[blackcloud77]

Hi all.

Well my trusty 2001 MT that I love to brag about because I never have to fix anything...has been giving me headaches.

I put in a ticket with Hybrid Automotive because recently when connecting their automatic discharger, the voltage read zero and it would not start the discharge sequence, obviously. A couple days later, the car set a P1444 code. I did some reading and decided to probe for the voltage leak to the chassis. Indeed, I found current between the HV battery and the chassis. Quickly the multimeter would ramp up to 50v then taper slowly down to about 1v over the course of 10 seconds or so when reading across the positive terminal and chassis. The voltage seemed to build back up with the leads removed, as the voltage would be higher with increased time between re-reading the voltage. The result was similar between both positive and negative HV terminals.

What I did NOT expect was ZERO voltage across both HV terminals. I had the breaker off, so I flipped it on real quick to check again and indeed zero voltage. This explains why the discharger is reading zero, I think. However, with the HA grid charger connected, it reads 181v. Strange. Also, it reads zero mA, assuming because it cannot charge due to whatever the problems is/are.

I inspected the grid charger wiring as a couple threads suggested and saw no evidence of abrasion but also didn’t put the meter to it.

Neither the charger or discharger were connected when driving and the code was set.

I read a lot of P1444 threads and most seemed to go down different rabbit holes and none had these symptoms. I don’t have a shady shop or garage to leave the car in for days so I’m looking for some guidance or even elimination procedure before ripping the battery out to get at the sticks. As usual, any help is appreciated!

 

[eq1]

What I did NOT expect was ZERO voltage across both HV terminals. I had the breaker off, so I flipped it on real quick to check again and indeed zero voltage. This explains why the discharger is reading zero, I think.

When you say "HV terminals" are you talking about the two big terminals on top of the pack electronics board, with usually orange-painted nuts? If so you won't get voltage there unless the key is ON... Also, you need to have that switch in the ON position to charge/discharge...

However, with the HA grid charger connected, it reads 181v. Strange. Also, it reads zero mA, assuming because it cannot charge due to whatever the problems is/are.

When you say "it reads 181V," I assume you mean the charger voltage meter?... It probably shouldn't read 181V - unless it's unloaded, i.e. if it were really charging/connected to the pack the voltage would likely be lower, unless the pack were totally chock-full of charge...

I inspected the grid charger wiring as a couple threads suggested and saw no evidence of abrasion but also didn’t put the meter to it.

I'd double check the harness install, make sure it's connected at the right places.

 

[blackcloud77]

When you say "HV terminals" are you talking about the two big terminals on top of the pack electronics board, with usually orange-painted nuts?

That's correct. I didn't know the key had to be on for voltage to appear there, that's a simple explanation. Thanks for that. So apparently not having voltage across those terminals does NOT explain why the auto discharger is reading 0v, because the discharger normally works and sees high voltage regardless of the key position. So that's still an issue. I read elsewhere on the forum that the HV relay will not engage when an IMA code is set; but the way the harness is wired in...an IMA code should not prevent grid charging/discharging, right?

When you say "it reads 181V," I assume you mean the charger voltage meter?... It probably shouldn't read 181V - unless it's unloaded, i.e. if it were really charging/connected to the pack the voltage would likely be lower, unless the pack were totally chock-full of charge...

Yes, the voltage reading on the charger. It reads ~181 volts, and the car has been sitting for a week as well, without being driven and no charging taking place. Hm. It's possible the breaker was off, and the install instructions of the grid charger do say the voltage will be about 180 until it's turned on. Will check that again tonight, with the breaker on.

The grid charger harness has been installed and working reliably for years so it's connected at the right places, and didn't seem to be abraded or damaged at all. Since both the charger and discharger not working properly, we have a short to chassis code and that seems to be more commonly caused by a harness fault than battery sticks... the harness certainly warrants further probing.

Thinking through this out loud, check me on this.

• I'm going to probe for voltage between the red + black pins of the harness, and the chassis.
• If voltage is found, include/exclude the harness as the offender by removing it and seeing if the code clears. Is this the easiest way to determine if it's the harness or if the problem is deeper inside the pack?
• Ideally there should be ~144v across the red and black pins with the breaker on?

 

[blackcloud77]

Also...Hybrid Automotive has suggested that the fuse in the harness may be blown. Still trying to figure out if these two issues are related...

 

[eq1]

So apparently not having voltage across those terminals does NOT explain why the auto discharger is reading 0v, because the discharger normally works and sees high voltage regardless of the key position.

That's right.

I read elsewhere on the forum that the HV relay will not engage when an IMA code is set...

Depends on the code, in general that's probably more often the case than not... In your case it probably is the case.

...but the way the harness is wired in...an IMA code should not prevent grid charging/discharging, right?

If the harness is wired correctly - that's right.

It reads ~181 volts, and the car has been sitting for a week as well...It's possible the breaker was off, and the install instructions of the grid charger do say the voltage will be about 180 until it's turned on. Will check that again tonight, with the breaker on.

