Battery charging -weird: Kymco Agility City

[mwb1000]

Hi guys - first post so bear with me on this...

Problem is to do with my battery - and its charging.  I have tested it with a multimeter and get the following readings:

At rest: 12.6v
Engine on at idle: climbs up to 14.5v given a couple of minutes
Turn on headlight: drops to 12.5v
Headlight on and stoplight: further drop to 12.2v

If I apply more gas - volts stay at this level but sometimes the multimeter shows figures of 10 or 11v very briefly...

If I turn off the lights the volts increase again but only slightly and stay below 13v until a few minutes when it will get back to 14v

So the stator seems to be supplying a charge - it just seems that the lights draw too much current for the stator to supply?

I would be grateful if anyone has any ideas what to check: stator, regulator whatever, or do I need to measure amps - it's just driving me crazy that the battery goes flat every few days - as its the law to ride with lights on all the time here  

Great forum by the way!

Thanks in advance

Matt

[MaryK]

At idle speed, the charging system can be "overloaded" by the lighting & engine loads.
Also, the battery should be fully charged.

Place the scooter on the center stand and insure that the rear wheel isn't touching ground.
Measure the voltages again at 2000 and 3000 rpm.  At driving RPM, the electrical system should be
outputting about 14 volts, even with the headlight on. 
No more than 14.5 volts, or the high voltage may damage the electronic ignition.

Also, get the battery fully charged and have it tested under load at an autoparts store or electric shop.
They should test it for free.

Scoot safely,

[mwb1000]

Hi - thanks for your reply! 

Well I have checked things over in more depth today.  Battery showed 12.7v before starting. Taking the met-in box out to get access, I have tested the AC volts being produced by the generator.  Measuring across the yellow and pink (if I remember the colors correctly) I got 55v-60v at fast idle (cold start choke was on) and giving some gas this figure increased nicely.

So I have at least for now eliminated the generator as being at issue.  This I think leaves just the regulator/rectifier but I have absolutely no clue as to test that!  I guess as the max. volts at the battery when running is 14.5v the regulator bit is doing it's job but maybe the rectifier is having problems when the light is turned on.  Or maybe I'm going crazy and there's nothing going on and it's just my driving habits  :

I think I'll see how to test the reg./rect. unit and go from there.  Maybe a new one might be the answer...

Out of interest - would a damaged CDI cause low charging when the lights are on?  Hmmm maybe I'm thinking too much now...

Thanks!

Matt

[MaryK]

You can check the rectifiers with an ohmmeter.
Each rectifier is a diode that passes electricity in one polarity and does not pass any in the reverse polarity.
So the ohms (resistance) should be low when the probes of the ohmmeter are applied in one direction
and high when the probes are reversed. 
There should be 2 diodes for each wire coming from the alternator.  If any diodes don't read right,
then the rectifier is not capable of putting out the full current and needs to be replaced.

Checking the voltage regulator is much harder.  In many cases, it is potted in with the Rectifiers and cannot be
tested independently.  In any case, if you could test it, you would need a good variable DC voltage supply and a voltmeter.
Most people lack the voltage supply, and a new regulator is cheaper to buy.
Normally, you just monitor the voltage and see that it never exceeds 14.5 volts, but if the alternator & rectifiers are good,
then the regulator may be faulty if the voltage never behave.

If the battery is load tested to be good and the alternator is good, then I'd replace the R/R if they are in one package.

Scoot safely

[JustWantToRide]

Most bikes will drain the battery when the lights are on and the engine is only idling.  12.6v with everything off and 14.5v when running are normal levels.  14.5v with the lights on and running about 3 to 4000rpm would also be normal.

Is your battery dying when you're riding or something?  Why do you feel these levels are a problem?

[mwb1000]

Thanks for the replies guys!

The problem is that the original battery got low every week - so I relaced with a new battery - and it too loses it after about a week and I need to charge it off the bike. 

No matter if I take the bike out for a long ride the thing just goes on me.  Last week for example (battery fully charged) I rode to work and back - about 36 miles round trip - everything fine and good.  The next day I took the train to work, so I rode to the station (about 1.5 miles).  On pulling over to park (light on, brake light on and turn signal) the bike starts hesitating in tune with the flashing turn signal - power and then no power!  On the way home in the evening I can hardly see a thing  -  the headlight is dim and I can't reach full speed unless I turn the lights off completely!!  I checked out the battery at home and it was a little down on volts.

Am I thinking correctly here?!

I think I'll try the resistance test on the regulator-rectifier but maybe I just order a new one even just as a backup.

Thanks.

Matt

[JustWantToRide]

Thanks Matt - that explains a lot.

Something simple to check for is the connections from the battery to the alternator and to ground.  I've seen that cause this more times than not.  Check that the cables are tight at both connections and have no crimps or damaged spots.  If they look ok then check the cables for resistance. 

It's not the battery because you've replaced it.  If the cables are ok then it's either the charging system or an excessive drain.

Is this a new bike, one you've had for years, or one you recently bought used?

Is the headlight a 35w or 55w?  If the headlight bulb is stock and there isn't a short in it causing extra drain - then it's your charging system.  When I've had regulators go they either let too much current through or none at all - so I would suspect the alternator - but my experience with the Agility is limited.  Before replacing anything inspect and clean it and all of the contacts.  Trace the wires and check the connections for tightness, crimps, or discolorations. 

[mwb1000]

Hi everyone - bit of late reply I'm afraid but I have fixed the problem - a new regulator-rectifier seems to have solved it.  Changing the unit took 1 minute - but taking off the bodywork and putting it all together again took me over 3 hours!!  The first thing I noticed with the new unit in place was that the headlight shone brighter than I can remember before - so the old unit may have been duff from when I got the scoot...

Thanks for the earlier replies 

Regards

Matt