I've been reading and posting here for about a year, and there's no longer any doubt. Honda has a severe problem with dying IMA batteries and most HCH owners are eventually going to experience what we have ... gas mileage dropping by about 10 mpg for no apparent reason, and more and more frequent recalibrations. In fact, these are two sides of same coin. The loss in mileage comes from the engine working harder to drive the car without battery assist and from using more of it's output to recharge the battery.

TSB-59 and software upgrades are just a diversion for Honda to buy time to avoid or delay replacing IMA batteries under the warranty. Until your IMA light comes on they'll be telling you it's because of hot weather, cold weather, sunspots or anything else they can think of. It's not your control arms, new tires, different oil, or any of the other theories posted here. Very simply, the IMA batteries have a lifecycle and for whatever reason, it's turning out to be much shorter than Honda and we owners expected.

Honda's response is horrendous and it's hurting the brand. If you take a look at the proposed class action settlement, you'll see it's nominally about owners not getting the 'advertised' gas mileage. In fact, it's an artfully concealed pitch for dissatisfied hybrid owners to trade into a traditional gasoline-only car. Without admitting it, they are hoping enough of us trade for another Honda to slip the problem under the rug.

This is a terrible way to treat a group of sophisticated owners who took some risk to try a new product category and contribute to lower fuel consumption, lower emissions and other social good for our planet. We've been had.

 

Hi Tom
Well I hope your theory is incorrect because I really like my 2006 HCH. The only problems I have had are the upper control arm issue and a cover under the rear seat to protect damage to a wire connection. The car has been very FE and great on trips. It handles almost as well as my Miata and that is a great car on the by ways. I have never had a better car.
Cheers,
Hal

 

Hal,
Do you think that this IMA battery issue is chronic? Sounds from reading this forum as a new comer that we do have a problem here. Makes me feel that I should have purchased a regular Honda Civic because the rest of the car is fantastic. To be honest I am not worried about other issues on the car except the IMA Battery. Honda should extend warranty and honor all failed batteries since I believe this is a design fault. Does the Toyota Prius also suffer from premature battery failure?

 

I am not really concerned about it! I worry about all maintenance items. All kinds of thins can happen to our cars. If the IMA gives me problems then I'll deal with it. I did purchase the extended warranty, so I,m OK for some time. Cheers,Hal

 

I wonder if there is such a phenomena as a "borderline" battery, ie: one that isn't sick enough to trigger error codes, but eats into your mileage as the OP describes, due to the engine running less efficiently, devoting increased hp to recharging the battery, have less assist available. It would be very nice if there were some DIY diagnostics possible, to assess the battery state.

 

I am no expert but that condition seam logical to me.IMA Battery slowly degrading should impact FE, should it not? Surely the battery SOC is not good then bad with no grey middle.

 

My guess is that some of us '06 owners have battery packs that aren't completely balanced so some cells charge/discharge at a different rate than the others. This would cause the BCM to get into the "yellow zone" (i.e. recalibration) a little more frequently than normal. I hope the yellow zone as I'm calling it is conservative enough to prevent any of the cells going into the "red zone" and causing damage.

If my theory is true, those cells will have a shorter lifespan than if everything were perfectly balanced. I'm hoping that the lifespan is either significantly shorter (meaning I need the pack replaced before my 100k mile extended warranty expires), or that it's a non-issue and the car goes 125k plus (after which I will be ready for something different anyway).

Regardless, even with the frequent recalibrations that I was experiencing, the car has exceeded my mileage expecations so I'm a happy customer.

 

Hi Mendel,
Allot of the packs being changed seem to only have one week cell. I sounds like it does not take much to trigger codes for the IMA. A couple mths. ago a chap repaired his own pack. He is on this site and he must be a electrical mind. He claims it was not that difficult. Also some have purchased used packs. I have a friend that I would get to repair mine if it requires it. Hal

 

Toss me in as a happy customer too.

This is the best and smoothest car I ever owned and a real gem to keep if you care about learning how to drive it right.

My MPG's ? It exceed my early hopes by a BIG margin and the rest of the other goodies (no problems at all after 2.5 years) are the icing on the cake. Did I say this was the best car I ever had?
Add green-Clean too without the "Prius-look at me"

ks

 

I own the car 6 days now and overall so far I am happy with the performance. Not great mileage as you guys but then it is winter here and my driving is a bit aggressive to achieve 50MPG. No worries I like the car looks and the interior instrumentation is fantastic. Like Star Trek!! I would say best car I ever own. Now hopefully my battery does not fail. Cheers