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Thread: '89 R100RT generator light and Omega 600 alternator

  1. #1

    '89 R100RT generator light and Omega 600 alternator

    Hello all,
    I recently completed a mini restoration of an '89 R100RT. As part of the work performed, I installed an Omega 600W alternator. The bike already had an Emerald Island Diode Board and solid mounts. The voltage regulator was replaced and set to 14.3V @2500 rpm. A new Odissey battery was installed, as well as a Katdash in the instrument cluster.

    What I noticed is that the generator light does not extinguish until the RPMs are well above idle and stays on (albeit dim) even above 2000 rpm. I know the battery is charging because I have both the standard analog and a digital voltmeter installed and can see that the voltage values are what I would consider normal (and well above 12 volts).

    I read somewhere (but now I can't find the reference) that the GEN light not extinguishing is 'normal' for bikes equipped with the Omega system. Can anyone confirm this? Does anyone know why this is happening? I'm not really worried that the battery isn't charging as I have evidence that it is, I'm just wondering why this anomalous behavior.


  2. #2
    Liaison 20774's Avatar
    Join Date
    Sep 2005
    San Antonio, TX
    Can't say as I've heard that about the Omega system. What does the supplier say? On the OEM system, I'm not clear as to why it takes say 1200-1500 RPM to extinguish the light...maybe it because it takes that much RPM to begin cutting the lines of magnetism in the rotor to begin to produce voltage. Possibly for the Omega, its design requires more RPM to do the same thing??? I thought the Omega was a permanent magnet system...the OEM is not a permanent magnet system, but the rotor effectively creates one as current flow.

    The light tells you that voltage on either side of the bulb contacts is different. One side represents the battery voltage while the other side represents the alternator output. If the bulb lights up, it suggests that the alternator is not outputting the needed voltage soon enough.
    Kurt -- Forum Liaison ---> Resources and Links Thread <---
    '78 R100/7 & '69 R69S & '52 R25/2
    mine-ineye-deatheah-pielayah-jooa-kalayus. oolah-minane-hay-meeriah-kal-oyus-algay-a-thaykin', buddy!

  3. #3
    Registered User STEVENRANKIN's Avatar
    Join Date
    Dec 2006
    Spencerport, NY

    My Omega

    I have the same system in my two bikes, despite the increased charging capacity with the new systems, they still do not charge below certain RPM. Sorry, I can't give you an exact RPM. This is normal. As to the dim light in the Katdash, I have had the same thing happen, I have yet to contact Katdash as some of the scuttlebutt is this may be normal as well. Scuttlebutt is the Katdash light diodes are more sensitive to a tiny amount of current getting by the blocking diode that controls the charge light on and off.

    Since I have checked and rechecked the charging system's function and found it to be working in spec, I haven't bothered to contact Katdash.

    If you do contact your suppliers please let us know the results. St.

  4. #4
    BMWMOA #24809 jhall's Avatar
    Join Date
    Aug 2020

    My Omega 600 Does Same

    I installed the Omega 600 in my 95 R100RTlast December, and 17,000 miles ago. It has always done the same, including before and after the Katdash, which I installed more recently. The dimly lit charging light is only a shade brighter with the Katdash than it was with the OEM lights. I have only had one problem with the Omega 600, the voltage regulator went out 9000 miles ago, just before I left for a trip to Florida. I replaced the (higher cap) VR that came with the Omega, with the OEM, which I had kept as a spare. The RT's charge needle does not come up quite as high, but otherwise the system still works perfectly.

    I was just out on the RT last night, and really like the brighter Katdash, and LED light bulbs I installed in the clock and charge meter. Yep, the charge light was still dimly light last night, as it has been since day one with the Omega. Not to worry!
    BMWMOA #24809

  5. #5
    BMWMOA #24809 jhall's Avatar
    Join Date
    Aug 2020

    More Info

    I was out on the RT again last night, this time longer, and paid more attention to the charge light, as well as the volt meter. Yes, the Katdash charge light is definitely brighter. The OEM was only visible at night, and even then only at second glance. The Kat dash is easily visible at night, and even in daytime, as long as the sun is not too bright. It clearly dims, at around 2000 RPM and up, as before, but remains much brighter now.

    Update: Reading on Katdash web site, they say the charge light may go out a bit later, but will then act exactly as the OEM light and go out completely. They also mention LEDs are more sensitive to current and ground, and any LED in their system may remain on if there are related problems. Reading further, they say if the charge bulb flickers, or does not go out when above 2500 RPM, there may be a charging problem, and refer to Snowbum's article on troubleshooting. They do NOT address possible issues with the Omega. Gonna call them and discuss further.

    Further update: No luck calling Katdash. On their web site I can find links to Snowbum, and other vendors' phone numbers, but NO phone number or email fo Katdash. Hmm
    Last edited by jhall; 07-12-2021 at 04:01 PM.
    BMWMOA #24809

  6. #6
    I installed one of the early prototype Katdash units when they were being developed and commented that my Gen light doesn't extinguish on startup unless the bike is revved past 2500. I have a Motorrad Elektrik V.R. installed as well on my '74 R90s.

    and my GEN light flickers sometimes once its running, but if the lights are turned on, it's much less noticeable.

    Katdash said the flickering is normal due to the diode's ability to display voltage transitions quicker than a conventional bulb.

    No issues other than that. (Stock alternator btw, with a Thunderchild diode board)

    Charges perfectly

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