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  1. #1
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    Feb 2009
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    Turning off Gen1 HCH Battery Module

    Does anybody know if the Gen1 (2003-2005) Honda Civic Hybrid battery module is switched off, will the car operate on gasoline alone?

    Thanks!

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  3. #2
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    Oct 2006
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    Yes, it will... but that is

    Yes, it will... but that is a form of operation that is not sustainable in the longer term. If you do so switch it off, make sure you monitor the health of the 12V battery as well the state of the legacy starter.

    Also to watch for is the acceleration rate as well (the car will be VERY slow) as other minor behaviors that are the result of no assist from the battery pack. Power steering, HVAC, potentially bad fuel economy and greater engine wear are the common areas of interest.

    Cheers;

    MSantos

  4. #3
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    Thanks MSantos, very

    Thanks MSantos, very informative.

    A few follow-up questions:

    - Are there any statistics on the impact to the 12V battery or starter? i.e. How long could this mode be sustained?

    - What would cause the impact on the 12V battery and starter that would make this not a long-term option?

    - Why would Power steering and HVAC be affected? Does the battery pack provide power to components other than the electric motor?

    - What is the cost of a replacement G1 battery pack these days?

    My 5 year old HCH recently passed 100k miles. Although my battery pack doesn't seem to stay fully charged quite as long as it used to, it still works very well. Should it fail completely in the future, I'm not sure it would be worth the cost to replace it. I have the 2002-2003 HCH Repair Manual and read about the Battery Module switch and have been wondering if switching it off when the batteries die completely would be a viable option. My current daily commute is such (20 mile round trip on a 45 MPH secondary road) that I could accept the performance and fuel economy impact, but I wouldn't be willing to accept any safety compromises.

  5. #4
    Junior Member
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    Oct 2006
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    Hi Mattph76; The 12V battery

    Hi Mattph76;

    The 12V battery is usually unable to cope with prolonged demands if the IMA system is not supplementing the power requirements on an regular basis.

    In simple terms, the HCH does not have an alternator to charge the 12V battery like in most cars. Instead, it depends on the DC-DC controller to provide the 12V charge level it needs to stay healthy. However, the DC-DC controller gets its power straight from the electric motor/stator which happens to be a primary hybrid component as well as power from the battery pack. When one of the last two are offline, then the 12V battery will be operating in a deficit sometime afterward.

    Night driving, using the defroster or the HVAC fan use will just deplete the 12V battery even faster. As I said, it is not a sustainable situation for very long and certainly not worth the hassle for some folks especially if you need to use an external 12V battery charger every day.

    The other problem is that this type of operation will force the 12V battery to incur significant charge/discharge cycles and the more there are, the lower its life expectancy. That's life.

    The power steering is electric and it gobbles us significant amounts of peak energy when it is used. The 12V battery will be adversely affected by that as well in the long run as the DC-DC will not be able to always provide all the power the power steering needs.

    Basically, the hybrid battery pack powers everything in the car and the 12V battery simply acts as a brief and very temporary buffer that also helps power up the IMA system when starting up the car. That's all the 12V battery is there for.

    NiMH Battery packs have come down in price... a lot. Right now the cost of a brand new pack with a new BCM orbits around $2500 but depending on whether your car has been serviced at a dealership and the state of the remaining warranty (8 years worth), it may cost you much less. It will definitely cost less (if not the same) as a transmission replacement on a regular car.

    Check with your dealer just to make sure and get whatever software updates are due for your car - especially if it is a CVT equipped model. Having an OK relationship with a good dealer can literally save you thousands in good will alone in addition to avoiding the hassle factor later on.

    Cheers;

    MSantos

  6. #5
    Junior Member
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    Feb 2009
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    MSantos, another concise and

    MSantos, another concise and informative post.

    Although it doesn't sound like turning the battery off is an option, I have a great relationship with my dealership and since the car is only 5 years old, it sounds like I'm in good shape for at least a couple more years.

    Thanks again!
    Matt

  7. #6
    Guest

    Hi MSantos, A really really

    Hi MSantos,

    A really really informative post. I can't believe that you have accurately described all the problems that I have been having with my 2005 hybrid civic. My IMA battery light has been on for a while. Recently, the 12V battery light on the dashboard has also started flickering! I have also began to observe that I need to put in a little more effort on my steering wheel (it doesn't seem to be power steering any more!!).

    I got my 12 V battery changed 2 days ago but that didnt stop the battery light from flickering! I was thinking that the alternator in the first place had a problem but after reading your post, I believe that changing the IMA battery is the only solution. Unfortunately, the warranty has expired I am not sure how will I do this with my poor graduate student salary (

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