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K100-forum.com » Technical, repair and troubleshooting » Electrical » K75 Clock always on: Is this normal?

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roach374

roach374
Silver member
Silver member
The dash clock on my '93 K75 is always on, even without the key in the ignition (see picture). Is this normal? I'm a little concerned that there is a constant (small) current draw on my battery. What gives?

K75 Clock always on: Is this normal? Pxl_2010

    

Point-Seven-five

Point-Seven-five
Life time member
Life time member
Perfectly normal. Digital clocks can run for years on a single AA battery, so I doubt the ones on our bikes draw anywhere near enough to run down the big batteries the bikes have. I seem to recall that the clocks on our bikes use less than 1 amp of power in a month and a half.


__________________________________________________
Present: 1991 K100RS "Moby Brick Too"
 
Past:
1994 K75RT "Ilsa, She Wolf of the SS"
1988 K100RS SE "Special Ed"
1994 K75S "Cheetos"
1992 K100RS "Moby Brick" R.I.P.
1982 Honda FT500
1979 Honda XR185
1977 Honda XL125
1974 Honda XL125
1972 OSSA Pioneer 250
1968 Kawasaki 175
    

robmack

robmack
Life time member
Life time member
Point seven-five is right.  The PCF1171 clock chip in the dash draws 400uA (about 0.4mA) constantly from the battery.  With the LCD on, that current draw is somewhere around 800 - 900uA (about 0.9mA). That's a total of 12 mW of power.


__________________________________________________
Robert
1987 K75 @k75retro.blogspot.ca
http://k75retro.blogspot.ca/
    

cycleman

cycleman
Silver member
Silver member
The amp draw down is enough that after several months of inactivity, like with winter storage it can lower the voltage enough that the bike won't start. That is why you put a battery tender on the battery.

    

Rick G

Rick G
admin
admin
The current drain of the clock is as Robmack has stated and that is not sufficient to discharge a 18ah battery so that it wont start the bike after a winter lay up. The natural drain that any automotive battery suffers over a winter lay up is more than the clock draws ( probably 2-3 times that) it is this drain that causes the biggest need to use a battery tender charger.


__________________________________________________
"Man sacrifices his health in order to make money.
Then he sacrifices money to recuperate his health.
And then he is so anxious about the future that he does not enjoy the present; the result being that he does not live in the present or the future; he lives as if he is never going to die, and then dies having never really lived."   Dalai Lama


Bikes 1999 K1100 LT with a Big Block 1200
    

cycleman

cycleman
Silver member
Silver member
The clock on my R1100R would draw the battery down enough in 2 months that when you turned the ignition on, head lights on etc, the voltage was too low and the fuel injection pump wouldn't start. Non fuel injected bike not a problem and would likely start.

My rule of thumb has always been if the bike is sitting for more than a month, then I put the battery on a tender. Battery lasts much longer.

    

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