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Discussion Starter #1
I'm pulling my hair out over this one. I haven't found a single person on the World Wide Web that shows to have had this problem. Hopefully, someone here on the forum knows what I need to do.

Problem:

Several weeks ago the "Check Charging System" message popped up on the information display, along with a glowing "battery" light.

The van always starts, the battery has never gone dead and all other electrical systems work as they should.

What I've tried so far:

Had battery Load Tested several times, by different places. Even though it's 4 years old, it checks "Good".

Had the alternator checked several times, by different places. Checked it myself with a DMM. It shows to be working fine.

Replaced the ELD (electrical load detector). No change.

Took van to Honda dealer. They do an ECU update and check for codes. No codes found. They say I "might" need a new alternator.

Dealer wanted $1,100.00 to replace the alternator and no guarantee that it would solve the problem.

Load tested both battery cables. They were fine.

Removed alternator and had it bench tested, which showed it was good. Technician took it apart and replaced the voltage regulator and diodes for the rectifier.
Still have the message and light.

Had the battery tested by Interstate Battery today and after (3) simulated starts at the maximum Cold Cranking Amps, it was on the border-line of marginal & good.

Went ahead and replaced the battery. No change.

Did a Battery Cable Reset without any luck.

This is our 14th Honda and 5th Odyssey and unfortunately, this is first one to ever have a problem and it's a doozy.

Any ideas on what to do next, other than trade for a Sienna?
 

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After it sits overnight, is the battery voltage around 12.6 volts?
With the engine running, does it measure around 14v with most of the acc on, including seat heaters,lights, etc and at a fast idle?
The two main grounding connections are from the bat (-) term to the frame and the other is from the frame (near the radiator top on the battery side) to the engine, at least on my '03.
Course there are many more grounds scattered throughout.
Tough to trouble shoot and I sure hope someone who had that problem has the answer and posts it. :ahh:
Buffalo4
 

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Some with a similar problem posted,but unfortunately they never found the cause. Interesting read, and perhaps some hints.
http://www.odyclub.com/forums/52-2005-2010-odyssey/234226-check-charging-system-light-alternator-battery-diagnostics-good.html.
Just read your post of Apr 12 where you did test the voltage with the accessories on and the engine running and it sounded good.
You also stated that one time your ABS and Traction Control indicators went on, but then stayed off after a reset. Probably a bad connection 'somewhere' causing all your problems.
More searching on the Internet for one thing at a time may be helpful, esp if you can find a common cause.
Just read your yesterday's post about the rebuilding of the alternator. http://www.odyclub.com/forums/54-2011-odyssey/269785-check-charging-system-message.html\

Well, post back with the result. Sad you are having such a problem, but at least it is driveable. :(

Buffalo4
 

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Since:
"Had the alternator checked several times, by different places. Checked it myself with a DMM. It shows to be working fine."
"Removed alternator and had it bench tested, which showed it was good. Technician took it apart and replaced the voltage regulator and diodes for the rectifier.
Still have the message and light."
What finally happened that made you finally replace the alternator? A different test or did it finally just not work anymore?
Any idea which part was the guilty party?
Did you use a rebuilt, re-mfg,new aftermarket or an OEM alternator for the replacement?
Thanks for any additional info and suggestions.
Buffalo4
 

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Discussion Starter #9
My apologies for not being more specific in my previous response.

Specifically: After the voltage regulator & diodes were replaced in the alternator, the technician ran another bench test, which indicated the alternator was working correctly, just as it did before they rebuilt it. I reinstalled it and still had the trouble lights, so I called the repair shop. They had me remove it and bring it back in. In the meantime, the owner of the shop reached-out to a company who actually manufactures alternators, to see if they could offer some suggestions. What he found was my alternator, like many of the newer alternators, is a "smart" device. It is constantly communicating with the ECM and other computers on the vehicle. When they bench tested the alternator, after the rebuild, it basically screwed-up the communication pathway between the alternator and ECM. The manufacturer instructed him to replace the voltage regulator & diodes and install it back in the vehicle, without a bench test.

It worked and everything is good!!!!

Hope this helps.
 

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Yes I did...It was the alternator.
Hello. I am having the same problem and just got my car back from the Dealer service. They replaced my alternator and battery and told me that the problem was solved. Unfortunately as soon I drove out of the car shop, I had the warning beep and the Check Charging System & Battery light came in again.
It is very frustrating and it looks like the Dealer that I go to don't care . They keep insisting that there is nothing wrong, but there must be a reason for this light come on and off.
 

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Were you able to fix yours? Mine has the same problem and the alternator and the battery were replaced but the warnings still pop once and while. Let me know if there is anything else that I should check.
 

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2011 Odyssey LX
The car has around 80k miles and is running well. Battery is about 3 years old.

My wife took this pic yesterday while driving. It shows the charging light (battery light) ON, **AND** the display shows CHANGE bATT.

IMG_1789.jpg

She reported the charging light as coming on and going off, and then later it went off and stayed off (but on, of course, when the engine is not running). She confirmed battery voltage at 12.52V (engine off, after sitting for a while), and voltage at terminals with engine running to be 14.3V (and the charging light off at that point). Since those numbers looked good, I gave her the green light to drive home, and she did so without incident. The charging light has not come on since then.

