Hi all,

Robmack has been amazing, not only did he help get my bike back on the road, but he's been helping solve this strange occurrence where my bike draws power from the battery while it sits with no key in the ignition. The first order was to install a battery cut-off switch. Once that was done we began troubleshooting using a K100/RT wiring diagram to find the source. Unfortunately because the diagram isn't for a 16V/ABS K100RS we stopped short of tracing the problem. The bike has standard components. The only aftermarket add were cheap heated-grips which have since be disconnected. Otherwise we can't seem to find where we are loosing .108 MA as it continues to draw power. 

Has anyone got a wiring diagram for the K100RS with ABS, or heard of an issue where this type of leak happens at .108 MA? It's a substantial amount of power and it certainly isn't' the clock.

Edit: I have to show the photo of the battery cut-off Robmack suggested I get, even with the computer in and a slight modification to the l-bracket terminal and plastic key shown, it fits perfectly and works without a millimetre to spare. Not only is this a temp fix for the power loss it's great for theft prevention  photo of full install forthcoming.



Thanks,
C

Duck got it: http://classickbikes.com/ckb.tech/0.ckb.tech.files/kwiring/kwiring.htm

Chris noticed a dead battery after two weeks of sitting idle.

I measured the current draw with the bike off by disconnecting the positive battery lead from the battery and inserting an ammeter into the circuit.  The current draw was 108 mA with the bike off.  I would expect to see a much lower value than this, possibly in the 3-5 mA range.  The only device that should draw power from the battery constantly should be the clock.

To isolate the circuit drawing the power, we subsequently pulled fuse 3, then Fuse 4 then fuse 5.  After each removal, the current did not change from 108 mA.  This indicates that the current draw is not related to circuits attached to these branches.

That leaves any aftermarket accessories or ABS components.

I didn't have a schematic for 4V ABS so I don't know what additional circuits are directly connected to the battery.  Chris had aftermarket heated grips installed directly to the battery at one point in time.  We removed the remnants of the wiring to make sure it wasn't that.

I couldn't think of any other sources for such a large current draw.

I recommended that he install a ground cutoff switch to prevent depleting the battery again in case the bike sits idle for a long time (until this problem is solved).

All "unswitched" power to the ABS is via the ABS relay, that narrows it down a bit.

I had a similar problem on my 16v with ABS.

Removing the ABS relay caused the current load to disappear.

I swapped the ABS relay with a spare and no more problems.

Thanks for adding your precision Robmack. All roads are pointing to the ABS relay, thanks for chiming in you guys.

For the record the heated grips were not installed by me, I just disconnected them. Some butcher of a mechanic installed a hotwire direct to the battery for the previous owner, not sure what he was smokin :smoke:

I had a similar problem with a friends bike. Turned out there was an issue with the alternator, which is directly coupled to the battery (i.e. you wouldn't see any change in current draw; unplugging all fuses had no effect). I think one of the diodes was gone and thus created a current draw (better electricians can explain that :-) ). Easy test, unplug the alternator plug on its back and see if you still have the 'leakage'.

ReneZ wrote:Easy test, unplug the alternator plug on its back and see if you still have the 'leakage'.

 
Thanks ReneZ!

Thanks Rene.  That's a possibility.  I had assumed that the alternator was good because the battery gets charged when the bike is running.  However it is a possibility that a diode has begun to leak.

Chris, I have a spare diode board we can use to swap if the diagnosis points to the alternator.

BTW, I don't know if people understand how to convert a DMM into an ammeter.  It's really simple.  I bought two 2 Ohm 10 watt power resistors and wired them in parallel.  This created a 1 Ohm 20 watt resistor.  I open the circuit under test at a point where I wanted to insert the ammeter (all current measurements have to be done in series).  I connected the 1 Ohm resistor into the circuit break and put the probes of the digital multimeter across the resistor.  I set the DMM on DC volts and read the voltage across the resistor.  In this example, Chris'' bike showed 0.108 volts.  Using Ohms Law, I = E/R.  R in this case is 1 so the equation becomes I=E.  Current was 0.108 Amps, or 108 mA.

robmack wrote:Chris, I have a spare diode board we can use to swap if the diagnosis points to the alternator.

Thanks Robmack!

I have the same problem with my '91 K100RS. The battery goes dead within 3 weeks if I don't use a battery trickle charger. I'll try replacing the ABS relay and see what happens. I bought the bike from a relative after it had sat for 6 years. Maybe that is part of the problem. Very annoying. Love the bike!!