You were probably just reading the unloaded voltage of the charger...

The grid charger harness has been installed and working reliably for years so it's connected at the right places, and didn't seem to be abraded or damaged at all. Since both the charger and discharger not working properly, we have a short to chassis code and that seems to be more commonly caused by a harness fault than battery sticks... the harness certainly warrants further probing.

Earlier you said you read 0V in the discharger mode. Forget the charger itself at this point - you should be able to probe your harness and measure a substantial positive voltage. If you don't, something's probably wrong with the harness...

You should probably open up the IMA compartment and measure voltage at the 2-wire connector at far right, with the pack switch ON. That will tell you what the actual voltage of the pack is. While you're there, you might as well check stick-pair voltages at the connector to the left - back probe the connector, here's a link to a diagram: The quintessential Insight NiMH voltage thread

Thinking through this out loud, check me on this.

• I'm going to probe for voltage between the red + black pins of the harness, and the chassis.
• If voltage is found, include/exclude the harness as the offender by removing it and seeing if the code clears. Is this the easiest way to determine if it's the harness or if the problem is deeper inside the pack?
• Ideally there should be ~144v across the red and black pins with the breaker on?

That all sounds about right... Once you detach the harness from the pack connection points, I think you should be able to backprobe the 'right' connector red wire (+) with positive DMM probe, negative DMM probe to chassis, pack switch ON, to verify if there's a HV short between pack and chassis, rather than depending on the clearing of the code alone.

 

[blackcloud77]

Well...fun times, eq!

It started raining (Florida, go figure...) so I could do all the testing I wanted but here's what I got so far...

Between the red and black pins on the end of the harness, I was able to read about 152v with the breaker on. I turned the breaker off for the rest of testing for safety, however I'm now questioning if it needed to be on, because I don't know where the breaker is in the circuit.
Anyway, here's what I found:
Harness Red - Black, breaker on = 152v 👍
Harness Red - Chassis, breaker off = 50v, ramps down to 1v
Harness Black - Chassis, breaker off = 50v, ramps down to 1v
Battery 10mm Red, breaker off - 50v, ramps down to 1v
Battery 10mm Black, breaker off - 50v, ramps down to 1v

--Removed Harness --
Battery 10mm Red, breaker off - 50v, ramps down to 1v
Battery 10mm Black, breaker off - 50v, ramps down to 1v

So removing the harness doesn't seem to have affected anything. In addition, I checked for continuity along the red harness wire (because Hybrid Automotive was suggesting a blown fuse) and read about 1 ohm. This is suggesting to me that 1) the fuse is likely OK and 2) the harness isn't causing the short to chassis. Do you agree?

Also, you suggested to read the total battery voltage at the 2-wire connection at the far right. I'm facing the rear of the car, and the 10mm terminals I am measuring to the chassis are on the LEFT side of the battery pack as I'm standing. It would be on the right if you were working from the front seat of the car. Are those the ones you're talking about, or is there another set of terminals I haven't found yet? I hope I'm not measuring the wrong place.

I'm going to go measure the taps next. I assume that's across each tap, to HV battery negative. In this case, maybe to negative AND to the chassis?

Thanks for all your help!

 

[eq1]

--Removed Harness --
Battery 10mm Red, breaker off - 50v, ramps down to 1v
Battery 10mm Black, breaker off - 50v, ramps down to 1v

When you say 10mm you mean the orange bolts, 'big HV terminals' on left side of pack, right? So above you're testing + to chassis and - to chassis, right? If so that says you got a short somewhere in the pack itself, including electronics, or maybe just the electronics...

So removing the harness doesn't seem to have affected anything....Do you agree?

Yes, it doesn't sound like the harness has an issue; the short itself obviously can't be the harness - if you measured voltage between pack and chassis with harness removed...

Also, you suggested to read the total battery voltage at the 2-wire connection at the far right. I'm facing the rear of the car, and the 10mm terminals I am measuring to the chassis are on the LEFT side of the battery pack as I'm standing.... Are those the ones you're talking about, or is there another set of terminals I haven't found yet? I hope I'm not measuring the wrong place.

You need to visit that link I posted earlier. The 'ones on the right' are at the connector on the MCM, there's one connector on the right hand computer, with two wires. With pack switch ON that will give you the pack voltage... At this point though I'm not sure what needs to be done -- besides taking the pack out of the car, breaking it down, and finding what's causing the short.

I'm going to go measure the taps next. I assume that's across each tap, to HV battery negative. In this case, maybe to negative AND to the chassis?

Again, consult that link I posted and get clear on what needs to be measured, where. Taps are measured at the connector on the back of the BCM - the connector on the left hand computer. I don't see a major diagnostic reason to do that at this point, because as far as I can tell the pack needs to come out and be inspected closely. But, it wouldn't hurt, you might see a glaring outlier that would suggest the problem...