Now, before I go through the troubleshooting, does anyone know if the charging light could be triggered by a battery issue? As of now, the problem seems to be gone, but I expect there is a problem somewhere, and she's going on a 6 hour round trip on Thursday.

The alternator on my '99 was working perfectly when I did a pre-emptive rebuild (brushes and bearings) at around 220k. So it just would seem odd to me to have a failure at only ~80k miles on this one. But please let me know if they are now built to fail. For example, on my '99, I'll estimate that the brushes had used about 90% of their life in the 220k miles, and the bearings were replaced just because I was in there.

Also, it seems the LX has different error reporting than some of the other models, which makes the information I've found via search here confusing.

I know how to do all the battery and alternator testing, as if this were a normal car. But I don't know all of the weird stuff on these new Odysseys. So any advice there might help.
 

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Yeah, charging systems are more complicated than they used to be. Below is the diagram for the charging system on the 2011 Ody:

http://www.revbase.com/BBBMotor/Wd/DownloadPdf?id=890005

Basically, the PCM knows the amount of load on the electrical system by monitoring the ELD. Then, based on what it sees going through the ELD, it will control the field of the alternator by duty cycling it with a voltage from the PCM. I don't recall which wire it is, the C or the FR, that is the control for that, though.

I would check the voltage at the battery with as many accessories turned on as possible. See if the alternator is keeping up. While the alternator is providing current, you can also do a voltage drop test across the battery positive terminal of the battery and the battery lead wire on the back of the alternator (heavy gauge wire.) You should see nearly zero volts. If you see 1-2 volts or more then you have a problem with the charging wire from the alternator to the battery. If you come up with nothing on that then I'd probably replace the battery and monitor for a while longer.
 

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Thanks for the info. Side question on the ELD ... I don't think my '99 Odyssey EX has this, so what year did they start using them?

Yesterday, after my post, and before the Warriors game, I confirmed voltages (but not having seen your post, did not do the more detailed testing - will do that later today, I hope) and swapped batteries with another car.

I was very careful to check on clean tight clamping at the posts, and the "new" battery (used for a few months with no problems at all in a different car) is dated Jan 2017. Cables basically look good. Very little corrosion of any sort anywhere on this car. Alternator has never been touched on this car. Belt is good, tensioner moves smoothly, tension seems good.

Voltages checked and good, no warnings or lights on...

And then my wife just reported (11 AM today) that when she turned the car off after driving, there was a beeping sound and the "CHANGE bATT" warning flashed.

I have zero doubt in the "new" battery or its installation. I'll continue troubleshooting as suggested, and will happily accept any new advice on how to isolate the problem.


Also - no CEL of course (I would have reported that). And other posts above refer to a message on the "charging system." Mine does not say that, just the "CHANGE bATT" message, as shown in the photo. Would it make sense to read codes if there is no CEL?
 

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UPDATE ...
The new error message, when turning off is "bATT LOW" / "CHECK MANUAL" - alternating between the two for a few times after the car is turned off after driving.

Me measuring voltage just now, showed 12.2 with the engine off (yes, a little low), 14.07 with the engine on and minimal electrical, and 13.93 with high beams, AC, stereo, etc. on.

So I've got a charger on the battery now, and will try again later. This new battery that is on there was formerly in my older Odyssey, which is not driven much. So although the battery is new, it may make sense that it is a little on the low side.

I also recall something about pulling the gray 2-pin connector off the negative terminal to reset some battery management feature. I'm looking into that as well.
 

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... and the Voltage drop from the alternator to the + battery post, with engine running, measured at 0.051V

battery seems almost finished charging up.

Also, from searching here, I think by removing the 2P gray connector on the negative battery terminal for 10+ seconds, I have reset some aspect of the battery management system. Maybe doing that when swapping batteries would have avoided the bATT LOW warning.

I'm planning to now sit and wait to see if error messages or lights come back.
 

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Yeah, just keep an eye on it. Most likely, if it returns, it's just an alternator problem. Alternators are a 100-130K mile item. Some make it further and some make it less.
 

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FOLLOW-UP ...

No problems since those reported above. I wanted to wait a while to be sure. My wife drives this van almost every day. Good to have learned how to interpret and address some of the advanced battery management systems here.

Looking back, the only thing I can think of that would have caused this is a marginally loose connection from the negative battery cable to a battery quick-disconnect I installed several months ago. It was tight when I installed it, but due to the geometry of the cables, it was under a little stress, and I can believe that it was borderline loose, intermittently. While swapping batteries, I also re-positioned this quick-disconnect so it is un-stressed and tight.

In a less advanced car, this would have led to some cases of the charging light coming on, which would have led me to the same result but with less confusion (batt low, change batt, etc. warnings when there was actually not a problem with either of the batteries). Thanks to John Clark for the help navigating that.

BTW, the reason I put the quick-disconnect in was so I can easily disconnect power for safety reasons while working on the car. No good deed goes unpunished ...
 

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Thanks for the follow up post.
I would imagine that the not sufficiently 'tight' battery connection was the root cause of your warnings and problems.
Voltage fluctuations in Honda's seem to cause all kinds of problems, esp warning lights. :ahh:
Thanks,
Buffalo4
 
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