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Author [ES] [CA] [PL] [PT] [IT] [DE] [FR] [NL] [DK] [NO] [GR] [TR] Topic: Alternator "brushes" ?  (Read 709 times)

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Offline DJN

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Alternator "brushes" ?
« on: August 26, 2020, 01:43:47 PM »
 Recently had a  totally flat battery; due to that stupid Parking Light  :006: ...
 This was at work and after no signs of life from bump starting , I called the AA recovery
  With the bike on jump leads it would start but kept cutting out.  The AA man -who was
clueless about bikes - measured the  voltage at only 11.9V.   At the fourth starting attempt , the machine ticked over with battery voltage showing at  13.2V. 
  AA man mentioned that, in his experience, some car alternators  sometimes required a sharp tap to free up stuck brushes.  I'm pretty sure that the GW's alternator is of the modern brushless type.
  Can anyone  suggest what else might temporarily block the alternators output
from reaching the battery?

Offline WaffleHouse

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Re: Alternator "brushes" ?
« Reply #1 on: August 27, 2020, 11:31:28 AM »
I think I remember something about fuel-injected bikes needing a certain voltage
to other components not on old carbureted bikes--maybe injectors, the fuel pump, or sensors (???) before they will make combustion happy.

Offline Robell

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Re: Alternator "brushes" ?
« Reply #2 on: August 28, 2020, 08:31:42 PM »
I think it was just taking a while to get the battery back up to a decent level.

Once the battery's fully charged, I suspect it will show more than 13.2v, when it's running
" it's better to burn out, than to fade away "

Offline DJN

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Re: Alternator "brushes" ?
« Reply #3 on: August 29, 2020, 11:51:28 AM »
..Oh yes, it  (new YUASA YTX9-BS) showed 14.6V under load after fully being fully charged.
    I was revving it to 5,000 rpm  when the low voltage was measured. Hence my questioning the alternator's output.
 Anyway no further problems since. Note that the original battery lasted 4 years; which is quite good for a small battery.