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Discussion Starter #1
I'm wondering if anyone else has experienced this.

I seem to have (what I think is) a fully charged IMA battery (175-179V when I hook up the Prolong charger or discharger) but it's showing as almost empty on the dash.

When I start the car it always shows only 1 or 2 bars of (orange) battery lights and 4 bars of (green) charging lights come on for a few minutes then go out. Sometimes the battery lights increase in number until it shows fully charged and sometimes only a few more will turn on but regardless of how many lights come on, within a few seconds they start to go out until there are only one or two lights left on.

If I drive away before the (green) charging lights go out the IMA light will come on and stay on until I turn the car off. If I wait until the (green) charging lights go out before I drive away the IMA light does not come on but the car constantly tries to charge the IMA battery every chance it gets but only with a maximum of 4 bars.

While I'm driving the battery lights will sometimes increase in number but it's rare. Sometimes the car will give me a few bars of assist lights but that's also rare. Sometimes the car will auto-stop when I come to a stop but that's even more rare.

I know I need a new IMA battery, and I'm trying to get one, but while I'm waiting I'm interested in finding out what might be wrong with the one I have. I have checked the codes and I can't remember them at the moment but I know I have all the ones that indicate an unbalanced pack.

The car is a 2006 Insight with 55,000 KM on it. It has spent most of it's life parked in a garage. When I bought it the owner said his wife had bought it in 2008, driven it for a year and then parked it. I bought it in 2019.

I disconnected the battery for two months last summer (turned the switch off and disconnected the two plugs above the front of the battery pack) but I've since reconnected everything.

One other thing to note is that it's winter here now and the temperature has been between 0C and -30C since the beginning of December. The IMA light was on all the time during the summer (no matter how many times I deep cycled it) but once the temperature dropped below 0C the IMA light started going out on it's own.

At first I was thinking I had a bad/intermittent connection somewhere but if that was the case I think the charge state lights would be more intermittent/erratic.
 

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Honda Insight 2006 MT 55,000KM
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Discussion Starter #3
These are the codes I got in October before I disconnected the IMA battery... I haven't checked them again since then.

The car actually behaved normally during the first winter (2019/2020) that I had it. It only started experiencing IMA problems during the spring of 2020.
_

Blink Codes

Slow Fast
Engine Light
6 9
9
6 9
9
6 9

EPS
2
2

IMA
5 8
7 4
7 8

OBDII Codes
P0A7F - Hybrid Battery Pack Deterioration
P1446 - See service manual
P1600 - IMA System Malfunction
P0497 - EVAP
P0457 - EVAP

OBDII + Blink Codes
P0A7F (78) - Battery Modual Deterioration
P1446 (74) - Battery module Individual Voltage Input Deviation
(58) - Charge Discharge Balance Problem
 

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Looks like your IMA battery is poorly.

Read up on measuring the ten BCM voltage taps.

Read the voltages accurately and post them here for comment along with the current codes.
 

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Discussion Starter #5
I think you may have missed a word there Peter. lol

"Looks like your IMA battery is _ poorly."

I have been thinking about doing some more analysis on the batterys condition but... it's -20C outside at the moment and as much as I'd like to find out what the problem is I'd prefer to sit here by the warm glow of my computer screen. =D It's going to be several months before it's warm enough for me to want to spend that much time on the car. It's my only car and I use it every day so I can't take it apart unless I'm going to be putting it back together that day.

I was really just curious as to whether or not this was a common thing as the battery degraded. As I said, it seems to have a full charge (measured at the IMA) but that's not how it behaves.
 

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You know you need a new IMA battery, install one and enjoy the next 3/5 years of driving with no issues! It will only take a few hours to install. The low mile car sounds well worth the investment.
 

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Discussion Starter #7
The IMA battery is on the list of things to buy; right after food, shelter, clothing, etc. lol I want to get the car back to fully running condition again... but then I want to sell it. It's a great little car but I want to get a fully electric vehicle.
 

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I just invested in a new IMA battery when I started getting DTC's on my G1. I looked around and could not find a reason not to do it. A used electric car will have it's own battery problems soon enough, and I have range anxiety that most affordable electric cars won't ease.

Good luck with your G1, it will be easy to sell with or with out a new IMA battery due to it's very low mileage!
 

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I was really just curious as to whether or not this was a common thing as the battery degraded. As I said, it seems to have a full charge (measured at the IMA) but that's not how it behaves.
Your circumstances probably result in fairly uncommon behavior of common behavior... For example, part of what you're seeing is likely the result of the cold - the IMA has different charging behavior when it's cold. And underlying that is a dodgy pack with probably at least a 'bad cell' or two, like fast self discharge. The whole pack can have a high voltage, but if only 1 cell discharges faster than the others that cell will usually be near empty - and the IMA won't function properly. The voltage difference will only be about -0.2V -- will barely register measuring pack voltage.

