BMW K bikes (Bricks)

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1Back to top Go down    Charging? on Thu May 18, 2017 7:08 am

nino


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New electrical problem: When bike idling with lights on battery goes empty and chances for next start become fifty fifty. Battery usualy mesures 12,8 - 12,9 volts.
Where to look? Voltage regulator? What should be charging current on idle?

    

2Back to top Go down    Re: Charging? on Thu May 18, 2017 7:44 am

92KK 84WW Olaf

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If you start the K and just let it idle it doesn't charge. Idling for long period with lights on will eventually drain the battery I think, the charge light often glows on tickover with lights on.

If you have a meter 12.8 - 12.9v battery sounds good but when charging should be I think around but not more than 14v

If you put the meter on the battery, then startthe enginewithout revving it you will probably see it drop as the starter turns and then go back to 12.8 or so, then rev it you should see the voltage rise significantly over 13.5v. If when you rev it you see no change then suspect a charging issue. But first check your earths and connections to the battery, if bad they can mean it will not charge.


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1992 K100LT 0193214 101,000 miles
1984 K100RT 0022575 Baja Red bought 36,000 now 87,100 miles
1997 K1100LT 58,000 miles
    

3Back to top Go down    Re: Charging? on Thu May 18, 2017 7:58 am

RicK G

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Ideally you should get 14.2V at 3000 rpm but down to 13.6V is OK but you will find that if you use the bike for short runs the battery will not get fully charged and will deteriorate quickly.
It is possibly just worn brushes but any time that happens you should clean and if possible machine it true and install a new regulator or at the very least new brushes.


__________________________________________________
If everything seems under control then you aint goin fast enough:- Mario Andretti
Bikes 1986 K100RT, 1993 K1100 LT, 1994 K1100 LT, 1993 K75 RT, 1996 K75RT, 1986 K75 GS, 1979 Z1300 Kawasaki X 2 & 1976 SR 500 Yamaha for now
    

4Back to top Go down    Re: Charging? on Thu May 18, 2017 11:50 am

charlie99

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nino have you noticed that the charge light stays on till you rev the bike a little over 1500 revs ?

if you just start the bike and let it idle ..,.the indicator in the instruments stays alight indicating - no charge is occurring ...a quick blip of the throttle usually puts the alternator into full excited mode as the field current in the alternator reaches a critical level and the indicator lamp will extinguish .

the battery will still discharge somewhat , with lights on etc running at idle


just a question nino

I thought I read that you placed an oring (rubber thingy ) between the engine and alternator some time ago ?


are you sure that you have a good earth contact to the alternator from the engine ?

perhaps the contact of the 3 mounting bolts to the alternator has become lossy ?

I would be putting a large cable bolted to the alternator body and the earth side of the battery , perhaps at the gearbox - battery earth point

there is a threaded hole (5mm) at the back of the alternator ....I think for mounting a suppression capacitor that might be suitable

see the attached picture


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cheezy grin whilst riding, kinda bloke ....oh the joy !!!! ...... ( brick aviator )

'86 K100 RT..#0090401 ..."Gerty" ( Gertrude Von Clickandshift ) --------O%O
    

5Back to top Go down    Re: Charging? on Thu May 18, 2017 1:26 pm

nino


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Thanks Olaf, Rick, Charlie:

Yes the red light stays on after 1500 rpm. I see it at night but not at daylight, but its usual. I put O rings between alternator and engine which checked yesterday and it didnt loose contact. I ll try additional ground wire from alternator to gearbox. Tommorow I ll measure charging. I plan to buy new charging regulator anyhow because this one is old.
Regards

    

6Back to top Go down    Re: Charging? on Thu May 18, 2017 9:08 pm

RicK G

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What is the reason behind the O-rings, I didn't catch up with that.


__________________________________________________
If everything seems under control then you aint goin fast enough:- Mario Andretti
Bikes 1986 K100RT, 1993 K1100 LT, 1994 K1100 LT, 1993 K75 RT, 1996 K75RT, 1986 K75 GS, 1979 Z1300 Kawasaki X 2 & 1976 SR 500 Yamaha for now
    

7Back to top Go down    Re: Charging? on Fri May 19, 2017 2:31 am

nino


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I tried to supress noise from alternator with three O ring between alternator and engine housing. Rick, I have question for you as I red you use 60 A alternator. Is it less noisy than old 32 A alternator?

    

8Back to top Go down    Re: Charging? on Fri May 19, 2017 3:33 am

RicK G

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I have never had a noisy alternator but some I have fixed were noisy because the rubber dampers (monkey nutz) were lose and worn. Once they were replaced all was quiet. If you have any movement in the dampers they will get noisy, the vanes should be a very firm fit.


__________________________________________________
If everything seems under control then you aint goin fast enough:- Mario Andretti
Bikes 1986 K100RT, 1993 K1100 LT, 1994 K1100 LT, 1993 K75 RT, 1996 K75RT, 1986 K75 GS, 1979 Z1300 Kawasaki X 2 & 1976 SR 500 Yamaha for now
    

9Back to top Go down    Re: Charging? on Fri May 19, 2017 4:42 am

TacKler

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Nino,

These are the monkey nutz that Rick refers to.


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Red 1991 K75S
    

10Back to top Go down    Re: Charging? on Fri May 19, 2017 6:18 am

nino


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I bought new upgraded alternator rubbers from Motorworks and changed bearings in alternator. I am not shure but think that old 32 A alternator housing connected to engine produce a lot of resonating noise.

    

11Back to top Go down    Re: Charging? on Fri May 19, 2017 12:24 pm

nino


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New voltage regulator mounted, 14.01 charging voltage on 1200 - 1300 rpm with choke on half. Not original regulator, but some germane made item (allegedly), price 20 euro.

    

12Back to top Go down    Re: Charging? on Fri May 19, 2017 6:44 pm

charlie99

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good fix nino


__________________________________________________
cheezy grin whilst riding, kinda bloke ....oh the joy !!!! ...... ( brick aviator )

'86 K100 RT..#0090401 ..."Gerty" ( Gertrude Von Clickandshift ) --------O%O
    

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