XT550 regulator/rectifier fried?

[Bert Jan]

So, ive got an XT550 in the shop, owner ran it with no battery for a long time and 'then the lights went out'. I checked the wiring diagram and found out the stator (2 white wires from engine) gives around 30volts AC. Seems good to me. The other end of the white wires go into the rectifier/regulator. Out of it come 3 wires. A black one (ground) a brown one (power to lights etc) and a red one (battery loader).

Neither the red or brown one give me anything. Not AC, not DC, no shit. Around 0,6 volts AC, 0,1volts DC.
I lurked on Thumpertalk and ATVrider and it seems the regulator can't handle the 30volts AC from the engine for a extended period of time without battery. Normally, the extra power will be used for loading the battery and what's left is transferred into heath. But, without the battery the regulator has to transfer all the excess power into heat, causing it to frie itself.

Sounds logical but i don't believe it. XT's are about the most reliable bikes ever build and i can't believe that riding it without battery (or a broken one) causes the regulator to die.

I already started the bike (CDI has independent stator) and she runs fine. Both white wires gimme 30volts AC but when attached to regulator there's nothing coming out of it. regulator gets VERY hot in no time btw, like to hot to touch within minutes.

My questions are a follows;

1. How do i check the regulator, and if it seems the cruelpit, how do i make sure it does not happen again? the owner insisted not putting a battery back in as he wants it minimal as possible.
He wants a single lights low/hi switch and thats it. I included the wiring diagram for you all.

2. Why are red and brown connected in the ignition lock switch? Theoraticly they are both hot when bike runs. Why the hell need do they need to be connected? It has nothing to do with engine, when i pull the ignition wires plug off the bikes still runs and starts.

 

[Bert Jan]

nobody?

 

[TwinPlug]

Is the genny outputting 30 V AC accross the terminals or from each wire to ground? - although any output is a good sign here.

The reg/rec will charge the battery and dump off excess current via itself in the form of heat, it sounds from the info supplied that as it's been dumping everything from the generator into heat, it's got too hot and cooked.

Solid state electronics like to have loads on them, they're designed to have that load - removing the load will cause headaches.

As you've got a shop, do you have a spare single phase reg/rec knocking about, something from a scooter would do the trick for testing purposes, although it may be under rated for continueous use (or however you spell it )

The owner will have to face a few facts and put some form of load for the reg/rec not to fry itself again, be that a big capacitor or a small SLA battery - something needs to be there or it will happen again, or you could dump the lights altogether and just insulate the genny output wires.

 

[Bert Jan]

Cool, thanks for the info. That's exactly what i wanted to hear.

 

[Bert Jan]

Soooo, stupid thing decided vacation was over and started to work again!
I put a new fresh battery in, because i found out that my particular regulator needs a backing powersource. It calculates the batterypower and gives the system the needed back-up. As there was no battery, the regulator didn't do anything. I put everything back together and now i have 12.4 on battery with engine off and 14.3 with engine on. 13.5 with engine and lights on. YAY! BRAAAAAAAAPPPPP!!!

 

[TwinPlug]

Fixed - that's what I like to hear!