...Thinking about this, not terribly deeply, those 50V readings you measured should narrow down what's possible, if I'm understanding what you're measuring correctly. You say 50V between + HV terminal and chassis, 50V between neg HV terminal and chassis, both with pack switch OFF, both with key OFF. That seems really weird to me.

For one, you shouldn't see any voltage at those terminals with the key OFF. I can't remember if voltage remains at those terminals for a short time when you key-OFF, I think it does. Key-ing ON engages a relay or 'contactor' or something like that and allows power to flow from/to the battery. There's some big capacitors that charge - so those hold some charge and it can take some time to drain them*... You'd have to look at a diagram of the electronics board to trace the path, find the components...

So, with the key OFF, how do you get voltage from the + HV terminal to chassis? And the same thing from the negative HV terminal to chassis? And then, how do you get the same voltage -- with the pack switch OFF?

The switch breaks the pack in 12 and 8 stick halves, so with a total V of 152 you're looking at 91V and 61V...

I don't know, it'd take me a lot of sleuthing to figure this out. Maybe someone else has an idea and will chime-in...

*...Off the top of my head, and again, I'm not thinking super deeply or critically here, not an electronics expert -- I'm thinking maybe 'those capacitors' are charging, somehow, and the voltage you're measuring is actually a short between stuff 'on the left side' of the IMA compartment and chassis. I guess you'd need some kind of failure between 'that side' and the pack, though, to begin with...

Maybe try this, two measurements at connector on back of MCM, pack switch ON:

1. Pos and neg probes to pos (red wire) and neg terminals on connector on back of MCM (the two-wire one). That should give you pack voltage.
2. Pos probe to pos at connector, neg probe to chassis. That should tell you if there's a short between the battery sticks and chassis. You shouldn't measure any voltage.

And then where does this get you? I don't know, if you measure a normal pack voltage and then no voltage between the sticks and chassis, at least you'd know there's no short between the actual battery sticks and the chassis...

 

[blackcloud77]

When you say 10mm you mean the orange bolts, 'big HV terminals' on left side of pack, right? So above you're testing + to chassis and - to chassis, right? If so that says you got a short somewhere in the pack itself, including electronics, or maybe just the electronics...

Yes. Facing the rear of the car, the two large orange terminals with 10mm bolts on the top of the pack, on the left side.

...Thinking about this, not terribly deeply, those 50V readings you measured should narrow down what's possible, if I'm understanding what you're measuring correctly. You say 50V between + HV terminal and chassis, 50V between neg HV terminal and chassis, both with pack switch OFF, both with key OFF. That seems really weird to me.

That's correct, +50v to chassis on both terminals with the breaker OFF. Zero voltage between positive and negative. To be clear, these are the orange 10mm terminals on the top left of the pack. I too thought this was odd, but didn't make too much fuss about that because I assumed it was because there was something I didn't know about how the pack works.

So, with the key OFF, how do you get voltage from the + HV terminal to chassis? And the same thing from the negative HV terminal to chassis? And then, how do you get the same voltage -- with the pack switch OFF?

Yes. I can check it again, and post a video if that helps.

I agree, there's not too much benefit to probing the taps, because it looks like the pack has to come out at this point. Although as you mentioned, it could still uncover a glaring culprit.

I checked out that thread you linked, and does have the info to record the tap voltages. The pack still has to come out, I think. I will read the rest of that thread for further context though. Back to it!

 

[eq1]

Yes. I can check it again, and post a video if that helps.

No, those were just thinking-out-loud questions. I trust you measured stuff correctly... Basically, it seems like there's limited ways one can measure what you did under those circumstances. Just that I don't know the whole circuit well enough.

...Thought of one other thing you might do: Remove the cables leading to the 'HV' terminals, then measure voltage between those cables and chassis, and between the HV terminals and chassis. If you measure voltage between HV terminals and chassis with those cables removed, at least then you'd know the problem has nothing to do with the 'stuff on the left side' of IMA compartment.

Later... Your issue keeps bothering me. My brain is kind of drifting in and out of 'wondering' what the problem is. I just searched for something I vaguely recalled, that might provide a lead down the road. I'm linking to it here so I don't forget. I didn't even re-read it beyond what's at the linked page: High Voltage LTO Setup.. 96 Cells. Can it be done?

OK, so I glanced over a couple posts, a few below the one linked above is this, here's the whole post (emphasis added):

This capacitor network is a high frequency snubber that references the IMA pack to ground. This prevents high frequency noise from the IGBTs from causing interference. You really should keep the center-tapped ground connected to the chassis. Also note that there are two of these capacitor packs, one on the junction board and the other inside the PDU.

The P1444 issue you're seeing could certainly be due to this capacitor network leaking... other possible causes:
-leakage inside the IGBTs
-leakage inside the larger capacitors (inside the PDU)
-insulation breakdown in the BLAC motor.
-fault inside the DCDC.
-leakage inside the MCM (you should measure more than 300 kOhm from both MCM connector E wires to chassis ground).

