Analyzing, refurbishing/repairing a dead hybrid battery pack (2000 Honda Insight) - Fuel Economy, Hypermiling, EcoModding News and Forum

MetroMPG · 01-03-2012, 07:36 PM

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Warning!

A high-voltage hybrid battery pack can kill you. Even a "dead" one can make YOU dead. If you don't know how to work around & protect yourself from high voltage, don't muck around in there!)

Note: for detailed info about the procedure being followed in this discussion, see http://ecomodder.com/forum/showthrea...vic-13610.html

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Background: dead hybrid pack = good price on a used Insight

Last year, I bought my 2000 Honda Insight with a "dead" hybrid battery. The "check engine" light (CEL) and "Integrated Motor Assist" (IMA) light were both on.

The local Honda dealer had told the previous owners that the hybrid battery was dead, and would cost ~$3000+ to replace with a new one.

Fortunately for me, they thought a $3k+ repair bill was a bit steep for an 11 year-old car with 269,000 km (167k mi.) on it. So they traded it in at a different used car lot out in the country, and the lot owner was pleased to eventually unload that defective, weird little car on me.

Code red:

The car had a stored P1449 code. From what I've been able to gather, it's set for a number of potential IMA battery pack issues:

- cell over 80°C for at least 2 seconds
- pack out of balance (weak cell/s)
- shorted cell

Code reset! Happily ever after?

Resetting the CEL and IMA lights caused the hybrid functions to return to normal!

But only for a while.

The hybrid battery gauge would show recharging while driving or idling, and the electric assist, regenerative coasting/braking, and idle-stop functions worked fine.

But after a while (particularly after sustained charging or assist), the lights would come on again and the hybrid functions would cease.

A "crippled" hybrid that can still get 80+ mpg

Honda designed the car to work even with the hybrid functions disabled. The engine even has a "back-up", conventional 12 volt starter. (Normally it's started instantly & quietly via the IMA motor/generator.)

So I drove the car from July through November, minus the hybrid stuff, and managed to attain 80+ MPG (US) / 2.7 L/100 km over thousands of kilometers and 3 tanks of gas. How? Most of my travels were "driving with load" at moderate speeds (~80 km/h) on secondary highways (mostly flat to slightly rolling terrain) where the car could be held in lean burn mode for extended periods.

But the hybrid stuff is way cool

I could just leave the hybrid stuff disabled, and continue getting phenomenal fuel economy forever. Even without the hybrid functions, the Insight is a marvel of efficiency engineering: light, highly aerodynamic, efficient 3-cylinder gas engine with lean burn, and tall gearing.

I will never make back the money in added fuel savings that it will cost to repair, even if the cost is only in the low-mid hundreds of dollars.

But ... the hybrid stuff is teh geeky coolness. So I'm going to look at fixing it anyway. DIY, baby!

This thread will document the adventure.

I'll be pulling the pack out this weekend, and I've got myself a $80 NiMH battery/cell analyzer from eBay. Step one is gathering data/characterizing the health of the cells in this pack.

Until then, you may be interested in reviewing Mr Small's excellent thread on this very subject: http://ecomodder.com/forum/showthrea...vic-13610.html

That's the process I'll be following.

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EDIT: here's an index/summary of this thread's notable posts & milestones:

I posted the analysis of the pack capacity in this Google Docs spreadsheet: MetroMPG's battery pack analysis - 2000 Honda Insight (Google Docs spreadsheet)

Post #20: photos of the pack removed & disassembled here

Post #29: Sub-pack testing begins (Jan 7, 2012)

Post #35: How long will a complete pack analysis take? About 9 days of steady testing.

Post #36: What does the "peak detection" setting mean on the Super Brain (TM) battery analyzer that I'm using?

Post #39: IamIan's list of 9 possible courses of action for the owner of a bad hybrid battery pack

Post #49: Can you remove an Insight's battery pack and keep driving the car? Yes.

Post #63: So... how bad is the pack? Cycling seems to have restored it to 75% of nominal capacity

Post #71: What is the cost of battery analyzer/charger + grid charger needed to "refurbish" an unbalanced pack?

Post #79: Options for treating an old pack more gently, to prolong its life

Post #85: Marathon pack analysis... complete, with summary! (Jan 25, 2012)

Post #86: First test-drive of the re-balanced pack - an apparent success! (Feb 5, 2012)

Post #113: Insight owner eq1 posts his Insight pack "rejuvenation" results - also a success

Post #129: Beginning of a discussion of the limitations of the Super Brain battery analyzer, and other (better?) products available

Post #153: Discussion of the DC-DC converter - does it continue to charge the 12v battery while using the car with the IMA breaker switched OFF? Yes (sort of).

