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Discussion Starter · #1 ·
This is a mod I've done on a few bikes now and replaces the standard OEM thyristor based shunt regulator rectifier with a newer technology MOSFET shunt regulator rectifier.

Why upgrade

The OEM thyristor based units can get extremely hot and have a shorter lifetime as a result commonly failing in a couple of ways.

The first failure mode causes them to undercharge and, over time, this causes the battery to fail due to it being insufficiently charged long term.

The second failure mode causes them to stop shunting the excess current and the charging voltage goes through the roof. This can start to pop bulbs, kill instruments and has been known to cause ECU failure (although I haven't heard of that happening on a KTM).

A major advantage of the MOSFET unit is the stability of the charging voltage. Even at tickover with lights on and fan running, you'll still see somewhere between 13.8 and 14 volts. Just above tickover the voltage rises to somewhere in the region 14.3 volts and stays rock steady throughout the rev range.

So, upgrade if yours fails or if you want something more reliable than standard with a more stable voltage. Granted, a MOSFET unit isn't guaranteed to stay working but the failure rates seem tiny. I've only heard of two failed units. One was supplied from a breaker in a non-working condition so history unknown. The other was killed by someone connecting the +ve and -ve the wrong way round. They don't like that.

Why the Shindengen FH008

This will fit in the standard location and can be wired in salvaging the original connectors off the old regulator rectifier. A used unit can be found from a UK breaker for £60 to £80 delivered and all you need to do is chop the wires off the old unit and solder them onto the new one.

You can upgrade to waterproof connectors if you wish and if your connectors are completely corroded then you may need to but if everything is in serviceable condition and cleans up well, it's an easy upgrade.

Upgrading the regulator rectifier on my bike

My 990 had a Motobatt fitted by the previous owner around 14 months and not many miles ago. It was sluggish on the starter and the Optimate would always charge it at full rate even straight after a decent ride. Hooking up the multimeter showed why:



Checking the charging system showed it was struggling to get above 13.2 volts at best and the voltage was actually dropping off with increasing revs occasionally dropping below 13v.

So, I ordered one of these from a breaker:



Next, I removed the OEM regulator rectifer. I cut the leads off it and removed the connectors from the connector blocks. I cut the connectors off the FH008 ending up with this:



I ended up completely replacing the +ve and -ve wires and their connectors as the wires were corroded inside and the connectors had seen better days. The alternator wires and OEM 3-way connector were fine and these were just soldered on to give the same length as the OEM unit. All joints were covered with glue-lined heat shrink tubing. You should use glue-lined for covering the solder joints to keep the water out.

This is what I ended up with:


...and that just bolts on perfectly where the old one was without fouling the bash plate unlike the bigger MOSFET units:



As the saying goes, "the proof of the pudding is in the eating". Firing up the bike with the meter probes on the battery gave this rather better reading:



My work here is done.
 

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Go on, Alan.... what bikes have the FH008 fitted? Is it 8A capacity? Is the FH015 therefore 15A capacity?
 

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Discussion Starter · #8 ·
Go on, Alan.... what bikes have the FH008 fitted? Is it 8A capacity? Is the FH015 therefore 15A capacity?
According to the Shindengen spec sheet, the FH008 is rated 35A at 14.5v which means it's rated for up to 507.5 Watts. That's safely more than the KTM 990 Adventure kicks out. I've not heard of a FH015 but the bigger units like the FH012 are 50A rated and well over-engineered for the job (725 Watts!). They're just a bit big for the standard location on some bikes (like the Honda XL650V TransAlp, Africa Twin RD04 and KTM 990 Adventure) due to the connectors and so the FH008 is a good alternative.

One of these will work on any bike with a 3 phase alternator that it will physically bolt onto, or can be made to bolt onto, and that doesn't chuck out more than 507.5 watts as standard. If there is room to fit an FH012 or similar neatly then they are more common and can work out cheaper - but you really need the proper connectors for them.
 

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Nice job!
just to clarify the yellow wire are soldered in a like for like position (are they in the same order on both units) and the green and red just are joined two to one and go into the same connectors, as in the photo it seems that the green is not in the white block connector? I'm a numpty when it comes to this kind of electrical wiring thing, can solder though :D.

I ask because I will keep the link to the thread in my service/electrical folder on the desktop for future problem solving, then when I come to use the info, you wont be on a two week holiday in Wales with no wifi/phone signal and wont be able to answer the question then ;)
Cheers, and Bobs bike is always muddy:smokin:
 

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Bet you would of got the same result just cleaning up the connections, that's what makes them fail, you keep the connections clean and greased with dialectric grease you rarely get problems.
 

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Discussion Starter · #15 ·
Nice job!
just to clarify the yellow wire are soldered in a like for like position (are they in the same order on both units) and the green and red just are joined two to one and go into the same connectors, as in the photo it seems that the green is not in the white block connector? I'm a numpty when it comes to this kind of electrical wiring thing, can solder though :D
Yellow wire order doesn't matter.
The OEM has two green wires going to a ring connector bolted to the engine. Cut them and solder them onto the single green from the new unit. You can also add a single wire instead but make sure it's rated for at least 35A.
The OEM has two red/white wires each going to a 2 way multiconnector by the solenoid on the right hand side. Cut them and solder them to the single red from the new unit. If you're going to have a duff connection, this is the one that's most likely and if it's less than perfect, replace it with a decent waterproof connector. Mine was full of mud and grease but cleaned up okay.
If you lay them out on a bench side by side and mark the lead lengths, it's pretty straightforward. The most difficult bit was getting the brown connector apart.


Bet you would of got the same result just cleaning up the connections, that's what makes them fail, you keep the connections clean and greased with dialectric grease you rarely get problems.
Ah so that's where I've been going wrong. All I needed to do was clean the connectors ;) I did test all the connectors for voltage drop before replacing the regulator and they were all fine.

I do agree that duff connectors certainly make the problem worse and if you're not changing the unit, I'd thoroughly recommend keeping the connectors clean and greased as part of regular servicing. If the +ve 2 way one does break down, the regulator rectifier will end up sinking more current to compensate and hold its output voltage down. The already hot design will get even hotter and give up.
 

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.......... then I discovered that if you google Honda CBR regulator failure, it seems they have more problems with theirs than we have with ours......... ;)

In fact a top mod is to replace the standard regulator with one off a KTM 950/990 ;)

Only joking :)
 

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I was going to say have you seen the number of charging failures that Honda CBR/CBF1000's have.
 
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