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Howdy.

This is my first post and I joined this forum as a result of being completely dumbfounded by my bike's proclivity to blow up batteries and burn up regulator rectifiers.

It all started after a severe crash I had while casing a jump on my 1993 Suzuki DR350S (Road-legal, kickstart only dual sport), where the bike did a flip and landed hard on it's face. I replaced the forks, front wheel, handlebars, and some plastics &c. Got it all back together, fired her up and took her for a spin. After about 50 miles, the sulfuric smell of death came strongly from my battery and I limped her on home. The DR350 will run without a battery, though not happily, and this time it didn't manage to fry any electrics except for my headlight.

So I bought a used R/R, assured it was functional, and a new battery and off I went. Tested the bike, smelled fine, took it on a 20 mile ride and at the furthest part from the house the smell was worse than ever. I live in Northern New Mexico where cell reception is spotty so I had no choice but to either hitch home or force her and I just didn't feel like hitching so this was when every electric on the bike fried horribly. Headlight, Taillight, Indicators, Neutral Switch light, Speedo, horn, all of it. Nothing worked.

It was clear my bike was STILL overcharging despite the 'new' R/R and battery. So I bought another 'used' R/R and took it to my mechanic.

He installed the new R/R and ran the bike for a minute when sure enough the new battery read 19V. Shut it off and assumed now that the 2 used R/Rs I bought were faulty and that's the problem...

I am inclined not to agree. While yes, it's POSSIBLE, they were certified eBay purchases by reputable sellers with good reviews stating they came off functional bikes.

3 regulator rectifiers have failed on this bike now and I'm at a loss. I believe it has something to do with the wiring but everything LOOKS good. Neither one of us can make heads or tails of this so I'm reaching out to you folks. What are we missing? What in the wilds of possibility COULD be happening?

I haven't seen a single thread like this and hope it may benefit others in the future. Thanks for any help you can give me.

thebuffalo
 

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What output reading are you getting at the alternator and what is the specified output. Also, assuming the front end was repaired, what about all the wiring? Although how this could equate to an overcharge of around 5 vdc. Maybe the alternator is damaged and ends up frying the reg/rec??

Good luck and let us know what it was....please.
 

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Welcome.
The key to all of this is: Get a meter, make some measurements and quit guessing if possible.
Of course, that might also require a shop manual.

In addition to testing the AC output of the stator and making sure none of the windings are grounded, you need to check each of the wires connected to the R/R to be sure they are connected to what they should be connected to.

The grounding is important. Modern systems use a "shunt" regulator and excess power goes to ground.
If there isn't a good ground at the R/R, then the excess goes to the battery.
 
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