The proper method to test the capacitors for leakage is to test them while they have the full pack voltage across them. You'd place a small series resistor from each 'hot' leg, and then ground the capacitor bank. With the capacitors charged, you'd then place a DMM across both terminals on each resistor (one at a time). Using V=IR you can then calculate the leakage current. Ideally it should be pretty much 0 A.

OK, OK, here you go, start here: High Voltage LTO Setup.. 96 Cells. Can it be done?

Peter describes an unusual P1444 that turns out to be this capacitor 'snubber' unit. There's a vid there, watch it, read through the following posts, etc.

Looking at this a little closer I'm almost positive this is your problem. Forget all the other tests/measurements I mentioned earlier, but rather, do this: There's an orange-clad wire that crosses from pack electronics board to 'left side stuff', attached to top case of the DCDC converter, you can't miss it. It runs more or less parallel with those two larger cables.

That wire comes from the center tap of this capacitor snubber unit. Detach that wire then do your HV terminal-to-chassis voltage measurements again. Is the voltage now zero? if so, this thing has to be the problem... Re-attach, check again: Does the leak reappear? etc etc...

Here's an image of the electronics board with a few things labeled:

Here's a link to another image of the board, this one has other parts labeled. Mine's missing a couple parts/connections: Insight Battery switching/current monitoring - MIMA Honda Insight Modified Integrated Motor Assist


hmm... I'm not seeing how this thing gets charged, though, if you have the pack switch OFF... With the switch OFF, those two busbar eyelets at lower right sever the pack.

 

[retepsnikrep]

Just looked at this.

Is this an aftermarket pack?
Are the PTC strips fitted/in circuit?
Is this a leaky stick/s eating the heatshrink etc scenario.

Unplug the BCM Temperature sense plug.

Is there any voltage with the main switch on between the always HOT +/- live points on the HV battery and any of the connections on the BCM plug?

1) Check from the top negative terminal to each connection on the BCM plug

2) Check from the tricky positive terminal on the white resistor (grid charge connection point) to each connection on the BCM plug.

There should not be any voltage present....

If there is the pack will have to come out and apart for stick inspection.

 

[blackcloud77]

Thanks for all your input guys. I'm going to go back and comb through your responses, I scanned over them very quickly but I wanted to post up what I found on Friday, which wasn't much but I wanted to explain what I did so that we can be sure I'm testing and interpreting properly. I did snap photos when I measured the the tap voltages and I still plan on compiling that into something easier to analyze, but haven't done that yet.

So I opened up the pack, going down the road of chasing the voltage leak to chassis. What seems to be the next most talked about issue that causes this is the PTC strips, so that's what I intended to check. I removed the pack, and completely removed the orange plate on one side to access the sticks, which of course includes removing all the stick bolts and disconnecting the PTC strip. I checked for voltage between each stick and its respective PTC connection. No voltage found anywhere. On the flip side of the pack I did not completely remove the orange plate because it didn't seem necessary, I just disconnected the PTC strip and probed between it and its stick. In retrospect, I think I should have removed the plate to be able to isolate any current to a particular stick; but I found no voltage anywhere, anyway. So the PTC strips seem to be fine, unless I tested improperly.

As soon as I can get back to it today, I'm going to sift through the recent responses and follow any advice given and report back.

Peter, I can answer a couple of your questions real quick though. I do not believe this to be an aftermarket pack. I purchased the car about 5 years ago, I have only opened up the HV compartment to install the grid charger...until now. I seem to recall having checked the Honda dealer service records based on the VIN and found an IMA battery replacement having been done in 2004. So if it's not the original battery pack, it's a dealer-installed replacement. The PTC strips seem OK based on voltage tests, but I have not removed the sticks to visually inspect.

As always, thanks so much for your help guys.

 

[blackcloud77]

So it would seem that after reading your test suggestions that they must be conducted with the pack installed. Now that it’s out and assuming you agree with the idea that the PTC strips are OK since no voltage was measured between any of them and their respective strips... would you suggest re-assembling and reinstalling the pack and doing the recommended testing, or is there anything else I should look at or test while the pack is out and partially disassembled?

 

[blackcloud77]

Resurrecting this thread since it's the continuance of this ongoing saga. Here's where we're at now:

• Removed the battery pack and tested all sticks. Results in another thread called "Take a look at my stick load testing."
• Charger, discharger and harness have been sent back to Hybrid Automotive for diagnosis and/or repair; both charger and discharger were showing 0v on their displays and not functioning.
• HA suspects the harness as being why the charger and dischargers aren't working, and the source of the P1444. I could find no problems with it testing for continuity and lack thereof where appropriate. It's an electrically simple design and I could find no place where a short to chassis would be likely. However when I reinstalled the battery pack, I did not reinstall the harness and the P1444 has not resurfaced. No word back from HA as of yet.
• Reinstalled the battery pack and drove the car for about a week without any codes or issues.
• About a week ago, a P1449 was set. I also saw the P1449 when I first started this thread, but before that I had reset the codes and only the P1444 was set again. Currently there is no P1444 set, only the P1449.
• Checking the blink codes, I think I am seeing a 52 and 78. I'm a little confused about the 52. Looking at Mike D's reference, the 78 goes with the P1449 that is set, so that makes sense. 52 is correlated with a P1562 which is NOT set. Should I just pay attention to the blink codes and ignore whatever P-codes are or aren't set?
• I can upload video of the dash when getting the blink codes for re-interpretation if that helps.