I have just checked an ABS relay and it takes 135ma when activated  (fully charged battery). So could this battery draining be caused by the relay being permanently on. Prior to replacing my relay on my 16v ABS1 I tried all the documented reset methods for the ABS with no success. After replacing the relay I was able to clear the fault light and ABS has been working perfectly since.

Ringfad wrote:I have just checked an ABS relay and it takes 135ma when activated  (fully charged battery). So could this battery draining be caused by the relay being permanently on. Prior to replacing my relay on my 16v ABS1 I tried all the documented reset methods for the ABS with no success. After replacing the relay I was able to clear the fault light and ABS has been working perfectly since.

Interesting you couldn't reset your ABS! Same trouble here. I think we have a viable fix! Thanks for checking into that Ringfad.

Just wanted to tie up the loose end on this thread and say that my mysterious battery drain issue while the bike is off, was solved last Friday thanks to Robmack.

Turns out as others suggested, the 108ma was the ABS relay drawing current. Robmack was kind enough to offer a spare from a wiring harness he nabbed off ebay. Upon replacing the old one, the only current that is now drawing battery power is my clock. 

Mystery solved!!!

good result

happy riding

Thanks Chris that clears up a mystery for me as well.

Not sure if this will be read.  Have a current draw issue with a 84 K100RS
I have been a bit inactive, but working intermittently on a few problems in a k100 2valve 84 model.  Started off well a couple of months ago, but life gets in the way of hobbies.

So what are my problems -
1. the notorious parasitic current draw.
2.  Noisy timing Chain
3.  Gear whine and gear or layshaft roughness when taking off 
     (I read somewhere this is common,
                but in a probably genuine 60Klm bike?) 
4.  Getting mirrors repainted or getting Madison touch up paint
5.  Reconstructing the side-stand lock down latch

What have I done:
Have removed the two light relay combination that drew 120ma when ignition was turned off turned off. 
Removed the regulator board and cleaned it lost 30 or so milliamps there.

Want to do the Alternator, Clean and test diodes, however alternator bolts still seem to be frozen, so waiting for some penetrating oil before using leverage.

Greased splines, and found them in good condition.

have done a bit more clean up, but am stuck in trying to work out the electrical that is bugging me. Have wired a connector and 10A diode into a battery minder plug so I can have a solar panel plugged in at 13.2 volts to keep the battery healthy.........  BUT

I still have 140ma current draw when everything turned off.
Kill switch that was on bike now works and now kills that current draw, and also the clock,,,,, but it is a botch rather than a fix!

When kill switch is connecting power, there is no draw in fuses 3,4 & 5 and their individual or collective removal does not remove any part of the 140ma,,,,,,, so the draw is ?
?   Alternator
?   Flasher Unit
?   BMU

What also confuses me is that while there is no current draw across fuse 7, the fuse has .51 volts on both sides.   Looking at the circuit, this does not seem possible. 

The process followed in the listed  make me think that there is a lot of consulting experience in the people above, so was trying to slide in sideways for an opinion of what is most likely or best to target first.   If this does not get a reply, I will post on a new thread.
Oh yeah, I have not posted photos of the bike as yet.....   

Any ideas please?
Bob

Remove all 3 units from the equation by removing them, the alternator will unplug (they do get tight) and remove the flasher and BMU from the relay box under the rear of the tank. I take it that you have removed all the fuses and then unplugging the components and switches one by one.
I would not be too concerned about the gear whine the gearboxes are a very noisy item, they usually are somewhat quieter in 5th than the other 4 gears.
As for a noisy timing chain they are very haphazard about wearing out and BMW say to replace chain and guides ever 60K.

As turning off the killswitch makes a difference, you must search downstream from the kill switch.

First remove fuse #1, if that doesn't change the current draw....disconnect/check:
Coils.
FI relay.
Ignition ECU.

If removing fuse #1 stops the current Draw.....disconnect/check:
Instruments.
Clutch switch.
Brake light switches.
BMU.

As your kill switch also cuts the power to the clock indicates that the wiring is modified
(if we speaking about the genuine clock in the instruments), which usually
makes troubleshooting electrical problems to a kind of lottery.

Veka4,  Inge assumes that the kill switch is ENGAGED (i.e. it is breaking the circuit) when you follow his diagnosis process.

