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 Post subject: Re: XT500 12V
PostPosted: Tue Oct 16, 2012 7:02 am 
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An 8.99 2 lead trailer light from autozone.


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 Post subject: Re: XT500 12V
PostPosted: Sat Nov 28, 2015 6:35 pm 
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curly001 wrote:
The standard lighting coil will generate about 80watts as a 12 volt system need to modify the wire connection on the mounting plate as per attachment and run a single phase 12volt regulator/rectifier. Curly


Thanks for posting this Curly.

So what does modifying the stator wiring actually accomplish?

I am a curious person and engineering student and I'd love to know the 'why' of this.

Thanks.

Cam


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 Post subject: Re: XT500 12V
PostPosted: Sun Nov 29, 2015 12:54 pm 
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I can see how removing the common ground would be necessary to have one 12v and one 6v circuit.


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 Post subject: Re: XT500 12V
PostPosted: Sun Nov 29, 2015 6:20 pm 
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Pretty sure the XT500 has 2 x 6V supplies
1 is converted to DC & the other is left as AC
The centre tap of the winding is put to earth
So the centre tap is removed from earth & the whole coil is then 12V AC (maybe a bit more)
Then rectified to DC
Using the higher voltage is better for your existing wiring as the current will be halved for the same wattages
& you dont have the 2 systems
Put a few LEDs into the mix & the 80watts should be quite enough
I'm going 1 better & doing the CDI conversion too (Speedshop gear)
Cheers Dave

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 Post subject: Re: XT500 12V
PostPosted: Mon Nov 30, 2015 6:29 am 
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OK, going down this route will result in the generator burning out. Not maybe, its a matter of time before it burns outs.

We've found that playing with generators is not as straight forward as you'd think - which is why we will tell you that the output can't be changed by simply adding a few turns when we re-wind a lighting coil. Any one who claims they can do this has either been very lucky to have found a system that was de-rated and adding turns brings it back to full rating or they don't have the equipment to measure what they have done! 9 times out of 10 you get less output by adding more copper and a lot more heat.

Back in 2006 before I had the Speed Shop, we posted that method of converting XTs as a mod - in fact there is still one guy doing it! However we soon found it burnt the generator out. You can still find versions of the original drawings if you look hard.

The way we use now is far better as it doesn't stress the generator. The problem with using an all DC system is that the rectifier uses a lot of power. This is evident without a lot of test equipment as the DC unit gets very hot but the split AC/DC unit does not. When you split off a proportion as AC you don't get these losses. The AC system supplies about 6 amps while the DC about 2 - so you can see that you save a large percentage of power not rectifying it. When you go fully DC, at low revs there is not enough power being generated to meet the demand. What happens is the volts drops due to the load on the circuit and the current flow increases. The current flow increases to such a point that it fries the lighting coil. I've had lighting coils go blue on the test rig they got so hot!

With the split AC/DC in 12 volt mode you still have the same problem that at low RPM there is not enough power being made - however you don't have the rectifier losses on the AC circuit. Its by virtue of this alone the generator is kept in a safe operating zone.

To do a true DC kit you need to reduce the amount of current the lighting coil can make and increase the number of turns (considerably but not twice the 6 volt system). Doing this will keep the generator in a safe operating condition but you'll find its still a 80 watt generator!

I've squeezed 90 watts out of a single winding at 5,000RPM with the new heavy duty lighting coils we make, mainly by virtue that the iron core which has more laminates that are very thin compared to the Yamaha ones - it was a struggle and its taken months and months to work out what was going on. The main reason for doing it was to improve the low RPM performance. By adding more coils you an get more power but then the cost starts escalating considerably as does the power from the crank that the generator consumes.


All that said you can get decent 12 volts lights without going to the expense of replacing the whole generator!

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