My thoughts / questions at this point:

• Stick replacement vs battery pack replacement: I don't know if the battery pack is finally toast based on blink code 78, or if I'm just badly in need of a grid charge. My stick testing seemed to indicate a few potentially questionable sticks but most seemed pretty serviceable. Maybe I just replace the bad sticks. It seems to be the consensus on replacing all sticks vs buying a new pack (Bumblebee, etc) is to go for the new pack that will have a warranty. But it seems the consensus from manufacturers a new battery should only be expected to last about 5 years? Bumblebee's website claims a lifespan of OEM plus 30%. My OEM battery is 16 years old and just now starting to have problems. Should I then expect a high performance Bumblebee battery to last 20.8 years? Something tells me that's unrealistic.
• I can't grid charge now because HA is taking their time testing since receiving my returns a couple weeks ago. Maybe I better just build a new grid charger?
• I'm continuing to drive the car with the P1449 set (which obviously means IMA is self-disabled), will I be stranded at some point when the battery pack is finally dead? I've been commuting 30 miles or so for about a week now.

 

[eq1]

Reinstalled the battery pack and drove the car for about a week without any codes or issues.

When you reinstalled the pack, about what charge state should it have been at? I.e. How much time, usage had elapsed since last full grid charge? I'm assuming at some point you did get a full charge? or maybe you didn't, because your grid charger was faulty?

About a week ago, a P1449 was set... Currently there is no P1444 set, only the P1449.
Checking the blink codes, I think I am seeing a 52 and 78. I'm a little confused about the 52...

Not sure about blink code 52... I think I'd focus on the pack/P1449-78 first...

Stick replacement vs battery pack replacement: I don't know if the battery pack is finally toast based on blink code 78, or if I'm just badly in need of a grid charge.

I think you'll probably need to do a full grid charge, set things back to 'square one', before we'll be able to diagnose just how bad your pack is. Recalling your stick voltages*, one of those semi-outlier sticks could have had a relatively fast self discharge cell. Currently your usable capacity is stunted to below about 20% because the car can't charge the pack enough before hitting the full threshold. And then it's empty again in short order. That's because a tap or a cell within a tap is empty before the others. It's hard to say whether that's due to a fast self discharge cell or what because I don't know when the last time this pack had been charged to full, how it's been used or not used, etc.

*

Take a look at my stick load testing?

So I've got another thread going, chasing a P1444 and I need to reinstall the battery pack before continuing testing for that. While it's out I decided it'd be a good time to load test the sticks. TLDR: I'm not sure how to interpret the results. They look really good, but the low starting...

www.insightcentral.net

I'm continuing to drive the car with the P1449 set (which obviously means IMA is self-disabled), will I be stranded at some point when the battery pack is finally dead? I've been commuting 30 miles or so for about a week now.

You could be. If you do have a fast self discharge cell or more and a tap voltage drops too low, the DCDC will be disabled and your 12V battery won't get charged. Turn the pack switch OFF and disconnect connectors to the BCM (left hand computer).

 

[blackcloud77]

When you reinstalled the pack, about what charge state should it have been at? I.e. How much time, usage had elapsed since last full grid charge? I'm assuming at some point you did get a full charge? or maybe you didn't, because your grid charger was faulty?

Hm. I have no idea what the charge state should have been. It's been months since I got a grid charge on, maybe 3? It's a daily driver except for when the pack was disassembled, I drove another vehicle. When I reinstalled the pack and resumed driving the car, it seemed normal so I'm sure at a couple points (at least according to the SOC indicator) I got a full charge. You are correct though, I have not since had a grid charge, because the grid charger stopped working for still unknown reasons. I am in the process of sourcing parts to build olrowdy's DIY grid charger, because HA is not being very responsive.

Not sure about blink code 52... I think I'd focus on the pack/P1449-78 first...

10-4.

I think you'll probably need to do a full grid charge, set things back to 'square one', before we'll be able to diagnose just how bad your pack is.

10-4.

You could be. If you do have a fast self discharge cell or more and a tap voltage drops too low, the DCDC will be disabled and your 12V battery won't get charged. Turn the pack switch OFF and disconnect connectors to the BCM (left hand computer).

