]

How old is the battery? The battery may be shot from when the bike had its original regulator.

[Raul CB750K1]

How old is the battery? The battery may be shot from when the bike had its original regulator.

I should have mentioned it. I bought the battery just after I bought the bike, one year ago.

[DarkRider]

the battery could still be bad from the constant recharge and discharge. Age doesnt really have much to do with it if there is an issue like this. Also what wattage is your headlight bulb?

[TwoTired]

I'm surprised you haven't thought of this your self.
Mount a voltmeter or ammeter onto the bike.  Temporarily, if not permanent, so you can tell while riding when the battery is discharging, or when the load exceeds the alternator output.


Cheers,

[bryanj]

Voltmeter is good idea but make sure you get a moving coil not a moving iron meter. The latter is cheaper but can draw 1/4 amp to give reading whilst coil draws much less.
Still make sure it on a "switched" power or the battery will drain.

2nd thought could you have a slightly loose ground connection, had that on a Fiat and it stopped the battery charging fully intermittently

[Raul CB750K1]

the battery could still be bad from the constant recharge and discharge. Age doesnt really have much to do with it if there is an issue like this. Also what wattage is your headlight bulb?

The bulb is a regular H4 55/65. I know it because it seemed so dim -no wonder if the battery voltage is 12V at its best moment- that I replaced it to find a new one didn't glow much more.

Regarding the battery, even with several charge/discharge cycles, it shouldn't toast itself. Batteries can work in "float" mode or "cyclic" mode, and only the volts per cell to charge them differ. A good battery should last several tens -if not above a hundred- of charge/discharge cycles.

I'm surprised you haven't thought of this your self.
Mount a voltmeter or ammeter onto the bike.  Temporarily, if not permanent, so you can tell while riding when the battery is discharging, or when the load exceeds the alternator output.


Cheers,

Well, I must admit I didn't think about it. Couldn't see the forest for the trees. I just assumed that if in the shop it charged at 1A, it should charge the same on the road. It is indeed a good idea. Tomorrow I will tape one of my multimeters to the handlebars and check it out.

Voltmeter is good idea but make sure you get a moving coil not a moving iron meter. The latter is cheaper but can draw 1/4 amp to give reading whilst coil draws much less.
Still make sure it on a "switched" power or the battery will drain.

2nd thought could you have a slightly loose ground connection, had that on a Fiat and it stopped the battery charging fully intermittently

Voltmeter is a good idea but I rather go to the amp meter; directly between the battery negative and the earth cables. I already checked that there is no draw with the ignition off. My amp meter has a full scale of 10 Amps, but it has an internal shunt so it means that even if the current slightly exceeds 10 Amps nothing will toast- as long as you don't use the starter motor. I will check the other end of the ground wire - the battery lead is pretty well connected, have had to recharge the battery quite a few times...

[TwoTired]

I don't think the battery is a proven known good just yet.  Production processes aren't perfect.  Even new ones can be bad or faulty. They particularly don't like being deeply discharged.
While it "shouldn't" be bad, have tests proven it is good?

Does it trickle charge up to 14.5 V?  Will it stay at 12.6 volts after a rest and no load on it?

Does vibration shake something loose inside the battery?

Faith isn't a reliable troubleshooting aid, IMO.

Cheers,

[DarkRider]

i agree with two tired on this one..reason i suggested the battery is because my roomates truck just went through 3 new ones mind you those were boiled from a bad regulator but still the point being is a battery can be total crap right out of the box as well..

[Raul CB750K1]

Yeah, the battery could be faulty. While I don't have proof that it is good, I have evidence that the battery discharge is common in this type of bike, and assuming that the battery is -almost- new, I just followed that theory that says something in the line that "the simplest explanation of something is normally the best".


I didn't measure the voltage the two or three times that I have charged with the trickle charger. I can say that the bike cranked strong once I reinstalled it. It does stay at 12V with no load, even discharged. It has never been "deeply discharged" in what I understand as leaving it under load for an extended period of time. The maximum discharge it has undergone is when it was not able to crank the starter motor, but the starter relay clicked.


But it is pointless guessing about theories; tomorrow I'll connect the multimeter, ride the bike and will let you know the outcome. Obviously, if I ride for half an hour with positive charging current and the battery doesn't hold a charge, it is the battery. But I can say that as long as I ride with no low beam the battery charges. I point the fingers at the alternator, or why it is unable to deliver the rated power. It has no contacts, no brushes, I cut and soldered new terminals -old ones were corroded- so I'm confident the connections are clean and good. My guess was that an under-engineered regulator didn't feed the stator coil enough for it to deliver 14.4V, but a different model of regulator produces the same effect.


Tomorrow I will be able to post some data and I guess we can troubleshoot based on that evidence. Thanks all for your time.

[Raul CB750K1]

Rainy day today, couldn't test the setup. Hopefully tomorrow..... 