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redpoint5 · 01-03-2012, 08:40 PM

Your posts are among the most interesting and well written Metro- Thanks!

Best of luck on your endeavor. I tried and failed to repair a malfunctioning Roomba battery. I was able to locate 2 cells that were below voltage threshold and replace them, but alas, the darned robot still doesn't like the battery. I ended up buying a new one from Ebay for about $25.

I'm looking forward to gaining some wisdom from your experience, and possibly tackling that dead Roomba battery again.

MetroMPG · 01-03-2012, 08:53 PM

Thanks for the good wishes, redpoint5!

Coincidentally, this summer I also snagged a cheap (OK, FREE!) rechargeable (cordless) lawnmower because its battery was dead (see Reviving a free, dead 12V cordless Black & Decker mower - EcoRenovator ). I retrofitted a couple of smaller batteries in parallel in that and got it working. Seems I've got a theme going here...

There's got to be a Roomba forum where you can find a "DIY" thread like the one Robert Smalls posted on fixing the Honda hybrid pack...

Formula413 · 01-03-2012, 09:40 PM

I'll be following your progress since I have the same situation with my HCH. Are there known reliability issues with the Super Brain charger? Seems I've read that once or twice. Are there any other chargers suitable for this task?

Also, regarding your point about never recovering the expense of repairing the pack, don't overlook the increased resale value should you ever sell the car. Especially since I'm assuming you got a great deal on it due to the battery problems. I could drive my car forever as it sits now with no electric assist, but I'd take a huge hit if I ever tried to sell it like that. Plus the car is a LOT more fun to drive with electric assist, so there's that to consider as well.

MetroMPG · 01-03-2012, 09:57 PM

Quote:

Originally Posted by Formula413

Are there known reliability issues with the Super Brain charger?

Yes. I've read more than a couple of accounts of the unit failing. Maybe they're not really designed for the marathon use that analyzing a hybrid battery pack represents - they're really meant for small capacity batteries for remote control vehicle hobbyists.

I gather it's good advice to keep the unit as cool as possible while using it (even an external fan).

Quote:

Are there any other chargers suitable for this task?

I seem to recall the owner of hybrid-battery-repair saying he uses them in his business, and has many of them running simultaneously. He's experienced a few failures but is generally satisfied with them. I'm generally a lazy SOB, so rather than do any further research, I bought what he uses (and Mr Smalls uses, in his battery refurb thread).

Quote:

Also, regarding your point about never recovering the expense of repairing the pack, don't overlook the increased resale value should you ever sell the car.

Absolutely true. I could easily make a handsome profit if I fixed the hybrid battery and sold the car. But that's not in my plans. (I'm good at acquiring junk, not so good at getting rid of junk!

)

Quote:

Plus the car is a LOT more fun to drive with electric assist, so there's that to consider as well.

That's the main reason why I'm doing it. I'm looking forward to playing with the hybrid functions, and learning a new set of driving skills & strategies!

MetroMPG · 01-03-2012, 10:07 PM

Formula: just out of curiosity, have you tried the grid charger approach to balance your pack?

If I had to rely on my vehicle (ie. couldn't afford to pull it off the road for an extended period to tinker with it), I might start with that first.

It's possible you could return it to health without having to go through the tedious process of analyzing the subpacks with the Super Brain (or equivalent).

I'll definitely make/get a grid charger when this process is done anyway, particularly since I don't drive an awful lot. The car sits sometimes for weeks at a time, which is particularly terrible for the pack (cells drift out of balance through different rates of self-discharge).

Also, it will be fun to play at "mini-plug-in-hybrid" with a grid-charger.

Formula413 · 01-03-2012, 10:55 PM

Quote:

Originally Posted by MetroMPG

Formula: just out of curiosity, have you tried the grid charger approach to balance your pack?

As a matter of fact I have, I don't own one but I did get to give it a grid charging once, for several hours. The assist worked great for a few days, then the P1449 came back, and the usable capacity continued to whither. That tends to make me suspect that there is a weak cell in there somewhere. A grid charger is very expensive, and I'm somewhat reluctant to commit to that if I will still need to tear down the pack and find the bad subpacks.