Alternator overcharging
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Thread: Alternator overcharging

  1. #1
    crv|oc Rank: Member
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    Alternator overcharging

    My mechanic told me he tested the alternator and said it's overcharging. Is this something I need to take care of immediately? I'm assuming it's about $500. The CRV has 95,000 miles on it.

    Thanks for any advice

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  3. #2
    crv|oc Rank: Silver
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    The charging voltage can be checked close enough at the battery. In idle with a voltmeter it should be under 14.5v in most vehicles. Run it until it peaks out and goes no higher. It is a function of temperature so it can vary 13.5-14.5v.

    The regulator can be replaced by itself. If you can find a local automotive electrical rebuilder they should be able to do it under $150. Not all of them do that but both in my area do as they have a couple of bays to do the work in. I just buy the parts from them and DIY for about $40-60. They are also available online for slightly less. Some vehicles are much higher. Sometimes a bad or dry bearing is found as well as brushes so the cost goes up from there. That is why most just bite the bullet and replace the whole alternator. I do not know about Hondas but Toyotas last 60k to 150k+ miles. I have heard of a few up in the 200k miles

    The problem not fixing it is you will cook your battery by overcharging it. The light bulbs will burn out much sooner too.

    If it is not considerably over 14.0-14.5 volts I would just let it go. Batteries and bulbs are a lot cheaper than a new alternator. Your audio equipment should have internal regulation so it should not be a consideration as long as you do not go higher than say 16-18 volts. Most DC-DC automotive regulators in audio should be good up to 18v but this too can vary. The same should apply to the PCM and other electronic components.

    Check your battery electrolyte regularly and up to 14.5v regulation you should be OK.

    Radio Shack has pocket Digital Multimeters that go on sale $14-20 regularly $20-30. That is what I use get an idea of what the regulator is doing. Without having to drag out my bigger DVMs. They also come in handy for checking continuity. An amp meter is usefull too but it is a bit more complicated using those.

    -RG
    Last edited by Radar24; 01-20-2009 at 07:33 AM.

  4. #3
    Everything in Moderation Carbuff2's Avatar
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    Hold On!

    The V uses Honda's gas-saving charging system.

    The output is regulated from the car (the Electrical Load Detector, or ELD), NOT the alternator. The voltage should vary between 12.5 and 14.5VDC... and the alternator should ONLY charge when the voltage gets down to 12.8. If you have an OBD reader like a Scanguage you will see how it works. Or a passenger could just monitor the voltage while driving.

    Usually if the alternator is charging most of the time (14V) you have a weak battery.

    Here's a good graph of a Normal system:

    http://www.hondasuv.com/members/show...hlight=voltage
    Atwell "Buff" Haines
    '06 AWD CR-V, 5 speed MT!
    '07 Fit Sport, 5 speed MT!
    NJ

    In theory, there is no difference between Theory and Practice. In practice, there is. - Yogi Berra



  5. #4
    crv|oc Rank: Silver
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    Well, isn't that special!
    Honda has reinvented the wheel and turned the regulation digital!
    As you can see I have practically zero hands-on Honda specific experience.

    I do not like this ELD system when driving short trips in the deep freeze.
    Seems to me the battery might not be fully charged, or as charged as possible when the engine is turned off under those conditions. Like it would be with the old school analog regulation which tries to keep the voltage around 14.0v =/- 0.5 volts.

    Perhaps this situation has been taken into account. I like the idea of saving fuel but not at the expense of not being able to start the engine. Not with that puny group 51 battery when temperatures go below 0F.

    -RG
    Last edited by Radar24; 01-21-2009 at 06:39 PM.

  6. #5
    Everything in Moderation Carbuff2's Avatar
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    Quote Originally Posted by Radar24 View Post
    Well, isn't that special!
    Honda has reinvented the wheel and turned the regulation digital!


    I do not like this ELD system when driving short trips in the deep freeze.
    Seems to me the battery might not be fully charged, or as charged as possible when the engine is turned off under those conditions. Like it would be with the old school analog regulation which tries to keep the voltage around 14.0v =/- 0.5 volts.

    -RG
    As long as the voltage is low (as, after starting the engine) the ELD will allow the alternator to charge the battery at it's full rate. That's no different than a conventional system.

    It's just that AFTER the battery is charged, the alternator is "rested" so it loads the engine less. (I read somewhere that daytime running lights "cost" almost half an MPG.)

