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Hi folks,

I'm new on the forum, little experience with Rotax engines, need some advice.

The charge light on my 912 ULS is staying on.  I flattened the battery a week back (EarthX LiFePO4, down to about 12v), recharged it (it seemed to take the charge fine), now the charge light stays on.  I can't say whether the light always stayed on since recharging the battery or not, but now it is on.  Voltmeter is showing about 13.8v.  There is a battery warning light that isn't showing any issues with the battery.  My questions are:

Could the battery be ruined - so it's not taking charge and so the cause of the light being on?  Not sure that makes sense given what I've read on old posts here and I don't want to be replacing an expensive battery to find the problem is elsewhere.

If not where do I start trouble-shooting?  I have wiring consistent with Rotax standard I believe, R,B and C all connect to battery +ve via Master Relay & to main bus, and light connects back to the L terminal. 

Any thoughts?

Thanks,

Steve

  • Re: Charge light stays on

    by » 5 months ago


    Need just a tad more info.

    The battery shows 13.8 in flight, but did it start normal on the ground and before you turned the key to start what did the voltmeter read?


    Roger Lee
    LSRM-A & Rotax Instructor & Rotax IRC
    Tucson, AZ Ryan Airfield (KRYN)
    520-574-1080 Home (TRY HOME FIRST)
    520-349-7056 Cell

  • Re: Charge light stays on

    by » 5 months ago


    What did you use to recharge the EarthX?  Discharged lithium batteries need a special charger.


  • Re: Charge light stays on

    by » 5 months ago


    Roger - I don't recall having seen the light on after starting the engine and while on the ground - I'd hope I'd see the light on, but cannot say for sure it was off.  Now, engine off, the battery shows 13.4V and 13.3V when I have all the instruments running and lights on.  I think it was pretty much the same before running the engine, maybe a little higher - I didn't notice anything unusual when I put the battery back in, but didn't note the voltage.

    Tyler - I have an IMax B6AC charger, set up to charge LiFePO4 4 cell at 5A, which is well within the maximum charge-rate for the battery.  So, it is the appropriate charger type for this battery.

    I'm going to try two things next - first run the engine with a different battery.  See if that makes a difference.  Second, isolate the battery while the engine is running (Master Switch off).  The voltmeter will still register voltage from the alternator, so I should be able to see if I'm getting charge to the battery (when it's re-connected).  I assume the alternator will continue to output current without battery voltage to excite it, but please tell me if that assumption is wrong or running the engine battery disconnected is a bad idea (i.e. I'm going to fry the regulator). I have the capacitor located as per Rotax wiring, so I believe that shouldn't be a problem. 

    Steve

     


  • Re: Charge light stays on

    by » 5 months ago


    While your thinking about diagnostics here's something odd that was like your light being on. I have a friend with an Tecnam. His light looked to be on too when we were out of the hangar. Come to discover after looking around it was the sun coming through making it look like it was lit. Also make sure something else behind that light isn't causing false lit up indication. Might as well rule out everything and not just think the worst.


    Roger Lee
    LSRM-A & Rotax Instructor & Rotax IRC
    Tucson, AZ Ryan Airfield (KRYN)
    520-574-1080 Home (TRY HOME FIRST)
    520-349-7056 Cell

  • Re: Charge light stays on

    by » 5 months ago


    Now I am Confused. ???

    >>>I don't recall having seen the light on after starting the engine and while on the ground - I'd hope I'd see the light on, but cannot say for sure it was off.  <<< 

     

    The Light will be ON when the master switch is ON and the engine is STOPPED.

    Observe the battery voltage before starting the engine.

    12.6 = 100% charged.

    12.2 = 50%

    12.0 = 10%

    10.0 = 0%

    Your 12 volt discharge was Low but within normal limits and not damaging to the battery.

    If the battery Voltage show 13.8 - 14.2, after starting the engine, The battery is charging.

    Do not bother swapping the battery and do not intentionally run the alternator without the battery connected.

     

    The light has nothing to do with the battery.

    Under normal conditions, The voltage at the Rectifiers is much higher than the Battery, and the Regulator controls the difference.

    The light indicates that the Voltage at the Rectifiers is Lower than the Battery, indicating that the Regulator is Not being powered and the battery is NOT being charged.

    Engine OFF.  Light ON!  Is Normal. 

    Engine ON, Light OFF. Battery >13.6 is Normal.

    Engine ON, Light ON,  And/Or  Battery <13.6 is NOT Normal.


    Bill Hertzel
    Rotax 912is
    North Ridgeville, OH, USA
    Bill.Hertzel@Yahoo.com
    Clicking the "Thank You" is Always Appreciated.


    Thank you said by: Jerry Griego

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