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Help with diagnosing charging issue


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Unfortunately, my bike is not charging the battery. 2003 KLX400S without free power mod. With a fully charged battery, I can ride for about 20 minutes before my lights, blinkers, and dash begin to dim and eventually go out.

I read the charging system FAQ and tried to follow it word for word. I checked every connector I could could find, and checked for continuity with a multimeter on many of them. No connectors seem loose, but some do look a little tarnished. Not necessarily bad...just not bright and shiny.

Since I couldn't find an obvious bad connection, I moved on to step 2.

Motor off key off: 13.31v

Motor off key on: 12.8v

Motor @ idle: 12.5v

Motor @ 1/4 throttle (FAQ says 3000rpm, but i don't have a tach):12.2v-12.5v

Three yellow wires coming from stator to ground- No continuity

Three yellow wires to each other- All have continuity

Three yellow wires voltage at 1/4 throttle- 60ish volts

Ok so stator checks out. On to step 3

I removed the RR from the bike and did the test as described. I got about .5 volts one way, and nothing the other way for both wires, as described.

Now on to the "more info some redundant" section:

I stuck two pieces of safety wire into the connector coming from the RR so I could check voltage without compromising the insuation. I read 14.5v. I have not done the lightbulb test for current leakage, but hopefully I can tomorrow.

The last thing I did was go for a 15 minutes ride, then strip the bike down and and feel the connectors. Nothing felt out of the ordinary except for the connector coming from the RR. The red and black wires were about 2 inches before the connector were quite hot, and the red and black about two inches past the connector were hot. The connector itself was very hot. I could hold it in my fingers, but it was uncomforatable. If it was much hotter, you could call it painful.

Is it possible this one connection is the whole issue? It doesn't look corroded or melted or anything, but like I said, it was way too hot. Can all the current that is supposed to be going to the battery actually be dissipated as heat at that connector?

Just looking for some advice:ride:

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You should do the free power mod. I see that Eddie is selling a Free Power Mod harness for a fair price.

https://thumpertalk.com/forum/showthread.php?p=9566050#post9566050

The free power mod should solve the low charging voltage problem.

I am going to do it. I just emailed Eddie about it, actually. Since my stator and RR check out fine, that means the free power mod should definately fix the charging problem, right?

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When the wires cant allow the current to flow properly, the resistance increases which creates heat....

I did the free power mod and even with a battery that was basically dead, and would only hold a charge strong enough to start the bike for around an hour, I did 3 hours of riding without a single problem...

Even to the point that when I had to stop after around an hour and a half, it had enough to spin the starter enough for it to fire up :banana:

I have since replaced the battery and have gain 1v at idle, and it only increases around a 0.25v from idle to ~5000rpm...

Well worth the 15 mins to do the mod...

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The only thing that concerns me is that I didn't find an obvious "ah-ha, that's the culprit!" connector. Only the connector between the RR and harness was unusually hot, but not so hot that it was melting or otherwise damaged, atleast from a visual inspection. I guess we will see when I get the free power mod done!

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  • 3 weeks later...

The saga continues.

I installed Eddie's free power mod harness a few weeks ago, and afterwards, I was measuring 14.8v or so at idle at the battery, up from about 12.5v. I rode the bike around for a few minutes, and everything seemed fine, so I parked it, and knew she would be waiting for me to ride:thumbsup:

Flash forward to today. I put the key in the bike, turn the ignition on (all seems fine...headlight, taillight, etc brightly lit) and I hit the starter button. As soon as I hit the starter button, everything immediately shut down. No power whatsoever.

My first step was the check the fuse, which was fine. Next, I put a multimeter on the battery, and it measured around 9.5v. Remember, it was fully charged before I did the free power mod, and immediately after doing the mod, the bike started and rode fine.

