Bad 12V battery??

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

  1. Right Lane Cruiser

    Right Lane Cruiser Penguin of Notagascar

    Manuel, that mirrors my observation in my '02 Insight as well. I seem to only see 13.9V in cold weather... is that what you see?
  2. msantos

    msantos Eco Accelerometrist

    Hi Sean;

    Indeed. I see increased durations of the charge pulse in the winter as well, but that is justifiable since the power demands rise and yet the 12V battery capacity diminishes. The DC-DC naturally steps ups its power provisioning since the alternative is hardly attractive. :)

    A big objective of mine has always been the minimization of the work done by the DC-DC... and that means not only keeping the 12V consumption down, but also the 12V battery charge levels as high as possible. All the little mods I've done (LED lighting, solar, etc) on the HCH-II plus the ones I'm doing on the 3G Prius help deliver on that front.


  3. hunter44102

    hunter44102 Well-Known Member

    For those interested, below is a link with the 12v battery voltage graph (and data) during my morning ~22 mile one way commute.

    The headlights were ON the entire time -except- when I did the experiment at the end. The logging is 1 second intervals

    Here are the interesting findings:

    - After starting the vehicle at 7:02:51, voltage dips to 12.4 then starts off pulsing between 14.05 and 14.10, and gradually works its way to pulsing between 13.85 and 13.90.

    - At my first Auto-stop around 7:07AM, when the engine shut down with the headlights lights ON, the voltage immediately jumps back up to the 14.1 range.

    - After a few mins, it settles back to around 14V and pretty much stays there for most of the 21 miles of driving. There were a couple other auto-stops at 7:28 and 7:30 that made the voltage jump slightly because the lights were on.

    - At 7:33 I had the lights -OFF- and did an auto-stop. The voltage took a dive-bomb within a few seconds down to 12.8V and stayed there

    - At 7:34 I turned ON the headlights (while still in Auto-stop) and the voltage went up to 14.1 within a few seconds and stayed there until I turned off the vehicle around 7:35

    Conclusion: HCH2 inverter stays On during Auto stop only if there is significant load, otherwise it drops down to just 12.7v battery voltage and sensing

    you need Microsoft Excel for this file:
  4. Right Lane Cruiser

    Right Lane Cruiser Penguin of Notagascar

    Hunter, thanks for giving that a try!

    I would bet that you'd see significantly more voltage sag if when you go out to the car you turn the key to ON position without starting the car and then turn on the headlights. My Insight seems to hang around 12.6V or so when sitting, but if I turn to the ON position without starting it quickly drops down to 12.2V, then creeps down at an ever slower rate. It isn't hard for me to get it down to 11.7V with a moderate FAS -- which is why I installed the FAS switch (to trigger AS at any speed and consequently gain DC-DC functionality to keep the 12V at a higher voltage). In AS without the headlights on the voltage will bounce around between 12.0 and 12.3V. With headlights on in moderate temps it likes 13.6V, but will go up to 13.9V if cold (I suspect this has to do with the perceived battery capacity). I've also seen the voltage jump when triggering the wipers for a quick swipe of the windshield (with the headlights off).

    Good stuff!
  5. Mendel Leisk

    Mendel Leisk 2010 Prius (CAN Touring) Staff Member

    We had our '06's 12 volt battery changed today. The bill says:

    31500-SLN-C01JB BATTERY 44B19L(S)

    I think it's the right one, looking at the documentation, but not 100% sure. The battery itself appears to be identical in dimensions, but looks nothing like the original, as far as the Furukawa HiDash identifier. This one is simply called Genuine Honda. Also, there is no indicator window. I'll try to post some pictures:

    Overall view of the battery. Note: no indicator window, "Genuine Honda Parts" logo (not Furukawa):


    Close up, showing Honda part number:


    And a wider view, illustrating fit:

  6. Gairwyn

    Gairwyn think green

    I recently had to have the 12V battery replaced in my '04 HCH. The original battery had the "window indicators" with the circles showing the charge status. The replacement battery doesn't have the indicators.
    I'm wondering if the original batteries are only available in Japan, and the replacements here in the US and Canada are slightly different, although suitable for the cars. I liked those indicators, but my battery needed replacing even though the indicator showed it was supposed to have been fine.
  7. Mendel Leisk

