2001 R1150GS Low voltage when cranking.

In the beginning, I thought this would be simple. It's my buddy's bike and has approx 60k miles on it.
Just after the addition of a fuse block, the bike started to zero the clock and abs wouldn't initialize.
New battery was installed. No joy.
Voltage dropped to,about 6v when cranking. 12.9 when key off, 12.4 when key on. About 13.9 v at about 2000 rpm.
Battery tender was used to ensure battery was charged.

Bike draws about 3 milliamps when key is off. Sounds right to me for the clock.

I noticed the + cable battery end had a good bit of white corrosion at the crimp.
Cleaned solenoid end of starter cable even though no corrosion apparent. I stripped insulation back a couple inches from the battery end and it was shiny. Measured resistance of cable...battery end to starter is about 2 ohms. Replaced the cable end.
Cranking voltage then at 9 to 10 volts. Thinking corrosion was the issue because replacing ring terminal and cleaning connection at solenoid had brought the cranking volts from 6 to 9 and there could be more unseen corrosion in the cable, a new cable was made up and tried.
No improvement in cranking voltage.

Only thing I could see left in the equation was the starter. Ran it on bench. Turned freely and spun down normally when power removed. Hmmm. Took it apart, cleaned it and saw the magnets are still glued to the case. Brushes look ok, but I didn't remove them. Perhaps I should have, but only 60k miles on bike,so...

Clock doesn't zero, but abs won't initialize consistently and I believe it's the low cranking voltage that's causing it. It doesn't occur on every start, perhaps 50% or so.
Bike starts and runs ok otherwise.

I was going to try charging his battery, but then saw my Odyssey charger has gone belly up. Rats!
I have others, but they're maintainers, not 6 amp ones.

If I've missed something, I'd sure like to hear what it is(and so would my buddy!).

Thanks

Comments:
Bike voltage should be 10+V cranking
Make sure the armature is not rubbing against the planetary cover (covers come loose and will short the end)
Starter should draw about 150A no load on the bench.
Remove the the armature and take to a repair shop and have them put it on a growler to check for shorts.

Jeff488 said:

150A?
Can't be. 15, perhaps.
The starter turned freely on the bench. I didn't notice any wear marks on the planetary gear cover.

I couldn't get the armature free from the brush holder assembly. The bearing wouldn't come free and I didn't want to beat on it. I don't know of an electric motor repair shop around here.
Can't the armature be checked with an ohmmeter? Remove the brushes and do it from that end?

Tomorrow I plan to try a seperate ground from the battery to the starter. Maybe there's a poor ground in that circuit. Doubt it, but it eliminates the possibility and it's easy to try.

Thanks for the ideas.

Click to expand...

150

1 hp = 746w

15 does nothing.

The cap must be removed to expose the circlip that retains the armature

Ohmmeter will not find a short.

I have bench tested SDT410 starters, the kind that take 1000 Amps to turn a crank and rarely are they as high as 150 on the bench. I have bench tested lots of these little starters and start to question them at 75.

However, one bad phase in the armature could yield 15 amps but should result in a dragging starter.

I'm going with grounds on this one.

You didn’t mention what type of battery but if it’s an AGM like the Odyssey PC680 and the “tender” you mentioned is a Battery Tender Jr, I see three possibilities:

—since you found corrosion on the plus cable, I’d check both ends of the ground cable.

—Oilhead starters are prone to drawing too much current for no apparent reason.

—using a BT Jr., you can trickle charge a PC680 or AGM battery into a higher resistance state. Its charging and maintenance voltages are too low. It’s happened on many bikes, including both of mine, one worse than the other. You can usually drain and properly recharge it (4-5 times) back to health.

If you are curious about the innards of your starter, this Best of Forum may help- https://forums.bmwmoa.org/showthread.php?69483-A-peek-inside-your-starter
OM

Thanks for the suggestions, guys.

Today I'll run a separate ground cable for the starter, if my bud brings the bike over(pretty rainy today). Low hanging fruit, etc.

Since my Odyssey charger croaked, I can't do discharge/charge cycles. So that'll have to wait till it's replaced.

FWIW, when the started was apart, the commutator looked clean and smooth. No signs of arcing.

Can someone tell where the oem ground attachment point is?
So far, it's successfully hidden from me.

Jeff488 said:

Can someone tell where the oem ground attachment point is?
So far, it's successfully hidden from me.

Click to expand...

Under the battery box on the left side right at the end of the engine block where it mates to the transmission.
M6 bolt.
A real treat to get at.

Thank you sir.

I'll have a look next week.

Since I last posted, the starter has been replaced with an Enduralast from EME and an additional ground cable installed. No joy.
The starter solenoid had gone to Valeo purgatory, so it's not as though we're just throwing parts at the bike.

Reset the abs by using the 'ground the br/blu wire in the diagnostic plug and depressing abs button for 8 seconds' method. No help.

I learned that the oem positive cable cannot be replaced without consequence. The bike won't charge without it. The charge light stays on, dimly, and volts at the battery are about 11.8 when running.
I also learned I didn't examine the schematic carefully enough. Kinda embarrassing.

Everything seems to work ok except the abs won't initialize.

The quest continues, but not till after we return from Barber this weekend.
If you see me there, I'll be the guy looking haunted by failed troubleshooting ghosts.