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Has anyone here ran thier HCH-II without the IMA system working (i.e. batery pack disabled)? How much did it effect the FE overall. Also, other than the lack of assist in a low power ICE what other loss is there?

I think I've read of someone trying it for a while but I can't locate the post. You are talking about just flipping the IMA switch, right? If you unplug anything the car won't be able to keep the 12V charged.

You'll lose autostop, assist, soft glide, IMA starts, and regen. I don't know if the electric scroll portion of the AC will still be able to operate. Otherwise it should operate pretty much as it does now.

Is there something wrong with your IMA system?

Yes, the car has frequent battery pack regen, about every other day. Financially we can not afford to go to Honda Service or replace the pack if that is the problem, the car has over 83k miles so warranty is not an option.

Yes, I had looked for that post about disconnecting the battery, it was detailed and told how to do it without interfering with the 12v battery charge capability, but I could not locate it either.

As long as you simply flip the main IMA switch I think you'll be fine.

Manuel, do you have any input on this?

Yes, the car has frequent battery pack regen, about every other day

If what you mean by "regen" is that the displayed state of charge suddenly drops, assist becomes very limitted, and the car doesn't AutoStop, but instead forces charging:

I see no point in disconnecting the battery. For starters, if it would even run, it would be extremely sluggish.

The behaviours you're seeing are the computer's reaction to having "lost track" of the main battery's state of charge. In other words, it thinks it has a certain amount, makes a request for electricity, doesn't get what it wants, and decides there's something wrong with it's perception, so it initiates a recalibration: force charging, limitting assist, and re-establishing it's assesment of the battery.

If recalibrations are happening, frequently, it's a sign of a battery that's "writing cheques it can't cash", ie: deteriorating. How much is the big question. And it might be partially reversable.

Have you got the software update? We got a notification in August 2010, for or previous '06 Civic Hybrid. At the time we were having at least two recalibrations per week. We got the update: I'm not sure how much of a difference it made; it changes the car's behaviour, not night-and-day, just a bit less assist, especially after the initial boost when accelerating.

The car is still on the road, still functioning, and still having the occasional recalibration, a year on, still with a family member.

I would check into the software update, #1. It might have been done, and it's not a panacea, but it's worth trying if it hasn't been done. And then, I would just continue to drive it, live with the recalibration behaviours. Try to limit assist by being easy on acceleration, and also try to avoid excessive EV instances (when the car drives on battery alone).

"If what you mean by "regen" is that the displayed state of charge suddenly drops, assist becomes very limitted, and the car doesn't AutoStop, but instead forces charging:"

Yes, that is exactly what is happening.

"Have you got the software update? We got a notification in August 2010, for or previous '06 Civic Hybrid. At the time we were having at least two recalibrations per week. We got the update: I'm not sure how much of a difference it made; it changes the car's behaviour, not night-and-day, just a bit less assist, especially after the initial boost when accelerating."

Not sure on the update, I am a second owner, but if the update was released in August 2010 Honda America did not contact me even though I registered with them as the new owner when I got the code to reset the radio when we bought the car.

"I would check into the software update, #1. It might have been done, and it's not a panacea, but it's worth trying if it hasn't been done. And then, I would just continue to drive it, live with the recalibration behaviours."

I am new to hypermiling and this site, so I was frustrated with all the "regens" I thought it was something I was doing wrong in the way I was driving and trying to learn hypermiling techniques and had in a way decided to live with the annoyance and keep on learning and driving, my trip to work today was 61.1 MPG and my overall on this tank is 51.2 MPG, just cannot seem to get the hang of the FAS technique, sometimes it worls for me and sometimes it does not.

"Try to limit assist by being easy on acceleration, and also try to avoid excessive EV instances (when the car drives on battery alone)."


This is the on place I have made a mistake as far as the battery is concerned, although I am easy on accelleration, I was impressed and allowed the EV mode to run as often as I could, especially coming down \the road at work to the parking lot and coming home in my neighborhood, I have travelled as far as 2 miles in EV, albeit slow as far as MPH, but in EV none the less. I did not think it could go that long and the battery still had 5 bars SOC, did it just this morning coming to work

"I see no point in disconnecting the battery. For starters, if it would even run, it would be extremely sluggish."

