Bad 12V battery??

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

  1. hunter44102

    hunter44102 Well-Known Member

    Too bad none of the hybrid mfgr's, including honda, didn't take the opportunity to put in a 42V subsystem. (does anyone remember when all cars were supposed to be 42V by now instead of 12v).

    It would have removed a ton of weight (less copper needed for i2r losses) and would make everything more efficient

    But there were issues that just couldn't be resolved and standards to be broken. (like 42v relay arcing problems)

    Also back to the topic, another idea is to put a jack in the front, (maybe by the block heater connection) to connect a 'battery tender' which just puts a trickle charge on the 12V battery to keep it topped off. This may be a better idea than solar for us who live in the cloudy north with short days in the winter

    (or you get a Optima/Odyssey battery which can be discharged all the way down hundreds of times, but at a higher up-front cost)
  2. pasadena_commut

    pasadena_commut Well-Known Member

    Well, you can hardly blame Honda for that one - they certainly never intended the car to be driven (move) without the motor running!

    If you are going to drive that way then why not set up a voltmeter so that you can check the 12V battery voltage when the motor is off. If you see 12.06V or less (25% charge) then give the motor a chance to charge the battery. An inexpensive digital multimeter can be had for $5 or less and it could easily be wired in to continuously monitor the battery voltage.
  3. msantos

    msantos Eco Accelerometrist

    Hi Pasadena;

    You are quite right. A hot operating environment is a battery killer for sure and keeping it charged is not going to change its prospects of a shorter life.

    However, many of us are not subject to a chronically hot climate so while the heat factor remains a concern a few times in the summer, that concern remains just academic in nature for many.

    I guess we all tend to regard the problem from different perspectives and since the kind of heat you are talking about is not a worry for many of us the remaining issue most of us share in common (in moderate and cold climates) is the consequences related to the 12V charge deficits.

    Also, while your interpretation of the system and the energy conversions are on the ball, they remain perhaps a bit too simplistic especially as far as today's hybrids are concerned. For instance:
    - A hybrid system incurs far more losses in terms of energy conversions when keeping its legacy subsystem charged than the regular non-hybrid vehicle. Why? Well perhaps the following illustrations will help paint a rough picture:

    For a traditional gas powered vehicle:


    And now for a current generation hybrid vehicle:

    The concepts in the above illustrations, underscore why it is so important to keep the 12V system in good health. And that is also why Honda's original specifications for the 12V battery are so lame in the eyes of many. In other words, charging the 12V battery and keeping it charged in a newer gen hybrid (HCH-2, Prius, gen II insight, etc) is a far more costly undertaking than it is for a traditional vehicle. For many of these systems, the charge regimen is pulsed and relatively tame in duration and amplitude by comparison to other cars.

    On a related note: Because of their design, the Gen 1 Insight and Gen 1 HCH can in some instances continue to charge the 12V battery even if the main traction battery and/or BCM is reporting a problem. This is not the case with the newer gen4 + IMA systems.

    Another note:
    Toyota has a far more aggressive 12V charging regimen than what Honda implemented, but then again, their 12V demands are also higher and like the Hondas they suffer rather severely if not driven often enough or over longer distances on regular basis. For folks in northern climates this makes it even more delicate since the power demands go high and yet the 12V battery capacities go down and still, the charging opportunities remain the same.


    Last edited: Nov 20, 2009
  4. Right Lane Cruiser

    Right Lane Cruiser Penguin of Notagascar

    Hi, Pasadena -- I have a ScanGauge attached specifically so I can keep an eye on it. Now that I have a FAS switch which allows me to keep the DC-DC converter active when the engine is switched off I don't have to worry about it as much, though the HV SoC management demands have gone up. :rolleyes:
  5. pasadena_commut

    pasadena_commut Well-Known Member

    If there are green bars does not the diagram simplify somewhat, with the 3rd and 4th boxes from the top being eliminated? At least I assume the DC to DC converter is electrically in parallel with the IMA battery, with both having a common point fed by the output of the electric motor acting as a generator. So if the electric motor is running "backwards" and generating electricity that can be converted to 12V without having to be stored and then retrieved from the IMA battery. NiMH batteries, depending on how fast they are being charged, can waste a lot of energy, like 150 Joules out from the charger, but only 100 Joules stored in the battery. Sending the current directly into the DC-DC converter, bypassing the IMA battery, should charge the 12V more efficiently. DC-DC converters can be very efficient, 95% or better, and that effectively removes the 2nd to last box too, reducing the hybrid diagram to the conventional one. It would really surprise me if the hybrids don't turn on the DC-DC converter pretty much every time the regen current is available and the 12V battery is capable of accepting charge.
  6. Right Lane Cruiser

