Just did a CVT fluid change on my 07 HCH II that has about 240,000ish miles on it. It would occasionally shutter from a stop. I bought 9 quarts of of CVT fluid. I drained filled drove around the block a few times and repeated for a total of 3 times. Seemed to be ok, took the family out to dinner 45 miles away with zero issues. Until the return. Started shuttering again but seems more often. I do have a question. How exactly do we check fluid level? I have checked by the owners manual months ago and it showed low(a quart). I added a quart and drove it. When I drained the fluid the first go around it did seem like it was about 4 quarts in there.

 

There should be exactly 3 quarts. There are marks on the dipstick; however, I just make sure to put exactly 3 quarts in at change.

Someone may have overfilled it to try to address the shutter.

Shutter can also be caused by the IMA system not delivering power smoothly. Take out your rear seats, remove the safety cover and disable the IMA battery switch. Drive around for several miles and see if the shuttering returns. It will be gutless, and you will only charge the 12V between about 1500 and 3500 rpm.

 

What would cause the system from delivering power smoothly? I drove her in to work this morning(65 mile commute) and it drove OK. until my last stoplight which is slightly uphill. Battery had a full charge on it at this point and had an ever so slight shudder.

 

The SoC gauge really isn't an indication of "full charge". I frequently have 7-8 bars when the car decides to do a recalibration and charge for an extended period.

Now that I think back, I don't recall if it applied to the HCH2. It may have been particular to the HCH1. I helped someone service a battery pack back when I thought it might do some good. We installed an empty pack in "bypass" mode. One thing she noticed right away was how smooth the car was when accelerating. Prior to that, it would "shudder".

As your only real solutions are continued fluid flushes or a replacement CVT, I got nothing else.

Personally, I change fluid every other oil change, so about every 15K miles.

 

So how do you know when the battery is re-calibrating. All I ever notice is when the battery level gets to the 2 bar level it starts what I call a hard charge(using the engine and breaking). Unless that is what is called re-calibrating.

I will try to turn off the battery to see what happens. I was thinking of building a grid charger for it. But still have not had the time. due to my lengthy drive times I am not sure I need one, unless I do to recondition a pack.

 

That's exactly a recalibration. You're at some typical state of charge, say 4-8 bars. The IMA system tapers off assist and drops to 2 bars at 1 bar/second. It force charges for a period of time. Sometimes, it just creeps back into the 3-8 bar operating range, sometimes, it climbs back to 8 bars at 1 bar/second.

Start paying close attention to your recalibrations. If they are happening often enough for you to notice, you likely have a deteriorating pack. Your lengthy drive time does nothing for pack health aside from not utilize it for stop and go traffic.

What happens is that 1 or more cells out of the 132 in the pack are deteriorating. it's likely 6-7 cells scattered across as many sub-packs. They are likely at a higher state of self-discharge than their companions. The high discharge cells cause the voltage of their sub-pack to drop rapidly. The car detects this at the subpack level. The car force-charges the pack to try to maximize the voltage across the subpacks; however, the healthiest sub-packs register as full, and the car has to stop force-charging to prevent over-charging of the healthiest packs. This generally only imparts a partial charge to the ailing subpacks.

In short, your worst subpack (group of 12 welded cells) determines the low end of the charge and your strongest subpack determines the top end of the charge. When this imbalance occurs, capacity is greatly diminished. Eventually, you will cross the threshold of performance, and you'll get an IMA light.

Given that extended highway driving is very easy on the IMA system, recalibrations are even more concerning. Start logging them. If you're seeing more than one every couple weeks, you likely need to take preventative measures ASAP.

 

Well, with that information I would think I am in trouble. For the past month or so, when I am on my commute home by the time I hit our Fast Track lane which is about 2-3 miles away it is in re-calibrate mode based on your description. Though I do have my AC on full blast and I have stop and go up until the fast track. By the time I leave the fast track lane which is about 10-11 miles the battery show full charge.

 

You are definitely on the downhill slope of battery life. A/C is very hard on an ailing battery. If you can tolerate your morning commute, you might try comparing A/C vs. non-A/C battery performance. Additionally, it is important to use the A/C only in AUTO mode set to a conservative temp. I find 78-82°F works acceptably well here in AZ.

If you're patient and obsessive, you can start at 86°F and inch downwards and really improve mpg/performance.

A couple hot-weather tips:

1) If the car is parked in the sun, it is very important to leave your rear windows cracked to help keep the pack from getting too hot. If you can park facing west with a sunshade in your front window, it's better than any other orientation. Interior temps in the sun in hot environments can subject the batteries to temperatures that can cause accelerated deterioration.

2) Even with the above precautions, you should drive gently, avoid A/C use and roll your windows down for a short while to purge the hottest air out of the car. The battery cooling fan draws air in from the vent in the rear deck. If you're drawing 120°F+ air in for cooling, you're not doing the battery any good.

This is far less convenient than your typical "go and blow" process for taking off in a hot car, but the Honda IMA battery packs are admittedly marginal for the design, and you can either drive them like a normal car and get 60-80K miles out of a pack, or you can take some precautions and likely extend that life.

I would recommend you pursue grid charging AND discharging. If you want to build your own, you need to remove the pack from the car as the fan requires a PWM signal to drive it. An alternative would be to connect a 12V charger to the car battery and leave the ignition on while you run the grid charger. The car will cycle the fan as needed. Obviously, you would need to do this in a secure location. If you're looking for a turnkey solution, I recommend a grid charger with the discharge option from Hybrid Automotive. They're pricey compared to DIY, but they are turnkey and HA provides great support.

 

One more thing... At some point, I'll tell you to disconnect your 12V. This is me covering my a$$...

If you disable the IMA master switch, you'll throw an IMA and Check Engine Light (CEL). To clear them, you will need to disconnect/reconnect your 12V battery. This will also necessitate you entering in the security code for your Honda audio unit or navigation unit if so equipped. Make sure you have that available. If you don't, the dealer will provide it to you in person with proof of ownership.

 

I am the Sales Manager for Derale Performance and we build a PWM fan control that can handle up to 60 amps. We build this in house. I also dable in Arduino programming and have built high amp fan controls using PWM signal to run a MOSFET powering the fans. What would I need to do to build my own charger?