Battery sensor bypass not working...

Hello all, I was having problems with the battery sensor on my Yamaha Maxim XJ 750, where the warning light and low battery indicator stayed on all the time. I decided to falow the directions on this web site, a picture well detailed on how to bypass the battery sensor in order to get rid of the warning indicator. I did everything mentioned in the instructions, yet I still get the same result!? Something I did wrong, or is this not the solution for my bike?

Thank you and take care. 8)

 

I'm curious as to what you built. Can you send a picture showing location and attachment of the wires? Should work for the 81-84 models.

 

Hello, here is the diagram and instruction I fallowed exactly as it is mentioned!!!!

 

I'm sorry, I was referring to your bike not my diagram. I apologize for not being more precise in my question.

 

Ok, sorry about that, I will take a picture tomorow and post it. Basically it is like the diagram, one end of it is connected to the positive of the battery, and the other end is conected to the wire that was leading to the battersensor.

Let me know if this is incorrect, i will still post the picture tomorow. Thank you. 8)

 

On my '82 SECA, the PO hooked the batt sensor wire directly up to the batt side of the solenoid. It has been connected for some time now, and my batt warning indicator never comes on. I'm not sure if this will fry something down the road, only time will tell, I guess.

Nachoman

 

Have you checked resistence through the cable with a multi meter?

I'm geussing maybe a faulty connection or maybe dud resistor

 

A 2k resistor [2 thousand ohms] is marked [coloured bands] red/black/red/silver for a 5% one or red/red/red/silver for a 2.2k 5% one , test with a mulimeter....the mod should work everytime.....

 

Well, if you are attached to the positive lead of the battery directly to the sensor wire, I'd be puzzled too! Need to check all the connections of your bypass set up and ensure the 2,000 ohm resistance is in fact 2,000 ohms. Might have gotten a dud or have a bad connection. Waiting for your reply.

 

My Experience...Re: Battery sensor bypass not working...

I also did the battery swap to sealed and had to do the resistor mod. I used one 2k residtor from radio shack and conected my hot wire via the brown (hot wire) going to thr rear brake switch... did not work, batt light still came on. I then added a second 2 k resistor and voila, it worked.
That was on my 82 XJ750 Seca... When I attempted this on my XJ750 Maxim neither the singe nor dual resistor mod worked. i check the resistance through the wire and it was @ 2200...
I don't know where to go from here, but I suspect a crack on the circuit board or some such is causing the fault (did not work correctly with the battery probe either on this Maxim)...
Anybody else have something to add here or a circuit check sequence that might get me closer to the problem?

 

What year is your Maxim?
Off the cuff, I'd say ohm out the line from the sensor connector to the circuit board in the cluster and insure you have continuity from point A to point B. The flashing light is the defalt unless a voltage/current (this is still being debated and I'm on the fence as to which it is) is sensed. If your line is good, the problem might be in the circuit board (cracked solder run or corrosion issues).

 

I installed a 2.2K Ohm resistor between the positive terminal of the battery and what was left of the wire from the battery level sensor. I am still having problems with the battery light coming on. Any ideas?

 

you can take out your resistor and put a fuse in there, +12 volts through a fuse to the white/red wire and your good to go.
or our parts guy "chacal" or Len sells a little kit to put in that monitors the battery and charging system better than the old battery light, for not too much $

 

Indeed he does.

(shameless plug)

 

I would like more info on the kit. I know the battery is good, but the light coming on is annoying. Thanks for hte reply, I was hoping this thread wasn't dead seeing a the last post before mine was in 2006.

 

fobeauchamp76 did you connect the "bypass" to the correct wire on the wiring harness? Most of our bikes do have few spare unused wires. You COULD have plugged it into the wrong one maybe?

 

I am certainly no expert, but I will put in my two cents in hopes it will help (and maybe I'll learn something if someone corrects me). The way I understand it is the sensor essentially attempts to read the voltage of half the battery's cells by putting a small lead sensor into the battery at the midway point. This is approximately 5.5-7 volts depending on the state of the battery.

The plans in this thread assume that 2 kohms will work to produce this voltage. I am confused about why this ever works. The input impedance for the battery warning light circuit should be fairly high (I'd guess on order of about a Mohm), otherwise it would be a needless current drain. If that is the case, then unless the resistor you use is approximately equal to the input impedance you will not get the right voltage.

Assuming it is for a moment 1 Mohm, and you used a 2 kohm resistor, and the battery was outputting exactly 12V, the sensor would be reading about 11.98 Volts. In fact the only time you'd read 6 Volts is if the warning light circuit input impedance was exactly 2 kohms.

I think the best way to build a bypass is to use a voltage divider. To do this you use two resistors of the same value, but smaller than the input impedance of the warning light circuit, but big enough so they don't draw a lot of current. Then source the warning light circuit between the resistors. With this setup, you get approximately half the battery's voltage regardless of the input impedance of the warning light circuit (within reason).

I would also suggest not hooking it directly to the battery as it will drain the battery over time (perhaps imperceptible), but I see no reason not to go off the one of the fuses (I used the Main).

I did exactly this, this evening. With the bike key in the on position, with the kill switch on, I measured the input impedance of the battery warning light circuit to be about 0.715 Mohms. Satisfied it was large enough I found two resistors (2.2 Kohm, though in principle many others would work, maybe 10 kohm would be a bit better) and wired it as shown in the very rough diagram. This circuit draws approximately 3 milliAmps (the 10k would draw less than 1 mA). Measuring the voltage at the point where I connect the battery sensor to I get approximately 6 volts, and the warning light works perfectly. I don't know the cutoffs for the warning light to flash so I don't know if it will be useful in determining over/under charged states, but at least the annoying flashing battery light is gone.

 

Tried using the same design as in the first diagram, but using a 4.7K ohm 1/2 watt resistor as mentioned on another website and nothing. Stupid light still comes on.