10-4 and thanks for that. I'm going to do it anyway, but just so I understand... I thought that the ability to regenerate electricity was why the car does not need an alternator to charge the 12v battery, and I assume that since IMA has disabled itself, it cannot regen. Maybe that's not true? The IMA pack is the the only source of electricity to run the engine in either case; or to keep the 12v charged to keep the engine running. No charging = finite driving range. How does disconnecting the IMA battery and unplugging the BCM fix this? Or does it? I am probably just misinterpreting what really is or isn't happening with the P1449 code set, IMA light on and the inability to get assist or see any charging happening on the dash. I realize now that I assumed the entire IMA system was disabled and not functioning.

As always, I appreciate your help, eq.

 

[eq1]

...It's been months since I got a grid charge on, maybe 3? It's a daily driver except for when the pack was disassembled...When I reinstalled the pack and resumed driving, it seemed normal so I'm sure at a couple points (at least according to the SOC indicator) I got a full charge...

hmm, so, there's basically two main possibilities:

1) You have one or more relatively fast self discharge cells. You charge the pack, use it, etc., but over that ~3 month time span these cells discharge faster than others and the cells (taps) end up imbalanced. The empty cells trigger 'empty', and when the car tries to charge, it can't get much into the pack before a voltage tap hits the upper voltage threshold. That's when the P1449-78 triggers...

2) One or more cells has languished at low charge state for a long time, the 'top-end' has become 'crudded-up', and now these cells don't charge well enough. Basically, when you charge, these cells simply charge way less efficiently, slower, ultimately not as much as others - so whether or not they have faster self discharge, they simply never get charged as much as the others in the first place.

In general, most problematic packs probably have a combination of both of these things.

The general 'InsightCentral' remedy is a full grid charge, a relatively deep discharge, and another full grid charge. I personally don't like working with full packs like this, particularly with a P1449, because the imbalance is so extreme that you either end up overcharging a lot of cells or deeply reversing at least 1 cell. It's 'ham-handed' and has a lot of risk.

Instead, I work with taps - you can discharge 5 taps at a time, at a rate of about 14% per 24 hour period, simply by shorting the terminals at BCM connector C. If one were to do an analogous 'deep discharge' with taps, the super-low discharge load and only 12 cell series vs. full pack 120 cells, greatly reduce the risk and simply does a more thorough job than a 'light bulb' load on the full pack.

Lately I've been leaning toward a more incremental approach, though, you don't need to start with a full-on 'deep discharge'; rather, you can simply try to identify the lowest, most discharged tap -- and discharge the others to bring them closer to the lowest. That should free-up room at the top and allow the car to charge the pack more. If that doesn't help, one can then try something more radical...

...I thought that the ability to regenerate electricity was why the car does not need an alternator to charge the 12v battery, and I assume that since IMA has disabled itself, it cannot regen. Maybe that's not true?... How does disconnecting the IMA battery and unplugging the BCM fix this? Or does it?

I'm not positive about the exact circuits, algorithms, interactions and what-not. I'm pretty sure though that, even though the IMA is disabled with a P1449-78 code, it doesn't prevent other 'problem triggers' further down stream, lower on the totem pole. The P1449-78 is like the first step (or really it's more like 3rd or 4th) in a hierarchy of things that can limit functionality. If you leave the pack switched ON and the BCM connected, I guess it's still 'in play' enough that, once a tap voltage drops too low, the DCDC will be disabled, or it can be total pack voltage too low, too. If you turn the pack switch OFF and disconnect the BCM, these signals can't affect DCDC operation...

When you take the pack out of the loop like this, the gas engine and electric motor continue to power the DCDC for 12V system power, mostly uninhibited (you don't get charge at idle or above 4000 RPM though).

 

[blackcloud77]

When you take the pack out of the loop like this, the gas engine and electric motor continue to power the DCDC for 12V system power, mostly uninhibited (you don't get charge at idle or above 4000 RPM though).

Ahhhh. That's the part I was looking for, I didn't understand that 12v charging is still happening under this condition.

Instead, I work with taps - you can discharge 5 taps at a time, at a rate of about 14% per 24 hour period, simply by shorting the terminals at BCM connector C. If one were to do an analogous 'deep discharge' with taps, the super-low discharge load and only 12 cell series vs. full pack 120 cells, greatly reduce the risk and simply does a more thorough job than a 'light bulb' load on the full pack.

I'm going to look further into this, I found your posts about a year ago where you re-posted photos and I'll be doing more reading today. I certainly would appreciate any additional pointers that might not already be out there, and if you'd like me to take additional measurements or provide other information as potentially one of the first/few to attempt a confirmation on the idea, I'd be glad to do what I can. Have the "godfathers" (Mike D, Peter P., Jeff at HA, etc) chimed in on what they thought of the idea?

Lately I've been leaning toward a more incremental approach, though, you don't need to start with a full-on 'deep discharge'; rather, you can simply try to identify the lowest, most discharged tap -- and discharge the others to bring them closer to the lowest. That should free-up room at the top and allow the car to charge the pack more. If that doesn't help, one can then try something more radical...