Sounds like you had the pack bypassed at some point, so you must know that's an option. Trying to fix the pack probably isn't worth the time and effort - sounds like you already tried the cycling stuff, that's usually about as much as people can handle.

[edit]
Just in case you're the curious type, here's a chart of tap voltage measurements and a few words about what they (generally) mean. This is the kind of stuff you'd need to do to figure out what's going on/wrong...

89046


The chart shows 3 sets of tap voltage measurements, the grey bars are voltages before the drive ('B4'), the outlined bars show voltages after the drive with the car in autostop ('AS -1.2', 'AS2 -1.1', i.e. -1.2A load, -1.1A load).

The numerical values are the difference between the B4 value and the higher outlined bar, the first measurement in autostop. The second measurement in autostop is taken when the battery computer 'neg recals' - sees an empty cell.

You can see that most of the bars are about even, Tap 6 is the lowest, but Tap 7 actually has a steeper discharge slope; you can see that in the size of the gap between the top outline bar and the top of the next outlined bar...

When cells are approaching empty, the discharge curve tanks - the voltage drops rapidly. I'm pretty sure that's what the car uses to determine when the pack is empty - even though it can be caused by only a single cell being empty.

I guess that's about it. You can do measurements similar to these and be able to tell which 'tap' is causing the problem - if it is indeed just a single cell or single tap. It can take some work, though, and it's almost always not as clear as what I've depicted here...
 

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Discussion Starter #10
Thanks eq1. =)

During the summer I did think about going through the process of trying to find the bad cell(s) but then I figured that with a 15 to 20 year old pack, if I fixed one problem, another would pop up in a few months. I'd rather start with a new IMA and hopefully not have to worry about it again before the zombie apocalypse.

At one point I was thinking that, because batteries don't like cold weather, I could use the Prolong charger to warm up the interior of the car during the winter months by putting it on a timer and having it start charging the IMA a few hours before I went to work each morning... but it turns out that charging the battery creates almost no heat at all once you get down near 0C. lol

I find it kind of funny that Honda made the Insights gas engine is really easy to work on (compared to most other cars) but made the IMA battery and computer (components that they knew were going to cause problems) difficult to get to and awkward to work on. I know they were trying to stop people from getting shocked but the gas engine can injure you just as quick and it's pretty much out in the open.
 

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During the summer I did think about going through the process of trying to find the bad cell(s) but then I figured that with a 15 to 20 year old pack, if I fixed one problem, another would pop up in a few months. I'd rather start with a new IMA and hopefully not have to worry about it again before the zombie apocalypse.
Yeah, that could very well end up being the case - 'fix' the problem only to have more later. For most people it's probably best just to get a new pack, or bypass all together.

At one point I was thinking that, because batteries don't like cold weather, I could use the Prolong charger to warm up the interior of the car during the winter months by putting it on a timer and having it start charging the IMA a few hours before I went to work each morning... but it turns out that charging the battery creates almost no heat at all once you get down near 0C.
hmm, not sure how much these cells 'like', or 'dislike', the cold. Dislike is the common belief, but it's probably not as bad as people think. Panasonic has written that the gas absorption process that happens during charge is hampered under 50 degrees F, that optimal charging happens between 50 and 80 F. I tend to use that 50F mark as a target - I generally won't let the pack charge at full braking regen, at minimum, until the pack warms up to around 45F-50F, by means of cabin heating.

On the other hand, Eli at Bumblebee Batteries has said that the best core batteries he gets in have come from cold climate areas, and I think he has generally believed that cold is good, not necessarily because it's good for the 'chemistry', but rather, because the management regime is different - the packs get extra charging... Not sure how much I buy-in to this idea, though...

At the time Eli was talking about this, I did a test myself - stuck some cells into the freezer. The results weren't nearly as bad as I thought they'd be. Here's a link to that post: The quintessential Insight NiMH voltage thread

The difference between cold (20 degrees F) and room temp was a loss of only about 2% energy, measured upon discharge.

In my daily drives and 'testing'/measurement, I don't see any impact of cold. Just today I started with the pack at 37 degrees F. Once the cells see some charge/charging, voltages upon discharge lift up to pretty much normal levels - even though the cells are still cold. This is really astonishing to me. I used to think that voltages slumped a lot due to cold; but with many more tests/experiments/observations, I see that that's not the case.

