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Discussion Starter #1
My 06my 5sp Insight has never managed the IMA battery properly. It tends to assist when it shouldn’t and will do this even when the battery is at 1 bar. My reference point is my 02my cvt Insight that I totaled in Jan of 18. Most of my driving is on the hilly roads of Tennessee. The IMA will assist up the hill and charge down the hill. It has a real hard time keeping the battery properly charged Last week I drove the car to Charleston SC where the roads are typically ruler flat. I always though if I could get on a level road for a long stretch, the battery would stay charged. What I discovered was the opposite. If I try to hold the car at a steady speed on level ground, the battery slowly dies until Only one bar. Anyone seen this behavior before and what could be causing this issue.

Jimmy
 

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Your IMA battery needs a re-balancing. Next will be an IMA light and probably a code set.
 

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Your description makes no sense, especially this part:

My 06my 5sp Insight has never managed the IMA battery properly. It tends to assist when it shouldn’t and will do this even when the battery is at 1 bar....
In general it sounds like what Willie says. Your pack is muffing, imbalanced, and the IMA is usually in 'state of charge determination' mode, i.e. muff-mode. But the part above - that wouldn't happen during normal dysfunctional operation. The IMA never assists at 1 BATT bar, or at least it shouldn't... Maybe, for starters, you should try simply pulling the 12V neg cable or the underdash #18 fuse to reset the computers...

I always thought if I could get on a level road for a long stretch, the battery would stay charged. What I discovered was the opposite. If I try to hold the car at a steady speed on level ground, the battery slowly dies until Only one bar.
If the pack is low, management will tend to charge under such circumstances. But seeing the BATT gauge drop as you describe is catching management when its finding a problem - you're getting a 'neg recal', where state of charge drops to a nominal 25%, the car then tries to force charge the pack, and if it can it will until 'full', if it can't charge enough you should be getting an IMA light, most likely a P1449-78 code... Usually you'd see the green charge bars for some time after the BATT gauge drops to 1 bar, you'd see the BATT gauge tick up slowly to maybe at least half, at which point you might see BATT gauge tick up quickly to 19 bars (with a good pack you'd see the BATT gauge tick up slowly all the way, no quick jumps)... At some point during this slow up-tick, you'd see the green charge bars go away even though the pack is still being charged in the background...

In any event, you're not really describing what I'm describing, only pieces of it. So, maybe it's what's going on and you're just not noticing it, or maybe there's some other wacky problem; hence, the idea to just start by resetting the computers...

Ultimately you'll probably need to do some kind of reconditioning, such as at least a grid charge... Oh yeah, also, check your 12V system grounds - two left/under air box, one at the firewall. Those corrode and break and can cause a lot of weird problems...
 

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Discussion Starter #4
Thanks for the advice. I've done the usual things one does to an Insight such as replacing the ground wires, cleaning the EGR path and installing a new valve, replacing the ignition coils, installing proper spark plugs, etc. Of course I've reset the ECUs. Not lately so I'll do that again because its easy. I know the IMA battery is imbalanced but I believe the vehicle hastened the process due to mismanagement. The battery is managed very differently from how my 02MY CVT did. I drove that vehicle with a failing battery until I purchased a new one from BB so I had a chance to see how the same vehicle behaves with a good and failed battery. I have a couple of sets of older MCM and BCM ECUs and intend to install a set when I get time. However its my experience ECUs in general rarely fail and problems are usually with sensors so I'm not confident changing the ECUs will correct the problem. BTW: Currently no DTCs and IMA light is off.

Jimmy
 

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An 06 MT to an 02 CVT is not the best comparison. An MT gives you much greater influence over the battery utilization. The CVT takes it out of your hands. Regardless, what you describe is very unusual.

How's the fuel economy?

If you're describing a VERY slow drop to 1 bar (over the course of several minutes) and it just stays there without forced charging, then that's not a negative recalibration.

Have you ever measured the tap voltages in that state, i.e., what do they read when the gauge is at 1 bar?
 