    Many if not all car companies use an ELD in their charging systems nowadays...
    Atwell "Buff" Haines
    '06 AWD CR-V, 5 speed MT!
    '07 Fit Sport, 5 speed MT!
    NJ

    In theory, there is no difference between Theory and Practice. In practice, there is. - Yogi Berra



  7. #6
    crv|oc Rank: Silver
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    But wait, once started after the recovery period when the ELD gets the battery up to full charge, it will drift back to the low voltage. Lets say you turn the engine of just as it reaches the low voltage point instead of at the high point. The old analog non ELD system on the other hand kept the battery at maximum charge it can recover to if turned off at any point in time.

    I do not see how it can possibly be as good under those conditions. Sometimes it makes no difference with the ELD and other times it does. Depending on at what point the engine is turned off.
    -RG

  8. #7
    Everything in Moderation Carbuff2's Avatar
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    <<<Topic Drift Alert>>>

    Look at the graphs posted in my other reference. Your Honda will be "running on the battery" longer....

    Still, it's only a 2 volt difference. Would not hurt the battery (like leaving the lights on overnight would)!

    Unless your car is in a "sardine can" parking garage and the valets are moving it for 20 seconds each start several times a day, it's probably not an issue. We see some owners experiencing burned out headlamp bulbs, though.


    I once ran my my old Triumph for days (not nights!) with a non-functioning alternator. (Yeah, I was bump-starting it to save the "juice")
    Atwell "Buff" Haines
    '06 AWD CR-V, 5 speed MT!
    '07 Fit Sport, 5 speed MT!
    NJ

    In theory, there is no difference between Theory and Practice. In practice, there is. - Yogi Berra



  9. #8
    crv|oc Rank: Member
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    alternator overcharging

    I have a 2002 CRV only has 4,400 miles on it. The last year or so, it began to have trouble starting. Last week, I changed the battery, and now I am told by Honda service dealer that I need a new alternator and a headlight lamp since it failed to start after a brand new battery ( a cost of over 500 dollars). I wondered if it's the similar problem.

    Any inputs and comments are greatly appreciated.

  10. #9
    crv|oc Rank: Silver
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    ELD vs analog charging in the deep freeze

    CarBuff2,
    I understand what you are getting at. We seem to be going in circles though.

    For the sake of argument let’s say that the high point is 105% charged. Now the low point is 90% charged. That extra 10-15% might just be enough to allow you to start when it is minus 20F. The extra charge will make a difference be it 10%, 5% or even 2%. When it is border line starting the extra charge will allow cranking fast enough while still having enough voltage for the PCM etc to function. The ignition module needs enough voltage to create a spark at the same time.

    The working no load voltage of a lead acid battery used for starting purposes is somewhere from around 11.5 to 12.9 volts once the surface charge bleeds off from 14.5 volts. Since all the high and low ELD points are not fixed but have a distribution or range, allowing the battery to drop down to 12.5 volts or less before charging will result in a battery that is not 100% charged all the time. In some cases very close but not in all cases.

    My figures are all relative and not actual numbers. So you can dispute them if you want. The ELD seems to be alternating from slight less than fully charged to possibly slightly over charged.

    Give me the old analog system in the deep freeze any day. The rest of the time the ELD is probably better. Allowing you to save on gas, less wear and tear of the alternator and prolonging battery life by not keeping it at 14.5 volts mast all of the time. That is how I see it based on the numbers given for the ELD system.

    Now if you can guarantee that the ELD fluctuates from 13.0v to 14.2v at ambient 120F to minus 40F, now that would be a totally different story.

    What was that? HAH!
    I see, that would increase the ELD regulator cost 300%. HUMMM!

    -RG
    Last edited by Radar24; 01-21-2009 at 11:02 PM.

  11. #10
    crv|oc Rank: Member
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    Sorry to revive an old thread, but I'm having issues along these lines. Our 2005 has under 50k and has just killed it's 2nd battery. After the stock one quit after 3 years, I replaced w/ an optoma yellow top. I know now that optomas are not all they're cracked up to be, but my first experience w/ a red top lasted me 10 years so I was very happy to buy a new one. Any way, now after 3 years this yellow top is failing. It won't take any charge, but I can jump start it. Before starting the battery reads 14 volts, but I guess there's just not enough amps to start it. Odd thing is once I jump it and re-read the voltage it says 17 volts. I assume this is the ELD doing its thing trying to charge a dead battery? My research has also led me to an interesting fact on AGM style batteries; They don't last when over charged! I'm wondering if I've always been over charging, maybe a faulty ELD or alternator. I'm going to have to replace the battery no matter what. I'm going to get the cheapest lead acid I can. Install it and check voltage, if it's still 17v (oh, and this was at idle), I know I've got a bad alternator, or ELD, right? If it's 17 volts, I can then assume that the alternator is good but regulator/ELD is bad? Thanx for any help!

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