Lost an alternator phase

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JimNH

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Just like my oil pressure gauge helped identify a split conical seal before it caused a problem my voltage monitor in place of the nearly useless red light identified a charging problem.

I've got a 3 phase Sparks alternator and normally, with the headlight on, anything above about 2300 RPM will keep the monitor green. Suddenly it needed 3500 RPM for the same so I suspected that I lost one leg of the alternator.

I pulled the oil tank to get at the bullet connectors hiding under there. They were good but I was able to confirm one leg open. I suspected the failure might be right at the stator so pulled the primary but it looked OK. Pulled the stator and found the broken wire where vibration had cut through the plastic split sleeve I had put around the alternator leads. Repaired, heat shrinked, sleeved, re-positioned, etc.

The clutch was getting a little draggy so it was time to clean the plates anyway. It occurred to me that I've done more oil changes due to issues than to oil change intervals!

Whole lot O' shakin' goin' on.
 
Hello
Are you using the sparks power box (voltage rectifier/regulator) with your 3 phase alternator?
I had a breakdown a couple of years ago, toddling along one sunday and the red ignition light came on (Mk3) still running but decided to head for home, approx 20 miles away. A few miles further on she cut out completely, recovered back home and investigating what happen, with the help of Al Osbourne, (he checked the power box out for me and told me how to check the output of the alternator using just a headlight bulb) The powerbox had failed, but had fed AC current into the system at quite some amps, heating the battery up till it was red hot and killing the electronic ignition.
The battery when it cooled down was completely knackered (it looked as though someone had sucked all the insides out, it was that deformed)
I was extremely lucky it did not explode.
Refitted the old boyer that the bike came with, a new battery, and one of Al Osbourne's power boxes and she was back on the road.
Just thinking about this, i wonder if it might pay to fit a couple of diodes in the DC output from the power box to prevent this type of failure cooking the bikes electrics/battery?
Regards
Peter
 
dobba99 said:
...I was extremely lucky it (the battery) did not explode. ...I wonder if it might pay to fit a couple of diodes in the DC output from the power box to prevent this type of failure cooking the bikes electrics/battery?
Click to expand...
I've not seen one of these fail in the "close" position; always burns open as if it were a fuse. It would seem that enough current to cook your battery should have popped the inline fuse. It might behoove you to verify its rating...

So glad it didn't melt the battery all over your bike!

Nathan
 
dobba99 said:
Hello
Are you using the sparks power box (voltage rectifier/regulator) with your 3 phase alternator?
I had a breakdown a couple of years ago, toddling along one sunday and the red ignition light came on (Mk3) still running but decided to head for home, approx 20 miles away. A few miles further on she cut out completely, recovered back home and investigating what happen, with the help of Al Osbourne, (he checked the power box out for me and told me how to check the output of the alternator using just a headlight bulb) The powerbox had failed, but had fed AC current into the system at quite some amps, heating the battery up till it was red hot and killing the electronic ignition.
The battery when it cooled down was completely knackered (it looked as though someone had sucked all the insides out, it was that deformed)
I was extremely lucky it did not explode.
Refitted the old boyer that the bike came with, a new battery, and one of Al Osbourne's power boxes and she was back on the road.
Just thinking about this, i wonder if it might pay to fit a couple of diodes in the DC output from the power box to prevent this type of failure cooking the bikes electrics/battery?
Regards
Peter
Click to expand...

Interesting failure.

If you put additional diodes in the circuit you'd have the voltage drop across them decreasing the charging voltage.

I'm surprised the red light came on as all it really does is monitor the AC voltage out, and it seems you had that.

The regulator that I have is unmarked so I don't know who the manufacturer is. The stator proudly says Sparks so I would think they'd mark their rectifier/regulator as well.

Do you have a Sparks 3 phase?
 
JimNH said:
dobba99 said:
Hello
Are you using the sparks power box (voltage rectifier/regulator) with your 3 phase alternator?
I had a breakdown a couple of years ago, toddling along one sunday and the red ignition light came on (Mk3) still running but decided to head for home, approx 20 miles away. A few miles further on she cut out completely, recovered back home and investigating what happen, with the help of Al Osbourne, (he checked the power box out for me and told me how to check the output of the alternator using just a headlight bulb) The powerbox had failed, but had fed AC current into the system at quite some amps, heating the battery up till it was red hot and killing the electronic ignition.
The battery when it cooled down was completely knackered (it looked as though someone had sucked all the insides out, it was that deformed)
I was extremely lucky it did not explode.
Refitted the old boyer that the bike came with, a new battery, and one of Al Osbourne's power boxes and she was back on the road.
Just thinking about this, i wonder if it might pay to fit a couple of diodes in the DC output from the power box to prevent this type of failure cooking the bikes electrics/battery?
Regards
Peter
Click to expand...

Interesting failure.

If you put additional diodes in the circuit you'd have the voltage drop across them decreasing the charging voltage.

I'm surprised the red light came on as all it really does is monitor the AC voltage out, and it seems you had that.

The regulator that I have is unmarked so I don't know who the manufacturer is. The stator proudly says Sparks so I would think they'd mark their rectifier/regulator as well.

Do you have a Sparks 3 phase?
Click to expand...

When I bought the bike there was a dud sparx alternator in the box of spares that came with it. Don't know if it was a 3 phase one or not.
the power box that failed was a 3 phase sparx unit.
it also knackered the charge indicator unit ( don't quite know how, as you point out all that did is monitor the output from the alternator)
i replaced that with one of Al Osbournes battery status monitors that now sits next to the warning light console and one of his charge light monitors that feeds the igintion warning lamp in the console itself
 
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