This makes a LOT of logical sense, and it seems like a better way to do things. .

It would be neat to see a grid charger/discharger that functions at the tap level, but I bet it would be expensive. Maybe it's not possible, because everything is in series? Would a typical grid charger work on a lower level such as taps or even sticks? It would be convenient to just make another adapter for someone's existing grid charger if they wanted to do some work on the stick level. I'm building a new grid charger right now anyway, it would be a good time to consider additions/alterations to work on a lower level if it becomes necessary.

 

[eq1]

...I'm going to look further into this, I found your posts about a year ago where you re-posted photos and I'll be doing more reading today. I certainly would appreciate any additional pointers that might not already be out there...

No major pointers -- except for what I said earlier, that I've shifted to an incremental approach, etc. You should generally ignore specific voltage recommendations in any of those posts. I think it's better to handle things on a case-by-case basis than to suggest a one-size fits all regime.

These days I usually suggest trying to identify the lowest tap and then just bring down the others before doing anything else. In your case, I think I'd suggest 48 hours per set of 5 taps, excluding whichever one we think is the lowest/causing neg recal. To identify that one, you'll probably have to measure taps, then put a discharge load on the pack (light bulb), then measure again: the one that drops the most and/or has the lowest voltage should be the one causing the neg recal.

In its revised form, this method is pretty straight forward.

Having said that, I generally don't think this will 'fix' most if any packs. I see it more as a way of avoiding blind, risky full pack operations - at minimum pulling taps more into balance before doing anything full pack, for instance. In your case, you probably got at least one faster self discharge cell - so it's pretty unlikely that just some 'minor' rebalance will do anything that lasts... But the procedures for 'minor rebalance' vs. say an 'ultra deep discharge' are basically the same, just that one lasts a lot longer, so when you grasp and try the 'minor rebalance' you're getting a handle on the state/condition of your pack, for one, plus you're learning how to do anything more, like the 'tap UDD'...

Have the "godfathers" (Mike D, Peter P., Jeff at HA, etc) chimed in on what they thought of the idea?

Not really. I'm not really sure why others haven't caught on to the utility of discharging through the taps. Part of it might be different conceptions of 'theory' underlying successful pack reconditioning, i.e. they probably don't think very low current deep/super deep/ultra deep discharge helps much if at all in the first place, so extending that to taps wouldn't make sense.

On the other hand, they do generally do deep to super deep full pack at say 300-ish mA; I think they think that's good enough, if the pack doesn't revive, so be it, it wasn't good enough to start with... And then, I imagine some of the more seasoned veterans would simply think it's too 'fiddly' - too much trouble, too hard to deal with, takes too long, poses dangers to the lay person fiddling around high voltage, etc.

I think that's probably the main thing: people who come around here looking for help to 'fix' their packs can barely deal with grid charging, let alone discharging and grid charging. Throw in tap discharging and it's just too much to explain and too much for them to handle, in most cases probably simply because people don't have the time to fool around with this stuff...

It would be neat to see a grid charger/discharger that functions at the tap level, but I bet it would be expensive. Maybe it's not possible, because everything is in series?

I don't think charging through the taps is possible, or maybe it is, but it'd have to be like a <5mA current or something like that. The resistance of the PTCs is too high. For example, at only a 0.1A charge, the ~380 ohms per tap resistance would cause a voltage increase of 38V. The taps would need to charge at up to around 18V so your charger would have to put out 38 + 18 = 56V, just to get that 0.1A current to flow (I think this is the way it works). Meantime, the PTCs are heating up and the resistance is increasing even more... Maybe you could lower the current to 0.01A, or 10mA, but then we're talking tiny current so by then it's virtually pointless...

Plus, no one cares about this stuff any longer. A few people here and there want to try to fix their packs, the rest buy a replacement pack - or a different car.

I've thought about trying to make something for the discharge aspect, like a tap voltage reader plus tap discharge-balancer. Even thought about something like that as a perpetual, always-on type device. But I'm not really up to speed with the electronics and all that, I generally don't like fiddling with electronics...

Would a typical grid charger work on a lower level such as taps or even sticks?...

Not on the taps, for reasons mentioned above. Most grid chargers have a usable voltage range from like 80V to 200V, so they wouldn't work on anything with a lower voltage, like sticks. You buy a 'hobby charger' to work with sticks. But, most of us find it pretty pointless,* in light of other aggregate methods that seem to do the job.

I still occasionally use a hobby device to test sticks and cells, mostly as a check-point to figure out just where the sticks and cells in my car are really at. It's hard to know the actual condition/charge state unless you pull them out of the car and work with them on the bench, including working with cells... My 'tap' methods are actually supposed to be a middle ground - between that 'bench work' and working with full packs in the car. Bench work is way too cumbersome,* full pack work is too sloppy, tap level happy median...