Today I started with a near empty pack, at 37 degrees F, charged maybe 5%, and was seeing discharge voltages, at even fairly high rates (20 amps +), of around 144V, normal...

I find it kind of funny that Honda made the Insight's gas engine easy to work on but made the IMA battery and computer difficult to get to and awkward to work on. I know they were trying to stop people from getting shocked but the gas engine can injure you just as quick and it's pretty much out in the open.
Once you've tinkered around the battery a bit, it's actually pretty easy to work on. But it is rather tedious, cumbersome to get at...and the work itself can be tedious. Overall though, I think Insight battery and electronics are about as easy as it could ever be to work on/with - like it's probably a lot easier than working with more modern batteries and electronics, simply because the Insight's stuff is more primitive, and there's actually much less 'management' that goes on. I don't know, batteries and management are a lot more complicated than it would seem at first blush, so unless you know something about it, there's not a lot one could do any way...
 

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I've bookmarked that thread for complete reading later. =)

I was thinking that if the car was built is such a way that the IMA were easy to access, stick swapping could be done while the pack was in the car. But who in their right mind would do that? I don't mind tinkering with the things I own to make them work better but I don't really want to make the IMA my life's work. lol

This morning when I went to work it was -35C. I've found that the IMA won't start the car once it gets below -25C, it uses the regular 12V battery instead. While I was letting the car warm up (10 minutes) the IMA battery charge went from 1 bar to fully charged and then back down again about 10 times. That's the main reason I've been thinking my problem is an intermittent connection and not just bad cells/sticks. Last year at this time when I was starting the car in cold weather I found that the IMA maintained it's charge overnight and even over a weekend if I didn't drive it for a few days. It still wouldn't start the car below -25C but it would behave normally once the car was running.

I've been wondering if anyone knows what the bars on the charge gauge represent. I know they are an indicator of something the computer is reading but I'm not sure what. If it was an accurate indicator of voltage the movement of the bars should be much quicker. The only thing I can think of, at the moment, that would cause the indication of charge to increase or decrease so slowly would be if the computer was slowly "opening the tap" so that a fuse (or other component) didn't blow due to the sudden increase in current. At the moment I think of it as a pretty display and not much else.
 

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This morning when I went to work it was -35C. I've found that the IMA won't start the car once it gets below -25C, it uses the regular 12V battery instead...
Yeah, keep in mind that when I was talking about quote 'cold' earlier, I guess my version of 'cold' isn't really that cold. My test was at 20 degrees F, I mentioned that I drove at 37 F. These aren't really all that cold - but the temps you mention are probably an order of magnitude difference, in terms of how the cells will behave...

I've been wondering if anyone knows what the bars on the charge gauge represent. I know they are an indicator of something the computer is reading but I'm not sure what. If it was an accurate indicator of voltage the movement of the bars should be much quicker. The only thing I can think of, at the moment, that would cause the indication of charge to increase or decrease so slowly would be if the computer was slowly "opening the tap" so that a fuse (or other component) didn't blow due to the sudden increase in current. At the moment I think of it as a pretty display and not much else.
I've been wondering that - and trying to figure it out - for the last 10 years. I thought I knew at one time, but since then Peter P. posted some info about the 'QBATT' line to the ECM that makes it seem not so cut-and-dried, plus I've seen a variety of behavior that doesn't jibe with the more straight forward take I had earlier...

In general, under most normal conditions and with a couple exceptions, the bars have a linear relationship with 'state of charge' in percentage terms - that the BCM keeps track of. The top 3 bars are equal to like 6% of total capacity, and the rest are equal to about 2%. Since total capacity isn't used, though, the actual usable capacity is about double these figures - so top 3 bars about 36%, bottom 17 the rest (I realize that doesn't quite add up)...

But, apparently the dash BAT gauge can rescale, like after problems happen. Then there isn't the one-to-one relationship between nominal capacity and the bars... Nominal capacity is 6500mAh total - so 1% equals 65mAh - that's what changes if the 'rescale' happens.

The couple exceptions include bottom and top thresholds, where the nominal, amp-hour counting doesn't dictate the nominal state of charge that the BCM keeps track of, but rather, tap voltage thresholds or voltage slope detection do. So, tap voltages determine the top and bottom - unless a cell or tap is actually found to be empty by virtue of a steep voltage drop (something similar probably exists at the top as well, just not sure), and amp-hour counting generally fills in the middle... When you see the BAT gauge gyrating between high and low levels, it's usually due to detection of an empty tap, which is usually a result of a genuinely empty cell...

Your extremely cold temps could play a role though. I don't have experience with such cold temps. As I recall people have reported weird IMA behavior in really cold temps...
 
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