I had thought of this and was thinking I would add a performance chip to make up for the lost "power" of no IMA.

A performance chip wouldn't replace the power, I think. The engine is quite small and low powered because it is intended for extremely efficient cruising performance. This leaves it without much extra for acceleration -- I'm guessing that you'd have to add a turbo to get the sort of power you have now with the IMA system.

Use the "EV" glide mode as much as you can -- just don't use electric assist when in that mode unless you can get a big payoff (such as a long downhill stretch on the other side of a small hill). The latter is what drives your SoC down and makes for fuel in-efficient forced regen to recover.

All righty then, thank you all for the helpful information.

Talked to Honda, they said to take the car for a free product update of the IMA computer... Also, I found out that this car was originally from Massachusetts before coming here to the Low Country of SC! Explains the high mileage on such a young car, over 84K in not quite 4 years.

Phone ahead to check it out, but I believe if you just get the car to a Honda dealer, they can verify if the software updated is applicable, from your Vehicle Identification Number. They might even be able to check if the updates been done, just from the VIN. At any rate, with the car at hand they should be able to sort it out.

The software is by no means a panacea. Some owners suspect one of it's purposes is to just prolong the battery's death throes, and reduce the conditions under which a warning light will go on. Still, my opinion: in for a penny, in for a pound: they can't fault you if you tried it.

Also, I believe your battery still under warranty. OTOH, they will not authorize replacement until it is completely kaput.

According to Manuel the software can actually improve battery behavior over the long term if you let it do its thing. This can be helped along by trying to "stay out of the pack" as much as possible. In other words, minimize assist when accelerating and avoid EV propulsion. Soft glides ("EV" mode without assist or regen... just rolling with the engine off) is perfectly fine and should be used as much as possible.

Bring it in and see what can be done for you!

Hi Sean & HCH2007;

That specific software update is intended to not only reduce the stress on the battery pack but also slowly help condition any cells that may otherwise experience premature failure.

Depending on the actual state of the battery pack, this process of rehabilitation can either be very short lived with little change (if not a minute improvements) in FE... or a totally long and frustrating process. In some cases, the pack (and often the driver too) is so beyond recovery that Honda will indeed replace the pack after the software update has proven to be of no help.

For those that have had the software applied I humbly suggest the following:

- Understand that forced regens from 4 to 7 bars are no longer the norm. Instead, you should get used to your charging pattern resembling that of a Prius (from 2 bars to 7) but with the now expected precipitous drop. The new forced regen events now can occur whenever the system feels appropriate and the invalidation of the SoC (which causes the force charge) can occur even when the SoC is at 6 bars. To keep things safe the system no longer waits for an SoC of 4 bars as it is likely that some of the bad cells may be approaching a reversal threshold. The system now aims at preventing those scenarios very aggressively. Instead of cursing at it, why not give it a hand?

- Again, the point of the update is to minimize the conditions of SoC deficit and on this front there are many things we can do. #1 is to minimize the use of electric assist whenever possible. #2 plan your deceleration and stops so that you can regen over longer distances and fewer regen bars on the display. #3 when at a stop light with a cold engine, simply place the transmission in L and keep it there until you are ready to move again. #4 when climbing ramps of hills at very slow speed place the transmission in L as well for as long as the RPMS remain low.

In many cases, doing the above will ensure a quick and painless reconditioning and may even help reverse the course towards permanent deterioration.

Lastly, I would not advise running the vehicle with the IMA IPU offline. On top of it not being a sustainable means of operating the car anyway, you are definitely worsening the situation by failing to keep the battery charged within safer levels.

Please note that these battery packs are made up of deep chains of cylindrical cells and if the battery pack is mis-behaving then it is quite likely that only one or two cells out of 122 are actually bad. Therefore, if you operate the vehicle for extended periods of time without ensuring that the pack as a whole remains within safe charge levels then you are literally condemning the whole pack to an early and regrettable death. Not a good choice no matter how we look at it.

