With Honda's updated BCM patch - the one that's supposed to make packs last longer, a healthy pack will tend to operate more in the mid-range. This is particularly true of a pack that has been deep discharged as charging voltage tends to peak at the voltage max a little sooner.

Being an aggressive A/C user (it was 110°F on Sat), I can attest that your mileage is exceptional especially for the described driving style. With a freshly topped off pack, I'll be 5-10 mpg below your numbers.

When a pack is ailing, the BCM will keep the SoC towards the top end of the range, so you were likely accustomed to seeing 7-8 bars normally. This will generally not be the case anymore.

The SoC gauge is computed based on a lot of variables and is only good for reference. Personally, I only find it useful to indicate if the car is recalibrating.

 

Just a follow up to say everything is working great after a few more weeks.

I've driven that hill multiple times since my battery reconditioning and I have not had any recals. Now that I've driven it more I'd say that the improvement is more around 30%, not 100% as I initially thought. Since I do not have recals the performance is consistent and I no longer have sudden power loss. In that respect my real-world usefulness is indeed 2x better.

MPG is hovering around 46mpg with normal driving with climate control full auto (72F).

 

Thanks for the follow-up. your results are very favorable. I have to be VERY conservative to get 46mpg with A/C. I think you're results are great.

The initial improvement of a "refreshed" pack FEELS DRAMATIC compared to the performance of a pack that frequently recalibrates. After the SoC stabilizes in whatever range the pack can accommodate, it's more muted, but as you've discovered, it's still substantial.

Keep an eye on it. You'll probably find yourself less attentive to the SoC gauge. If you ever happen to notice 2 bars on SoC, you've likely recalibrated, and you should start paying attention again.

 

Follow up!
Today, I had my first recal since doing battery reconditioning back in September. Which is it when the battery jumps from 6 to 8 bars? positive recal or negative recal? Anyway that's what happened today. It may have to do with the subzero temperatures and I park the car outside.

Meanwhile I put on snow tires which dropped my economy to 40mpg around-town heat-blasting driving.

If it starts doing recals often I'll try another round of reconditioning.

 

If it went from 6 to 8 at 1 bar/second, it was a positive recal. Not at all a bad sign and is likely temperature related.

The negative recal, 1 bar/second drop to 2 bars, the forced regen and THEN the positive recal back to 8 immediately thereafter... that's the mileage killer you need to watch out for.

Since defrost runs the compressor, you want to minimize its use since it's also running off the IMA battery. Try to use your heat on the auto setting in the 72-78 range. It's hard to get disciplined to do that, but those simple adjustments allow the car to balance climate control with economy.

A couple months to a 6-8 bar positive recal is a pretty good sign. It could mean nothing, but I'd be surprised if you have any significant issues for at least 1-2 months. Conservative driving and climate control use will help extend that trouble-free period.

Thanks for following up!

Steve

 

another follow up.
It is now March 2017, a year and a half since I posted this thread. I have put ~12000 miles on the car. I have had the occasional recals (going from 4 bars to 8 in seconds, 6 bars to 3 in seconds) but never had an IMA light or any other problems with the car. I had a forced regen once since my last update.

I may be one of the lucky ones still driving on the original pack (11-years old now) without IMA failure. I would bet that my pack capacity is poor compared to a new pack, but in normal driving it has not been a problem.

I also purchased a Toyota Prius v (large wagon) and that battery pack has way more reserve power than my HCH. The Toyota hybrid synergy drive charges the battery pack while accelerating, so that design inherently keeps the Prius battery topped off whereas the HCH drains the pack quickly while accelerating.

During the winter, with General Altimax Artic snow tires, I am averaging 38mpg. Pretty bad for HCH although still awesome compared to any conventional car. I hope my MPGs increase again with warm weather and all-season tires.

 

Good to hear. You are as lucky as they come. 1 in 6 batteries failed in 5-7 years. Given the age and miles, it might be worth considering getting a Hybrid Automotive Reconditioning package. Grid charging and discharging your pack would likely revive it to a much healthier state and help continue its longevity. They aren't cheap, but they beat replacing a battery pack.

Before Maximum fuelage pipes up, I'll let you know I'm an authorized installer for them. I've installed two, which netted me $40 to my bottom line. I receive no payment for recommendations. I recommend them because they're the 2nd best option out there and the best value by far.

The best option is the Hybrid ReVolt unit with discharge that will run you in excess of $1000. It's a fully programmable system that can do amazing things and basically automate the whole process for you. This was developed by Mike Dabrowski at 99mpg.com. Lots of detailed stuff there.

That unit is beyond the reach of and unnecessary for most. That's why I recommend HA.

You are incorrect in how the Prius system works pretty much all around. The Prius and all Toyota HSD vehicles do NOT keep the battery topped off. They aggressively maintain a 60% state of charge with upper and lower limits of 80 and 40%, respectively. Hondas tend to maintain around 70% SoC and allow a 20-80% range. The patch for the 06-08 HCH2 actually makes it behave more like a Prius by raising the 20% to a higher number. I don't know what that number is, but it's higher than 20% - which makes them last longer.

The fact that the prius only uses 40% of the available battery capacity vs. the 60% the Honda uses means the Prius has LESS "reserve capacity".

The Toyota HSD system does not have more reserve or more useful capacity by any meaningful amount. The Prius has a 6.5Ah capacity compared to 5.5Ah for the civic. Prius is 200V and the Honda is 158V. Honda assist current is limited to about 100A with 50-60A regen and the prius will put out 130-150A with 80-90A regen. I've personally witnessed all these numbers on Honda/Toyota's diagnostics software.

The Prius battery is bigger... because it has to be. The electric motor in a Prius uses WAY more juice than the small 20hp motor in the HCH2.

Your perception of the differences between the two is due almost exclusively to the operation of a near new battery vs. a very old battery.

Again, glad to hear your HCH2 hasn't given it up yet...

 

Thanks S.
I don't know all these technical details, all i was saying is that the Prius system can recharge the pack while accelerating, whereas the IMA system generally does not. I think that gives the Prius system an edge in "reserve power" (like the ability to climb longer hills with some usable SOC still left over) regardless of battery capacity.

I did install the HA grid charger with simple light bulb discharge kit, and the car has been through 3 full reconditioning cycles since I have owned it. First two times was when I started this thread. I did one last summer as maintenance.

 

The Honda can too, but it's 1.3L doesn't have the same power margin as the Prius 1.5 or 1.8L in the case of the Gen3/V, so you don't see it as often.

DOH! That rings a bell. Sorry. That was a long time ago. I'd continue to do an overnight (12 hr) grid charge every 3-6 months as needed with a reconditioning cycle once a year.