The New And Improved Unofficial R65 Forum V2

Technical Discussion => BMW Technical Q&A, Primarily R65 => Topic started by: Bill Conquest on February 27, 2011, 03:11:11 PM

Title: alternator not charging?
Post by: Bill Conquest on February 27, 2011, 03:11:11 PM

Can anyone remind me of what the proper charge should be coming out of the alternator when running?I plan to check the brushes and am wondering if there's anything I should watch for..Thanks in advace.. (i'm getting 12.4 volts give or take a little,at 3000 rpm)
Bill Conquest

Title: Re: alternator not charging?
Post by: Barry on February 27, 2011, 04:02:26 PM

Voltage regulators are nominally 14 Volts and you should ideally measure something in the range 13.8 - 14.2 volts with an absolute min of 13.5. At the other extreme 14.5 volts would be OK for a gel battery. The test should be done at the battery terminals and with a fully charged battery and also with no additional electrical load. 12.4 volts is much too low and would not bring a battery above 75% charge.

Title: Re: alternator not charging?
Post by: tvrla on February 27, 2011, 06:51:05 PM

Barry nailed it.

I doubt your brushes are to blame for the low voltage. Is the charge light staying on or glowing dimly?

Title: Re: alternator not charging?
Post by: Bill Conquest on March 01, 2011, 11:50:01 PM

I have an odysee 680 battery that seems to be o.k. - yes, the charge light is  glowing when I ride..what else should I be looking at if not the brushes? Thanks for the info.!
Bill Conquest

Title: Re: alternator not charging?
Post by: benlawlor85 on March 02, 2011, 02:31:39 AM

When i had problems with electrical system i found that the brushes were fine but that the springs had lost their spring and thus were not pushing the brushes hard enough! only a couple of pence to replace if i remember. worth a try.

Title: Re: alternator not charging?
Post by: Bill Conquest on March 03, 2011, 12:05:37 AM

Thanks, Ben i'll check that.. hope it's something that easy!
Bill Conquest

Title: Re: alternator not charging?
Post by: BMWcyc on March 04, 2011, 02:19:54 PM

If the current investigation doesn't completely solve.....

I wasn't getting any charge on mine...fast track to a dead battery!    Ended up being a small break somewhere in the Rotor wiring that could not be found...replaced rotor with a re-build that was done very well ...  problem completely solved.

Title: Re: alternator not charging?
Post by: Rob Valdez 79 R65 on March 04, 2011, 05:53:59 PM

Quote

If the current investigation doesn't completely solve.....

I wasn't getting any charge on mine...fast track to a dead battery!    Ended up being a small break somewhere in the Rotor wiring that could not be found...replaced rotor with a re-build that was done very well ...  problem completely solved.

Sometimes those rotor "opens" don't show up until the rotor is spinning.  At rest, with a ohm meter on them, they look fine.
I think it was someone on here that had this experience.