Lastly, the engine and power-train in this car was designed from the onset to benefit from the presence of a working motor/stator. That's how it was tuned and calibrated especially for improved torque and reduced stress on the engine with the vibration dampening effect (among others). On this last feature, the vibration dampening is quite real especially when temperatures are below the freezing point. Also, the big fuel saving features provided by this car are simply not available when the battery pack is off-line. Sorry.

One last item before I close this reply. Making frequent use of FAS in this car - especially with the OEM 12V battery still on it is a sure way to kill that tiny battery including risking the ramifications of a failed power up.
In fact, I suggest trying the above recommendations and making heavier use of soft glide patterns (what the car was built with) instead of replacing it all with a FAS. With practice you'll get better at it and while you wont get the same FE results as you would get with a FAS routine, your car will certainly thank you in the long run.

Cheers;


MSantos

"One last item before I close this reply. Making frequent use of Fas in this car - especially with the OEM 12V battery still on it is a sure way to kill that tiny battery including risking the ramifications of a failed power up.
In fact, I suggest trying the above recommendations and making heavier use of soft glide patterns (what the car was built with) instead of replacing it all with a Fas . With practice you'll get better at it and while you wont get the same FE results as you would get with a Fas routine, your car will certainly thank you in the long run."

Concerning FAS, if I wait until I absolutely need to restart and do not put the ignition iswitch nto run position, would that remove most of the stress on the system due to the 12v battery? Also can the OEM 12v battery be replaced with a larger capacity aftermarket one?

Don't ever coast with the key not in the run position!!! You lose all of your safety electronics that way -- including but not limited to airbags and ABS!!

We don't recommend replacing the 12V battery in a Honda hybrid with a larger capacity product -- the IMA system is tuned to deal most efficiently with the capacity and chemistry your vehicle came with from the factory. A larger capacity battery could cause the DC-DC converter to run longer in order to charge it up... causing more background regen and lower mileage. Extra loads on this system can also sometimes trigger recalibrations.

Hi HCH2007;

Sean is absolutely right. We strongly suggest you have your vehicle systems powered ON whenever the vehicle is in motion simply because you need the electric power steering, brakes and active safety systems to be always available should the unthinkable ever happen!

A larger capacity battery will certainly help as far as FAS heavy driving is concerned but such a choice is also not without detriments. Again, Sean's explanation is right on the money.

Lastly, a FAS heavy routine is NOT the type of long term fuel saving technique we suggest on the HCH-II - not if you own the car and you want it to last long. Yes, it will get you the very best numbers but it will also happen with too many detriments for it to be suitable for every day use. It only takes a handful of FAS sessions to bring the OEM battery to its knees simply because the legacy 12V system has so much device load already.

Did you know that the built-in fuel saving features get reset every time you perform a FAS and it takes up to 10 seconds for you to get them back? Again, this happens every single time even when the engine is fully warmed up and unless you have very extended coasting opportunities, this approach will only cause the engine to guzzle more than it needs to after powering up from a FAS.


Cheers;

MSantos

That explains the slight but noticable drops in mileage when I have FASed. Okay, Back to school for Wayne, need to get up to speed on the proper FE techniques for my little hybrid.

Thank you so much Sean & Manuel for all you help and information.

You are most welcome -- we love to help!

Good luck and be sure to post your numbers and any other questions you might have. :)

Got the software update, but everything is pretty much the same, I don't see any change in the way the car is running, still getting around 51 MPG per tank and the IMA + CEL are still on. Honda tech pulled code P0A7F when he checked the car and they say I need to spend about $3,000 total to replace the battery (not including labor) because, it is out of warranty. Well, I am not spending that much money on a car I am still paying for that has a balance of $12,000 left to pay. So, I guess I live with it until it dies and goes to the junk yard. I did do a general search of the internet on the code and several hits mention a degraded 12v battery can cause false errors for the IMA, I am going to check out the 12v system and see what is going on there. Anyway that is what I found out to this point. I remember somewhere I read that you can ask Honda for special consideration and if approved they will replace the IMA battery for free, not sure what to ask for though.