    Mendel Leisk 2010 Prius (CAN Touring) Staff Member

    I'm thinking similarly, and I miss the indicator windows as well. Even if they're not conclusive, ie: you can have OK display in indicator window and still have "borderline" battery, I think it's good for feedback. I'm not sure how you're supposed to keep an eye on the windowless batteries, at least as a DIY consumer.
  8. pasadena_commut

    pasadena_commut Well-Known Member

    For a first pass, load test the battery by leaving the lights on. Here are the expected voltages for a battery in various states of charge once the surface charge is gone:

    A real battery tester isn't something any of us are likely to have around the house, but it can be approximated by leaving the lights on, with the car off, for an extended period of time. A lot of bad batteries will run down much too quickly with just a headlight load, so you can at least detect that sort of failure. Also shorted cells will show up.

    Voltmeters are cheap these days, and if you don't have one, this is a good excuse to spend $5 at Harbor Freight to obtain one.

    There may be bad batteries that can't deliver high currents but can deliver low ones for a long time, and those won't be detected. In my experience the headlight test should be enough, with the exception of batteries that are killed by cold (Die Hards, I'm looking at you), which are perfectly fine until they get too cold one day, and then they are toast. Cold induced failure can't be predicted, as far as I know, and who is going to test their battery every day it gets cold? Once killed nothing sophisticated is needed, the battery just won't hold charge.
  9. Mendel Leisk

    Mendel Leisk 2010 Prius (CAN Touring) Staff Member

    Thanks for the link, I've bookmarked it.

    I have an old multi-meter, with the needle, not digital. I might pick up a digital model though: my 0-25 volt DC scale is really "fuzzy", about the only thing you can tell reasonably for sure is if the voltage is above/below 12.5 volts, the mid-point of the scale that has increments tailored for 0-5 volt range.
  10. pasadena_commut

    pasadena_commut Well-Known Member

    A digital is better for making accurate battery measurements. On the other hand, I prefer the old style analog meter for working on electrical problems where the voltage is changing rapidly. The analog meter is often fast enough that you can follow, qualitatively, the voltage changes, whereas the Digital ones lose all of this information as they integrate over the changing voltage.
  11. Mendel Leisk

    Mendel Leisk 2010 Prius (CAN Touring) Staff Member

  12. greenrider

    greenrider Well-Known Member

    I've used a similar, though not quite as nice, multi-stage charger on my HCH II (Optima yellow top) and I2 OEM batteries for the last several months with improved battery performance, in my opinion. CTEK charger can be a little pricey depending on model and vendor, but my battery has shown improvement and my SoC fluctuates less when I use a charger.
  13. Mendel Leisk

    Mendel Leisk 2010 Prius (CAN Touring) Staff Member

    If you don't mind, what's your charger?

    FWIW, I have an old 6 amp charger, purchased maybe 25 years back. It tapers off the charge as the battery recovers, but I suspect it's very crude compared to current offerings. But don't really know: I'm not that knowledable.

    Also, how often do you use it, for how long, etc.
  14. greenrider

    greenrider Well-Known Member

    It's a Duracell 3 or 4 stage charger I picked up awhile ago at Costco for 6 or 12 volt batteries. It works well with the small HCHII/I2 batteries but would probably not be sufficient for a large 12 volt battery. Harbor Freight has a similar one that's mounted onboard with a plug that hangs out for less than $20.
  15. pasadena_commut

    pasadena_commut Well-Known Member

    I don't see what good it would do.

    Assuming the car's charging system is functioning normally, and the 12V battery is OK, what benefit would there be from attaching a fully charged battery to a charger?
  16. Right Lane Cruiser

    Right Lane Cruiser Penguin of Notagascar

    The way some of us drive (with significant engine off time) the battery is NOT fully charged.
  17. msantos

    msantos Eco Accelerometrist

    Hi Mendel;

    That is an awesome unit. In fact, we have installed a previous model of this charger on a few hybrids around my parts with great results... especially for tjhose who have not bitten the solar panel bug.

    I would not hesitate purchasing one of those and use it on a frequent (if not daily) basis. In my view it is well worth the money - especially if it increases the chances that your 12V battery will last much longer than it is known to last at most 2-4 years in the vast majority of cases.