Definitely there is something amiss with the harness if engaging the Kill switch stops the clock on the instrument cluster.  Quite possibly, the quickest way to fix your problem is to purchase a used pre-85 wiring harness that has not been modified.

Hmm, not easy to understand what Inge assumes or not.....did read the post
with eyes wide open and brain disconnected.......was thinking ignition on.

And now a fresh start, brain in stand by......what the unswitched power and
the kill switch circuit have in common is the LSR, could be that you got a
internal short (as you also have a leak to the LSR output)....you could try
to disconnect the LSR, gotta start somewhere.....

Inge K. wrote:Hmm, not easy to understand what Inge assumes or not.....did read the post
with eyes wide open and brain disconnected.......was thinking ignition on.

If the kill switch was DISENGAGED (i.e. not breaking the circuit), both upstream and downstream circuits would be potentially contributing to leakage. Removing the fuse would not return categorical results (i.e. one could not eliminate the downstream circuitry as a contributing factor) However, with the kill switch ENGAGED, the downstream circuitry is eliminated as a source of leakage, and removing fuse #1 will test the upstream circuits according to your diagnosis.

And now a fresh start, brain in stand by......what the unswitched power and
the kill switch circuit have in common is the LSR, could be that you got a
internal short (as you also have a leak to the LSR output)....you could try
to disconnect the LSR, gotta start somewhere.....

+1. Look for common contributing elements.

sorry been off bikes for 25 years.   meant to say prior owner? fitted master switch..  sorry for confusion, could be kraft.

If master switch on I enabling voltage, this enables parasitic draw.
Removing each fuse does not diminish current draw at all on a 200ma multimeter range.
Juse recently measured mv (200 mv) across fuse and there iis no voltage drop across any fuse when all are in place, so it is not one current path hiding another.

As a weird check, I measured the fuse to ground on all fuses, and got a reading of other than 12.6 volts or ground on one fuse.
Fuse 7 i think it was (kraft again) shows  .51 volts to earth on both sides of the mentioned fuse.  
Obviously no current draw because the voltage is the same both prongs of the fuse.

Again sorry for the confusion.  
Profile is I am ex air force electronics technician turned manager, so l may have reached my peter principle level......

Correction 

When non-standard master switch is off there in no current draw from battery.
The clock and all circuits do not have power

Was going to remove the non standard thing, 
Was also going to redesign it with a p channel vmosfet or trenchfet in saturation with a bypass path to keep the clock on. 

When master switch  is turned off it is saving my battery at the moment. 
 As available time is shaping me up like to be a very casual rider at this stage it seems premature to buggarise around and remove something that is working for a benefit. 
###############################


When master switch is on, the current draw occurs.
,, the fuses can be removed and the draw persists at the same mili amperage.

Measured mv across fuses with  a mulitmeter on a 200 mv range, there was no millivolt difference across any of the fuses.
.
For some reason, I then measured from each fuses prongs to earth.
Each fuse had the same voltage on both prongs ( either 12v or 0v), except fuse 7 which had .51v (1/2 volt) on both pronngs  hope that clears up my gibberish.  Bob

So the previous owner put the master switch in there to prevent the current drain.Next I would be removing the relays one at a time. It is quite possible that one of them is stuck in and causing a current drain. In particular the Fuel injection relay as that would keep the ECU on all the time and it would probably draw about that current.
The relay box is under the rear of the tank.

+ 1 ....yep id be looking for something like that too
it would be most advantageous to get this one solved properly

then all the normal rules apply

good luck

Go to the portal where you find a wiring diagram at the middle of the page.

Click on the tab "battery drain" then you see all wires that is unswitched and
unfused at a glance.

Took the tank off today.
When master switch is turned on enabling power to the bike
  there is an unexplained 140ma current draw.

Removed all fuses and the three relays at the front of the relay box.
1984 K100RS
140ma draw still evident.
.
Removed the electronics unit from above battery, and unplugged it.  
No effect 140ma draw still present.
Reconnected the unit.

Unplugged the unit next to the steering column.
  I believe it is the motronics unit.
Still have 140ma  current draw.  

Master switch traced to a non-documented relay in the electronics box.
Relay is activated by switching power from the starter relay input terminal to the coil.
 Relay is 40A  and switch feeds relay coil, plain old earth on other side.  
Power from contacts feeds loon, but relay gets its power from a new wire? That seems to go into battery loom.