[TomC]

Hi Raul
     I have been riding a Yamaha SRX250 for some time. It has a 210 watt charging system. It is able to power my electric vest, 33watts, with no problem.
     "I thought to myself: no worries. It must be because of the spanish-made regulator. Let's use the original Yamaha XS400 regulator. But I had to do some modifications to the wiring loom: the original regulator -electronic, spanish made- regulates the "positive" of the stator coil, and the other end of the coil goes to ground. With the XS400 regulator, it regulates the "negative", and the other end of the coils goes to +12V. No problem. Stator coils shows 5 ohm or so."
     The stator coil does not have a "positive". It produces AC current which is rectified into DC current. My Yamaha manual shows the stator resistance as 0.36-0.51 ohms at 20C. At 5 ohms you have a problem if what you are measuring is one of the stator coils.
     The charging system on my Yamaha has a permanent magnet field. Does the XS400 have a permanent magnet or an electromagnetic field? 5 ohms would be about right for a field coil.
          TomC in Ohio

[Raul CB750K1]

You are right Tom, I was talking about the field coil, the one that is powered to generate the magnetic field.

I didn't check the stator coils; just checked there was voltage out of the three of them. But come to think of it, a check would be in order. Resistance between any two of the terminals, and half of it between the central terminal -not connected to anywhere- and any of the three terminals.

[Raul CB750K1]

I finally went around some measurements to see if I could understand what is going wrong with this bike. I connected two multimeters. The one above measuring voltage at the battery, the one below measuring current between the battery negative and the frame and negative cables. Negative values are "discharge", and vice-versa. In the right handlebar switch there is the light switch. Top left (1) is parking light, middle position (0) is "no lights" and top right (2) is "low beam".

I charged the battery with a charger for a few hours, connected the setup, started the bike -obviously with the kickstarter, because the current drawn by the starter motor can toast any thin wire-. At idle, the first measurement is this



With only the field coil and the ignition, it is drawing 3.62 amps (don't be fooled by the slow display refresh rate) and the battery drops to 11.42V. When I switch the parking light....




... the current draw drops to 3.24, while it should be higher.


Switching on the low beam....



voltage drops to 10.95 and current draw climbs to 8.69A. As the only difference is the low beam (55W), 55/11=5 amps, that is, approximately 3.24 amps (the previous reading) + 5 amps for the low beam.




I took the bike out for a short ride, looking at the multimeters all the way. After 20 minutes I stopped and took new pictures, this time revving the engine up to 6K rpm -the normal riding range-. This is what I got.


1. No lights.



Battery voltage is 14.21V, and charging rate is 7.02 amps. Sounds good to me.



2. Parking lights






Voltage is 12.67, charging current is 4.02. 3 amps less for charging. Parking lights means: parking light in the headlight shell, taillight, four illumination lights in the instruments and one idiot light in the dashboard. Being all T4 bulbs + a 5W bulb in the taililight, it means 4 + 5 + 5x(4) = 29W, that is, a little less than 3 amps. Measurements make sense.


3. Low beam.






Voltage is 12.09V, charging current is 0.91A. It is a little more than 3 amps more than in the previous scenario, and 3A is not enough for a low beam (55W). Still, there is positive charge. But the voltage has dropped very much, it should be about 14.4V.

The only thing between the alternator and the battery that could drop voltage at high current is the rectifier -connectors were renewed and I assume they are as good as new, I did it myself and have enough experience with soldering etc-. I replaced the rectifier for another one. To save you some time and pictures, the results were as inconclusive as this. While riding at high pace, at 6-7 K rpm, the voltage would slowly rise up to 13.0 V, and the charging current would still be around 1 amp. But as soon as you turn the blinkers -2 x 10W-, the voltage would drop to about 12V.


Seems that the alternator is capable of giving positive charge for the battery even with low beam, but not enough voltage to raise it to 14.4V. So the battery is always "undercharged" at 12V if you ride with the low beam on at all times. To support my theory, in one of our last rides I had the chance to see some pictures and my light was dimmer than the light of my riding buddies, being all of them H4's.



When I bought the bike it had the starter clutch broken. The bolts came loose sometime in its past. I had to drill and tap new holes in the rotor -posted pictures in the forum a while ago-, and by visual inspection I didn't see any damage in the alternator or field coil wires. The resistance measurements support the fact that they are not damaged. I could only think of a "bad" rotor, but as it is not suppoused to hold any charge, just break the magnetic field, it shouldn't give any trouble. I tried with a different regulator -as I said before- and it didn't make any difference.


I'm at a loss -sorry for the cheap joke- with this..... 




As a side note, I want to fix it under any circumstance. Besides my red Sanglas, I just bought another one in blue -the only two colours available. This one had everything original, from the paint to the exhaust, and only 10.470 km in the clock. I couldn't pass on it. I guess I would sell the red one, but as I only paid 500 euro for it and have spent -and learnt- a lot with it, I don't know what to do....

