Brake Warning Light

i am not very up on electrics what do you mean by [series or parallel] i have fitted one resistor to the white/red wire and the other end to the + battery terminal.will check tomorrow the voltage either side of the resistor.

 

my response was to crazynat post of 2 resistors at 1.1k ohms.

series is 2 motorcycles driving down the road one behind the other ( one end of resistor soldered to the end next resistor)

parallel is 2 motor cycles riding down the road side by side ( resistor side by side leads at each end twisted to gether)

 

one side ,battery side will be 12 volts the side to white /red wire will be less.

 

It worked for me, I ran them in series into the tail light our brake light wire. I've had it like that for a year and no problems, even got to test it earlier this year after the battery had been sitting. It was low and the light came on until I got it charged back up.

 

sounds good as the resistors convert it to a voltage tester. could be OP has to charge his battery.

 

update.battery voltage at resistor when running is 2.7v.sometimes the light goes out when started other times it stays on.not been out on the road yet but will see when i do and report back.

 

sounds like your battery is weak/old or just needs a good charging
sounds like the resistor setup is working properly.
you should check your charging voltages and your battery at rest after it sits over night.
How are the acid levels?
use distilled water to bring them up to level

and once again info from has good info on electrical and the charging system well worth the read as it tells what to look for if things are out of spec
The Ultimate Relay, Switch, Sensor, and Diodes Guide

Starting Load Test:

a) Adjust voltmeter to DC volts (20 volt range).
b) Place voltmeter leads to the battery terminals (positive to positive and negative to negative) .
c) Watch the voltmeter as you start your motorcycle, but before the engine is running.
d) If the voltage drops below 9.5 volts, the battery has very low capacity and should be replaced.


Charging System Tests:
For all XJ-series models, the maximum available charging output VOLTAGE should be as follows (all values are approximate):

* approximately 500-2000 rpms: 1.8 volts gradually increasing to 14.2 volts
* 2000+ rpms: 14.2 volts up to about 14.8 volts, with a maximum of 14.8 volts (all models except XJ700-X and XJ750-X)
* 3000+ rpms: 14.2 volts up to about 14.8 volts, with a maximum of 14.8 volts (all XJ700-X and XJ750-X)


Static Battery Voltage Test

Prior to conducting this test, make sure the battery has not been
recently charged. You must wait at least one hour after charging
your battery to conduct this test.

a) Adjust voltmeter to DC volts (20 volt range).
b) Place voltmeter leads to the battery terminals (positive to positive and negative to negative).
c) Read voltage and refer to the chart below.

State of Charge:

100% Charged with Sulfate Stop:
Using a syringe Hydrometer: 1.280
Using a Digital Voltmeter: 12.80 volts
Using a Floating-Ball Hydrometer: 5 balls floating

 

xj550H thanks for all the very good info will check it all out.

 

Is that a typo?

 

the resistor thread said it should be kept under 5 volts
2.7 may be the connector side of the resistor not the battery side.
voltage drop across the resistor.

robbo did say it was turning warning light off sometimes.
we need more data from people who have done this.
resistors used voltages ect...

going to buy me some resistors and check it out .


it would also be nice if those with the original style sensor could post some connector voltages

 

I can check mine if that would be helpful. Where exactly did you want the measurements?

Also, if you want some of the resistors I got you're welcome to a few. I got 25 of them because it was cheaper that way.

 

Some thought and speculation as I see it and subject to change as noted by the XJCD or other knowledgeable members. Note I have been running with the 5.6k resistor for the past month with no issues noted.

The original battery sensor installed in the 4th cell from negative battery supplied approximately 6.4 volts to the CMS for battery monitoring - 3x a fully charged battery where each cell would equal approximately 2.13 volts. The original setup was mainly a check for electrolyte level as the voltage decrease to set a fail would equate to a battery voltage of 6.6 volts, well below a useful voltage monitoring spec.

Installing a 2.2k resistor is really only useful for eliminating the battery warning, as that value combined with the internal components of the CMS would not detect a battery low voltage until the battery dropped to approximately 5 volts. Once again too low to be considered a useful voltage monitor.

The more appropriate size of the "bypass" resistor with wiring and switches that are in good working order is 5.6k, which will set the battery warning at approximately 10.8 volts, a warning that would be set in time before the bike would stop running from lack of voltage to power the TCI and ignition coils.

This is really close to what it should be. With no wiring / switch issues the calculated voltage using a 2.2k resistor is 2.88 volts at a battery voltage of 12.8 volts. If the battery warning is intermittent with the resistor then the most likely cause is what Len mentioned earlier, a downstream issue with the ignition switch contacts or wiring causing a momentary open or increased resistance. This should also be visible in the failed condition as a voltage much higher than 2.7 volts. A solid reading of 2.7 volts or so with the constant battery warning would be a bad sign as it would point to internal to the CMS.

CMS internals:

 

That makes a whole lot of sense. I got to re-thinking the resistor value myself this afternoon, but hadn't the time to work things out to determine the voltage needs.

Rooster, would you mind adding you post and schematic to the original bypass thread?

 

This thread?

http://xjbikes.com/forums/threads/battery-sensor-we-dont-need-no-stinkin-battery-sensor.820/

 

Yes.

 

update,battery voltage 12.55 when cranking drops to 9.2v.Went for a run of about seventy miles, light was on when started but after about two minutes of riding went out.I stopped five times shut off and restarted, each time light was on and went out after about two minutes of riding.Do you think i should now try the 5.6k resistor as mentioned.hope this is of use.

 

I think you should try a new battery.
Your systems monitor was telling the truth.

Changing to a 5.6K resistor would be a good thing IMHO.

 

Get a voltage measurement of the 2.2k resistor output during the failed condition if you can. Hopefully, it will be considerably higher than the 2.7v that you noted earlier and will be the result of a poor connection at the ignition switch connector or the 9 pin connector to the CMS, or just needing to clean the ignition switch. Or, better yet, it would read zero on the output side which could indicate a poor connection in the resistor installation.

 

update,battery voltage 12.55v(not used for 4 days} in failed condition{warning light on} 12.20v at resistor after about 2 minutes warning light goes out and voltage at resistor is 2.70v.so should i check for poor connection at ignition switch connector and cms connector.

 

You should get a new battery. The warning light is going out because the alternator is charging the battery back up to an acceptable voltage, but it is dropping below an acceptable voltage when you start the engine. The resting voltage is also low.