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Can I measure starter current draw?

Bill Dennes

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Bill Dennes

When starting my '02 R1150RT the first time each day, it's important that it catch on the first try. If it does not start on the first try, the starter will not crank the engine anymore - instead it spins but does not kick the bendix out to engage the flywheel. The bike's voltage goes low pretty quickly, too from 12.6 or so down into the 11s.


I'm chasing my tail around these possibilities:

  • The starter is drawing too much current and sucking the battery down.
  • The battery is not getting fully charged by the alternator.
  • The battery is hurting. Note that I found a loose battery ground after having put 15k miles or so on this battery. It's a Westco with a black case, so cannot look for sulfation.
  • My always-on clock/voltmeter is sucking the battery down overnight.


The bike (and starter) has 89k miles. I've torn down the starter and lubed it several times. The voltmeter says 13.9 when the bike is running, and 12.6 after it's sat overnight. The bike starts happily and at once when it's really warmed up.


BUT if I start the bike from cold and ride it a very short distance (say 1.5 miles) and then shut it off, it's almost certain that it will not crank again without a LOT of coaxing. Just spins the starter.


One more thing, it'll start if it's jumped, but the car's engine must be running. When the jumpers are first connected, the car's engine RPM are dragged WAY down as the voltage on the bike comes up over 13. The car revs back up in a few seconds.


Ideas? Can I buy a meter that clips over the starter's big lead like a timing light clip does? Can The Dealer run a test with their mega-tester and help me? Could the GS-911 help here?


I'd prefer to spend money on tools instead of on labor.





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Sure, you could get a clamp on amp meter, and they make some cheap ones that plug into a multimeter, if you have one. You might be able to go to a auto parts store, and borrow one from them, or a shop. Most auto part stores have tools you can borrow. I would try that before I bought one, you seldom use them.

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Stan Walker

Sure, you could get a clamp on amp meter,


Don't forget you are talking DC here!!! AC clamp-ons that you find in the local hardware store will NOT work!!!



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You can measure starter draw, but my guess is you have a bad battery especially as you say it will jump start and will start when warm but not after a short run. Sounds like the alternator is working but its having a hard time pushing amps to the battery.

The bendix kicks in on initial start so it isn't the bendix.

The whiring is the starter not getting up to sufficient speed to throw the bendix in.

Easy to check without a meter. Disconnect your battery from the system, jump a car battery to the leads that would normally go to the battery and try several starts with the engine cold. My guess you will start multiple times.

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If it's dragging down a Car engine when boosting,you have a high draw when engaging your starter,this could be something as simple as worn out armature bushings forcing the armature to grind against the field windings.

Listen for a "growling or grinding" when engaging the starter.

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If it's dragging down a Car engine when boosting,you have a high draw


He said when he FIRST hooks up the car for a boost.I am assuming that the draw is because it is seeing a shorted or high resistance in the battery. Hence the need to remove the battery from the system to test the starter without the battery in the system. IMHO

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You are probably correct, I was assuming that the engine lugged down while the starter was engaged which shouldn't happen with normal Amp draw on any bike (Boss Hoss excluded)

Even with an extremely small diameter booster cable the engine shouldn't even need to be running while boosting.

Unless like you say "the battery is probably pooched) thumbsup.gif

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Bill, Yes you can measure DC amp draw with a clamp-on meter. An AC ammeter won't work but there is a DC clamp-on ammeter. DC ammeters are not nearly as common as AC ones but work exactly the same way. I've used them 100's of times in my other life as an electric (as in battery operated) forklift mechanic.

As far as your starter problem, I'm guessing it's time for a new battery.


Regards, Ron

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+1 on the battery suggetion ... the current draw is very high ... if you use a multi-meter, make sure it has a very high range; mine only goes to 20 amps - not high enough to prevent meter burn out.

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The voltmeter says 13.9 when the bike is running, and 12.6 after it's sat overnight.
Presuming it was ran sufficiently to charge the battery before parking it, that's too much of a drop from just an overnight sitting. I'm guessing the battery is on its way out.
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Bill Dennes

LinearEagle gets the "that's correct" award for figuring out that the car's RPM were dragging down at jumper hookup time. Just as if the battery were soaking up some missing charge.


HOWEVER, when I tried the car battery test suggested by LinearEagle, the starter punked out on all tries except the first one. It would spin, but would not drive the Bendix to engagement. When it did start the first time it seemed to crank slowly, too.


So now I suspect the starter. When the engine warms it up, I suspect that one of the bearings or something in the planetary drive is growing a bit, enabling the starter to spin easily. When the starter is at or near room temperature, it seems tougher to crank.


By golly, it could be the starter and the battery! bncry.gif





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Could be a bad (Dirty) connection at the starter, or inside the starter. You could have bad connections on either end of the jumpers to the car.

It always amazes me how many electrical problems disappear when the battery is replaced. Just sayin'.

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By golly, it could be the starter and the battery!


Been thinking...I know...dangerous.


There could be a relay that is working but poorly working.

Try swapping the horn relay (which isn't used much) with the starter relay and then swap with the load-shedding relay if that didn't do it.

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What if you charged up your bike battery and then brought it into a shop that can put a load test on it? If it fails, then you know you at least have to get a quality battery like an Odyssey pc680 in there. Then, you could swap relays like the other gent said. I worked in my dad's auto/diesel electrical shop for a couple of years after high school doing grunt work, and if I remember correctly, there were times when a battery was on it's last leg along with the starter. Starters (especially the armature) don't like low voltage. So, yes, you could have 2 problems- battery and starter, perhaps along with dirty, corroded connections. Does the BMW starter have 2 bushings in it? One in the drive-end housing and one in the commutator endplate? If these are worn, the armature will also drag on the magnets in the field housing (main body of starter).

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Bill Dennes

The starter.


I elimanated all of the control circuitry by hooking up an old-time remote start switch across the hot terminal of the starter and the solenoid terminal. Then I used a car battery. The darn starter STILL would not pick up the flywheel. The new starter turns the motor a LOT faster than the old one did.


I've been quiet for a couple of days while I waited for my new starter to come from Euro Moto Electrics . Two-day service for $189 vs $355 from the dealer.

John Rayski (the boss) is a real godsend, providing OEM parts that fit right on and work great! Thrifty, too. I'm sporting am O2 sensor and a fuel pump from John, as well as the new starter.


Yay! clap.gif

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