[TomC]

Hi Raul
     I wondered how you and your Sanglas's electrical system were doing. The numbers you have sound more like my CB400F1 than my Yamaha SRX250. As the alternator of the CB400F1 is rated at about 2/3 of the alternator of the SRX250 which is about the same as your Sanglas  My quick guess is that one of the three phases of the alternator is not working. One set of coils in the stator is open or shorted. Or a diode or two is bad in the rectifier.
     I have been riding my CB400F1 with a voltmeter across the battery and one across the field at the voltage regulator. These two voltages should be the same, more or less, until the voltage has risen across the battery to the voltage were the regulator starts to reduce the field voltage. This should be about 14.25 +/- .25 volts. If the field voltage is much less that the battery voltage the alternator output will be less that full. If the field voltage is much less than the battery voltage when the alternator should be producing full output this could be your problem. When making battery voltage and current measurements it would be good to know that the regulator is not reducing the alternator output.
     Over the next few weeks I will measure the current output of my CB400F1. I am going to put the amp meter between the positive wire from the rectifier and the rest of the electrical system. I am doing this to have numbers to compare with the output of the CB550 alternator I plan the install later the summer. Maybe I will learn some thing of use to you.
     I hope this is of some help      TomC in Ohio

[bryanj]

Raul, have you got, or can you get, the specs on the alternator output for the Yamaha in watts or amps output maximum and at what revs?

Sounds to me more and more like you have a high resistance contact somewhere. A trick I found useful on Fiats is to measure the votage at each end of the ground wire (+ve direct to battery and -ve to batt then other end of ground). Fiats regularly used to loose 1/2 to 1 volt cos of bad fittings/dirty maetal on engine and this lowers the charging rate.

[Raul CB750K1]

Raul, have you got, or can you get, the specs on the alternator output for the Yamaha in watts or amps output maximum and at what revs?

Sounds to me more and more like you have a high resistance contact somewhere. A trick I found useful on Fiats is to measure the votage at each end of the ground wire (+ve direct to battery and -ve to batt then other end of ground). Fiats regularly used to loose 1/2 to 1 volt cos of bad fittings/dirty maetal on engine and this lowers the charging rate.

Rating is 180W at 5.000 rpm


I plan to do a couple of things. First, to connect the field coil directly to the battery and run the bike and see the progression of the output voltage. Second, I have a NOS alternator, with just a little surface rust, but never used -the guy I bought the new bike from gave it to me among other spares-, so I will use it to compare resistance measurements.

I have found many threads around the net talking about the same problem in XS400. All the directions were about replacing regulator and/or rectifier. A guy from the Sanglas forum suggested that, with time, the hot oil removes the varnish insulation so the spires of the alternator gets short-circuited. That would make some sense, but in the first 5.000 or 10.000 km (or miles) the oil has plenty of chances to get hot and burn the varnish. I hope that the resistance measurement give me some hints. The first thing I thought of was a non-working phase, but it doesn't seem to be the case.

[Raul CB750K1]

In spanish, "winding" is "espira". I just guessed that "spires" means the same. But then it dawned on me the Judas Priest song "Cathedral spires" so I may very well be wrong....

[Raul CB750K1]

Yesterday I met with another member of the Sanglas club. We were chatting Sanglas and the charging subject popped up. He told me he overcame it. I asked how, and he told me he was replacing regulators and rectifiers for good measures, when it dawned on him that maybe the field coil terminals were swapped. He swapped them and since then the bike had no more charging issues.


You can imagine how my jaw dropped when I heard that. I just asked him whether he was positive it was fixed and he said yes. Obviously, swapping the terminals only changes the polarity of the magnetic field, but I thought that maybe, after years, the rotor could have been magnetized and it didn't cut the magnetic field anymore.

So I swapped the terminals, did the same check this morning and..... guess what? With low beam, 1 amp charging and 14.4V at the battery terminals!!!!


It was too good to be true. After 20 minutes, battery voltage dropped again to 12V.

[DarkRider]

Now it might be a battery from being put through all the other tests with the termanals the way they were prior...

[Raul CB750K1]

Got some news on this. I got me an original XS400 regulator, the mechanical one. If it works in my CB750, why shouldn't it work in this bike?

The other day we had a run with the Sanglas club so it was the perfect time to check it. If the bike stalls I have always friends with tools and willing to help. So I run the bike with the original regulator, and when we stopped halfway for a rest the voltage was dropping, as before. Then I connected the mechanical regulator. It always charged at 14.4V with no lights or parking light, and 13.75 or so with low beam, that would drop to 12.5 V. Anyway, when I arrived home, I tried to start the bike with the starter motor and the low beam on and it did, the battery was fully loaded!!!

