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Thread: The task (lawn mower topic)

  1. #51

    Re: The task (lawn mower topic)

    Jwatte, I have room to mount a second blower on the other side, that would
    give me 540cfm of air on the alternator and woulds only cost 6amps of power at 24vdc.

    I don't know if the high heat is caused by an undersized alternator(50amp) or the
    high load placed on it (the motors are drawing 100amps from the batteries at times),
    or that it's just a cheap alternators($120.00).

    I know it's not the bearings, because it runs at 20 deg f over ambient with no load(not excited).

    I found a 24v 100amp alternator on ebay that I could give a try.

    because the blower(s) only need to operate when the engine is running the
    noise they make shouldn't cause me an issue(mower sounds like a vacuum cleaner when blower is on)
    Last edited by Tommy_T; 07-04-2019 at 09:18 PM.

  2. #52

    Re: The task (lawn mower topic)

    Many alternators have a regulator built in, and that regulator is, as far as I can tell, a linear regulator, meaning they sink a bunch of heat to the case when they would generate more voltage than the application draws.
    I wouldn't be surprised at all if the alternator heat came from the regulator, and not from anything mechanical!
    If that were the case, then using an unregulated alternator, and using a DC DC converter built to regulate battery charge from a varying input (high input voltage noise rejection) might help significantly.
    I guess one way of figuring out whether this is the case is to disconnect the alternator output (so it free runs) and see if it still gets hot when you run on batteries only?

  3. #53

    Re: The task (lawn mower topic)

    I may have found the issue with the alternator, it seems these are single wire devices,
    that self excite, but I wired the excite input to 24vdc when the engine is running.

    that could over ride the alternator's voltage regulator(maybe).

    while air movement may not be the fix for the alternator issue spending a little time on
    it could help me down the road.

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  4. #54

    Re: The task (lawn mower topic)

    with the blower running the servo motors are operating about 30degf cooler.

  5. #55

    Re: The task (lawn mower topic)

    That sounds pretty good!

  6. #56

    Re: The task (lawn mower topic)

    Crap, the alternator is at 85degf while mower is running, and batteries lasted 30min. ,
    that means alternator is cooked.

  7. #57

    Re: The task (lawn mower topic)

    Thinking the alternator in the image below with it's fan internal may keep
    cooler with 500+ cfm of air movement then the enclosed type I tried first.


    today the outside temps reached 90degf. after 30min of mowing with both blowers
    running the servo motors read 117degf on right motor 122degf on the left servo motor.

    before the blowers at 75degf outside temp. I'd see 150degf on the left and 170degf on the right.

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    Last edited by Tommy_T; 07-16-2019 at 03:40 PM.

  8. #58

    Re: The task (lawn mower topic)

    seems like a motor brush problem(spring broken).
    I know the feeling!

    WHY ... CAN'T ... THINGS ... STAY ... WORKING !?!?!?

  9. #59

    Re: The task (lawn mower topic)

    Sweet! new 100A alternator is charging batteries again.

    for no other reason then to test the blowers for controlling the temperature that
    the alternator operates at, I got the same type alternator(10SI).

    if the blowers can't do the job, I have a plan C.

    as a backup safety I'm putting a 200Amp relay between the alternator and batteries,
    if the alternator reaches 200degf the relay can shut the alternator down.
    Last edited by Tommy_T; 07-20-2019 at 08:34 PM.

  10. #60

    Re: The task (lawn mower topic)

    after 3 hours run time with outside temperature of 80degf, Alternator temperature 190degf, right motor 120degf, left motor 135degf, servo drive 100degf.

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