Bad 12V battery??

Discussion in 'Honda Hybrids' started by greenrider, Jun 10, 2009.

  1. Mendel Leisk

    Mendel Leisk 2010 Prius (CAN Touring) Staff Member

    How's the fit? I'm kind-of assuming the new battery is bigger: is that the case? Did you just put the new one in without the plastic surround pieces?
  2. hunter44102

    hunter44102 Well-Known Member

    The battery is much wider and slightly taller, but thinner. Yes I had to remove all the plastic that held the old battery. Its resting on the metal. I will check it periodically to make sure its not going to loosen, but it seems really secure even though there is space in front since the battery is not as deep.

    I'm guessing a battery insulator/protector may not be of much benefit since the Optima is essentially freeze proof and spill proof and can be fully discharged over 300 times without worrying about it going dead. We'll see how it holds up over time.
  3. greenrider

    greenrider Well-Known Member

    The D51r is not the correct battery for the HCH2, it's the battery for the regular Civic. The HCH2 uses the D35r, which is smaller. I have the D35R and it works great. The D51 can place an excessive load on the system.
  4. hunter44102

    hunter44102 Well-Known Member

    Optima does not make a D35R. They make a D35 but its MUCH bigger and 10lbs heavier than the D51 and D51R.

    The D51R is the closest to the OEM honda battery
  5. greenrider

    greenrider Well-Known Member

    I opened my hood are realized that I actually have a D51R. I remember researching this extensively, and I stand corrected.

    At any rate, my D51R has held up very well over the last 8 months or so and solved my issues with consistently low IMA charges and daily crashes.
  6. hunter44102

    hunter44102 Well-Known Member

    Good to hear the Optima is working for you. I remember you posting about it a while ago. I'll know this week if it helps the charging issues I've had
  7. greenrider

    greenrider Well-Known Member

    FWIW, One thing I did do was trickle charge the Optima for a couple of nights to be sure it was fully charged. Maybe it was incidental but the car had far more power and mpg was much higher with a trickle charge
  8. Dream'R

    Dream'R Well-Known Member

    For the benefit of HCH owners, here's some background info about conventional lead-acid 12 volt batteries:

    In a regular car, the 12 volt battery's primary role is to start the engine. Once the engine fires, the alternator takes over to provide power for all electrical loads. It only takes a few seconds to replenish the power drawn by the starter. Batteries designed for starting have grids which can deliver high current for brief periods. Prolonged drains such as leaving lights on will eventually cause permanent damage to the battery.

    In the HCH, the 12 volt battery rarely ever starts the engine (back-up if main IMA battery is too low or in extreme cold). Instead, the 12 volt battery provides power to the various electronic controls and powers the other electrical loads such as lights, fans, and air conditioning. When in "auto stop" the 12 volt battery has no source to be replenished. There is no alternator but instead, a DC-DC converter produces power to recharge the 12 volt battery from the 158 volt IMA battery pack. Eventually the "auto stop" feature will be defeated so the engine can replenish the IMA pack.

    In essence the HCH sometimes uses the 12 volt battery in a "deep cycle" mode, particularly if you are frequently in "auto stop" and have lights, air conditioning, etc. operating. This is why the "deep cycle" design of the Optima battery appears to be well suited. The spiral plates are heavier and able to withstand prolonged discharges far better.

    Owners of RVs and boats have long understood the advantages of deep cycle batteries.

    Hope this helps fill in some of the "blanks".


  9. Right Lane Cruiser

    Right Lane Cruiser Penguin of Notagascar

    Actually, the DC-DC stays active during Auto Stop.
  10. ematzen

    ematzen Well-Known Member

    Ok - So I bought the correct Honda battery for my 2006 HCHII. The batter that was installed was the proper battery for the Honda Civic, not the hybrid. In comparison, the gas civic battery is significantly larger than the one for the HCHII, plus, the terminals for the gas civic are SMALLER, which caused whomever installed the old battery to jury rig a way to keep the contact. I am also assuming that whatever plastic housing used to exist on my car near the batter has been removed, as the battery tray is larger than the battery. Now we'll see if this new battery impacts FE. Who knows. I doubt it will. My commute today, mostly in traffic, was around 40mpg, which is pretty good. No ac though.

    I'm curious to know of this proper battery is a deep cycle battery, and the other one was not. Any ideas?


  11. Right Lane Cruiser

    Right Lane Cruiser Penguin of Notagascar

    I don't believe the car is spec'd with a deep cycle battery but Manuel could answer that more easily than I.
  12. msantos

    msantos Eco Accelerometrist

    Based on the cases I've been following over the years, the larger battery will do very well for a good while... but equally important is the how, when and where the vehicle is operated because this alone can re-define the whole experience.

    For instance, the use of a larger battery in my part of of the country will begin to somewhat impact FE in the winter months when driven in an urban-only setting. Now, if your driving is mostly short and FE minded then the discrepancy is very noticeable. If you do not then it may not matter as much.

    As I recall, in some cases it was so bad that the dealer ended up securing the right battery (something they DO NOT like to do when they can just push out existing inventory) in order to resolve the issues. Yes, the dealer took back the larger battery and installed the OEM spec unit at their cost. The regular Civic battery was less expensive than the smaller HCH-II OEM unit. :eek:

    Anyway, the larger battery typically means a larger load, and the larger the load, the greater the amount of work the DC-DC will be asked to do. When the car is powered up, the DC-DC provides most (if not all) of the power for the legacy 12V subsystem requirements (among others) in addition to frequently pulsing a charge from ~12.5V to ~13.6V.
    But in some cases, the pulsing frequency may not be enough to keep a larger load 12V battery at a sustainable charge level and that is where the problems appear to creep in as the larger battery becomes the biggest load on the system thus upsetting the fine balance the 2006-2008 were originally designed for.

