UK Buell Enthusiasts Group

My battery is flat - battery or the charging system?
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Author:  pash [ Thu May 07, 2009 10:03 pm ]
Post subject:  My battery is flat - battery or the charging system?

Place holder :lol:

Nutah wrote:

with the bike switched off, connect the meter across the battery,set the meter to DC Volts should show around 12-13volts.

start the bike up with the meter STILL connected , the voltage on starting will drop to around 10volts , less than 9volts while turning over battery is knackered, (& it wont start )

if it starts while running the volts should rise as you rev the motor, to around 13-14volts
if it doesn't the voltage regulator OR the alternator needs checking as per manual.

hope this helps :yup:

lamo wrote:
Check the connectors behind the front sprocket cover can't remember if its the one between voltage reg and battery or v reg and stator that melts but check both its dead easy and easy fix

pash wrote:

buelllightening wrote:
Had the same problem,it was the 77 connector ,best junk it and hard wire with inline crimps,done mine no problems since,there is enough cable for a few goes if thr regulator does go at a later time

Maz wrote:
V.reg failure is VERY rare on XB's but stator failure is common.

.....tis the other way around with tubers

panther wrote:
just to be different ive had a regulater give up the ghost

Maz wrote:
Back to basics.......with the bike running at 2K rpm and a DC volt meter across the battery, what reading do you get ?....should be 13-15V.

Have you checked VR for bleeds ?.....should be zero
Have you checked stator windings for continuity to earth ?.....should be zero
Have you checked stator winding resistances ?....should be 0.1-0.3 ohms
Have you checked AC output of all 3 phases ?......should be around 35V @ 2K rpm.

Gunter wrote:
Well, although it didn't run as smooth as expected, I got it into parts now and found another proof of Buell's high quality work.

Scattered and sticking to the magnets:
and here what it did to the stator:
and at this point at least one wire is grounded:

As usual - BUELL = crappy production & missing quality control.
I bet this bike had a short circuit with the first turn of the engine.

And I need a new hex nut for the clutch.
Someone who has one in stock?

Thorkill The Tall wrote:
Compu-Fire replacement parts are quite highly recommended:

Author:  buelllightening [ Wed Jun 10, 2009 9:42 am ]
Post subject:  Re: My battery is flat - battery or the charging system?

Fitted a Cystal Dynamicis single LED voltage indicator to my Uly this winter,on a trip in France last week the led started to go fro Green (all OK) to amber then back to Green so thought nothing of it,Next day Light goes to amber,then red,then fashing red,then then engine
Check light came ON and then instruments went dead,stopped removed the 77 conector ,no burning ,so bent the terminals a bit and refitted it all ,bump started the bike as the battery was nearly dead and all was well,amber led for a while and then back to Green,Proves that the Crystal Dynamics LED is a good Early Warning device for pending failure and i should of taken notice of it the Day Before.Artical on fitting it on the Bad weather Bikers Forum

Author:  wobbly [ Mon Mar 21, 2011 8:54 am ]
Post subject:  Re: My battery is flat - battery or the charging system?

About halfway down the page.

Cheers, Richard.

Author:  ericry [ Wed Mar 07, 2012 3:51 pm ]
Post subject:  Re: My battery is flat - battery or the charging system?

See there is one made in the UK available now....called Sparkbright they trade on ebay...see here ... 4340.l2563

Seems a neat unit - cheaper than the SDC unit and you're keeping the money this side of the pond !


Author:  pash [ Wed May 14, 2014 7:10 pm ]
Post subject:  Re: My battery is flat - battery or the charging system?

I just changed my regulator... Here's what I did...

Battery was flat and not charging:

1. Charged the battery on the Optimate
2. Tested the battery terminals - they were tight
3. Put the voltmeter across the battery - it measured 12.62V DC
4. Started the engine
5. Put the voltmeter across the battery - it measured 11.8V DC
6. Split the 77 connector
7. Put the voltmeter across the battery side - it measured 11.8V DC
8. Put the voltmeter across the regulator side - it measured 3.2V DC
9. Split the stator outlet connector
10. Put the voltmeter across each pin to each pin (each winding) - it measured 15.6V AC on each
Image Image
11. Shut down the engine
12. Measured resistance across each winding - it measured 0.4 Ohms on each
Image Image
13. Measured the resistance of each pin to ground - it was Open Loop on each
14. Replaced the regulator
15. Tested again - 12.49V not running and 13.87V running
Image Image

As I was replacing the regulator, I:
i. Copaslipped the screws holding the regulator on
ii. Put liberal amounts of silicon grease inside the 77 connector - a known weakpoint
Image Image

Then, just like a grandfather, I stripped the old regulator of anything that may come in use another day...

I made a little troubleshooting flowchart too...

Author:  gunter [ Wed May 14, 2014 9:44 pm ]
Post subject:  Re: My battery is flat - battery or the charging system?

Kanpai, young fella ... :-)

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