    Right Lane Cruiser Penguin of Notagascar

    My Insight does not seem to do this. The 12V varies between 12.0V and 14.0V (on a cold day... more like 13.8V in warmer conditions) and I rarely see anything but 12.0V-12.2V when using regen.
  7. pasadena_commut

    pasadena_commut Well-Known Member

    The 14.0/13.8V is similar to the observed battery voltage in a conventional car when the alternator is running. Presumably that corresponds to times when the DC converter is running on the Insight. Interesting. With no load 12.0V and 12.2V are 25 and 50% charge, respectively. There is a load though, and we don't know what it is. Assuming it isn't much (just the ignition system and computers) that seems like a low enough battery voltage to warrant recharging. The drop in battery voltage with average load is worth knowing. If your gauge shows 12.2V with the car running what does a voltmeter show immediately after you turn the car off?
  8. Right Lane Cruiser

    Right Lane Cruiser Penguin of Notagascar

    With all systems off, the SG typically reports 12.5V at rest.
  9. Mendel Leisk

    Mendel Leisk 2010 Prius (CAN Touring) Staff Member

    Just a heads-up for anyone in British Columbia, with a Lordco Parts nearby, the CTEK MULTI US 3300 is on sale for $69.99 (Can) through December 31. It's regularly $89.99 at Canadian Tire, for comparison. I happened to call one Lordco, they told me of the sale, and also that they were sold out, and that was the end of it. I tried phoning a couple more stores, the last one was also out of stock, but offered to get one in, which they did, within a couple of days ;) That store's on North Road, Burnaby.
  10. Orient Express

    Orient Express New Member

    After 5 years, just replaced my 12V battery in my HCHII, it made all the difference in the world. I highly recommend it.

    I bought a Costco 51R battery, which is made by Johnson Controls who also makes the US Honda 12V batteries. it was $62 with tax.
  11. suchham

    suchham Member

    By this October, my 12v will be 5 years old. So far, I've seen no drop-off in mpg or any other indications that it's failing, BUT it has not been tested yet. Since I'm taking a long trip in September (~4000 miles round trip), my thinking is it's time to replace it anyway. It would probably conk out this winter, if not on the trip, and why wait for that to happen?
  12. msantos

    msantos Eco Accelerometrist

    Hi Suchham;

    Very wise and overall good policy.

    In fact, my 2006 HCH still had its original battery on and it tested great year after year.

    However, I decided to replace it before I sold the car a couple of months ago primarily because I wanted the experience of its new owner to be as flawless as mine was during its 5 years under my care.
    So far, the new owners are loving the car and I certainly do not mind that one bit. :)


  13. suchham

    suchham Member

    Today is the first day with a new 12v battery. I just got back from the shop and a freshly filled tank o' gas. Now I'll see what difference the new 12v makes. Just judging from the trip home, the mpg is gonna be up and the SOC seems to stay a little higher than before. It's now sitting at about 6 bars where it was staying at 4-5. It also seems that it's easier to keep the iMPG above 50 and the car seems to have more pep. I'll take that. :Banane06:
  14. HCH2007

    HCH2007 Journeyman Hypermiler

    So, even though 3 auto parts sights I have been to say this battery is not a correct fit, it will work, yes?
  15. mmrmnhrm

    mmrmnhrm Well-Known Member

    Well, it's debateable... see my thread about flashing dash and dead car... the OEM battery lasted a good while, the aftermarket D51R (which does fit... barely) wasn't so hot. At least at my dealership, they use batteries with a 100 month prorated warranty.

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