There appears to be an added 5mm yellow, white and brown wires from around headlamp loom back to relay box, it terminates on relays that seem to supplement the bikes headlamp switch.  Did not check bulb wattage but assume it is probably large.
Switching of relays  is two grey wires ( part of 2mm  fig 8 wire) that are spliced to ? They disappear  into the loom.
Got a bit cranky about then........
Put everything back where it is supposed to be.

Started checking other items.  Radiator top-up tank 3/4  but radiator not full.
Checked cap, and it was cruddy and probably not sealing with a buildup of hard stuff like calcium on cap and rubber washer.  .Also dirt but no oil or floating slick in pipe or on cap, bit worried there, so washed cap in sink with strong dishwashing liquid, then cleaned rubber and cap properly.
Topped up with ethylene gyclol, and made sure pipe to refill tank full as I was putting on cap.

Frame is rusty around filling fitting.
Windscreen has a few broken perspex mounts, but that could just be old perspex.
Right knee pad lower screw was held on with a wood screw.

I know it's an old bike, but feeling like prior owners might have been cowboys.
Had trouble with the fuel return line clamp, but put it all back together and was rewarded by a start, and steady idle.

Oh well more work to come.

Veka4

might pay to tip the bike a little to the left ...whilst on the centre stand... to get all the air out of the radiator and filler tubes

just a suggestion ..

have fun !

Took the tank off today.
When master switch is turned on enabling power to the bike
  there is an unexplained 140ma current draw.

Removed all fuses and the three relays at the front of the relay box.
1984 K100RS
140ma draw still evident.
.
Removed the electronics unit from above battery, and unplugged it.  
No effect 140ma draw still present.
Reconnected the unit.

Unplugged the unit next to the steering column.
  I believe it is the motronics unit.
Still have 140ma  current draw.  

Master switch traced to a non-documented relay in the electronics box.
Relay is activated by switching power from the starter relay input terminal to the coil.
 Relay is 40A  and switch feeds relay coil, plain old earth on other side.  
Power from contacts feeds loon, but relay gets its power from a new wire? That seems to go into battery loom.


There appears to be an added 5mm yellow, white and brown wires from around headlamp loom back to relay box, it terminates on relays that seem to supplement the bikes headlamp switch.  Did not check bulb wattage but assume it is probably large.
Switching of relays  is two grey wires ( part of 2mm  fig 8 wire) that are spliced to ? They disappear  into the loom.
Got a bit cranky about then........
Put everything back where it is supposed to be.

Started checking other items.  Radiator top-up tank 3/4  but radiator not full.
Checked cap, and it was cruddy and probably not sealing with a buildup of hard stuff like calcium on cap and rubber washer.  .Also dirt but no oil or floating slick in pipe or on cap, bit worried there, so washed cap in sink with strong dishwashing liquid, then cleaned rubber and cap properly.
Topped up with ethylene gyclol, and made sure pipe to refill tank full as I was putting on cap.

Frame is rusty around filling fitting.
Windscreen has a few broken perspex mounts, but that could just be old perspex.
Right knee pad lower screw was held on with a wood screw.

I know it's an old bike, but feeling like prior owners might have been cowboys.
Had trouble with the fuel return line clamp, but put it all back together and was rewarded by a start, and steady idle.

Oh well more work to come.

Veka4

If it ABS equipped, Check the ABS relay.  Little buggers go bad and cause a power drain.

I also have a 1984 K100RS in Maddison silver blue.
A few more issues, but some the same.
> Noisy timing  chain, which I believe is the oil tensioner on the timing slide.   
>  no gear indicator light.
>  no clock 
>  noisy alternator when engine slowing.  ? Peanuts.

I have replaced my fuel pump and pre-filter, but the filter I got was for the 1985 and later K100's.  Newer one has the return fuel line that attaches to a spigot on the side of the profiler.  The mounting plate has no cut out to allow the later fuel pre filter to be used.

I got the fuel pump kit from ebay, and when I found the error I communicated with the they and their supplier did  OT understand  until found a beamer site that mentioned the new and old part numbers.  While they were selling the new  model they referred to the part by the old number.  That was why no one mentioned it earlier as I was using  a pdf of the original pre-filter.

The only parts that are purposely not original is the top box (I have one I can lock my full face helmet in.
And the later series fuelcap, that does not leak water through the keyhole.
Bob