Next, I bump started it. The lights and dash flickered really bad at idle, and smoothed out at speed, but the headlight was still very dim. I rode it for about five minutes, came back, and checked the battery. At idle, it was reading anywhere from 5.5v to 8v and everything in between. The reading was bounching around like crazy. When i revved the bike, the voltage dropped to 4.5v-5.5v. Again, the reading bounced around between those numbers. I shut the bike off, and key off lights off, the battery measured 10.89v, up a little bit from before.

I felt the battery terminals, and they were not hot at all. Next, I felt down the new free power mod wires, and they felt fine. The connections I made coming from the RR were not hot at all, but about an inch before the connectors (about 3" from the RR) the wires started getting very hot. The RR itself was almost too hot to touch. Touching it more than 1 or 2 seconds was painful.

So, what in the world happened? To sum things up...the bike seemed fine after installing free power mod. After a short ride after the install, I parked the bike and it sat 2-3 weeks until today. The lights came on fine when I turned the key, but everything shut down when I hit the starter. Battery reading was around 9.5v, and after bump starting it, the battery was reading 5.5-8v at idle. Less at RPM.

:bonk::excuseme::foul:

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The R/R does indeed convert excess voltage to heat and dissipate it (which is why it's feeling hot).

I'd think about replacing the battery before ripping into the charging system. It may possibly now have a bad cell due being run down repeatedly. How does it respond when you put it on a charger?

Do you have a battery tender? I keep one on mine since the smaller 12v batteries seem to last longer that way.

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I would meter out your stator again.

Ok, I thought about this more and came back. The battery @9.5 V is a problem. Battery is very likely damaged. If you have a automatic type charger charge the battery off the bike and see how it behaves. While the battery is off the bike charging get your jumper cables out, connect the bike to vehicle (not started). Check voltage at bike. Start bike, noting behavior. If you have thin jumper cables it might turn a bit slow but it should start. Check voltage at bike end of jumpers again with it running. If it is even a little bit higher the bike is probably fine but battery bad.

Purchase a Lithium Iron Phosphate battery (such as Turntechbattery.com), install, ride.

Edited by slowriding
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Touching wires will not get you what you need.. Which is a methodical diagnostic approach to finding the failure point. Most any other way with electrical issues is costly, time consuming and if you do replace the right part, just an accident.

https://thumpertalk.com/forum/showthread.php?t=627031

Thats the correct charging system diagnosis procedure.. Follow it. and with a few Q&A.. I bet you find the actual issue.

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Touching wires will not get you what you need.. Which is a methodical diagnostic approach to finding the failure point. Most any other way with electrical issues is costly, time consuming and if you do replace the right part, just an accident.

https://thumpertalk.com/forum/showthread.php?t=627031

Thats the correct charging system diagnosis procedure.. Follow it. and with a few Q&A.. I bet you find the actual issue.

Thanks for the advice Bronco, but I have already gone through the charging diagnosis step by step. I did it very methodically, as desribed. The stator checked out fine, the RR checked out fine, and all of the connections appeared to look good. The charging system diagnosis does actually say to feel for hot wires and connectors, which I did, and I did not find anything that felt unusually hot. The plug coming from the RR felt hotter than all of the others, but not crazy hot.

A few posts back, I stated that everything tested out normaly per the FAQ, but I was still only getting 12.5v. Eddie himself said that the free power mod should fix me up, which it did temporarily. I guess I need to do the diagnosis again, though. It wouldn't hurt.

Perhaps it is the battery, as a few have mentioned. The battery is the upgraded Yuasa YTZ10S. It is almost a year old, but it has basically never been used. I have a 12v car charger that monitors the battery as it charges. It does normal, deep cycle, and AGM gel cell batteries. Would it be ok to use? Otherwise, all I have is a battery tender Jr.

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My first step was the check the fuse, which was fine. Next, I put a multimeter on the battery, and it measured around 9.5v. Remember, it was fully charged before I did the free power mod, and immediately after doing the mod, the bike started and rode fine.

