Battery not charging - what broke?

i have a wr250x 2011 euro model and suddenly the battery is not charging. When i checked the voltage output - its below 12v and nothing happens when you give it throttle. so it must be the Regulator/Rectifier, the R/R also gets very hot fast. i already ordered a new one but i would like to know ( to avoid destroying the new one) what caused it to fail? is it also possible that the stator is not working? how do i check if the stator is working? also, would a wrong headlight bulb destroyed the R/R?

btw, battery is fine. also checked the wires, connections and fuses.

If the regulator is getting hot quickly it sounds like the regulator is shunting too much power to ground.

i got the bike 2nd hand. we just noticed that the battery installed is YTX5L-BS. the manual says it should be YTZ7S. the YTX5L-BS has 12v 5Ah only while the YTZ7S is 12v 6Ah. do you think this caused the rectifier to fail? i used the bike with the YTX5L-BS battery for a year.

No, the regulator/rectifier doesn't know how many amp hours the battery is, It just regulates based on voltage. I have read about a few regulator & stator failures & decided to replace my original with a switching type.

I was curious, do you do a lot of highway riding?

Oh OK. so using a 5Ah battery is fine then? it will not affect the motorcycle charging system? yes, mostly highway riding. a month before my R/R broke, i replaced my headlight with a 100/90W bulb. could this be the culprit?

The way the charging system works on the R2 and most motorcycles, the alternator runs WFO all the time. The power the bike does not need is diverted to ground by the regulator & converted to heat. Running a higher wattage bulb should have no ill effect.

The reason I asked about highway riding is at higher RPM's the alternator is putting out 100% & the regulator is working overtime sending most of that current to ground. Most of the failures I've read about were from bikes that saw a lot of sustained high RPM use.

i ordered a new R/R already but i want to know what destroyed the old one. since i ride highways most of the time, what needs to be done so it wont happen to the new R/R?
Thank you!

Most people never have trouble & you very likely will never have an issue again.

I went this route because I "think" it's better than what the factory did.

https://wr250rforum.forumotion.com/t11070-stator-fried

R/Rs get hot.  And just like any other electrical item, they can fail without a secondary problem causing it.  As 4play said, replace it and most likely that will be the end of your troubles.

If you are looking for reasons yours might have failed you can blame heat, age, mileage, possibly some minor manufacturing defect, etc.  Your guess is as good as anyone's.   Now if your replacement R/R fails, that may raise suspicion that something else is going on.

i finally got the new R/R. installed it and it charges the battery but it gets hot very fast. it gets very hot just after 5 mins. of idling, it gets very hot after driving 30kph for 5 kilometers. seems fine when going fast.

The stock regulator shunts all the excess power from the alternator to ground converting it to heat. Stock at idle it's shunting ~150W to ground. If you want the regulator to work less, add some running lights. It will easily handle a pair of 50 watt auxiliary lights using the energy that's being wasted now to help you be seen.

4play wrote:

The stock regulator shunts all the excess power from the alternator to ground converting it to heat. Stock at idle it's shunting ~150W to ground. If you want the regulator to work less, add some running lights. It will easily handle a pair of 50 watt auxiliary lights using the energy that's being wasted now to help you be seen.

That's what we are planning to do now. What should be the stator's voltage output when checking directly at the rectifier plug?

At the battery 13-14 volts

at the battery im getting 14.3
how about if at the regulator plug? disconnect the r/r and check the voltage coming straight from the stator? im getting 25v with mine.