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Discussion Starter #6 (Edited)
Fuel economy is so so at 50 tp 55. I do not run RE92 tires. On level road, holding constant speed, IMA is not indicating assisting or charging. Battery gauge slowing decreases, over a half hour I guess, until a single bar. If I were to give it a little throttle at low battery level, IMA shows charging. Today I got assist at above 3 bars


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Normally the IMA will not show a charge at a steady throttle. That is when the "Hidden Charge" will be happening, using Peters OBDC&C gauge for verification.
 

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Discussion Starter #8
I probably should get one of Peter’s tools. Are they available?


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On level road, holding constant speed, IMA is not indicating assisting or charging. Battery gauge slowing decreases, over a half hour I guess, until a single bar. If I were to give it a little throttle at low battery level, IMA shows charging.
If your observations are accurate you've got some unusual problems happening. I've never seen nor heard anyone mention the battery gauge slowly decreasing to 1 bar even though no assist is being used. The closest thing is a neg recal, where the gauge will drop to 1 bar, but that happens like a bar lost every 3 seconds or so, so total gauge depopulated in less than a minute, not half an hour.

With the 'low battery, give it a little throttle and battery will charge' thing - weird too. The closest thing there is when the IMA is background charging - charging the pack off the ICE but the green charge bars don't show-up - but then they will show up if you raise engine speed above about 3k RPM... There's a few other things that are similar. IMA charging off the ICE in general is a weird, sometimes seemingly sporadic thing. I think it's commanded by the MCM - maybe you've got some mismatch between the MCM and BCM - just a wild guess...

Anyhow, reset the computers and see if anything changes...
 

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I probably should get one of Peter’s tools. Are they available?
Yes. E-mail me..

If your soc is decreasing very slowly without assist being used then something else is draining current or preventing regen, as the BCM is clearly counting it,
and decrementing the soc based on consumed Ah etc. The BCM only changes soc due to current counting. (Unless it's a positive or negative recalibration)

If the ima is def not assisting, then the only other thing that can drain a steady lowish current is the dc-dc converter.

Is the dc-dc stuck in high output mode? Is it faulty?

Is the battery current sensor defective, or the startup current sensor calibration off, and it's indicating current is being consumed when it isn't?
There is a check made between the BCM and MCM current sensors, but this only detects fairly gross errors,
it's possible for the BCM to be off by several amps without triggering an ima fault.

A proper negative recalibration is only triggered when a cell drops out, not just because the soc is low.
It's quite possible for the soc to tick down slowly on moderate currents to very low levels if the voltage taps stay in balance.

It's very possible for the mdm and ima battery etc to overheat (either genuinely or erroneously due to sensor issues)
without ima errors being set, in this condition assist or regen etc might be reduced or stopped but no errors set..

My Advice

First of all pull the 12v battery lead for 30 seconds and reset the system,
then let it tickover charge for 5 minutes, and then drive normally for a few days.
Have the symptoms returned?

If that doesn't help, then if you have a known good spare BCM or MCM , swap them in one at a time starting with the BCM to see if that changes anything?

If not then it's OBDIIC&C time, it will enable you to look at the various temperature values along with all the other stuff, then we have a fighting chance of sorting it..

Ultimately your problems might be due to a bad battery & temperature sensor fault or other IMA issue which is masking & confusing symptoms and errors..
 

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A proper negative recalibration is only triggered when a cell drops out, not just because the soc is low. It's quite possible for the soc to tick down slowly on moderate currents to very low levels if the voltage taps stay in balance.
fyi, I've wondered about this before, and I just experimented with it again. Maybe we have different definitions of what a "proper negative recalibration" is, but what I just saw suggests one form of 'neg recal' doesn't require an empty cell.

I took state of charge down to 28% (3 bars), where the nominal value hangs just as it does at the top end, at 72%. I was able to discharge some more with no major voltage change, and then at rest some moments later, with pack voltage around 144V, state of charge nominal dropped to 25% with BATT gauge dropping to 1 bar.