    The current crop of hybrid vehicles play within a very fine line when it comes to power and overall energy management. Some would say that the "game of minimums" that Honda plays with their hybrids is a significant detriment to those who either do not drive often or over longer distances. In these scenarios there's nothing a well functioning charging system can do to compensate for the accelerated losses.

    In the end, even if you ignore or dismiss the academic reasons why most folks operate their 12V battery in a deficit, you are still left with the financial bottom line of a less than stellar battery lifespan not to mention a measurably lower economy performance.

    Do I think the Honda approach to architecting and designing the 12V subsystem could stand some improvements?
    Heck YES, I do.
    But for now, any means of putting back the charge that we take out so often to ideal levels will only help the vast majority of folks who cannot get more than 3-4 years out of their 12V batteries.

    In my view, a device such as the one identified by Mendel is much more than an expenditure. It is a wise investment.


  18. Mendel Leisk

    Mendel Leisk 2010 Prius (CAN Touring) Staff Member

    Just some thoughts:

    1. I think the CTEK charger (or something similar) and a decent length grounded extension cord would be a couple of items worth stowing in the spare tire compartment if you were going on a vacation road trip. It only takes a map light left on overnight, or headlights left on an hour or two, to bring the 12 volt near discharge.

    2. The CTEK charger claims to have an initial "desulphating" phase: a pulsing of charge levels, supposedly making the battery more receptive to charging. It then goes through phases, ending up with a maintenance phase.

    It also has a simple indicator of dead, half-charged and fully charged. This was one issue on my mind, with the lack of indicator window on my new battery. I gather that window is a simple hydrometer, on one cell.

    3. I would think ultimately a good hydrometer, and the understanding of how to use it, considering ambient temperatures, etc, would give the best insight into your battery's status. But using one, in particular with "maintenance free" batteries, is a hassle.

    A load tester is probably more popular with service departments, but isn't it sort-of "testing to destruction" your battery: draining it a bit in the process of testing. Also, they are pretty expensive.

    It seems to me something the can give you feedback regarding your battery's state-of-charge and top-up it's charge at the same time is win-win.

    4. Regarding the price, I don't think it's too far out of line. With most everything coming from China, maybe we're lulled into the "Walmart" price model? It looks to be solidly built, full featured, and in the review it mentions a carrying case.
    Last edited: Nov 19, 2009
  19. pasadena_commut

    pasadena_commut Well-Known Member

    3-4 years is all a battery lasts in Southern California in any case, even on a conventional vehicle. The heat kills them.

    As for the economy part, are you saying that using the charger to "top off" the battery every night costs less for the charger + daily electricity than the equivalent cost in gas, or is there some other effect that is more important and increases the overall efficiency of the hybrid?

    I can sort of see how it might be cheaper to use wall electricity than gasoline, but don't expect it would be a huge difference. Also if the battery starts full the car doesn't have to use the regenerative braking -> IMA battery -> 12V battery to recharge it as much. Let's say the battery is 12V and 50Ah when fully charged, so 12*50*60*60= 2.16X10^6 = Joules, and is almost empty at the end of the day.

    Gasoline energy density is 1.3x10^8 Joules per gallon. So at 100% conversion efficiency (it isn't, but bear with me) it would take 0.017 gallons to provide that energy. Assume 25% efficiency, and that's 0.07 gallons, which at $3/gallon comes to $0.21.

    Electricity is sold in KWh, which is 1000*60*60 = 3.6*10^6 Joules. So it would take 0.6 KWh to charge the battery at 100% efficiency. Chargers are never that good though, so let's guess 50% efficiency for the charger, and 1.2 KWh consumed. Electricity costs on the order of $0.10 per KWh, so $0.12.

    Which with a lot of handwaving and guesswork comes out to 9 cents a day advantage electricity, assuming the battery must be fully charged once per day. 365 days a year comes to $32.85 savings. Now factor in the battery charger. Seems like a wash to me. (In terms of carbon usage it is closer still as there is another 50% loss in the transmission grid.)
  20. Mendel Leisk

    Mendel Leisk 2010 Prius (CAN Touring) Staff Member

    I can't see using a charger daily. Maybe hook it up overnight once a month or so? For batteries with no indicator windows in particular, this would keep you more up on your battery's status, if the charger has an indicator.

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