Any Ideas....

[Stig]

Good mornin Tossers - Help

My GS fails to start if its not been on the optimiser for a couple of days..
It just stuggles to turn over then the usual "clicks"...

It starts fine if its been on the optimiser..

Battery is new and has been tested by both the seller and my BMW dealer.. The bike had its 18k service last week and i mentioned this issue at the time - the dealer could find nothing wrong.. They checked battery for load and seapage etc etc...

If i take the bike out for a run and stop for an hr or so.. It always starts no prob.. It jus "gives up" after being stood for a couple of days!??.

I've left it and checked the battery at regular intervals over a few days and it holds its charge at about 13.5v ok

When i turn ignition on the voltage drops and then steady's at just over 12v ish.. But then it doesn't seem to have enough grunt to kick the bike into life!.. (unless - like i said its had that "boost" straight from optimiser..)

I dont have an alarm fitted.. And i've removed sat- nav and autocom .. But the issue continues to puzzle moi..

Note: The battery unbranded but the seller assures me that this "should easily do the job".. and there was no mention from the dealer that the battery wasn't up to it when they looked at it..

I've also checked leads to starter etc and they are all still in good condition..

Anyone else had this problem..

It's starting do do my head in!..

 

[The Nutter]

I'm not sure I can help much. From previous experience with batteries on the GS I know that if my battery dropped to anything below 12.2 volts with the ignition on, it would not start. That might explain with yours showing 12 volts, your bike won't start. I would still suspect the battery. Big twins need big power from the battery to turn over and that's why people spend big money on Odyssey and the like. The fact it will start after a good charge also points to the battery failing to hold it's charge. Voltage is only one measurement and it is not always a good way of telling the starting power of the battery. Have you tried jump starting? If this worked, again it points to the battery. Using a volt meter should help to track any drain that may be occuring with the ignition off but I doubt that's happening (though it is a possibility).
Just to add, I have put new batteries on the GS that have only lasted a few months. One way of checking the battery is to give it a full charge off of the bike in the house, check the voltage once charged, and then check it at regular intervals to see if it drops quickly. Hopefully, someone more technically minded will be along soon to offer better advice.

 

[ianp5uk]

Sounds like a battery problem. You should be getting about 12.5V across the terminals (or more is ok) disconnected. Less suggests a problem.

 

[Pukmeister]

Check under the bike for puddles. It sounds like your canbus fluid is leaking from somewhere......

Edit: Check you battery terminals are tight. If they are, my guess is your dealer is wrong and the battery is faulty. Terminal voltage is no indication of stored charge.

 

[DollyRocket]

Terminal voltage is no indication of stored charge

Quite right - You need to measure the battery voltage when the starter motor is spinning (or when it is clicking).
Ideally it should remain above 12V when the starter is running to have half a chance. Sounds like it is dropping to around 9 - 10V.

It could be a buggered battery, or a buggered starter (drawing too much current). If you have an ammeter (or current clamp) then measure the current whilst it is turning over.

 

[socket086]

by any chance is it mainly short trips as the battery will not recover to full charge

 

[DrFarkoff]

Sorry I don't agree once running an alternator will be putting 30 plus amps back in 5 minutes will recover normal starting discharge

by any chance is it mainly short trips as the battery will not recover to full charge

 

[bmwrich58]

Most likely soundz like a "defect" in the battery but why couldn't their be some sort of a "lectrical drain" on the battery noone found yet, if the battery keeps checking out to be good?

 

[Giles]

Edit: Check you battery terminals are tight.

+1 ... sometimes it's something really simple ..

 

[John Armstrong]

Sorry I don't agree once running an alternator will be putting 30 plus amps back in 5 minutes will recover normal starting discharge

I've read that they reckon 16 minutes need for a car to get back to the charge when you started.

 

[Giles]

I had a flat battery (but thought it was something more serious) and used the warranty BM recovery bloke. It turned out the bluetooth module was draining the battery. After he got all his techy stuff, tested the battery and jumped it, I said I'd put it on the optimate. He explained that just running for 20 mins or so would fully charge the battery and be far more effective than several hours on a trickle charger .....

 

[cookie]

Sounds like the battery is the problem to me.

Need to stop messing around measuring with a multimeter, and put it on a load tester.

 

[Stig]

Sounds like the battery is the problem to me.

Need to stop messing around measuring with a multimeter, and put it on a load tester.

Its been on a load tester at both the sellers premises and BMW dealer who both say its ok and should turn the engine... (however i suspect this has been done immediately after a charge - which i think is masking the problem..)

Also: Have checked for Canbus fluid - no signs of that anywhere... But I did notice some Swaffle Valve dust on the Cybernetic Redemption Cylinder... which will need further investigation at another time..

Thanks for replies... I too still suspect its the Battery.. but without there being a "Definative" fault its gonna be difficult to convince the seller to exchange... me thinks...

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