Charging systems, need advice !

6 months ago changed the battery and had charging between 14.2 V 14.4V with the lights on and off at idle and 5000 Rpm ( I have 2003 model with light switch) .Now, yesterday charging betwen 13.5V light on and 13.9 V light off ....before removing the alternator and check it who advised me to check ? Has anyone had problems like this ?

Generally Charging voltage can vary with battery condition (discharged battery will have lower charging voltage) and temperature. I have not had any experience specific to ST1300 other than battery replacement. I would summon the IGOFAR for specifics before tackling the alternator.

Smok3 said:

6 months ago changed the battery and had charging between 14.2 V 14.4V with the lights on and off at idle and 5000 Rpm ( I have 2003 model with light switch) .Now, yesterday charging betwen 13.5V light on and 13.9 V light off ....before removing the alternator and check it who advised me to check ? Has anyone had problems like this ?

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This is usually something simple. Don't go to tearing your alternator out until you look at everything else. Do you have a shop manual? There is a troubleshooting guide in there. Take your battery out of the bike, charge it. Then have it thoroughly tested, including a load test. If bad, replace it. They do go bad early, it happened to me. Also, check your battery connectiions and make sure they are clean and tight on both ends. Work from there.

understand that my "new" battery is to blame(is still in warranty ) motorcycle was used weekly but now the cold weather come out 2-3 degrees outside...Ok first I charge the battery and maybe I try with another battery ...battery contacts are clean.

Here is a motorcycle charging system diagnostic chart;
http://www.electrosport.com/media/pdf/fault-finding-diagram.pdf

I have never used it as I have a service manual so it is up to you to check its accuracy but it may give you some ideas.

Andrew Shadow said:

Here is a motorcycle charging system diagnostic chart;
http://www.electrosport.com/media/pdf/fault-finding-diagram.pdf

I have never used it as I have a service manual so it is up to you to check its accuracy but it may give you some ideas.

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In the above referenced diagnostic chart, it states that anything above 13.5 and below 14.8 perfectly OK. I don't see your problem, unless you're having low battery voltage after riding.

In the service manual, the standard for voltage, with engine running, is anything above resting battery voltage and below 15.5 @ 5000 RPM as listed in section 19-8. I just went out to the shop and checked my ST1300. Just off the battery tender it read 13.9. Not running, with lights on, 12.8. During starting, 10.8. (Probably time to replace 3 year old). Running with lights on, 13.8

I think your alternator is fine unless you're having starting problems.

John

Having recently removed my alternator to replace a leaking o-ring, it is an involved task to do. Not hard, just time consuming. Read the above posts and sounds like yours is fine.

Sounds like it is working fine to me, now go ride that bike.

All motorcycles that I had I had a voltmeter onboard and all I had trouble charging systems :
Aprilia RST Futura problem with brown conector, connector between alternator and rectifier melted(imperfect contact) - rectifier faild
Honda VFR 800 Vtec : faulty alternator- replaced, rectifier OK
and now ST .....oK I charged the battery I use a Optimate 6, battery is good, I checked and cleaned battery contacts and fuse of 30 Amps, no starting problem...bike starts well for now, but as I said the battery is full charged ! Charging values ​​remained unchanged 13.5 V light On and 13.9 V light Off...fans started, light on 13.2-13.3 V something is wrong In my opinion...Next day I do get a spare battery from a friend and I'll try again, I hope to have another result and not having to remove the alternator....possible to have imperfect contacts elsewhere?

Smok3 said:

but as I said the battery is full charged

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Keep in mind that the more fully charged the battery is the lower the voltage output you will see from the alternator when you are doing your test.

Andrew Shadow said:

Keep in mind that the more fully charged the battery is the lower the voltage output you will see from the alternator when you are doing your test.

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Sorry to disagree. The higher the charge the higher the voltage. As the battery approaches full charge the internal resistance goes up requiring higher voltage to push the current into it. The current flow drops off as the battery approaches full charge. The peak voltage is set by the regulator to keep the alternator from over charging (and destroying) the battery.

Check the condition of the alt sub harness & it's connectors.
More than one 1300 has stopped charging because of it.
The connector on my 03 melted down & fried the alt.
Kevin

Thanks for the advice Kevin !
but pretty please can you give me more details about this connector,
is a connector negative positive? who exactly is his position ?

Thank you Andrew.

There are 2 connectors that connect to the main wiring harness from the alt sub harness.
The white connector, bigger wire I believe to be the pos from the alt. This is the one that melted on my 03.
The other not so white I would think is the neg. If either of these are corroded it would hamper charging & create heat.
They come out from under the rubber mat on the back left hand side as sitting on the bike.
The insulation on this harness gets brittle also as it sees a lot of heat. This is about a $25 part.
Kevin

Kessie said:

There are 2 connectors that connect to the main wiring harness from the alt sub harness.
The white connector, bigger wire I believe to be the pos from the alt. This is the one that melted on my 03.
The other not so white I would think is the neg. If either of these are corroded it would hamper charging & create heat.
They come out from under the rubber mat on the back left hand side as sitting on the bike.
The insulation on this harness gets brittle also as it sees a lot of heat. This is about a $25 part.
Kevin

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Thanks Kevin coming days I will "undress" bike on the left side and I'll see what I find there, in this picture I do not see exactly where it the connector, but thanks for the explanation. I'm sure I'll find him and I will see what is the status of...I will write here the final results.

Having just removed my alternator, there is a single wire going to a post. A connector with two wires that plugs into the front of the alternator. Those must go to the connectors in the above picture.

Ok I have not had the patience and removed the left side, connectors look good , not melted but the white conector was oxidized, I cleaned with contact spray and we refitted the result was another 14 V lights on and off and I even found a small difference in my voltmeter.Thanks a lot guys , I hope I do not have problems.