    Again, keep in mind that the 2006-2008 models OEM specifications call for the smaller battery while the 2009-2010 call for the regular Civic's "gas powered" battery. Yes, as I recently discovered there were many subtle system revisions that account for this difference and while it is worthwhile to mention it, its just as important to know that Honda is also not confusing the two and neither should the dealers.


  13. hunter44102

    hunter44102 Well-Known Member

    Yes a larger batter -of the same type- would be a bigger load on the converter. I'm sure honda de-rated for that and you are ok, but you may lose a little bit of efficiency and energy loss keeping a larger battery charged up.

    Normal Lead-Acid (including starting) batteries have a self-discharge rate of 10-20% per month, so if you put in a bigger battery, there would be a larger percentage of discharge that would be dealt with.

    If one gets a different type of battery like AGM battery (like Optima Yellow or Odyssey). AGM batteries have only a 1-2% monthly self-discharge rate. Great for storage

    So in theory, you can get a slightly larger battery if its AGM, but AGM's are about 50% more expensive up front. I believe they pay themselves back if you keep your cars for a long time, and you never have to worry about adding water or spillage.
  14. hunter44102

    hunter44102 Well-Known Member

    Right Lane Cruiser "Actually, the DC-DC stays active during Auto Stop."

    This is not true. At least when I tested it today.

    After I got home from work, I put a logger on the 12V battery and started it up. Voltage was 14V, and I drove it and put it in Auto-Stop. It immediately went down to 13.25, then started slowly dropping to 12.8V for over 2 minutes in Auto-stop.

    Finally, I let my foot off the brake and it started and the voltage went up to 13.95

    So maybe it eventually would kick in, but interestingly the inverter did not keep charging during the flashing auto-stop period. The dropping voltage mirrored when I shut the car off for the night.
  15. PaleMelanesian

    PaleMelanesian Beat the System Staff Member

    I've never seen a lead-acid battery hold a charge above 12.6V, especially with a load on it. I'd expect to see something like 12.4 and dropping down to 12.2 or so.
  16. msantos

    msantos Eco Accelerometrist

    Folks, perhaps we need to be more specific so as to not let the usual binary interpretations creep in. ;)

    Here are the main governing/behavioral attributes for the DC-DC module in the HCH-II/Insight II:

    - In a fault free IMA system the DC-DC module is always ON whenever the car is fully powered up.
    - The primary roles of the DC-DC are:
    - To provide power for the required 12V legacy subsystem on a full-time-powered-on basis.
    - To charge the 12V battery with pulsing charges that vary from 13.5-13.9 V.
    - The DC-DC controller will not normally induce charge cycles when the vehicle is auto-stopped or in a soft glide pattern (cylinder idle mode). This is by design.
    - The charging pulses (frequency/duration) vary depending on the circumstances (12V subsystem load, DC-DC temperature, and the SoC as determined by the BCM.
    - If the DC-DC encounters a problem, it will send a cooperative request to the BCM to go off-line. At this stage an IMA warning light will appear on the instrument cluster.
    - Unlike previous IMA versions the DC-DC behavior is fully driven by software and governed by the synergy between it and the BCM. This happens over a serial communication bus so forget about hacking it with a wire tweak.
    - Under normal circumstances the DC-DC will provide a steady 12.4-12.6 level. The 12V battery is rarely tapped for power unless it has a surplus or the power demans are significant, unusual and prolonged.

    I hope the clarification helps.


  17. hunter44102

    hunter44102 Well-Known Member

    Msantos - thanks for the great expert details on the charging. Yeah its too bad its all software driven, who knows all the mysteries in there.

    what do you mean by 'under normal circumstances it will provide steady 12.4 to 12.6?? Every car I've ever driven, including the HCHII puts out 13.8V or higher while running, My Jeep Patriot puts out 14.1 or so.

    PaleM - AGM batteries have slightly higher voltage than standard Lead acid (especially in a brand new fully charged one), that could be why I saw the 12.8V even with slight load. Could be the voltage logger, but I believe its supposed to be within 0.5%
  18. Right Lane Cruiser

    Right Lane Cruiser Penguin of Notagascar

    Hunter, do me a favor and do your experiment again… but this time flip the headlights on. In my Insight this causes the Voltage to jump. The converter seems only to pump the voltage when in Auto Stop if a power surge is requested that drops the voltage to 11.9V — I've never seen this number on the SG but it never goes lower than 12V.
  19. hunter44102

    hunter44102 Well-Known Member

    RLC- will try it again tommorow after the car is warmed up. I'm pretty sure this is how it will work because I can't imaging the design would compromise the 12V battery when there is a large IMA battery to run things.
  20. msantos

    msantos Eco Accelerometrist

    Yes, the HCH-II is not like other cars. ;)

    To re-iterate, The HCH-II (and Insight II) are not always pumping 13+ volts. Instead, they normally provide a steady supply of 12.4-12.6 and administer the 12V battery charge in the form of pulses that peak at 13.9V.



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