Battery Light on when cold

[Kouros]

2004 R1150GSA

I changed the Alternator Belt a while back (500 Miles) and since then I've noticed that the Battery light is constantly on when letting the bike to warm up a bit before riding. As soon as I blip the throttle, it will turn off and I go about my business. It won't come on again unless the bike is parked and the bike is cold again. One note is that as soon as I blip the throttle, the pitch of its noise changes. The light does not go off until I blip the throttle, but once I do, it will go off and stay off.

 

When I initially installed the new belt, I made sure I lifted and tighten the upper pulley high enough so that it can only turn 90 degrees and not more. I inspected the belt today and nothing seems to be out of norm and the wear is good, especially on the edges of the belt and with no cracks. The battery itself is just a couple of months old while always on a trickle charger. I don't have charging issues when I ride long distance either.

 

Any clues as to why the light comes on?

Thanks in advance.

 

Kouros

[dirtrider]

Afternoon Kouros

 

A couple of things come to mind.

 

If you DIDN'T have the problem before installing the new belt then possibly a loose belt (on the 2004 1150 using the Elastomer belt the 1/4 belt twist method isn't tight enough. The Eastomer belt is ONLY properly tensioned by a special BMW tool or at the very least by upper to lower pulley spacing.

 

OR, if the problem has been there longer then the new belt install then possibly the dash warning light is not letting enough 12v power reach the voltage regulator to initially excite the alternator rotor without revving the engine. The only real cure here is to install a new different wattage dash light bulb.

 

 

Added: (IF) you have the Elatomer (stretchy) belt (that should have been OEM on your bike) & you want to go back in & measure the pulley spacing distance then the distance between upper & lower pulleys is 4.66" (118.5mm) & that is measured between the pulleys (right on the pulley ribs themselves).

 

OR, from lower pulley front flange to upper pulley front flange, (that is a LOT easier to measure) & that is 4.56" (116mm).

 

Caution: don't use these measurement IF you don't have the proper Elastomer belt installed.

 

[Kouros]

DR,

I didn't have the issue prior to bely change.

I did use the BMW tool on another R bike and I broke the tool and the special type nut on the alternator.

 

Do you know what the distance of the pulleys should be?

Thank you very much as you're always first with answers. I appreciate it much.

 

Kouros

[dirtrider]

Do you know what the distance of the pulleys should be?

Thank you very much as you're always first with answers. I appreciate it much.

 

Kouros

 

Afternoon Kouros

 

You can't use that SPECIAL nut for the Elastomer belt (that is for the older non stretchy belt) as you will break it every time, even so it won't give you the proper belt tension.

 

The proper Elastomer tool is little jack type affair that goes between the lower & upper pulley to force the pulleys apart to the proper spacing.

 

 

Added: (IF) you have the Elatomer (stretchy) belt (that should have been OEM on your bike) & you want to go back in & measure the pulley spacing distance then the distance between upper & lower pulleys is 4.66" (118.5mm) & that is measured between the pulleys (right on the pulley ribs themselves).

 

OR, from lower pulley front flange to upper pulley front flange, (that is a LOT easier to measure) & that is 4.56" (116mm).

 

Caution: don't use these measurement IF you don't have the proper Elastomer belt installed.

 

proper BMW tool (SHOWN ON RIGHT IN PIX)---

 

[roger 04 rt]

The other things you could try are: 1) swapping the 3W high beam bulb In place of the 1.7W batt bulb. The alternator will start faster and at lower RPMs if you do. Or 2) check that the D+ wire spade terminal is tight to the alternator. My '04RT had both problems. The 3W bulb is now standard for the batt position.

[dirtrider]

clip-- Or 2) check that the D+ wire spade terminal is tight to the alternator. My '04RT had both problems. The 3W bulb is now standard for the batt position.

 

Evening Roger

 

Seeing as the D+ spade terminal is the low (ground path) for the GEN light to light, that could easily cause a poor or delayed alternator excitation but a poor connection there would also put the GEN light out, or make it flicker, or illuminate it at a low intensity. A good solid GEN light should tell us the D+ connection is intact & has good continuity.

[roger 04 rt]

DR, You're right about the D+, come to think of it my bulb was out when that happened and then no start of the alternator.

 

But the 3W bulb fix is a good one to pursue.

RB