We are all under the impression that bigger is better - we've been conditioned to think that way.
To that end, many have fitted higher output alternators to our bikes thinking that it's going to be a big improvement and all of our problems are going to go away.
Actually it just introduces a new set of challenges.
The original charging system on a bike was provisioned to charge around the same amount as the electrical loads on a bike draws - kind of a balanced system.
If you look at the electrical consumers (loads) on the MK3 we can do a simple sum to get the worst case scenario:
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We draw under 30 amps from our bike with everything electrical switched on.
But typically in normal riding, we are drawing under 10 amps.
The MK3 was supplied with an RM23 alternator putting out 15 amps.
Adding the electric starter into the equation for the MK3 meant that after starting a bike twice in a day, the charging system spent most of it's time recharging a depleted battery.
What this means is that the two zener diodes weren't doing much, weren't getting over stressed or over heating.
The rectifier circuit was converting just enough AC to DC to charge up the battery, and the modest capacitor was helping to smooth out the peaks and troughs.
Adding a higher output alternator means that we are now over producing current, and the unused power being produced but not needed has to go somewhere.
So in a traditional charging system, more current is being dumped through the zener(s) to the frame.
The z-plates will be running hotter (noticeably by touch), but certainly still well within their capabilities.
We are running electronic ignitions with newer coils that as a package (deleting condensers and ballast resistor) are drawing less.
Some people are running LEDs which draw significantly less power.
Yet typically these upgrades are coupled to an uprated charging system that produces more power.
With the introduction of the combined regulator/rectifier everything was put into one unit.
It is the same rectifier package inside the casing - one of these:
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And for a three phase alternator, one of these instead:
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This is just a package of four diodes in this configuration:
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These cost less than $1 to manufacture.
The rectifier is exactly the same as the original Lucas rectifier:
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If you look closely, you can see the diodes between the heatsinking fins.
The zener diode piece of the puzzle (the regulator) leaks it's heat to the aluminium heatsink casing.
And because they can be used on positive or negative earth machines, over current is dumped through the relatively small gauge connection wires.
Because the gauge of these wires is so small, short-type units (Podtronics, Tympanium, Power Box etc) also short the AC side, which means the alternator will deal with most of the heat instead of the regulator/rectifier unit.
The only difference in the series-type units (Shindengen SH775 and SH847) is that they open the AC side, taking the load off the alternator stator coils.
Everything else is the same - the rectifiers are the same, the way it's connected up is the same etc...
The quality of the electricity converted with the original charging system, a Podtronics or a Shindengen is exactly the same.
The way they convert AC to DC is exactly the same.
But the way a short-type unit (Podtronics, Tympanium, Power Box etc) is putting additional load on your alternator stator coils.
An issue which is magnified if you have uprated your alternator, or if you have upgraded your lamps, swapping them for LEDs
The most important takeaway, I think, is that bigger is not always better.
The original charging system is adequate, so unless you are adding something that uses more power, remember that you need to keep things balanced.