It's pretty much impossible to see this total pack voltage behavior if a cell is empty... So, apparently, at this low voltage and/or low state of charge, it doesn't take a 'cell dropout' to trigger the immediate state of charge drop from 28% to 25% and the BATT gauge drop to 1 bar. Do we call that a 'neg recal'?

My guess is that an effectively empty cell (cell drop out) at higher charge states and total voltages would trigger the same behavior. But, if you can get the pack that low without a cell dropout, the car will 'neg recal' anyway, without a bona fide cell dropout...
 

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I would call that a total pack voltage and/or current counting recalibration. (But as you say some flexibility in interpretation)

It used to occur with my huge Lithium packs before the BCM interceptor and fixed 75% soc was invented.

The stock BCM would tick down under assist and then hold at three bars for several Ah hours before finally deciding that must be it and dropping down to one bar and forcing charge, even if the balanced pack voltage was still well above the nominal 144v.

The other variation is likely low (around nominal) but balanced pack voltages which may shorten the (3 bar hold) process described above by several Ah.

A negative recal in my eyes is the unbalanced pack phenomena most described on here (especially by new members) when the soc suddenly drops from any level above three bars down to one and then a forced charge starts. That's caused by a cell dropout.

Variations in BCM software might also mean results/behaviors vary slightly from module to module.
 

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Discussion Starter #14
Overall it sounds like the problem is most likely with the BCM. I have spares of every component in the IMA compartment. Someone suggested the problem could be the DC to DC converter. Maybe I should change that as well although I’m not having issues with the 12v system.
 

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From my earlier post

My Advice

First of all pull the 12v battery lead for 30 seconds and reset the system,
then let it tickover charge for 5 minutes, and then drive normally for a few days.
Have the symptoms returned?

If that doesn't help, then if you have a known good spare BCM or MCM , swap them in one at a time starting with the BCM to see if that changes anything?

If not then it's OBDIIC&C time, it will enable you to look at the various temperature values along with all the other stuff, then we have a fighting chance of sorting it..

Ultimately your problems might be due to a bad battery & temperature sensor fault or other IMA issue which is masking & confusing symptoms and errors..
Forget the dc-dc for now (unless new information points to it) they are incredibly reliable, and it's more of a pain to change it out. If needed you can unplug it's HV input to isolate it.
 

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Discussion Starter #17
Taking another drive to the South Carolina coast this Friday inspired me to change out the BCM today. The BCM I used is from a 2001 with nameplate ending in 010. I did a short test run and it is definitely managing the HV battery differently in that the charge level stays at much higher level. I’ve read this ECM was known to drain the battery in extreme cold weather. The true test will be if the battery level falls to 1 bar while driving level ground at constant speed.


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Discussion Starter #18
I dd not experience the dying IMA battery in the flatlands of SC with the replacement BCM. Therefore the original BCM has an issue.

Last week I deep discharged and grid charged the IMA battery. Currently the IMA system seems to be functioning as it should but time will tell.
 

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Did you do things sequentially so that you could rule out the other potential causes? For instance, did you reset the computers, still have problem, deep discharge and grid charge, still have problem, and then replace the computers - and not have the problem? I'm not seeing that sequence in the thread...
 

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Discussion Starter #20
Did you do things sequentially so that you could rule out the other potential causes? For instance, did you reset the computers, still have problem, deep discharge and grid charge, still have problem, and then replace the computers - and not have the problem? I'm not seeing that sequence in the thread...

EQ1,
Yes, yes, yes, & yes. I did all those things before I ever created the post. I had been having IMA problems since I purchased the car. Probably why the guy sold me his 2006 and kept his older beat up one. When I noticed it would kill the battery on level ground at constant speed I strongly suspected it was a battery management problem. My experience with this sort of thing told me it was more likely a sensor but that did not turn out to be the case. If you want the BCM for testing to perhaps gain a better understanding of this device, I’ll give it to you. Just pay shipping.

Jimmy White


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