Wiring a solid state rectifier

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Triton Thrasher said:
All I seem to be doing is annoying people, but what I’m interested in is the impedance of a Zener in a typical Britbike installation, when it is conducting at or over its Zener voltage or breakdown voltage.
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That's not one of the specs on a zener, because it's a function of current. Look at Dave's chart of volts vs current in post #25. 2 amps @ 14.8 v would be 7.4 ohms, 4 amps at 15.5 v would be 3.875 ohms.
 
Triton Thrasher said:
All I seem to be doing is annoying people, but what I’m interested in is the impedance of a Zener in a typical Britbike installation, when it is conducting at or over its Zener voltage or breakdown voltage.
Click to expand...
It doesn't have a set back side impedance. Below the set point, the back side impedance is infinite. As it rises above the set point, it's back side impedance changes to dissipate the excess voltage. Like a rheostat, the impedance starts high, then lowers to absorb more power, if the voltage continues to climb. DynoDave's graph shows that quite well.
Charlie K
 
If I ever retire from the day job, I’ll do cunning experiments with a thermometer and a Zener dunked in a vacuum flask of water, connected to an RM alternator spinning in a lathe.
 
Had a no charge issue a few years back and came home 550 miles dead loss with a new lawn tractor battery strapped to the seat . It was nursing the Commando ignition thru alligator clips.
My buddy said ditch that Zener setup for a Podtronics, he'd been using one for a decade or so.
I did that but in doing so discovered the problem wasn't in regulation, it was just a corroded bullet connector that stopped the charging.
The Podtronics was already mounted so I've left it connected and working ,thinking it was new, solid state and should remain trouble free.
It has, but am I commiting acts of extreme cruelty to the poor old RM23?
It never complains but perhaps I should revert to the original items, all still in place?

Glen
 
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worntorn said:
It has, but am I commiting acts of extreme cruelty to the poor old RM23?
It never complains but perhaps I should revert to the original items, all still in place?
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Regardless of what the naysayers and melted stator paranoia types will tell you, the type of regulator in the Podtronics is the most commonly used in the world by far. Motorcycles, ATVs, snow mobiles, jet skis, any motor using a permanent magnet alternator uses something similar. The Brits used zener diodes back in the day, but if you look at Andover Norton's parts offerings it's a Podtronics or maybe a Trispark equivalent that they will sell you today.

Some day I'm going to do an actual test on my bike and document the differences between my MOSFET shunting regulator and a 3 phase zener setup.
 
worntorn said:
Had a no charge issue a few years back and came home 550 miles dead loss with a new lawn tractor battery strapped to the seat . It was nursing the Commando ignition thru alligator clips.
My buddy said ditch that Zener setup for a Podtronics, he'd been using one for a decade or so.
I did that but in doing so discovered the problem wasn't in regulation, it was just a corroded bullet connector that stopped the charging.
The Podtronics was already mounted so I've left it connected and working ,thinking it was new, solid state and should remain trouble free.
It has, but am I commiting acts of extreme cruelty to the poor old RM23?
It never complains but perhaps I should revert to the original items, all still in place?

Glen
Click to expand...

If it really was harmful to your alternator, your alternator would have failed by now.
 
Triton Thrasher said:
If I ever retire from the day job, I’ll do cunning experiments with a thermometer and a Zener dunked in a vacuum flask of water, connected to an RM alternator spinning in a lathe.
Click to expand...
ON Semiconductors have a Handbook " Zener Theory and Design Considerations" HBD854-D rev.1 ,it is at their website. You should find most of the answers in this publication and page 20 for Zener impedance .
 
HRD said:
ON Semiconductors have a Handbook " Zener Theory and Design Considerations" HBD854-D rev.1 ,it is at their website. You should find most of the answers in this publication and page 20 for Zener impedance .
Click to expand...

Plenty to chew on there! Thanks.
 
Hi everyone
Fitted the solid state rectifier and wired it up correctly but the ignition light stays on even at 4,000 revs. The battery does charge up but i am only getting 13.5 volts charge across the battery terminals. Is that enough or should the charge be higher than that. Checked all the wiring connections which were all good except one Zenner diode to the Zed plate that was slightly furred up. Cleand the terminals but it did not improve the charge rate. My next move will be to check the a/c output of the Alternator. What should that be and at what revs.

Cheers ELLIS
 
ELLIS said:
Hi everyone
Fitted the solid state rectifier and wired it up correctly but the ignition light stays on even at 4,000 revs. The battery does charge up but i am only getting 13.5 volts charge across the battery terminals. Is that enough or should the charge be higher than that. Checked all the wiring connections which were all good except one Zenner diode to the Zed plate that was slightly furred up. Cleand the terminals but it did not improve the charge rate. My next move will be to check the a/c output of the Alternator. What should that be and at what revs.

Cheers ELLIS
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Should be on lead/acid battery charging at 14.3 to 14.7 volts.
You my have a dirty connection or a black copper wire in there somewhere.
 
Then yes Zenner at fault , it should cut in to stop battery boiling over and at the same time send excesses electric current to the heat sink.
Your comment of furring over suggests it should be replaced, sorry.
 
ELLIS said:
Hi everyone
Fitted the solid state rectifier and wired it up correctly but the ignition light stays on even at 4,000 revs. The battery does charge up but i am only getting 13.5 volts charge across the battery terminals. Is that enough or should the charge be higher than that. Checked all the wiring connections which were all good except one Zenner diode to the Zed plate that was slightly furred up. Cleand the terminals but it did not improve the charge rate. My next move will be to check the a/c output of the Alternator. What should that be and at what revs.

Cheers ELLIS
Click to expand...
You should see 22-24 VAC at about 2000-2500 revs, and 40+ VAC at 4000 RPM at the stator wires with nothing else connected.

Also, with the rectifier connected try temporarily disconnecting the Zeners and see what voltage you get. Only run for a few seconds with the Zeners disconnected, enough tome to get a reading and determine if they are the culprit.
 
Thanks Bernhard Thanks Derek
Found one faulty Zenner Diode. Two on order. Disconected the Zenners and the voltage went over 16.5 volts. Tested the AC and at 2500 got 24 Volts AC.

ELLIS
 
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