You aren't that far over the warranty mileage so it is worth asking!!

Besides Honda, you should check out these guys:

http://www.re-involt.com/

You seem to be getting very good mileage for a dying main battery. Hows the state-of-charge and recals going? Could just be an ailing 12 volt, get it changed?

With the main battery: I see no reason to do anything right away. Just keep driving it (getting that good mileage), and see how it goes. Follow the tips for staying off the pack.

or look for a used battery (from a wreck) with low mileage. I've seen some for $300-$400 http://www.car-part.com/

Checked the site out and they have one listed from a 2009 for $400, wonder if it will work in my 2007???

I am positive it will! H

Personally: I'd spend a few more bucks, and go with one that's been tested and reconditioned professionally. Salvage batteries sound like something that would be better suited for someone like Re-Involt to purchase and test/refurb. There's a a chance that "salvage" battery you buy is in more-or-less the same state as the one you currently have.

The issue you run into with packs that have sat around for a bit is that the self discharge rates differ with age. Self discharge won't harm the cells but trying to pull current from them while they are in an unbalance state most certainly can (by resulting in cell reversal -- the process where surrounding cells push current the wrong way through the cell because its voltage is too low). Proper conditioning before the pack is used in a vehicle can prevent damage and provide strong and trouble free performance. I wouldn't simply purchase an unknown condition pack and install it hoping for the best.

Additionally, salvage can have several meanings. I've seen pictures of salvage packs from flooded vehicles and it isn't pretty at all. The cells may still be okay but all of the electronics and connections are heavily corroded.

I echo Manuel and Mendel's advice -- if you want to go the used pack route spend the money on a refurbishing service that will help you avoid the pitfalls.

Again, not to sound like a broken record but some of these battery repair outfits have been at it for quite a while and if you were to take advantage of their hard earned expertise then you would be still better off than just replacing your pack with a salvaged unit. Retrieving it from a recent accident write-off could make it more attractive though but even then I see those packs as nothing more than a source of parts for battery repair outfits.

Still, look at it this way: Except for a couple of bad cells, your pack is a good as what you would get from a Honda supplied replacement pack. In fact, what you get out of a salvage purchase is probably as bad as it gets since whoever extracted it, likely did not care for it, kept in storage or under the elements and does not even know its history.

For now however and while you avoid a pack replacement, I would suggest following the "program" and giving the software a little help whenever possible. Yes, the behavior is different now but that will remain even if you get a Honda sourced battery replacement... so it all boils down to embracing the new battery management routines and the idea that the SoC indicator in its mid-range values no longer offers an accurate representation of the battery charge. With the system doing its thing and us embracing the new set of strategies I believe it is possible to preserve and even improve on much of the FE potential this car has always offered. ;)


Cheers;


MSantos

Thank you, Manuel, Sean & Mendel for all the advice and information. Since the car is still getting good mileage, I believe the give the software update a chance to work position is the best, even though it is quite stressfull to drive my very best FE wise and watch my mileage drop, but once the computer is done I am able to make it up and then some(67.3 MPG on a 20 mile trip to work this A.M. and overall 52.3 so far on the tank. City driving was always a killer on the mileage, but it is much worse (so far) now. The hard thing to accomplish is staying out of the battery pack, because the car seems to want to soft glide at times even when not initiated by myself and before I realize it I am going 40 MPH in a 65 MPH minimum 45 MPH speed zone, kind of annoys the other drivers and causes me to accelerate with assist to get back to a safe speed. Also, just getting up to speed when the computer is doing a recall kills mileage. But, I love this car and I am going to get things straight and what I am learning now will help me to teach my wife when I buy a second FE car, most likely another Honda (probably an Accord Hybrid since my wife really does not like to drive very small cars). The odd thing is when ever the pack comes out of recal the IMA light comes back on when the charge goes back to 8 bars Soc???