Battery not charging, test and replace alternator?

Joined
Nov 11, 2007
Messages
151
Location
Greer, SC
Yesterday I took my bike out and noticed that it was not charging. I have a battery minder and it shows the voltage. I confirmed the issue using a good voltage meter. However, while riding I saw it not charging at all and then at times 13.x volts. So it seems to be intermittent, but today I cannot get it to charge. I searched the threads for any advice / pictures on testing the alternator. My bike only has 70K miles and I see people are changing their alternators way after this, so the low mileage and intermittent issue makes me feel it might not be the alternator. I just prices one, they are over $600 is this normal? The regulator assy is also over $200. Do those go before the alternator? Any advice is appreciated.
 
Start with the battery. Take it to a shop and have it tested...I use my local O'Reilly's for bike and auto batteries.
Inspect the charging system wiring, fuse and connectors for corrosion, bare wires, insulation, overtemp.
Inspect both the ignition switch/wiring and the kill switch/wiring.
If the above are fine, check out the alternator output.
Check connections on the regulator for corrosion/overheat.
That's the set of charging problems in order of likelihood.
In my opinion, anyway.
 
I am 99% sure the battery is good as it is about a year old and on a tender all the time. Also it is discharging as I am playing and charging correctly after the tender is back on. Everyone says check the battery first, but wouldn't the charging voltage be 13.X even if the battery was completely dead? Once the engine is running it is producing voltage, a bad battery would not be able to charge. I personally hate electric problems more than anything, that is why I am asking about the battery. If I am wrong, then yea, battery is the cheapest repair.
 
It does not, as a matter of fact the voltage goes down the longer the bike is running. And the battery is fully charge and reading above 12 volts. The only weird thing is this. It is a good meter I am using. When i first put the leads on the battery it shows over 13V like it is charging and then immediately goes to 11.8v
 
A 1300 with the key left on will kill a battery in a few minutes. If the alternator went out while riding it would quit running in about 10-15 minutes. I know from experience.

For now forget about any aftermarket installed voltage meter. It won’t be accurate for trouble shooting. It might even be the problem.

With a known good multimeter test battery voltage right on the battery terminals key off and running at 5000 rpm. The service manual test is 15.5 volts or less at that rpm. This is the alternator test without removing the alternator

Key off should be 12.2 to 13 volts and running at 5000 rpm it should be 14.2 to 15.5.

$600 is accurate and the regulator is built in to the unit. It’s not a separate cost item.
 
Leave the volt meter connected while key is off and observe voltage. Around 12 v, while starting should go no lower than 9.5. Running should be above 13v . Put the volt meter on a/c voltage and it should be below 50 millivolts running. Anything above that and that would indicate a bad diode internal in the alternator.
 
I am 99% sure the battery is good as it is about a year old and on a tender all the time. Also it is discharging as I am playing and charging correctly after the tender is back on. Everyone says check the battery first, but wouldn't the charging voltage be 13.X even if the battery was completely dead? Once the engine is running it is producing voltage, a bad battery would not be able to charge. I personally hate electric problems more than anything, that is why I am asking about the battery. If I am wrong, then yea, battery is the cheapest repair.

Never assume. You have no way of knowing what the internal cell condition is, and you have no way of knowing that your maintainer (assuming that it's a true maintainer and not a trickle charger) was working correctly.

Trust the guys on this - Always start from a known good condition battery. (Note that I didn't say "new", I said "known good".) If your battery isn't working properly, then all the alternator diagnosing and replacing in the world won't make a hill of difference.
 
Yesterday I took my bike out and noticed that it was not charging. I have a battery minder and it shows the voltage. I confirmed the issue using a good voltage meter. However, while riding I saw it not charging at all and then at times 13.x volts. So it seems to be intermittent, but today I cannot get it to charge. I searched the threads for any advice / pictures on testing the alternator. My bike only has 70K miles and I see people are changing their alternators way after this, so the low mileage and intermittent issue makes me feel it might not be the alternator. I just prices one, they are over $600 is this normal? The regulator assy is also over $200. Do those go before the alternator? Any advice is appreciated.
If its a pre 1997 st1100 check all the wiring and connectors. Do a 40 amp upgrade
 
Never assume. You have no way of knowing what the internal cell condition is, and you have no way of knowing that your maintainer (assuming that it's a true maintainer and not a trickle charger) was working correctly.

Trust the guys on this - Always start from a known good condition battery. (Note that I didn't say "new", I said "known good".) If your battery isn't working properly, then all the alternator diagnosing and replacing in the world won't make a hill of difference.
The battery is 100% ok. I have a tester and just put a load on it.
 
In my limited electrical knowledge, I wouldn’t suspect your battery in this case. You should read more that 13v at idle. If its intermittent, you might get lucky and find corroded wires or cables. Hopefully you dont have to remove the alt to inspect it and have it tested. Good luck.
 
Did you take the battery cables off and clean and tighten them? If you have done this then you are correct that you will have to check the circuits going to and from the alternator itself.
 
It looks to me that if the bike runs then you need to get to the leads at the alternator itself for further diagnosis. This is due to the fact that if fuse D or the main fuse were blown the engine would not run. I assuming that you have a ST1300 ABS.
 
I am 99% sure the battery is good as it is about a year old and on a tender all the time. Also it is discharging as I am playing and charging correctly after the tender is back on. Everyone says check the battery first, but wouldn't the charging voltage be 13.X even if the battery was completely dead? Once the engine is running it is producing voltage, a bad battery would not be able to charge. I personally hate electric problems more than anything, that is why I am asking about the battery. If I am wrong, then yea, battery is the cheapest repair.
I just helped my neighbor changed out his 1 year old battery that was dead. It was showing 0.05 volts on the volt meter at rest. When he tried to jump start it he got dim lights and no start. Guess what I'm trying to say is just because its only a year old it still could be bad. New battery immediate start.
 
Ok so we know the battery is good, load test, terminals are clean, I took most of the bike apart and then decided I just do not have the time to fix this. Put the bike back together and took it for a ride. As soon as I hit 7K rpm, the battery was charging at 13.9V. Then it stayed good until idle, which showed 12.v volts. For some reason I suspected the heated grips as drawing so much power that it was not showing a charge, that happens at idle when using the grips. I tried to turn the grips on and they do not work. So I suspect the heated grips are have some sort of short in them and it is drawing all the power when at low idle. I am in SC now and really do not need them so I am going to disconnect and see if that fixes it.
 
Fixed, These are the steps I took after suspecting the heated grips.
1. turned on motorcycle, not charging
2. tried to turn on grips, were not working
3. Revved engine to 5K then 7K rpm till I started charging at 13.9v
4. Turned on the grips to level 3, now the lights came on and they started to blink
5. Turned grips down to 1 setting and it stayed on, battery still charging
6. Let the bike to go idle with 1 heat setting on and it was charging.
7. Turned off grips, shut engine
8. Turned on engine and it is working fine.

So the grips were in some sort of high setting drawing all the power but not registering on the control panel or making the grips hot. It seems to have fixed itself.
 
Never assume. You have no way of knowing what the internal cell condition is.
I used this Solar conductive tester to check the internal cell condition.
It's my go to tool when I have electrical charging/battery problems.

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