My Honda Insight hybrid is a 2002 model and has already had its battery pack replaced in 2008. Well, in its 13th year (7 years on the new pack), the pack started reporting degradation of the battery requiring some decisions. Considering the value of a car with 165,000 miles and 13 years on it, replacing the pack (even with a refurbished/reconditioned battery) would constitute over 50% of the value of the vehicle, so it’s not a good idea at this point IMHO.
That leaves two options, but if you found this article then I need you to learn from my mistakes:
- Keep driving, ignoring the lights, with IMA going in and out
- Disable and bypass the hybrid battery
The Honda Insight, at its core, is a 3-cylinder 67-hp engine and can function without the battery with the loss of auto-stop, regenerative braking, and some MPG. However, depending on when your pack was made, the decision above will be made for you. To explain, I’ll briefly tell you my experience and logic.
My Big Oops
The big concern, with the failing battery pack (ODB codes P1447 and P1449), is that it will not be able to transfer power to the 12v battery under the hood (it acts like an alternator with its DC-to-DC converter) and eventually you will be stranded and unable to start the car. When you Google around, you eventually find the article linked above and some forum conversations about needing to bypass the hybrid battery to make this work.
So that’s what I did. Some sockets, Torx T30 bit, and about an hour and I could easily disable the hybrid battery pack and unplug the Battery Control Module (BCM). However, when I started the car up again, it had a very difficult time starting. I immediately believed it was my small under-the-hood battery and went to my local auto parts store for a free test. The battery was good, but needed a recharge. So, I went for a drive on the highway for an hour, at 2500 RPMs. One important weird behaviour happened: Exceeding 4000 RPM trigged the battery and brake lights to come on, but dropping below 3k for about 1 minute would make the lights go out again. This should have been my first clue.
When I tested the battery again, it had improved, but not enough, and it would no longer start on its own. I had to push-start it (I drive a manual transmission) to get going again. Shortening the story, it was time for a multimeter and some testing and the end result was a loss of charging when idle, and a gain at higher RPMs, but a complete inability to start the car. After speaking with my Honda Dealership rep and a 3rd party hybrid specialist, we had come to a few conclusions:
- Some Honda Insights will continue to work for a long time (lights on/off, charge/assist working and not) without bypassing the hybrid battery
- It’s no longer recommended to do the bypass because it may or may not work
Based on my research, the reason it may or may not work is because the trick is necessary for original IMA systems. However, remember, my pack was replaced in 2008 (there was no sticker on the BCM when I opened things up; my second clue). Honda updated the BCM with the pack, and thus they made the trick unnecessary. So, the decision is made for you: if you have an original pack, the bypass will be necessary. If it’s been replaced (I’m guessing that covers 99% of Honda Insights due to the 10 year warranty), then it’s not necessary.
Of course, if you need to pass an emissions test, you’ll need a replacement battery pack, because you’ll have that Check Engine Light. :( For me, I’ll be retiring my Insight 3 months shy of its 15th birthday. It was a good run.
Update: June 2016
It’s hard to say why, but I went into the dealership to have any error codes cleared and suddenly everything that was working fine (no large battery) went to hell. Long story short, I was dead in the water. The vehicle would no longer function disconnected from the system as a DC-DC converter and thus I had to either sell a dead car or replace the pack. I replaced the pack for ~$2500 (not at the dealership). It’s running great now, back with a battery, now that its life has been extended. It seems 15 years was just not enough in its heart, so we keep going.