My motorcycle (CBRF2) has gone through 3 batteries in the past 1.5 years. The first battery came with the bike, so when it went dead I assumed it was just an old battery. I bought a new one and this battery lasted 1 year exactly, then it started giving me trouble. I took it out and noticed the battery had expanded / bloated a lot. I took the battery to the honda dealer and he said there could be too much current going to the battery and it could be a bad rectifier (I think that's what it's called). I bought a new battery while I was there and I tested it on the bike with a multimeter to make sure it had a constant voltage at 14v while revving it up. It passed the test, so I assumed the second battery was just a "bad" battery and there was nothing wrong with the charing system. I rode my bike 120 miles yesterday and while I was riding the new battery started acting up. I stopped the bike and couldn't restart it. I got the battery recharged at Napa, but the battery was still dead. This battery only lasted 3 weeks. Any thoughts?

update: I did the test again (checking the voltage at the battery while revving) with the bike warmed up and it failed the test! At idle it was at 13.51-13.57v, @ 2000rpm it jumped to ~17v, and @ 5000rpm it jumped to 18v

 

I really hate working with electrical but this may help you. I think you have done everything but check the leakage.

https://cbrforum.com/forum/general-tech-stickies-106/how-diagnose-charging-system-51691/

 

Thanks for replying! I just did the leakage test. Weird thing is the multimeter remained at -00.0mA. I disconnected the rectifer and it still was -00.0mA. Any more suggestions?

 

All fuses are good.

 

I did a "wiring harness" check where I disconnected the rectifier and used a voltmeter to connect the red/white wire (+) and the green wire (-). It passed the test at 12.9V. Now checking the Rectifier resistances.

 

I would bet your rectifier is bad. As far as I know, there is not a test to do on a rectifier to tell if its bad or not. You rule out the rectifier by checking the other components of the charging system. If everything else checks out, the rectifier is replaced.

Having said that, the rectifier not only maintains the correct voltage, but it also converts AC power that is provided by the stator, to usable DC power. Even though your seeing 14 volts, your rectifier may not be completely converting the voltage to DC, which will fry your battery quick. It will short out the cells internally and will boil the acid. which is what your describing.

Since your charging 14 volts, your stator is working fine. I'd replace the rectifier, or at the very least, inspect it to make sure the wire plug is not damaged on the rectifier. A melted plug is a sign the rectifier is bad.

 

Thanks justasquid! My clymer manual says to test the resistance between the pins on the rectifier, and it has a table of correct ohm values for each combo of pins. I did the test and it failed, so I was also thinking the rectifier is bad. Don't know if this test is valid (or if I did it correctly), but your explanation made sense. Plug is not melted, but it is discolored like it has been through some heat.

 

actually there is a test to see if the rectifier is bad. its a diode test i believe.

but i had the same exact problem, so dont do what i did.

what happened to me was that my rectifier went bad, and i was over charging batteries, so i said to myself, ok just by a new one, put it on and your done.

WRONG! the thing i didnt notice it my rush to get the bike ready for the road was that after my rectifier blew out and i replaced it. my brand new one broke in 15 mins. this was because the stator got fried after the first rectifier went on me.

i had to replace the stator and by another rectifier. since then everything is gravy.

so check your stator before anything else then check the rectifier etc. or you might have to by more parts then you want to!

 

Thanks for info!

 

Short somewhere in the wiring.