Next, I bump started it. The lights and dash flickered really bad at idle, and smoothed out at speed, but the headlight was still very dim. I rode it for about five minutes, came back, and checked the battery. At idle, it was reading anywhere from 5.5v to 8v and everything in between. The reading was bounching around like crazy. When i revved the bike, the voltage dropped to 4.5v-5.5v. Again, the reading bounced around between those numbers. I shut the bike off, and key off lights off, the battery measured 10.89v, up a little bit from before.

I felt the battery terminals, and they were not hot at all. Next, I felt down the new free power mod wires, and they felt fine. The connections I made coming from the RR were not hot at all, but about an inch before the connectors (about 3" from the RR) the wires started getting very hot. The RR itself was almost too hot to touch. Touching it more than 1 or 2 seconds was painful.

:

May I suggest you go back and perform a though diagnostic on the charging system :bonk:

What you described in your post will not get you the results your looking for.

If you understand all that :foul: Then your good to go, best of luck, let us know how it turns out, or if you have a question you would like the group to Weigh in on. :D

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May I suggest you go back and perform a though diagnostic on the charging system :bonk:

What you described in your post will not get you the results your looking for.

If you understand all that :foul: Then your good to go, best of luck, let us know how it turns out, or if you have a question you would like the group to Weigh in on. :D

But I have! From the first post in this thread. Have you even read the whole thread?🤣:usa:👍

Unfortunately, my bike is not charging the battery. 2003 KLX400S without free power mod. With a fully charged battery, I can ride for about 20 minutes before my lights, blinkers, and dash begin to dim and eventually go out.

I read the charging system FAQ and tried to follow it word for word. I checked every connector I could could find, and checked for continuity with a multimeter on many of them. No connectors seem loose, but some do look a little tarnished. Not necessarily bad...just not bright and shiny.

Since I couldn't find an obvious bad connection, I moved on to step 2.

Motor off key off: 13.31v

Motor off key on: 12.8v

Motor @ idle: 12.5v

Motor @ 1/4 throttle (FAQ says 3000rpm, but i don't have a tach):12.2v-12.5v

Three yellow wires coming from stator to ground- No continuity

Three yellow wires to each other- All have continuity

Three yellow wires voltage at 1/4 throttle- 60ish volts

Ok so stator checks out. On to step 3

I removed the RR from the bike and did the test as described. I got about .5 volts one way, and nothing the other way for both wires, as described.

Now on to the "more info some redundant" section:

I stuck two pieces of safety wire into the connector coming from the RR so I could check voltage without compromising the insuation. I read 14.5v. I have not done the lightbulb test for current leakage, but hopefully I can tomorrow.

As you can see, I have done everything I know how to do. If you think I missed something, please let me know.

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Can somebody tell me if I can use a regular car charger on the Yuasa? It is a Schumaker Speed Charger Computer Smart. Charges at 2A, and supposedly monitors the battery as it charges.

Or should I stick the battery tender on it?

As long as it only charges with 2 amps.....you will be ok.... The ones to avoid are the high volt/current car chargers that feed 15+ volts and 20+ amps into your Z`s battery.

:bonk:👍

Erling

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But I have! From the first post in this thread. Have you even read the whole thread?:foul:🤣👍

.

I read the thread, where you did some work, things got better, then failed again,, and after the second time you brought out the diagnostic finger and checked wire temps :D

So, what I'm suggestion is now that you have a new/ reoccurring failure.. start from the beginning, assume nothing, check all connections, fuses, wires for chafing.. and DO THE diagnostic procedures AGAIN.

You will likely find the issue, or something else to ask a find based question on.. Once you do that, folks here can assist.

As pointed out.. sounds like you can use the battery charger you have which is good as you do need to start with a charged battery,, and as you stated, the battery tender is not really a charger and not the right tool.

So go get after it and post up what you find,, lest see if the collective can help you help your self.

:bonk:

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