Today I went for another ride. Presuming that I had found the problem, while I was on my way I thought it would be a good idea to revert to the original (electronic) regulator and check what the charging voltage is, and if it drops, stop and connect again the mechanical regulator as it proved to be in good order. So I stop at a gas station, connect the original regulator -I had the replacement under the seat, so it is just a matter of changing a block connector. Switch the ignition off, swap the connectors, switch on, kickstart it, off I go, and a few meters away in the road the bike just suddenly dies. WTF?? I stop and I see smoke coming from where the original regulator is, under the battery.


From my experience, both intentionally and unintentionally, when an electronic device smokes it has given away its life. So why did the original regulator blow? Obviously, I put the mechanical regulator back, started the bike, continued my ride and when I arrived home, I stopped the bike and started it with the starter motor, no less than 15 times with either the low or high beam on. In all of them the bike started fine, the battery was fully loaded.

So it seems that it is time to put this new regulator in place of the fried one. Now it is time to theorize about what happened with the original regulator. Maybe it degraded with time, and it was unable to provide the field coil with enough current -not tension- as to generate a strong magnetic field. The connection to a well-charged battery may have proved too much for it, as it has been working for years with batteries not loaded to its fully charge. The theory of wrong connections is not valid because the connector block is keyed, there is no way to connect it reversed.

Unfortunately, it is somewhat something like "swiming for days just to die at the sand". The bike burns smoke like a two-stroker, an engine rebuild is in order, I have bought another same bike with much less miles that runs like a champ and I will be -probably- selling this soon. But at least, if the charging circuit is in order, you can run the hell out of the bike as long as you don't forget to top off the oil. I would like to keep both bikes -those of you with two bikes of the same model know what I'm talking about-, but I have another five bikes and still want another one, so it will have to go sooner or later. So I will either sell it stating the actual condition, or wait, rebuild the engine myself, and either keep it or sell it at a higher price. Not because I can make any profit with the engine rebuild, but because it is easier to sell a bike that has just been rebuilt and is ready to go.

[bryanj]

Raul, everything on the last post , to me, points to a bad ground at the regulator rectifier this would give an incorrect voltage at the reg which electronics dont like but mechanicals can live with.

Might i suggest a seperate, extra, ground wire connecting the regulator, engine case and battery negative

[Raul CB750K1]

Raul, everything on the last post , to me, points to a bad ground at the regulator rectifier this would give an incorrect voltage at the reg which electronics dont like but mechanicals can live with.

Might i suggest a seperate, extra, ground wire connecting the regulator, engine case and battery negative

As you suggested in previous posts, I checked the ground connection at the engine -the thick cable between battery negative and chassis. Well, this engine has rubber mounts, therefore the ground is connected to the engine itself instead of the frame. The connection was solid and clean.

The alternator is a three-phase star. The center connection is left as is, not connected to ground. Then the other three poles go to the rectifier, from where the rectified voltage comes. Negative to ground, positive to +. That's where the regulator is connected. It is connected in parallel with the output voltage, and depending on the voltage it gives an output voltage to the field coil. The regulator has only three wires: positive, negative (ground) and output. The three of them go to the block connector; the regulator doesn't get the ground from the mechanical connection. Furthermore, I renewed all the blade connectors when I bought the bike.

I was pissed off when the regulator blown, but also, gave me some relief as if the mfcker who had been causing trouble for so long was taking a little punishment that it deserved....    That is, if the bike was working well with another regulator, and reverting to the one that was in service for the last 25 years caused it to burn, then there should be something wrong with it. It could also be something else what was wrong and burned the regulator, but then again, why did it burn it after using another one and not before?

[rchrdms]

Raul,

Hi. I suggest that you charge the battery off the bike and then leave it on your bench for a full day. If it drops to 10v or less you have a dead cell. This will cause your rectifier to go wrong too.

Another idea is to test the battery votage at idle with a voltmeter to make sure its charging above 12v. If it's very high, it's a voltage meter; if it's too low, it's the charging curcuit(alternator or rectifier).

You can find the specs in your manual(I hope) this will tell what rpm's to test at.

Hondas in the CB models are famous for electrical problems too.

Good Luck.

Richard

PS you can look through the forums for advice on making your own rectifier--it will save you a lot of money. I think it was Texpert who showed me.


 

[Raul CB750K1]

Thanks for the advice Richard. The battery is OK, it keeps 12.5 V even after two weeks sitting on the bike.


This bike has the regulator and rectifier as separate units. The rectifier -diodes- is OK; it is the regulator the one that seems to be giving trouble. Problem is that it has somewhat -degraded-. That is, if you don't get charge, you replace the regulator. But it was working well with the low beam off, band working bad with the low beam on.


I guess that now that it is toasted -or so it seems- it is clear that a replacement is in order....