Charging the 12V battery on 2007 HCH

Discussion in 'Honda Hybrids' started by HCH2007, May 20, 2015.

  1. HCH2007

    HCH2007 Journeyman Hypermiler

    Exactly, how is the 12V battery charged on my 2007 HCH? I see there is no alternator so,...
  2. S Keith

    S Keith Well-Known Member

    DC-DC converter that steps down the 158V IMA battery to charge the 12V.

    The IMA motor can also be the source (acting as a generator through the DC-DC converter), but only through the range of approximately 1500-3500 rpm. Outside that the IMA motor is producing too little or too much voltage.
  3. HCH2007

    HCH2007 Journeyman Hypermiler

    Okay, got it.

    Thank you so much,
  4. HCH2007

    HCH2007 Journeyman Hypermiler

    I was checking my battery voltage level and voltage across the battery terminals was 12.9v, but voltage from chassis ground to the positive post was 13.6 volts. If I remember basic DC Theory correctly I have a bad ground to the motor from the battery. I had the battery and charging circuit tested and they are good.=, but I feel as if I am forgetting or missing something. So, am I correct or off base?
  5. S Keith

    S Keith Well-Known Member

  6. HCH2007

    HCH2007 Journeyman Hypermiler

    All grounds check out, so I disconnected the battery and checked post to post and the battery reads 12.9V and positive to chassis ground reads 13.6V. Looks like I have a slightly bad battery, but not bad enough for Honda to replace under the warrenty.

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  7. S Keith

    S Keith Well-Known Member

    It's still not clear to me what allowed you to draw any conclusion.

    If you're telling me you're getting 13.6 chassis to (+) w/o the charging system active, I'm dumbfounded. Can you clarify?

    Here in AZ, we're lucky to get > 2 years from a 12V battery. The heat is hard on them.

    More importantly, the 151R battery in the Hybrid is a turd. Pull out all the plastic and clamp in a 51R - the larger 12V is a larger reserve and puts less load on the DC-DC converter.

    Never buy another 12V battery from Honda. You're paying a premium for nothing.

  8. Mendel Leisk

    Mendel Leisk 2010 Prius (CAN Touring) Staff Member

    12.9 volts across the posts is champion, I'd be happy to see 12.6 volts on an in-use battery.

    Regarding your disconnection of the battery: do you have the radio code? Honda, in their "wisdom", requires you to enter a code any time the radio loses power supply. If you don't have the code the radio's basically a brick. I believe you can go through some process in the 'States to recover the code, might involve some $ outlay. Considering the radio has a VERY proprietary shape, is no great shakes, it's not one of their brightest decisions.

    It's a good idea if you have the code (it comes on a sticker with the car when new, or should) to stick it somewhere like inside of glove box, prominent and identified.
  9. HCH2007

    HCH2007 Journeyman Hypermiler

    Yes, I have the code. Got it from Honda America 5 years back, amazingly enough for free.


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