* IF one has a genuine interest in batteries in general, then "bench work" - buying a hobby charger and working with sticks and cells - isn't pointless or too cumbersome. It can be quite interesting and educational. It's just not recommended for people who 'want to get the job done' and get on with their lives...

 

[blackcloud77]

Great, thanks for the detailed explanations. This is all good stuff. Primarily just filling time until my grid charger parts show up on Tuesday, so maybe in the meantime I can disconnect the battery and BCM and get some tap discharge going.

I have seen a number of videos of people using those hobby chargers to work with sticks but the only things I've happened to read on the forums about it seemed to be negative. Maybe it was like you say, its seen as a lot of extra time and effort for not much benefit. But...in my case where I've already removed and reinstalled the pack once, done somewhat of a load test and have some data that looks like most of the sticks are servicable...do you think it would make sense to remove what looks like the problem children, shape them up with a hobby charger and stick them back in?

At this point, I can't bring myself to spend $2400 on a battery pack that I can only expect to get 5 years out of, and the car starting to look pretty rough isn't encouraging me dump that kind of cash in it either. Economically it would still be better than buying another car but if economics are the priority then I'd bypass the IMA and forget about all this foolishness. I guess what I'm rambling about is that I don't cherish having to do a lot of work, but I do want the car to work as designed if that can be done for reasonable sums of money. At the end of the day if I'm being totally honest, I'm probably going to do whatever I need to do to get this pack going again, and I probably won't be buying a replacement pack.

I was bouncing around and saw your other posts about the motor mount too, I think that's one more thing I'm going to have to address. I've got a pretty good shudder taking off in 1st gear. I have been hoping that wasn't the clutch going out but the symptoms seem very similar to the motor mount issue.. Not to get off on another topic, but it looks like you got your hands in just about every part of this car.

 

[eq1]

...Primarily just filling time until my grid charger parts show up on Tuesday, so maybe in the meantime I can disconnect the battery and BCM and get some tap discharge going.

Sounds like a good idea. Take some unloaded and loaded tap voltages and report back. Hopefully we'll be able to spot something.

I have seen a number of videos of people using those hobby chargers to work with sticks but the only things I've happened to read on the forums about it seemed to be negative...do you think it would make sense to remove what looks like the problem children, shape them up with a hobby charger and stick them back in?

Most likely the stuff you see on youtube is people using an old, out-dated and stupid method - cycling sticks. That was the first thing I tried back in 2012. Grid charging hadn't become too well established yet, no one was doing any discharging... Eventually those became the more feasible methods and not many people stuck with the hobby charger stuff. Personally, I stuck with it, tried various things, as well as full pack methods, and now I am where I am...

Probably not worth breaking down your pack and working with sticks at this juncture... 'Working with sticks' basically IS finding the "problem children." And it generally comes down to working with cells in some way. Slippery slope.

What you'd have to do is basically break the pack apart, discharge a full stick then discharge the residual on each cell of that stick. That will give you the out-of-car capacity of all your cells and suggest which ones are bad (i.e. the ones that don't discharge much). Then you'd do 'some kind' of conditioning routine, cycle, and testing. And then you'd have to charge each stick and let them sit for a long time (probably at least 2 weeks) to measure self discharge. Et al. Anything less than this makes stick work pointless... The self discharge test is particularly important - but it's often skipped or not done well enough.

There's other ways to skin this cat, but in general, it's a lot of work if you want to actually know you'll have a good pack in the end. Shortcuts mean you're just guessing and getting lucky -- or doomed to failure sooner rather than later...

At this point, I can't bring myself to spend $2400 on a battery pack that I can only expect to get 5 years out of.... Economically it would still be better than buying another car but if economics are the priority then I'd bypass the IMA and forget about all this foolishness....I'm probably going to do whatever I need to do to get this pack going again, and I probably won't be buying a replacement pack.

You can get replacements cheaper than $2400. But, I can see how the economics don't wash. If you can't get your pack going within a reasonable amount of input labor, then I'd suggest you look into the 'LTO' mod - get an LTO replacement pack. Lots of threads these days. Maybe about $1000 plus a week of labor and research...

Either that or bypass. If I were someone who had no interest in the work or ability to do it, then I'd just remove the whole IMA. You don't really miss much without it, frankly, especially if you remove the pack, get rid of that weight. I'd like to get another Insight at some point and make it gas-only - remove pack/IMA stuff, install a Civic or maybe Honda Fit transmission (better gearing). I don't really miss the power when my IMA is disabled - if I keep engine speed high. The car feels pretty spry to me. It's just the gearing (and ignition tuning) that screws it up, at low RPM...

There's quite a bit around here about these options. IC user "Ecky" I think has done a full gas-only modded car, with different transmission, plus fixed-up hatch area. Maybe user "Bulldog" as well...

Not to get off on another topic, but it looks like you got your hands in just about every part of this car.

Not all of it, but quite a bit. I've hardly touched the engine, just minor maintenance stuff.